JP2001047295A - Die for pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily form a resin pipe narrow in the temperature range changing from a molten condition to a solid condition at a high speed by directly connecting a resin development path of a body to a sizer to form a resin distribution path, forming a surface of the sizer of a heat resistant lubricant, and feeding the lubricant thereto. SOLUTION: A small circular opening part 8 is formed so as to form an annular outlet 9 by a mandrel 2 at one end part of a base body 3, and directly connected to a sizer 7. A molten resin advances in a resin development path, and further passes through a molten resin regulation part 2d in a cylindrical shape, flows through a resin distribution path, flows out of the outlet 9 and passes through the sizer 7 and is solidified. A stock material of the heat resistant lubricant to form an inner circumferential surface of an outer sizer 17 and an outer circumferential surface of an inner sizer 24 is preferably, for example, polyfluoroethylene resin. The lubricant is fed between the inner surface of the sizer 17 and the outer surface of the resin, and between the outer surface of the sizer 24 and the inner surface of the resin to smoothly extrude the solidified resin by the discharge pressure of the succeeding molten resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe die, and more particularly, to a pipe capable of easily producing a polyethylene terephthalate resin pipe which has been difficult to form by, for example, melt extrusion, at a high production rate. For die.

[0002]

2. Description of the Related Art Pipes are manufactured from general-purpose resins such as polyethylene and polyvinyl chloride by combining a pipe die for extruding a molten resin into a ring and a sizer for molding a high-temperature solidified resin extruded in a ring. The technology to do
well known. In this technique, the pipe die and the sizer are not directly connected, and the sizer is arranged at a predetermined distance from the discharge port of the pipe die. Then, the extruded material in a semi-solid state, which is lower than the melting temperature but high in temperature but discharged from the pipe die, is introduced into a sizer, and the extruded material is shaped and gradually reduced. I'm cold.

It is conceivable that such a pipe manufacturing technique is diverted to polyethylene terephthalate (hereinafter referred to as PET) to manufacture a PET pipe. In reality, however, a PET pipe can be manufactured. Did not.

The reason is as follows. Amorphous polymers, such as polyvinyl chloride resin and polystyrene resin, and general-purpose crystalline resins, such as polyethylene and polypropylene, have a wide temperature range in which the polymer transitions from a melt or plasticized state to a solid phase. Since the viscosity in the die is high, cooling and solidification in the molding sizing die (sizer) can be easily performed. In contrast, PET
When extruding, PE flowing through the die of the extruder
The melt of T has a viscosity much lower than that of the amorphous polymer and the general-purpose crystalline resin and is in a syrup state. Therefore, PET cannot be extruded in a semi-molten state from the discharge port of the die, and the melt of PET flows down from the discharge port and cannot be guided to the sizer.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to
It is an object of the present invention to provide a pipe die capable of easily manufacturing a resin pipe having a narrow temperature range in which a temperature changes from a molten state to a solid state, which is exemplified by ET, at a high manufacturing speed.

[0006]

A means for solving the above-mentioned problem is that an outer sizer and an inner sizer form a cylindrical resin flow path, and the outer sizer is a part of the resin flow path. The inner surface is formed of a heat-resistant lubricant, and the outer surface of the inner sizer that is a part of the resin flow passage is provided with a sizer formed of the heat-resistant lubricant, and a resin introduction portion into which the molten resin is introduced, A resin development path formed so that the resin injected from the resin introduction portion expands in a cylindrical shape, and a die capable of directly connecting the sizer so that the resin development path and the resin flow path coincide and communicate with each other. A main body, first lubricant supply means for supplying a lubricant to an inner peripheral surface of an outer sizer forming a part of the resin flow passage, and lubrication of an outer peripheral surface of an inner sizer forming a part of the resin flow passage; Agent A pipe die, characterized by comprising a Kyusuru second lubricant supplying means.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A pipe die according to the present invention
It has a sizer, a die body, a first lubricant supply unit, and a second lubricant supply unit.

-Sizer-The sizer has a first function of circulating the cylindrical resin extruded from the die body and adjusting the shape of the resin.

In order to exert the above-mentioned unique function, the sizer has an outer sizer and an inner sizer. A resin flow passage is formed by the outer sizer and the inner sizer. The resin flow path is a cylindrical path through which the resin in a non-molten state flows. This resin flow passage may have any structure as long as it can be formed into a cylindrical shape by combining the outer sizer and the inner sizer, but usually has a cylindrical inner peripheral surface. The inner peripheral surface of the outer sizer and the outer peripheral surface of the inner sizer having a cylindrical outer peripheral surface can be formed so that a cross section orthogonal to the center axis is annular. The outer diameter of the resin flow passage having an annular cross section, that is, the inner peripheral diameter of the outsizer, and the inner diameter of the resin flow passage having an annular cross section, that is, the outer diameter of the inner sizer are the outer diameter of the resin pipe to be molded and It is determined according to the inner diameter. The length of the resin flow passage in the axial direction is determined according to the type of the resin, and when the resin is PET,
Usually 10 to 200 cm, preferably 20 to 80 c
m. When the axial length of the resin flow passage is within the above range, a tubular pipe is formed. When the resin is a resin other than PET, the appropriate axial length of the resin flow passage can be appropriately determined.

The outer sizer is formed in a tubular body having a cylindrical inner peripheral surface. The outer sizer may be a single long tubular body, or may be formed by connecting a plurality of short tubular bodies. It may be a single tubular body. The inner sizer is also formed in a tubular body having a cylindrical outer peripheral surface, but may be a single tubular body or a single tubular body formed by connecting a plurality of tubular bodies. It may be.

The inner peripheral surface of the outer sizer and the outer peripheral surface of the inner sizer are each made of a high-temperature resin such as P
It is made of a heat-resistant lubricating material which is not deteriorated by ET and has a small frictional resistance with a solidified resin such as PET. By forming the inner circumferential surface of the outer sizer and the outer circumferential surface of the inner sizer with a heat-resistant lubricant,
Resin present in the resin flow passage does not cause a flow obstruction due to frictional resistance on the inner peripheral surface and the outer peripheral surface,
Distribute smoothly.

As a material for forming the heat-resistant lubricating material, for example, carbon, polytetrafluoroethylene resin, silicone resin and the like are suitable, and preferably polytetrafluoroethylene resin can be mentioned. This polytetrafluoroethylene resin has good heat resistance and lubricity with respect to the high-temperature resin passing through the resin flow passage, and does not damage the resin surface. The material of the heat-resistant lubricating material forming the inner peripheral surface of the outer sizer and the material of the heat-resistant lubricating material forming the outer peripheral surface of the inner sizer may be of the same type or different types. Is also good.

The heat-resistant lubricant forming the inner peripheral surface of the outer sizer and the outer peripheral surface of the inner sizer may be present as a coating film. When the heat-resistant lubricant is carbon, a carbon tube obtained by cutting a round bar of carbon is loaded on the inner peripheral surface of the outer sizer, and the carbon tube is loaded on the outer surface of the inner sizer. Is also good.

Preferably, each of the outer sizer and the inner sizer has a temperature adjusting means. With the provision of the temperature adjusting means, the high-temperature resin, for example, PET, which passes through the resin flow passage in the sizer is gradually cooled and its shape is adjusted.

As the temperature adjusting means provided in the outer sizer, that is, the external temperature adjusting means, there can be mentioned a heat medium circulating means provided with a heat medium flow passage provided in a portion adjacent to the inner surface of the outer sizer. The heat medium circulating means may adopt a device configuration that realizes a temperature gradient such that the temperature of heating by the heat medium decreases as the distance from the portion near the die body to the position away from the die body increases.

As the temperature adjusting means provided in the inner sizer, that is, the internal temperature adjusting means, a heat medium introducing means inserted into the inner sizer to introduce a heat medium into the inner sizer, and a heat medium in the inner sizer to the outside. It can be formed by the heat medium deriving means for deriving. Also,
A heat medium is introduced into the inner sizer such that a temperature gradient is formed in a direction away from a side closer to the die body of the inner sizer, and then an internal temperature adjusting means formed to discharge the heat medium in the inner sizer. You can also mention.

The sizer is mounted on the die body while being directly connected to the die body. That is, the sizer is coupled to the die body such that the annular discharge port in the die body directly communicates with the cylindrical resin flow passage of the sizer.
In other words, the sizer is coupled to the die body such that the resin discharged from the annular discharge port in the die body immediately enters the resin flow passage in the sizer.

The fact that the sizer is directly connected to the die body is one of the important matters of the present invention. If the die body and the sizer are separated from each other, even if a resin having a narrow temperature range for changing from a molten state to a solid state, such as PET, is discharged from the discharge port of the die body, the resin is not solidified from the discharge port. If the resin flows down, the resin cannot be introduced into the resin flow passage of the sizer, and therefore, a pipe of the resin cannot be manufactured.

-Die body- The die body has a function of introducing a resin, such as PET, having a narrow temperature range in which the temperature changes from a molten state to a solid state in a molten state, and discharging the resin in a cylindrical shape.

Therefore, the die body has a resin introduction portion for receiving the resin in a molten state, and a resin development path for developing the molten resin into a cylindrical shape.

This resin developing path is connected to an annular discharge port for discharging the molten resin. The resin introduction portion may be a single location or a plurality of locations. That is, a resin introduction section may be formed in the resin development path so as to inject a molten resin from one resin introduction section,
The molten resin may be injected from a plurality of, for example, two resin introduction portions into the resin development path.

In the case where the number of the resin introduction portions is one, the resin development path includes a tubular resin flow passage formed in a tubular shape communicating with the annular discharge port, and a flow of the molten resin introduced from the resin introduction portion. And a resin guide path for guiding the divided resin flows to the cylindrical resin flow path. When there are a plurality of resin introduction paths, a plurality of resin guide paths for guiding the molten resin introduced from each of the resin introduction paths to the cylindrical resin flow path are required.

The die body is so arranged that the resin is discharged from the discharge port in a molten state and the molten state is maintained until the resin introduced from the resin introduction section is discharged from the discharge port. It is preferable to attach a heating means for heating the body. As a heating means, an electric heater or the like is convenient. The temperature for heating by the heating means is appropriately determined depending on the type of the resin.

-First Lubricant Supply Means- The first lubricant supply means has a function of supplying a lubricant to the inner surface of the outer sizer which forms the resin flow passage.

The lubricant supply position on the inner surface of the outer sizer may be any point or site where the resin starts to solidify in the resin flow passage. Usually, a portion directly connected to the sizer and the die body, in other words, the die body The joint between the discharge port at the end and the opening at the end of the resin flow path in the sizer is the lubricant supply position. The lubricant supply position may be a portion or a point where the resin starts to solidify in the resin flow passage in the sizer, or may be near the discharge port in the die body.

The supply of the lubricant is preferably performed so that the lubricant supply position is annular. If the lubricant is supplied to the resin flow passage at a spot, good lubrication over the entire circumference of the resin flow passage may not be achieved. Therefore,
A preferred supply port for the lubricant is formed in an annular shape.

The lubricant may be any substance that can provide lubricity between the inner peripheral surface of the outer sizer and the solidified resin, such as metal soap such as calcium stearate, hydrocarbon lubricant such as liquid paraffin, and sizer. Temperature in the resin flow passage at 100 to 150 ° C.
And the like, which can be in a fluidized state, for example, a molten state in the above temperature range.

-Second lubricant supply means- The second lubricant supply means has a function of supplying a lubricant to an outer surface of the inner sizer which forms a resin flow passage.

The lubricant supply position on the outer surface of the inner sizer may be any point or site where the resin starts to solidify in the resin flow passage. Usually, a portion directly connected to the sizer and the die body, in other words, the die body The joint between the discharge port at the end and the opening at the end of the resin flow path in the sizer is the lubricant supply position. The lubricant supply position may be a portion or point in the resin flow passage in the sizer where the resin starts to solidify. The preferred lubricant supply location is the first
The position or site corresponds to the position or site where the lubricant is supplied by the lubricant supply means.

The supply of the lubricant is preferably performed so that the lubricant supply position is annular. If the lubricant is supplied to the resin flow passage at a spot, good lubrication over the entire circumference of the resin flow passage may not be achieved. Therefore,
A preferred supply port for the lubricant is formed in an annular shape.

As the lubricant, the same kind of lubricant as that used in the first lubricant supply means can be used.
The same or different lubricant as employed in the first lubricant supply means can be used.

Operation of Pipe Die A pipe is formed using the pipe die as follows.

The molten resin is supplied from the extruder to the die body. The molten resin supplied to the die body is developed into a cylindrical shape. The molten resin developed in a cylindrical shape is supplied to a sizer directly connected to the die body. The resin supplied to the sizer solidifies. The resin solidified in a cylindrical shape receives the discharge pressure of the molten resin. In the resin flow passage in the sizer, the inner peripheral surface of the outer sizer and the outer peripheral surface of the inner sizer are formed of a heat-resistant lubricant, and a first lubricant supply means is provided between the inner peripheral surface of the outer sizer and the solidified resin. The lubricant is supplied by the second lubricant supply means between the outer peripheral surface of the inner sizer and the solidified resin, so that the resin is solidified in the resin flow passage in the sizer. The solidified resin moves smoothly in the resin flow passage, and the solidified pipe is discharged from the outlet of the sizer.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example of a pipe die according to the present invention will be described with reference to the drawings. It goes without saying that the present invention is not limited to this specific example.

FIG. 1 is a schematic explanatory view showing a die body directly connected to a sizer with a part thereof cut away, and FIG. 2 is a sectional view showing the sizer.

As shown in FIG. 1, the die body 1 has a mandrel 2, a base 3 on which the mandrel 2 is loaded, a fixing ring 4 and a fixing member 5 for fixing the loaded mandrel 2.

The base 3 is provided with a mounting through hole 6 penetrating from one end to the other end. More specifically, the substrate 3
At one end, i.e., one end directly connected to the sizer 7, with the mandrel 2, which will be described later, so as to form an annular discharge port 9 when viewed from the center axis direction, so that the small circular opening 8 is formed.
Is formed at the other end of the base 3, and a large circular opening 10 having a diameter larger than the small circular opening 8 for inserting the mandrel 2 is formed.

The circular small opening 8 and the circular large opening 1
0 communicates within the base 3 to form the mounting through hole 6. In the mounting through-hole 6, from the small circular opening 8 toward the back to the center of the mounting through-hole 6,
A cylindrical inner peripheral surface 11 having the same diameter as the small circular opening 8 is formed. The mounting through hole 6 has a conical inner peripheral surface from the large circular opening 10 to the end of the cylindrical inner peripheral surface 11, and serves as a mandrel mounting hole 12 for mounting and fixing the mandrel 2. .

On the side surface of the base 3, there is provided a resin introduction hole 14 for receiving the molten resin and guiding the resin to a resin introduction portion 13 described later.

In this embodiment, the guide member mounting portion 16 for mounting the guide member 15 for guiding the molten resin extruded from the die of the extruder to the resin introduction hole 14 is provided.
Provided. The structure of the guide member mounting portion 16 is not particularly limited as long as the guide member 15 is connected to the base 3 and the molten resin can be guided to the resin introduction hole 14 without solidifying.

The base 3 has an outer lubricant injection hole 18 for injecting a lubricant (referred to as an outer lubricant for convenience) supplied between the inner peripheral surface of the outer sizer 17 and the outer surface of the solidified resin. And an annular outer lubricant reservoir 19 for storing the outer lubricant injected from the outer lubricant injection hole 18 and having an annular shape as viewed from the center axis. The outer lubricant injection hole 18 is connected to a pipe communicating with an outer lubricant storage tank (not shown).

The end face of one end of the base 3 is formed with an annular shallow concave surface as viewed from the center axis direction, where the small circular opening 8 is defined as the inner circumference. At the end face of the one end and the end face of the mounting ring, and the annular recessed face formed at the tip face of the base body 3, a very small gap communicating from the annular outer lubricant reservoir 19 to the small circular opening 8 is formed. This gap allows the outer lubricant to flow from the annular outer lubricant reservoir 19 into the small circular opening 8. This gap is referred to as the outer lubricant supply passage 20.

The outer lubricant supply passage 20 is provided between the outer peripheral surface of the cylindrical resin and the inner peripheral surface of the outer sizer 17 from the annular outer lubricant reservoir 19. What is necessary is just to be formed so that it may be supplied. Therefore, even if it is not an annular depression formed on the distal end surface of the base 3 as described above, it is even a gap formed between the end surface of one end of the outer sizer 17 and the end surface of the mounting ring and the distal end surface of the base 3. Then, various configurations and forms such as seams can be adopted.

In this embodiment, the first lubricant supply means comprises:
An outer lubricant reservoir (not shown), the outer lubricant injection hole 18, a pipe (not shown) connecting the outer lubricant reservoir and the outer lubricant injection hole 18, and an annular outer lubricant reservoir. A portion 19 and the outer lubricant supply passage 20 are formed.

The mandrel 2 penetrates from one end to the other end so that a long, straight tubular pipe (to be referred to as an internal heat medium supply pipe 21) for feeding the heat medium can be inserted and arranged. Through hole, tip 2a inserted into sizer 7, and resin passage 2b through which molten resin passes
Passage forming portion 2c having an outer peripheral surface serving as an inner surface of the resin passage
And a molten resin regulating portion 2d that regulates the flow of the supplied molten resin, a conical portion 2e that expands in a conical shape toward the rear end, and a rear end protruding portion 2f.

The inner diameter of the through-hole is determined by the internal heat medium supply pipe 21 for feeding an internal heat medium described later into the inner sizer 24.
Can be inserted, and the internal heat medium supply pipe 2
The inner heat medium is determined so as to have a gap between the outer periphery of the first heat transfer member 1 and the inner peripheral surface of the through hole 22 itself as a return path for discharging the internal heat medium to the outside. This gap is called a heat medium return channel 23.

At the end of the through hole 22, that is, at the end opposite to the end facing the inner sizer 24, that is, at the rear end, a heat medium discharge pipe for discharging the internal heat medium supply pipe 21 and the internal heat medium outside. It is formed so that a double pipe 25 having a path (this may be referred to as a return path) is mounted. In the double pipe 25, the flow path for feeding the heat medium to the inner sizer 24 may be referred to as "outgoing path".

The tip of the mandrel 2 is
Inner sizer 24 in sizer 7 directly connected to
The female screw formed on the inner peripheral surface of the concave portion 26 and the male screw formed on the outer periphery of the distal end portion of the mandrel 2 can be screwed together. Is formed. Therefore, the mandrel 2 and the inner sizer 24 are directly connected integrally with each other by screwing the male screw formed on the outer periphery of the distal end portion of the mandrel 2 and the female screw formed on the inner peripheral surface of the recess 26.

The resin passage forming section 2c has a cylindrical outer peripheral surface. A cylindrical resin passage 2b through which the resin flows is formed between the cylindrical outer peripheral surface and the inner peripheral surface of the through hole formed in the base 3, that is, the cylindrical inner peripheral surface. When the mandrel 2 is mounted on the base 3, the annular slit formed by the circular edge of the resin passage forming section 2 c and the edge of the small circular opening 8 of the base 3 provides: An outlet 9 for the molten resin is formed.

The end face of the resin passage forming portion 2c, that is, the end face toward the inner sizer 24, is the end face of the rear end of the inner sizer 24. The annular inner lubricant reservoir formed in an annular shape when viewed from the center axis direction. A very small gap is formed between the annular inner lubricant reservoir 27 and the outer peripheral surface of the inner sizer 24 so that the lubricant can flow. When viewed from the center axis direction, the gap has an annular shape in which the circular edge of the resin passage forming surface portion 2c is an outer circle and the edge of the annular inner lubricant reservoir 27 is an inner circle.
It is a very shallow pit. This shallow recess forms the inner lubricant supply passage 28.

In this embodiment, the inner lubricant supply passage 2
The inner lubricant supply passage 28 supplies an inner lubricant supply passage 28 between the inner surface of the cylindrical resin and the outer surface of the inner sizer 24 from the annular inner lubricant reservoir 27, although the recess 8 is formed by the shallow recessed portion. The inner lubricant supply passage 28 can be formed in various configurations or forms, such as seams, as long as possible.

The annular inner lubricant reservoir 27 communicates with an inner lubricant supply hole 29 formed in the mandrel 2.
The inner lubricant supply hole 29 opens at the rear end of the mandrel 2. A pipe communicating with an internal lubricant storage tank (not shown) is connected to the opening.

In this embodiment, the second lubricant supply means comprises:
Inner lubricant reservoir (not shown) and inner lubricant supply hole 29
And the inner lubricant reservoir and the inner lubricant supply hole 29.
(Not shown), an annular inner lubricant reservoir 27, and the inner lubricant supply passage 28.

The molten resin restricting portion 2d formed on the mandrel 2 is a portion for restricting the flow of the molten resin flowing through the resin developing path 30 described later so that the molten resin is formed in a completely cylindrical shape. is there. This molten resin regulating section 2d
Cylindrical inner peripheral surface 1 of resin passageway forming portion 2c and base 3
1 has a diameter larger than the diameter of the resin passage formation portion 2c so as to be smaller than the gap formed by the resin passage 1. Therefore, the flow velocity of the molten resin flowing from the resin developing path 30 is once reduced by the molten resin restricting section 2d, and the molten resin flows into the cylindrical space formed between the molten resin restricting section 2d and the resin developing path 30. After being sufficiently developed and then flowing through a small gap formed by the molten resin regulating portion 2d and the cylindrical inner peripheral surface 11 of the base 3, the cylindrical passage between the resin passage forming portion 2c and the base 3 is formed. Peripheral surface 11
Then, the molten resin flows through the cylindrical resin passage 2b formed by the steps (1) and (2) so as to be completely cylindrical.

In the conical portion 2e of the mandrel 2, a resin introduction portion 13 and a resin developing path 30 are formed on the conical surface. The resin introduction portion 13 is a groove provided on the conical surface of the mandrel 2 at a position corresponding to the resin introduction hole 14 when the mandrel 2 is mounted in the mandrel mounting hole 12. A resin development path 30 is formed continuously with the resin introduction section 13. The resin development path 30 has a function of developing the molten resin introduced from the resin introduction part 13 into a cylindrical shape. In this embodiment, when viewed from a direction perpendicular to the central axis, the resin developing path 30 is formed such that the resin developing path 30 is divided into left and right parts in the circumferential direction on the conical surface with respect to the resin introduction part 13. Are formed, and the flow path divided into right and left is changed at about 90 degrees from the resin introduction portion 13 about the central axis to a direction along the central axis, and the flow path is formed along the central axis. Are formed so that the width of the flow path is widened and finally, the flow paths divided into right and left merge. The resin development path 30 may be formed so as to have a function of guiding the molten resin to flow so that the molten resin introduced from the resin introduction unit 13 is developed in a cylindrical shape, and is limited to the form shown in FIG. Needless to say, it cannot be done.

The mandrel 2 mounted in the mandrel mounting hole 12 has a fixed member 5 into which the rear end protruding portion 2f is fitted.
Is fixed to the base 3 integrally with the base 3.

On the other hand, the sizer 7 includes an inner sizer 24 and an outer sizer 17, as shown in FIG.

The inner sizer 24 is a cylindrical tube having a closed bottom end and a second end attached to the front end of the mandrel 2. Inside the inner sizer 24 attached to the tip of the mandrel 2, an internal heat medium supply pipe 21 is provided.
Are inserted and arranged until the distal end opening is located near the distal end of the inner sizer 24. Therefore, the internal heat medium of a predetermined temperature supplied from the outward path in the double pipe 25 passes through the internal heat medium supply pipe 21 and is sent into the inner sizer 24 from the opening at the end thereof. The fed internal heat medium returns in the opposite direction from the tip of the inner sizer 24, reaches the return path in the double pipe 25 via the heat medium return flow path 23, and exits via the discharge pipe after passing through the return path. To go. The inner sizer 24 is heated by such a flow of the heat medium.

The outer peripheral surface of the inner sizer 24 is covered with a polytetrafluoroethylene resin.

The outer sizer 17 is a long tube formed by connecting three short tubes 31 each having an opening at both ends and provided with heating means on the outside thereof. Three short tubes 31
Have the same outer diameter. Each of the three short tubes 31 is provided with a heating jacket 32, and the inside of the short tube 31 can be heated by introducing an external heat medium into the jacket from the inlet and drawing out the external heat medium from the outlet. It is made up of A long tube formed by connecting the three short tubes 31 to each other has an inner peripheral surface that is flush with the long tube.

The outer peripheral surface of the outer sizer 17, in other words, the outer peripheral surfaces of the three short tubes 31 are covered with tetrafluoroethylene.

One end surface of the outer sizer 17 abuts on the distal end surface of the base 3 and is screwed into the female screw of the fixing ring 4 fixed to the distal end surface of the base 3, thereby connecting the outer sizer 17 to the die body 1. Are integrally connected.

The inner sizer 24 is disposed inside the outer sizer 17. Therefore, a resin flow passage 33 through which the resin passes is formed by the inner peripheral surface of the outer sizer 17 and the outer peripheral surface of the inner sizer 24.

Using the pipe die having the above configuration, a pipe is formed as follows.

The internal heat medium is supplied from the internal heat medium supply pipe 21 to the inside of the inner sizer 24, and the internal heat medium in the inner sizer 24 passes through the heat medium return flow path 23 and the return path of the double pipe 25. Go outside. On the other hand, in the outer sizer 17, an external heat medium is supplied to the heating jackets 32 attached to the short tubes 31, flows through the heating jackets 32, and is discharged to the outside.

Thus, the inner sizer 24 and the outer sizer 17 are heated by the internal heat medium and the external heat medium. The heating jacket 32 provided on each of the three short tubes 31 may evenly heat the inside of the sizer from a portion near the die body to the tip of the sizer, and may be provided on each of the three short tubes 31. An external heating medium of a different temperature is supplied to the heating jacket 32, and the heating temperature of the short tube 31 near the die body 1 by the heating jacket 32 and the heating temperature of the short tube 31 farther from the die body 1 by the heating jacket 32. The heating temperature of the outer jacket may be adjusted so that there is a temperature gradient between the heating temperature and the heating temperature. In this embodiment, since there are three outer jackets, only three temperatures can be adjusted.
Whatever the number, when the resin to be molded into the pipe is, for example, PET, the temperature from the die body 1 side to the tip of the sizer is preferably adjusted within a range of usually 100 to 230 ° C. If the temperature of the tip of the sizer is made lower than the temperature of the die body side, although the reason is not clear, the cylindrical shape of the resin in the resin flow passage in the tip of the sizer may be beautifully finished.

On the other hand, the resin developing path 3 in the die body 1
For example, when the resin is PET, the temperature in the resin flow passage is preferably adjusted to 250 ° C. or more and less than 300 ° C.

With the die body 1 and the sizer heated as described above, the molten resin is supplied from the resin introduction hole 14. The molten resin introduced from the resin introduction hole 14 flows through the resin development path 30 which is divided into right and left from the resin introduction hole 14,
The molten resin advances in the resin expanding path 30 spreading wide,
The molten resin also becomes cylindrical as the resin development paths 30 divided into right and left are united to form a cylinder. The flow of the molten resin is blocked by the molten resin restricting portion 2d, so that there is no residue in the molten resin that develops in a cylindrical shape. The completely unified molten resin passes through the molten resin regulating portion 2d and flows through the resin flow passage. The molten resin that has exited the discharge port 9 from the resin flow path flows through the resin flow path in the sizer 7. Since the temperature of the sizer 7 is set lower than the temperature of the die body 1, the resin that has reached the flow passage of the sizer 7 is solidified.

The outer lubricant is injected into the outer lubricant reservoir from the outer lubricant injection hole 18, and the outer lubricant in the outer lubricant reservoir gradually passes through the outer lubricant supply passage 20 and is formed in the outer sizer 17. It leaches between the peripheral surface and the outer surface of the resin developed in a cylindrical shape.

Similarly, the internal lubricant is injected into the internal lubricant reservoir from the internal lubricant supply hole 29, and the internal lubricant in the internal lubricant reservoir gradually passes through the internal lubricant supply passage 28 and passes through the inner sizer. Leach between the outer peripheral surface of the resin 24 and the inner surface of the resin developed in a cylindrical shape.

The outer surface of the inner sizer 24 and the inner surface of the outer sizer 17 are formed of a heat-resistant lubricant, and between the inner surface of the outer sizer 17 and the outer surface of the resin and between the outer surface of the inner sizer 24 and the resin. Since the lubricant is supplied to the inner surface, even if the resin is solidified in the resin flow path in the sizer 7, the solidified resin is smoothly formed in the resin flow path by the subsequent discharge pressure of the molten resin. Moreover, it progresses at a high speed. For example, when the resin is PET, the PET pipe discharged from the sizer in the pipe die according to the present invention has a discharge pressure of several tens to ten.
When the pressure is 0 kg, the liquid can be discharged at a high speed of several tens to 100 mm / min. As a result, the solidified cylindrical pipe is extruded at a high speed from the outlet in the resin flow passage in the sizer 7.

[0072]

According to the present invention, it is possible to provide a pipe die capable of easily forming a resin having a small temperature range, for example, PET, which changes from a molten state to a solid state into a pipe at a high speed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a die main body in a pipe die according to the present invention.

FIG. 2 is a sectional view showing an example of a sizer in the pipe die of the present invention.

FIG. 3 is an enlarged view of an example of the die body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Die main body, 2 ... Mandrel, 2a ... Tip part, 2b ...
Resin passageway, 2c: resin passageway forming portion, 2d: molten resin regulating portion, 2e: conical portion, 2f ... rear end protruding portion 2f, 3 ... base, 4 ... fixing ring, 5 ... fixing member, 6 ... mounting through Hole,
7 ... sizer, 8 ... small circular opening, 9 ... discharge port, 10 ...
Large circular opening, 11: cylindrical inner peripheral surface, 12: mandrel mounting hole, 13: resin introduction part, 14: resin introduction hole, 15 ...
Guide member, 16: Guide member mounting portion, 17: Outer sizer, 18: Outer lubricant injection hole, 19: Annular outer lubricant reservoir, 20: Outer lubricant supply path, 21: Internal heat medium supply pipe, 22 ... Through hole, 23 ... heat medium return channel, 24
... inner sizer, 25 ... double pipe, 26 ... recessed part, 2
7 ... annular inner lubricant reservoir, 28 ... inner lubricant supply passage,
29: inside lubricant supply hole, 30: resin development path, 31: short pipe, 32: heating jacket, 33: resin flow path.

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[Procedure amendment]

[Submission Date] September 16, 1999 (1999.9.1)
6)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 3

FIG. 2

Claims (1)

[Claims] 1. An outer sizer and an inner sizer form a cylindrical resin flow path, and an inner surface of the outer sizer which is a part of the resin flow path is formed of a heat-resistant lubricating material. An outer surface of an inner sizer that is a part of a road, a sizer formed of a heat-resistant lubricant,
A resin introduction section into which the molten resin is introduced is provided, and a resin development path formed so that the resin injected from the resin introduction section expands in a cylindrical shape, and the resin development path matches the resin flow path. A die body capable of directly connecting the sizer so as to communicate with the first sizer, first lubricant supply means for supplying a lubricant to an inner peripheral surface of an outer sizer which forms a part of the resin flow path, A second lubricant supply means for supplying a lubricant to an outer peripheral surface of an inner sizer forming a part of the inner sizer.