JP2000211015A - Equipment for manufacturing resin pipes of different diameters - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a nose part in a precursor molding process based on extrusion molding by providing an outside diameter calibration sizer whose inside diameter differs in large and small sizes at the front of an extruder for extruding tubularly a thermoplastic synthetic resin to control the outer surface of the extruded tubular body while it is sucked under vacuum condition. SOLUTION: A molten tubular body 3 extruded from a die 1 is at first successively passed through the insides of outside diameter calibration sizers 5 and 7 for a small diameter part and a large diameter part of vacuum rooms 4 and 6 filled with water and is held by a take-off machine 8. Then, the vacuum room 6 on downstream side is made vacuum and the molten tubular body 3 is brought into contact with the sizer 7 and it is cooled and solidified to form a large diameter part 9A. Successively, when the large diameter part 9A with a specified length is obtd., the vacuum room 4 on upstream side is made vacuum to form a small diameter part 9B. In addition, being timed to formation of the small diameter part 9B, pressure reduction in the vacuum room 6 is stopped to complete formation of the large diameter part 9A. Thereafter, under this condition as it is, molding of the small diameter part 9B is continued until the small diameter part 9B reaches a specified length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a resin pipe having a different diameter. Specifically, a large-diameter portion and a small-diameter portion suitable for use in producing a drawn pipe having excellent strength by solid-phase drawing using a thermoplastic resin tubular molded body are made of a resin-made different-diameter pipe. It relates to a manufacturing device.

[0002]

2. Description of the Related Art JP-B-4-55379, JP-A-10-2
According to the solid-state drawing method of a resin tubular molded product which is drawn through an outer diameter regulating die and an inner diameter regulating former at the same time as shown in 25982 and the like and stretched by a tensile force, a resin pipe biaxially stretched in an axial direction and a circumferential direction. Can be produced, and a high-performance tube with improved mechanical properties can be obtained.

An example of a method for manufacturing a biaxially stretched resin tube will be specifically described. For example, as shown in FIG. 6, using a heating device 16, a thermoplastic synthetic resin precursor 17 is heated to a predetermined temperature, and immediately after passing through an internal foamer 18 and a die 19, the refrigerant 20 is filled. This is a method of passing through the cooling tank 21. That is, the pipe (tube) 2 immediately after being biaxially stretched by the die 19 and the former 18.
2 is immediately cooled in the cooling tank 21 without cooling once.

The cooling bath 21 and the internal former 18 are arranged as shown in FIG.
It is preferable that the internal former 18 enters near the end of the cooling bath 21 and overlaps as described above, but the cooling former 21 may enter the cooling bath 21 immediately after passing through the internal former 18. In the drawing, reference numeral 23 denotes a sealing material for maintaining watertightness between the cooling water and the pipe 22. As the cooling means, for example, a means for cooling by bringing a liquid such as water or a gas such as air into contact with the stretched hollow tubular stretched molded body 22 from the outside may be used. When a liquid is used for cooling, a hollow tubular stretched molded body 22 stretched in a state where the coolant 20 is filled in a tank 21 provided with an inlet and an outlet provided with a mechanism for preventing the coolant from leaking by a seal packing 23 or the like is provided. It can be cooled by passing it through or spraying a coolant on the surface of the stretched stretched body 22.

[0005] The cooling medium may use both gas and liquid. It is also possible to cool by passing a stretched hollow workpiece through a cylinder made of rubber, metal, or the like through which a liquid is passed. In addition, a hollow tubular stretch-formed body 22 made of a thermoplastic synthetic resin is formed by, for example, forming a stretched thermoplastic synthetic resin pipe obtained by molding without using the cooling tank 21 in the apparatus shown in FIG. It can also be obtained by heat-treating the thermoplastic resin constituting the body at a temperature from the melting point of -10 ° C to -25 ° C.

When heat treatment is performed in an oven, the treatment time is as follows:
The time is from 10 minutes to 60 minutes, preferably from 30 minutes to 60 minutes. As a heating oven, a contact type or a non-contact type, such as a far-infrared heating type, a hot air circulation type, a heating medium type such as an oil tank or steam, and the like can be appropriately used depending on purposes. Stretched molded body 22
Is manufactured by the method as described above, but in the case of the above-described method, the precursor (small diameter, thick resin tube) is used at the time of starting the process.
An operation of covering one end of 17 with an inner diameter regulating former 18 having a maximum outer diameter considerably larger than the inner diameter of the precursor is indispensable.

[0007] Since the maximum outer diameter of the inner diameter regulating former 18 is usually much larger than the inner diameter of the precursor 17 in terms of system, this operation is considerably difficult. Conventionally, one end of the precursor 17 is heated and pushed with a diameter-expanding jig or the like to form an enlarged-diameter portion called a nose, which is covered with the inner-diameter regulating former 18, or by cutting the inner diameter of the precursor 17. A method of increasing the size and covering the former 18 with the inner diameter regulating former 18 is used.

[0008]

According to the above-mentioned method, the above-mentioned solid-phase drawing can be certainly started, but there are some problems in using it for industrial production.
First, a significant amount of raw material is cut or lost during machining of this end. Second, the processing requires time and heating energy, resulting in poor production efficiency.

Third, the outer diameter expansion ratio in the case of solid phase drawing using a precursor whose end enlarged diameter portion is formed by post-processing as described above is limited to about 1.2 times. Exceeding the value will cause material destruction. For use as a pressure-resistant tube, a high internal pressure strength is required, and for that purpose, a draw ratio of 1.3 times or more in outer diameter expansion ratio is required. In order to solve such a problem, it is preferable that a nose portion having an inner diameter larger than the outer diameter of the former used in the solid phase stretching during the molding of the hollow precursor can be formed.

According to a molding method using a mold such as injection molding or blow molding, the formation of a nose portion is relatively easy.
On the other hand, since a metal mold becomes extremely large in order to form a thick tubular body having a length of several meters, an extremely large molding machine is required, which is impractical. Further, in this case, the solid phase stretching step cannot be performed continuously after the precursor molding step. Therefore, an apparatus capable of forming a nose portion in a precursor molding process based on extrusion molding has been required.

[0011]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the problem at the time of starting the resin tubular body in the solid-phase stretching, and as a result, a special structure is provided in front of the extruder for extruding the tubular body. It has been found that the problem can be solved by providing an outer diameter regulating and shaping device, and the present invention has been completed. That is, the gist of the present invention is to provide, in front of an extruder for extruding a thermoplastic synthetic resin into a tubular shape, an outer diameter regulating sizer for regulating the outer surface of the extruded tubular body while sucking the same under reduced pressure. The diameter-regulating sizer is a two-stage sizer having a small diameter on the upstream side and a large diameter on the downstream side and having different inner diameters.

A procedure for manufacturing a resin-made different-diameter pipe using the apparatus of the present invention will be described with reference to the process charts shown in FIGS. 1, 2 and 3. In the figure, 1 is a die, 2 is a mandrel, 3 is a molten tubular body, 4 is a first decompression chamber, 5 is an outer diameter regulating sizer for a small diameter portion,
6 is a second decompression chamber, 7 is an outer diameter regulating sizer for a large diameter portion, 8 is a take-off machine, 9A is a large diameter portion, 9B is a small diameter portion, 10 is a reheating tank, 11 is a wire, 12 is an inner diameter regulating former, 13 is an outer diameter regulating die, 14 is a cooling means, and 15 is a pulling means.

As the thermoplastic synthetic resin for forming the different-diameter tube by the production apparatus of the present invention, a crystalline thermoplastic synthetic resin is preferably used. Examples include unsubstituted or halogen-substituted vinyl polymers, unsubstituted or hydroxy-substituted polyesters, polyamides, polyetherketones, aliphatic polyketones, polyoxymethylene, and the like.

More preferably, a linear polymer of ethylene or propylene or a linear copolymer of ethylene or propylene with at least one other comonomer, polyvinylidene fluoride, polyoxymethylene and at least one other of these. And a copolymer with a comonomer. Particularly preferred are linear polymers of ethylene or propylene or linear copolymers of these with at least one comonomer.

These thermoplastic resins may contain fibrous fillers such as glass and carbon, plate-like fillers such as talc and mica, or granular fillers such as calcium carbonate, barium sulfate and carbon. First, the extruder (not shown) is started, and the molten tubular body 3 is constantly extruded from the die 1.

The tip of the outer diameter regulating sizer 5 for the small diameter portion of the first decompression chamber 4 filled with water is passed through the tip thereof, and then the outer diameter regulation sizer for the large diameter portion of the second decompression chamber 6 filled with water. 7
Is passed through, and is gripped by the take-up machine 8 to operate the take-up machine. In this state, the second decompression chamber 6 on the downstream side is decompressed, and the molten tubular body 3 is brought into contact with the sizer 7 to be cooled and solidified to form the large-diameter portion 9.
Form A. (Fig. 1)

The decompression chamber 6 comprises a sizer 7 made of a cylindrical porous plate and an outer box. The outer box is provided with a supply hole and a suction hole for cooling water. Therefore, when the gas (air, water vapor) in the decompression chamber 6 is sucked from the suction hole while supplying the cooling water to keep the water surface lower than the suction hole, the cooling water is in a reduced pressure state. Although depending on the degree of pressure reduction, a large amount of steam is usually generated from the cooling water. That is, the temperature of the cooling water becomes close to the boiling point due to the reduced pressure, and a large amount of steam is generated.

When the suction of water vapor is further continued and stabilized, the molten tubular body 3 is in a state of being adsorbed on the inner surface of the sizer 7.
Normally, the suction is performed so that the pressure in the decompression chamber 6 becomes about 0.9 to 0.1 atm. At this time, contact with the sizer 7 is stabilized by supplying a gas for diameter expansion (stabilization) such as air from the mandrel 2 into the melting tube. At this time, the first decompression chamber 4 does not operate, and a large diameter portion is formed.

When a large-diameter portion 9A having a predetermined length is obtained, the first decompression chamber 4 is operated to reduce the pressure, thereby forming a small-diameter portion 9B. The formation of the large-diameter portion 9A is completed by synchronizing the timing with the formation of the small-diameter portion 9B and stopping the decompression of the second decompression chamber 6. (FIG. 2) In this state, molding of the small-diameter portion 9B is continued until the small-diameter portion 9B has a predetermined length. (Fig. 3)

The different diameter pipe in the case of batch production of the solid phase stretching is obtained by cutting the different diameter pipe at the time when the small diameter portion is produced at a predetermined length. It is necessary to cut and remove the irregular-shaped portion of the tip formed at the time of startup, but after startup, the large-diameter portion 9A is formed of a continuous pipe by alternately performing the depressurizing operations of the decompression chambers 4 and 6. It is possible to obtain different diameter pipes formed at a plurality of places in the middle. By cutting at the cutting position C shown in FIG. 4, a different-diameter tube for batch stretching can be easily obtained without waste.

Referring to FIG. 5, a method of continuously performing a solid phase stretching step following the step of extruding a deformed pipe using the apparatus of the present invention will be described. First, a large-diameter portion is formed at the tip according to the above-described method, and when the large-diameter portion 9A passes through the take-off machine 8 while extruding a thermoplastic resin tube to which the small-diameter portion is connected later, the irregular-shaped portion at the tip is cut.

The inner diameter regulating former 1 which is guided into the small diameter portion of the reheating tank 10 and connected to the wire 11 as it is.
2 and pass through the outer diameter regulating die 13. In order for this operation to be performed smoothly, it is necessary that the outer diameter of the large diameter portion 9A be smaller than the inner diameter of the outer diameter regulating die 13 and that the inner diameter of the large diameter portion 9A be larger than the outer diameter of the inner diameter regulating former 12. Need to be designed.

Next, the production of the small diameter portion is continued and the large diameter portion 9A is formed.
Through the cooling means 14 and reach the pulling means 15,
The pulling means is started while being synchronized with the speed of the take-off machine 8.
(FIG. 5 shows this state, the small diameter portion has not yet reached the inner diameter regulating former 12) In this state, the temperature of the reheating tank 10 is raised to a predetermined temperature, and the small diameter portion 9B that has entered the reheating tank 10 is sufficiently removed. Heat to

When the small-diameter portion 9B starts to ride on the former 12, the speed of the pulling means 15 is gradually increased while finely adjusting the positional relationship between the former 12 and the die 13, and attention is paid so that stretching is induced and the balance is not broken. The state is gradually shifted to a predetermined steady operation condition. In this way,
A predetermined resin-made tubular stretch-formed body is formed. The tension means has a structure in which the end of the hollow precursor is gripped and mechanically pulled, and specifically, a mechanical, hydraulic, pneumatic or other hollow precursor gripping mechanism, a wire type, and a chain. A device connected to a pulling mechanism such as a rack and pinion type can be used.

Alternatively, stretching can also be performed by continuously applying a tensile force to the hollow workpiece using a pulling machine such as an endless belt type pipe. Alternatively, stretching can also be performed by continuously applying a tensile force to the hollow precursor using a device that enables continuous tension by combining two motor winches.
At this time, the stretching ratio is controlled by the speed ratio between the take-up machine 8 and the pulling means 15.

[0026]

As described above, according to the apparatus of the present invention, the nose having an inner diameter larger than the outer diameter of the former used in the solid-phase drawing is formed by extrusion at the same time as the molding of the hollow precursor. It can be formed in a process.

[Brief description of the drawings]

FIG. 1 is a process diagram for manufacturing a resin-made different-diameter pipe using an example of the apparatus of the present invention.

FIG. 2 is a process chart for manufacturing a resin-made different-diameter pipe using an example of the apparatus of the present invention.

FIG. 3 is a process chart for manufacturing a resin-made different-diameter pipe using an example of the apparatus of the present invention.

FIG. 4 is a longitudinal sectional view of an example of a resin-made different diameter pipe.

FIG. 5 is an explanatory view showing an example of a case where a solid phase drawing step is continuously performed following the extrusion forming step of a deformed pipe.

FIG. 6 is an explanatory diagram showing an example of a case where a solid phase stretching step is performed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 die 2 mandrel 3 molten tubular body 4 first decompression chamber 5 outer diameter regulating sizer for small diameter section 6 second decompression chamber 7 outer diameter regulating sizer for large diameter section 8 take-off machine 9A large diameter section 9B small diameter section 10 reheating tank 11 Wire 12 Inner diameter regulating former 13 Outer diameter regulating die 14 Cooling means 15 Pulling means

Continued on the front page F term (reference) 4F207 AA04 AA11 AB16 AB25 AG09 AM28 KA01 KA17 KK76 KK90 KL74

Claims (1)

[Claims] An outer diameter regulating sizer is provided in front of an extruder for extruding a thermoplastic synthetic resin into a tubular shape, the outer diameter regulating sizer regulating the outer surface of the extruded tubular body while sucking it under reduced pressure. Is a two-stage sizer having a different diameter with a small diameter on the upstream side and a large diameter on the downstream side.