JPH09155949A - Spiral die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the fluidity of molten resin in a spiral passage, and reduce the outer diameter dimensions thereof. SOLUTION: An inside spiral groove 31d is formed on the outer peripheral surface 31c of a spiral nozzle 31, and an outside spiral groove 32b is formed on the inner peripheral surface 32a of a die main body 32, then the spiral nozzle 31 and die main body 32 are put into close contact with each other, thus forming a spiral passage 36 with both the grooves 31d, 32b. In the divided condition of the spiral nozzle 31 and die main body 32, since both the grooves 31d, 32b are released outward, polishing work can be facilitated with the result that the inner surface 36 of spiral passages can be finished smoothly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die used for extrusion-molding a tubular resin film, a hollow pipe, or other tubular resin by an extrusion molding method, and more specifically, it has a spiral passage through which a molten resin passes. Regarding spiral die.

[0002]

2. Description of the Related Art When molding a thermoplastic tubular resin by an extrusion molding method, a molten resin is continuously extruded through an annular passage of an appropriately heated die to form a resin bubble or an annular resin. Further, air is blown into the bubble or the annular resin to appropriately expand it, thereby obtaining an extruded product such as an annular film or a hollow pipe having a desired inner diameter. The molded tubular resin is cut into an appropriate length, and depending on the product, the bottom portion is welded and used as a shopping bag or the like by the inflation molding method, or as a bottle or a pipe by the hollow molding method.

Here, in addition to the annular passage serving as a discharge port of the annular resin, the die has a distribution passage for distributing the molten resin supplied from the extruder to each portion in the annular passage. As a part of the distribution passage, there may be a case where a spiral passage (usually, a plurality of spiral passages) is formed spirally around the extrusion direction axis. In a spiral die having such a spiral passage, when the molten resin enters the annular passage from the spiral passage, the flow rate distribution in the circumferential direction is made uniform, and a homogeneous resin bubble or annular resin is molded. You can

A spiral die having such a structure is disclosed in Japanese Patent Application Laid-Open No. 2-225021 and Japanese Patent Application Laid-Open No. 7-95.
Some are disclosed in Japanese Patent No. 36. JP-A 2-2
The spiral die disclosed in Japanese Patent No. 25021 is
The purpose of the present invention is to mold a multi-layer blown film, and to correct the problem in the cylindrical spiral type annular die (die) shown in FIG.
An opening for inflow of molten resin is provided on the outer peripheral portion of the mating surface of the disk-shaped ring, and a spiral passage is formed from this opening toward the resin flow path communicating with the die lip (annular passage) on one side flat surface portion of the mating surface. Is forming.

Further, Japanese Patent Application Laid-Open No. 7-9536 discloses a die in which a spiral passage is formed in a flat surface on one side of a mating surface of each disc ring, as in the above spiral die. Further, instead of the disc-shaped ring, an inner ring with a tapered projection and an outer ring for fitting and receiving the tapered projection are used, and a spiral passage is formed on one side of a fitting portion (a mating surface) of these rings. Things are also disclosed.

By the way, when the spiral passage is formed on one side of the mating surface, the cross-sectional shape of the spiral passage is semicircular, so that the molten resin is likely to stay. When stagnation occurs,
That is, if the fluidity of the molten resin in the spiral passage is not sufficiently ensured, the flow of the molten resin is biased and a weld line remains in the discharged resin bubble (film) or annular resin (pipe) or film or The wall thickness of the pipe may become uneven.

For this reason, the spiral passage is not formed only on one side of the mating surface of the ring as in the above-mentioned respective dies, but rather like the spiral die disclosed in FIG. 3 of JP-A-7-9536. In addition, a spiral passage is formed on both flat surfaces of the mating surfaces of the disc-shaped rings so that the cross-sectional shape of the spiral passage is substantially circular so that molten resin does not easily stay in the passage, It is preferable to reduce the flow resistance of the flowing molten resin. In particular, each of the above dies is for forming a multilayer extrusion molded article,
By improving the flow of the molten resin, it is possible to mold a good quality extruded product in which the thickness of each layer is uniform.

[0008]

Here, even in the spiral die for forming a single-layer extruded product, in order to form a good quality extruded product, the cross-sectional shape of the spiral passage is made substantially circular. It is preferable. However, JP-A-7-95
As disclosed in Japanese Patent No. 36, No. 36, when the molten resin inflow hole is opened on the outer peripheral surface of the die to form a spiral die, there is a problem that the outer diameter dimension becomes large even for a single-layer spiral die. there were.

In order to prevent the outer diameter from unnecessarily increasing, therefore, as disclosed in FIG. 5 of Japanese Patent Laid-Open No. 2-225021, the spiral die is provided on the side opposite to the discharge port of the resin bubble. A molten resin inlet hole is formed on the surface (lower surface of the spiral die), or a molten resin channel is formed toward the lower surface of the spiral die, and the channel is connected to the inlet port formed on the side surface of the die. It is conceivable to form a spiral passage around the axis of the resin extrusion direction and to form the spiral passage in a substantially circular shape by connecting with the.

That is, as shown in FIGS. 11 and 12 of the present application, the main body portion 10 of the die main bodies 1031 and 1131.
31a and 1131a have spiral grooves 1031d and 113
The spiral dies 103 and 113 in which the spiral grooves 1032a and 1132a are formed on the inner circumferences of the rings 1032 and 1132 as well as forming the 1d are conceivable. In these spiral dies 103 and the like, by inserting the main body portion 1031a and the like inside the rings 1032 and the like, a spiral passage 1036 and the like having a substantially circular cross section is formed.

Here, in order to improve the flow of the molten resin, the inner circumference of the spiral passage needs to be smoothed by polishing or chrome plating or nickel plating. In addition, a ceramic or the like may be coated if necessary. With such a shape, the main body portion 1031 is inserted before the ring 1032 or the like is inserted inside.
Since the outer periphery such as a is exposed, the work such as polishing work on the spiral groove 1031d and the like can be easily performed.

However, in the ring 1032 or the like, even if the spiral groove 1032a or the like can be cut,
It was difficult to insert working tools into the inner space of the ring 1032 or the like, and it was difficult to perform polishing work or the like on the spiral groove 1032a or the like. (For this reason, JP-A-2-2250
In the die disclosed in Japanese Patent No. 21, a spiral passage is formed on the outer peripheral surface exposed at the time of disassembly. )

The present invention has been made in view of the above circumstances, and an object thereof is to provide a spiral die capable of improving the fluidity of a molten resin in a spiral passage and reducing the outer dimensions. I am trying.

[0014]

In order to achieve the above object, in the present invention, a spiral die for resin extrusion comprises an inner member and an outer member disposed outside the inner member. There is. The inner member has an upwardly projecting tapered protrusion, and the outer member has a receiving portion that fits and receives the tapered protrusion.

A spiral passage is formed in the fitting portion between the inner member and the outer member, and the spiral passage is formed in a spiral shape that extends upward around the axis in the extrusion direction, through which the molten resin passes. It is like this. An annular passage for ejecting the annular resin upward is connected to the forward end of the spiral passage in the extrusion direction. The spiral passage has a substantially circular cross-sectional shape formed by an inner spiral groove formed on the outer peripheral surface of the tapered projection and an outer spiral groove formed on the inner peripheral surface of the receiving portion. Further, an inflow hole for allowing molten resin to flow into the spiral passage is formed in the lower surface of the inner member of the spiral die or on the outer peripheral surface below the inner spiral groove formed in the inner member. A spiral die for multilayer resin extrusion can be obtained by disposing a plurality of sets of inner members and outer members.

According to the spiral die thus constructed, since the annular passage is composed of the inner spiral groove and the outer spiral groove at the fitting portion between the inner member and the outer member, the inner member and the outer member are separated from each other. When divided, the outer spiral groove formed on the inner peripheral surface of the outer member is exposed, so that not only in the annular passage but also in the spiral passage having a complicated shape, not only the cutting work but also the friction coefficient of the spiral groove is increased. Polishing processing and coating processing for reducing the amount can be easily performed. Molten resin entering from the inlet below the die passes through the spiral passageway and is discharged from the annular passage formed above the die.The spiral passage is formed into a substantially circular cross section and has an inner circumference. The surface is formed smoothly.

Therefore, by improving the fluidity of the molten resin passing through the inside, the flow distribution in the circumferential direction when entering the annular passage is made uniform, and a single-layer or multi-layer resin bubble is formed uniformly. be able to. Furthermore, since the spiral passage is formed in a spiral shape that extends upward around the extrusion direction axis and the inlet is formed on the lower surface of the die, it is possible to reduce the radial dimension of the die (particularly the upper dimension). it can.
Further, even if the inflow hole is formed in the outer peripheral surface of the die, the flow path of the molten resin can be connected from the inside of the spiral passage, so that the radial dimension of the die can be reduced.

The inflow hole for injecting the molten resin into the spiral passage may be formed in the outer peripheral surface of the outer member, and the spiral die formed in this manner allows the molten resin to pass therethrough. Since the fluidity is improved and the flow distribution in the circumferential direction when entering the annular passage is made uniform, a single-layer or multi-layer resin bubble can be formed uniformly.

Another spiral die of the present invention is a spiral die for extruding a single-layer resin film, and a lower member,
The upper member is disposed above the lower member. The lower member has a flat upper end surface, and the upper member has a lower end surface closely contacting the upper end surface.

A spiral passage is formed in a close contact portion between the lower member and the upper member, and the spiral passage is formed in a spiral shape radially inward around the extrusion direction axis to melt the inside. The resin passes through. An annular passage for ejecting the annular resin upward is connected to the forward end of the spiral passage in the extrusion direction. The spiral passage has a substantially circular cross-sectional shape formed by a lower spiral groove formed on the upper end surface of the lower member and an upper spiral groove formed on the lower end surface of the upper member. further,
The lower surface of the lower member of the spiral die or the outer peripheral surface below the lower spiral groove is formed with an inflow hole for allowing molten resin to flow into the spiral passage.

According to the spiral die configured as described above, the annular passage is composed of the lower spiral groove and the upper spiral groove at the fitting portion between the lower member and the upper member. The lower and upper spiral grooves are exposed when the member is split. Therefore, like the spiral die, polishing and coating can be easily performed, and a uniform single-layer annular resin can be formed.
Further, since the spiral passage is horizontally formed inward in the radial direction around the axis in the extrusion direction, the vertical dimension of the die can be made small (thin).

Further, the spiral die may be composed of a lower member and an upper member, and the annular resin having a desired number of layers may be formed by increasing the number of steps of the upper member. In such a spiral die, the lower member is composed of an inner member having a tapered protrusion and an outer member disposed outside the inner member, and the upper member is composed of two members, as in the spiral die described at the beginning. Like the spiral die described in the second item, it is composed of a lower member and an upper member disposed above the lower member.
Then, similar to the above-mentioned both spiral dies, a spiral passage is formed in the fitting portion between the inner member and the outer member and the close contact portion between the lower member and the upper member, and both spiral passages in the extruding direction Forming an annular passage. In the lower member, the inflow hole is formed in the lower surface of the inner member or in the outer peripheral surface below the lower spiral passage, but in the upper member, the lower member is arranged below, so the inflow hole is formed in the outer peripheral surface. Is formed.

According to the spiral die thus formed, polishing and coating can be easily carried out, and a homogeneous multi-layered annular resin can be formed, like the spiral die. Furthermore, since a thin die is used for the upper stage member, the shape of the entire die can be made compact even with a spiral die that forms a multilayer annular resin.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, a case where inflation molding of a tubular resin film, which is an example of extrusion molding, is performed using the spiral die according to the present invention will be described. FIG. 4 shows an apparatus for inflation molding of a tubular resin film using the spiral die according to the present invention. This device is a resin material for inflation molding (for example, polyolefin resin).
And an extruder 2 which is connected to the hopper 1 and has a screw 2a which is melted and kneaded with a resin material and pushed out to the spiral die 3.

A spiral die 3 for molding a single-layer blown film, which is a first embodiment of the spiral die according to the present invention, will be described with reference to FIG. The spiral die 3 includes a spiral nozzle (inner member) 31, a die body (outer member) 32, an upper nozzle 33, an uneven thickness adjusting ring 34, and a center nozzle 35. The spiral nozzle 31 is composed of a tapered main body portion 31a and a flange portion 31b projecting radially from the main body portion 31a.

The main body 31a is formed in a taper (mountain shape) that is inclined with respect to the axial direction so that the diameter becomes smaller as it goes upward, and the outer peripheral surface 31c has an upper portion around the axis of the main body 31a. A plurality of grooves (hereinafter, referred to as “inner spiral grooves”) 31d that spirally extend toward each other are formed. These spiral grooves 31d start at a plurality of locations in the circumferential direction below the main body 31a and extend to the upper part of the main body 31a. Each spiral groove 31d has a U-shaped cross-sectional shape, and the depth thereof becomes shallower toward the upper portion of the main body 31a.

A nozzle accommodating groove 31e opening downward is formed at the lower end of the main body 31a, and a nozzle accommodating groove 31 extending in the radial direction is formed at the lower part of the main body 31a.
A distribution path 31f is formed which connects the opening formed in the center of the upper portion of e and the starting point of each spiral groove 31d. further,
A first air passage 31g that is open at the center of the upper surface and at the lower portion of the side surface is formed in the body portion 31a.

The die main body 32 is formed in a cylindrical shape having a concave portion which is in close contact with the main body portion 31a, and is attached to the outer periphery of the main body portion 31a of the spiral nozzle 31 (mounted on the upper surface of the flange portion 31b). It is fixed by a bolt (not shown). A plurality of grooves 32b (hereinafter, referred to as “outer spiral grooves”) 32 spirally extending upward around the axis are formed in a portion of the inner peripheral surface 32a of the die body 32 that faces the inner spiral grooves 31d. . These spiral grooves 3
2b also has a U-shaped cross-sectional shape, and the depth thereof becomes shallower toward the upper portion of the die body 32.

The spiral nozzle 3 thus constructed
1 and the die body 32 are in close contact engagement with each other.
A spiral passage 36 having a substantially circular cross section is formed between the inner peripheral surface 32a of the die main body 32 and the outer peripheral surface 31c of the spiral nozzle 31 opposed thereto.

Since the molten resin flows into the spiral passage 36 as described later in detail, the inner peripheral surface of the spiral passage 36 must be formed as smoothly as possible. Therefore, the spiral passage 36
In forming the inner and outer spiral grooves 31d, 3
After forming 2b by cutting, polishing is performed.

Here, the inner spiral groove 31d corresponds to the main body 31
Since it is formed so as to be exposed on the outer periphery of a, polishing work can be easily performed. Further, the outer spiral groove 32b is formed on the inner peripheral surface 32a of the die body 32. However, since the inner peripheral surface 32a is formed in a so-called mortar shape, the working tool is slanted downward from inside. It can be brought into contact with and brought into contact with the peripheral surface, and polishing work can be performed.

The upper nozzle 33 is the spiral nozzle 31.
Is a disk-shaped member having an outer diameter equal to the outer diameter of the upper end of the main body 31a, and is mounted on the upper surface of the main body 31a and fixed by a bolt (not shown). The outer peripheral surface 33a of the upper nozzle 33 is formed in a shape in which the upper portion protrudes slightly outward from the lower portion. Also, the upper nozzle 3
A second air passage 33b is formed at the center in the radial direction of 3, and opens on the upper and lower surfaces.

The uneven thickness adjusting ring 34 is a ring-shaped member having an inner diameter equal to the inner diameter of the die body 32, is placed on the upper surface of the die body 32, and is fixed by a bolt (not shown). Thereby, the inner peripheral surface 3 of the thickness deviation adjusting ring 34
4a and the outer peripheral surface 33a of the upper nozzle 33 mounted on the upper surface of the spiral nozzle 31 face each other, and an annular passage 37 is formed between them. Note that the above-described upper nozzle 33
Due to the shape of the outer peripheral surface 33a, the upper portion of the annular passage 37 has a smaller width than the lower portion.

The center nozzle 35 is a cylindrical member having a first inner peripheral surface 35a formed with a female screw, and is housed in the nozzle housing groove 31e of the spiral nozzle 31.
As shown in FIG. 4, a male screw portion (not shown) on the upper portion of the die joint 2b attached to the outlet of the extruder 2 can be screwed into the female screw. In addition, the center nozzle 3
A communication port 35c having a second inner peripheral surface 35b having an inner diameter smaller than that of the first inner peripheral surface 35a is formed at the center of the upper portion of the No. 5. The communication port 35c communicates with each distribution passage 31f of the spiral nozzle 31.

When a tubular film is produced by using the spiral die 3 thus constructed, a heater (not shown) is attached to the die body 32 and the uneven thickness adjusting ring 34 of the spiral die 3 and heated to a required temperature. It Then, from the die joint 2b of the extruder 2 to the center nozzle 3
The molten resin supplied to the inner space of No. 5 is supplied to the annular passage 37 through the distribution passage 31f and each spiral passage 36. When entering the annular passage 37 from each spiral passage 36, the flow rate distribution of the molten resin in the circumferential direction is made uniform, and the molten resin is made uniform.

Then, the tubular resin bubble 50 is continuously discharged upward from the annular passage 37. At this time,
The molten resin flowing in the distribution passage 31f is distributed into the distribution passage 31f.
At the confluence of the spiral passage 36 and the spiral passage 36.
Flows into the spiral passage 36 by hitting the outer spiral groove 32b forming the outer half circumference. Here, since the cross-sectional shape of the outer spiral groove 32b is formed in a substantially semicircular shape, the molten resin smoothly flows into the spiral passage 36, and the molten resin stays at the portion where the distribution passage 31f moves to the spiral passage 36. It gets harder.

Further, since the inner surface of each spiral passage 36 is formed into a substantially circular shape and is polished, the flowability of the molten resin in the passage is improved, and the resin is hardly accumulated in the passage. Therefore, the flow of the molten resin is not biased, and a weld line is not formed in the discharged resin bubble (film) and the thickness of the resin bubble is not uneven.

In the discharged resin bubble 50, the first and second air passages 31 formed in the spiral die 3 are formed.
Air is blown through g and 33b. This allows
As shown in FIG. 4, the resin bubble 50 expands and deforms in the radial direction, and the expanded bubble 50 is cooled as it goes upward, and becomes a tubular film 50 '.

The tubular film 50 'is sandwiched between a pair of stabilizers 8 which are arranged in a V shape so as to be opposed to each other on the left and right and have a narrower interval toward the upper part, and are folded into a sheet shape, while these stabilizers 8 , 8 is pulled up by the take-up pinch roll 5 located above. Then, the tubular film (sheet) pulled up by the pinch rolls 5
50 'is wound around the winding shaft 7a of the winding device 7 while being guided by a plurality of guide rolls 6a to 6d.

According to the spiral die 3 thus constructed, the spiral passage 36 for forming the resin bubble of good quality can be easily formed, and the die for forming the resin bubble can be made compact ( In particular, the radial dimension can be reduced). Furthermore, the distribution path 3
Since 1f only needs to be formed on the spiral nozzle 31 (it is not necessary to process it after combining it with other members), the process is easy.

In the above embodiments, the case where the spiral die 3 is a single-layer spiral die for molding a single-layer resin film has been described, but the present invention is not limited to this. A spiral die for extrusion of a multilayer resin film can be obtained by forming the outer periphery of the die body 32 to be further tapered and disposing an outer member further having a taper receiving portion on the outer periphery thereof.

Next, another embodiment of the spiral die according to the present invention will be described with reference to FIG. The spiral die 13 is a spiral die for forming a single-layer blown film, similar to the spiral die 3, and includes a lower nozzle 131, an upper die body (upper member) 132, an upper nozzle 133, and an uneven thickness adjusting ring. 134, a center nozzle 135, and a lower die body (lower member) 138.

The lower nozzle 131 is composed of a main body portion 131a formed in a substantially columnar shape, and a flange portion 131b protruding from the main body portion 131a in the radial direction.
The outer peripheral surface 131c of the main body 131a is slightly inclined with respect to the axial direction such that the diameter becomes smaller as it goes upward.

Outer periphery of the main body 131a (flange 131
The lower die main body 138 and the upper die main body 132 are disposed on the upper side of b). The upper end surface of the lower die body 138 and the lower end surface of the upper die body 132 are formed flat (substantially horizontal), and a groove (hereinafter, referred to as a “helical groove”) 138b spirally extending inward in the radial direction around the axis. And 132
A plurality of b are formed at opposite positions. Both spiral grooves 1
38b and 132b have a U-shaped cross section,
The depth decreases toward the center of the die bodies 132 and 138.

In a state where the upper and lower die bodies 132, 138 thus configured are closely engaged with each other by bolts (not shown), the cross-sectional shape is substantially circular in the substantially middle portion of both die bodies 132, 138. Spiral passage 13
6 are formed.

Since the molten resin flows into the spiral passage 136 as described above, it is necessary to form the inner peripheral surface of the spiral passage 136 as smoothly as possible. Therefore, this spiral passage 136
Also, the inner peripheral surface is polished. Here, in a state where both the die bodies 132 and 138 are divided, both the spiral grooves 132b and 138b are exposed, so that the working tool can be brought into contact with and contact with the inner peripheral surface, and the polishing work is easily performed. be able to.

Both die bodies 132, 138 having the spiral passage 136 formed in this manner are attached to the lower nozzle 131 by bolts (not shown). A distribution passage 131f is formed in the lower nozzle 131 and the lower die main body 138. An upper end opening of the distribution passage 131f is connected to the spiral passage 136, and a lower end opening thereof is connected to the communication port 135c.

In the spiral die 13, the upper nozzle 133, the uneven thickness adjusting ring 134 and the center nozzle 135, which are components other than those described above, are the upper nozzle 33, the uneven thickness adjusting ring 34 and the center nozzle in the spiral die 3. Since it has the same configuration as 35,
The reference numeral added with 100 is given and detailed description is omitted.

The spiral die 13 configured as described above
Also in this case, the spiral passage 136 for forming the resin bubble of good quality can be easily formed. Further, since the spiral passage 136 is formed on the horizontal plane, the discharge pressure of the resin in the extruder that supplies the molten resin from the center nozzle 135 can be lowered. Further, since the spiral passage 136 is formed horizontally in the radial direction, the vertical dimension of the spiral die 13 can be made small (thickness can be made thin).

Next, another embodiment of the present invention will be described with reference to FIG. The spiral die 23 is a spiral die for molding a two-layer blown film, and includes a lower step portion 230 and an upper step portion 330. The lower part 230 is the spiral die 3
The spiral nozzle 231, the die body 32, and the center nozzle 35 are formed in the same manner as the spiral nozzle 31, the die body 32, and the center nozzle 35 in FIG.

The upper stage portion 330 includes the upper die body 132 and the upper nozzle 13 of the spiral die 13.
3, the uneven thickness adjusting ring 134, the lower die body 138, and the upper die body 332, the upper nozzle 333, which are formed in substantially the same manner as the body portion 131a of the lower nozzle 131,
It is composed of an uneven thickness adjusting ring 334, a lower die main body 338 and an intermediate nozzle 331. The upper part 3
In 30, the molten resin is supplied from a communication port 335c formed by opening on the outer peripheral surface.

The lower step portion 230 and the upper step portion 330 thus configured are joined by a bolt (not shown). Then, the molten resin supplied from both the communication ports 235c and 335c flows through the spiral passages 236 and 336 and joins at the joining portion 337a in the annular passage 337 to form a two-layer resin bubble, which is continuously upward. Is ejected.

The spiral die 23 configured as described above
In the above, since the two kinds of molten resin flow in the polished spiral passages 236 and 336, respectively, a good quality resin bubble is formed. Further, even a die for molding a two-layer blown film can have a compact external dimension.

The present invention is not necessarily limited to the die for molding the two-layer blown film.
That is, by stacking a plurality of upper stages 330,
It can be used as a die for easily forming an inflation film having three or more layers. Even in this case,
Since the die having the increased number of steps is the thin upper step portion 330, the entire spiral die can be made compact.

Next, the case of forming a hollow pipe using the spiral die according to the present invention will be described. When forming a hollow pipe, the molten resin is used in the center nozzle 35 as in the above spiral dies 3, 13, 23.
It may be supplied from the outer peripheral surface of the center nozzle instead of being supplied to the inner space such as. Therefore, a case where a hollow pipe is molded using a so-called side-feed type die that supplies the molten resin from the outer peripheral surface will be described below.

FIG. 10 (A) shows a plan view of a hollow pipe forming apparatus, and FIG. 10 (B) shows a side view thereof. This device has a hopper 91 and a screw 9
It has an extruder 92 equipped with 2a. This extruder 92
A die joint 92b is formed laterally in the extrusion direction of
Side feed type die 4 is attached to this die joint 92b.
3 are connected. The die 43 is arranged so that the discharge direction of the annular resin is lateral (to the right in FIG. 10). Further, a cooling device 94 is provided in front of the die 43 in the direction of discharging the annular resin, and a drawing device 95 for taking the formed hollow pipe 150 is provided further in front of the cooling device 94. There is.

According to the hollow pipe molding apparatus thus constructed, the annular resin 150 can be molded by supplying the molten resin from the die joint 92b of the extruder 92 to the spiral die 43. 150
By cooling, the hollow pipe 150 'can be molded. The formed hollow pipe 150 '
Is collected by the collecting operation of the collecting device 95,
It is cut into a predetermined length by a cutting device (not shown).

As the side-feed type spiral die suitable for forming the hollow pipe as described above, the spiral dies 43, 53, 73, 8 shown in FIGS.
There are 3,153. First, the spiral die 43 for molding a single-layer hollow pipe will be described with reference to FIG. This spiral die 43 is the spiral die 3 shown in FIG.
The configuration of the upper nozzle 433 and the center nozzle 435 is different from that of the upper nozzle 33 and the center nozzle 35.

The center nozzle 435 has an outer diameter substantially equal to the outer diameter of the spiral nozzle 431, and the spiral nozzle 431 is mounted on the upper surface thereof. The opening 435a corresponding to the first inner peripheral surface 35a of the center nozzle 35 has a female screw formed on the inner periphery thereof so that the center nozzle 4 has
The outer peripheral surface of 35 is opened. Opening 435
Two communication ports 435c are formed from a, extending in the left-right direction and extending in a V-shape toward the center. The communication port 435c communicates with each distribution passage 431f of the spiral nozzle 431. The outer diameter dimension of the center nozzle 435 does not necessarily have to be formed equal to the outer diameter dimension of the spiral nozzle 431.

In the spiral nozzle 431, since the shape of the center nozzle 435 is different, the shape of the distribution passage 431f, the shape of the second air passage 431g and the shape of the mounting portion of the center nozzle 435 are different from those of the spiral nozzle 31. The upper nozzle 43 is formed in a different shape.
A second air passage 433b is formed at 3.

The spiral die 43 formed in this way
When a hollow pipe is made using, the molten resin is supplied to the annular passage 437 through the center nozzle 435 having the die joint 2b connected to the outer peripheral surface, as in the case of making a tubular film using the spiral die 3. To be done. As a result, the tubular resin 150 is moved upward from the annular passage 437 (see FIG.
At 0, it is continuously discharged to the right), but the flow of the molten resin is not biased even at this time, a weld line is formed in the discharged resin molded product, and the wall thickness becomes uneven. There is nothing to do.

Inside the discharged annular resin 150, the first and second air passages 4 formed in the spiral die 43 are formed.
Air is blown through 31g and 433b. As a result, as shown in FIG. 10, the annular resin 150 is cooled as it progresses to the right, and the hollow pipe 150 'is formed.

The spiral die 43 formed in this way
Also, since the spiral passage 436 for forming the high-quality annular resin can be easily formed, and the connecting portion with the extruder 2 is the side surface of the center nozzle 435 located below the spiral nozzle 431. In particular, it is possible to make the portion forming the annular resin compact.

Also in the above spiral die 43, the outer periphery of the die body 32 is further tapered, and an outer member having a taper receiving portion is arranged on the outer periphery thereof, whereby a spiral die for multilayer resin extrusion is provided. May be An example of such a spiral die for multilayer resin extrusion is shown in FIG. This spiral die 53 has a lower part 5
30 and an upper step portion 630, a lower step side spiral passage 536 is formed in the lower step portion 530, and
An upper stage spiral passage 636 is formed at the joint between the lower stage 530 and the upper stage 630.

The center nozzle 535 in the lower portion 530
An opening 535a is formed on the outer peripheral surface of the upper step 630, and an opening 635a is also formed on the outer peripheral surface of the upper step 630. Then, the molten resin supplied from both the communication ports 535a and 635a flows through the spiral passages 536 and 636 and merges in the annular passage 637, becomes a two-layer tubular resin and is continuously discharged upward.

In the spiral die 53, the center nozzle 535, which is the outer peripheral surface of the opening 535a below the lower spiral passage 536, is formed.
However, as in the spiral die 153 shown in FIG. 7, the opening 1535a may be formed laterally (upwardly) instead of below the lower spiral passage 1536. Good.

Similar to the spiral die 53, the spiral die 153 is composed of a lower step portion 1530 and an upper step portion 630, and an upper step side spiral passage 636 is formed at a joint portion between the lower step portion 1530 and the upper step portion 630. Has been done. The lower part 1530 is a spiral nozzle (inner member) 1531.
And a die body (outer member) 1532, and a lower spiral passage 1536 is formed at the joint portion.
The upper spiral passage 6 is formed on the outer peripheral surface of the upper portion 630.
36 is formed with an opening 635a connected to the die main body 15
On the outer circumference of 32, an opening 1535a is formed which is connected to the lower spiral passage 1536.

The spiral die 15 formed in this way
Also in the third example, the molten resin supplied from both openings 1535a and 635a has the spiral passages 1536 and 636.
Flow through the annular passages 637 and merge into a two-layer tubular resin, which is continuously discharged upward. The spiral die 153 is for molding two layers of annular resin as described above. However, in the spiral die for molding a single layer of annular resin, the opening is formed on the outer periphery of the die body. May be. That is, in the spiral die formed in the same manner as the spiral die 43, the opening connected to the spiral passage 436 may be formed in the die body 32.

Next, another spiral die 73 according to the present invention will be described with reference to FIG. The spiral die 73 has a configuration similar to that of the spiral die 13 and has the same differences as those of the spiral die 43 and the spiral die 3 described above. That is, the shapes of the lower nozzle 731, the upper nozzle 733, the center nozzle 735, and the lower die main body 738, the formation positions of the openings 735a formed in these members, the communication ports 735c, the distribution passages 731f, the first and second air. The shapes of the passages 731g and 733b are different from those of the spiral die 13. Since the configuration of the other parts is the same as that of the spiral die 13, the same reference numerals are given and detailed description thereof is omitted.

The spiral die 73 configured as described above
Also in this case, the spiral passage 136 for forming the high-quality annular resin can be easily formed. Further, since the spiral passage 136 is formed on the horizontal plane, the discharge pressure of the resin in the extruder for supplying the molten resin from the center nozzle 735 can be lowered. Furthermore, the spiral passage 1
Since 36 is formed horizontally in the radial direction and the opening 735a is also formed on the outer peripheral surface of the center nozzle 735, the vertical mounting dimension of the spiral die 73 can be made smaller.

Next, another spiral die 83 according to the present invention will be described with reference to FIG. The spiral die 83 is a spiral die for two-layer extrusion molding, and has a configuration similar to that of the spiral die 23. That is, also in the spiral die 83, the lower die 830 and the upper die 930 have the same differences as the spiral die 43 and the spiral die 3 and the spiral die 73 and the spiral die 13.
It is composed of

Therefore, the intermediate nozzle 931, the upper nozzle 933, the center nozzle 835, and the spiral nozzle 8 are provided.
31 and the openings 8 formed in these members
35a forming position, communication port 835c, distribution path 831f,
The shapes of the first and second air passages 831g and 933b are different from those of the spiral die 23. Since the configuration of the other parts is the same as that of the spiral die 23, the same reference numerals are given and detailed description thereof is omitted.

Spiral die 83 configured as described above
In this case, since the two kinds of molten resin flow through the polished spiral passages 236 and 336, respectively, a good-quality annular resin is formed. Further, even a die for molding a two-layer hollow pipe can have a compact external dimension.

The present invention is not necessarily limited to the die for molding the double-layer hollow pipe. That is, by stacking a plurality of upper steps 930, a die for easily forming an extrusion-molded article having three or more layers can be obtained. Even in this case, since the die for increasing the number of steps is the thin upper step portion 930, the entire spiral die can be made compact.

Further, in each of the above-mentioned embodiments, the inner peripheral surface of each spiral passage 36, 136, etc. is polished and finished. However, the inner peripheral surface is plated with chrome or nickel, or a ceramic material is used. Alternatively, a material having a low friction coefficient, such as, may be coated to smooth the flow of the molten resin.

In the above-described embodiment, the die (annular passage) is arranged upward, and the resin film is discharged upward to form the inflation film, or the die is arranged laterally. Although the case of forming a hollow pipe or tube has been described above, the direction in which the die is arranged is not necessarily limited to these directions, but may be appropriately changed depending on the molding method and the material. For example, the die may be facing downward when performing blow molding or when forming an inflation film film.

[0077]

As described above, according to the spiral die of the present invention, the entire circumference of the inner peripheral surface of the spiral passage formed to make the flow distribution in the circumferential direction uniform can be easily smoothed. Can be finished. That is, in the disassembled state of the die, since each surface on which the spiral groove is formed faces outward, it is possible to easily use the working device for polishing finish and the working device for coating. Can be approached. Thereby, the fluidity of the molten resin flowing in the spiral passage can be improved, and a homogeneous resin bubble can be molded. Also, the opening for supplying the molten resin is
Since it is formed on the lower surface of the die or on the outer peripheral surface of the lower portion of the die, the outer dimension of the die (in particular, the dimension of the portion where the spiral passage is formed) can be reduced. Also,
By forming an opening for supplying the molten resin on the outer peripheral surface of the die, the vertical dimension of the die can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a spiral die according to the present invention.

FIG. 2 is a side sectional view of another spiral die according to the present invention.

FIG. 3 is a side sectional view of another spiral die according to the present invention.

FIG. 4 is an overall view of an inflation molding device using the spiral die.

FIG. 5 is a side sectional view of another spiral die according to the present invention.

FIG. 6 is a side sectional view of another spiral die according to the present invention.

FIG. 7 is a side sectional view of another spiral die according to the present invention.

FIG. 8 is a side sectional view of another spiral die according to the present invention.

FIG. 9 is a side sectional view of another spiral die according to the present invention.

FIG. 10 shows a plan view of an extrusion molding apparatus using the above spiral die in (A), and a side view in (B).

FIG. 11 is a side cross-sectional view of a spiral die, which is conceived in order to correct the defects of the conventional spiral die.

FIG. 12 is a side cross-sectional view of a spiral die, which was conceived in order to correct the defects of the conventional spiral die.

[Explanation of symbols]

3,13,23,43,53,73,83,153 Spiral die 36,136,236,336,436,536,63
6,736,836,936,1536 spiral passage 37,137,337,437,537,737,83
7 circular passage

Claims (7)

[Claims] 1. An inner member having an upwardly protruding taper projection, and an outer member having a receiving portion for fitting and receiving the taper projection and arranged outside the inner member,
A resin extrusion die used for extrusion molding, wherein a spiral passage formed in a spiral shape extending upward around an extrusion direction axis at a fitting portion between the inner member and the outer member and through which the molten resin passes. And an annular passage that is connected to the front of the spiral passage in the extrusion direction and discharges the annular resin upward, wherein the spiral passage has an inner spiral groove formed on the outer peripheral surface of the taper protrusion and the receiving portion. A spiral having an approximately circular cross-section formed from an outer spiral groove formed on the inner peripheral surface of the spiral groove, and an inflow hole for allowing molten resin to flow into the spiral passage is formed so as to open downward. Die. 2. A lower member having a flat upper end surface and an upper member having a lower end surface in close contact with the upper end surface and arranged above the lower member, and used for extrusion molding. A single-layer resin extrusion die, which is a spiral passage formed in a spiral shape extending radially inward around an extrusion direction axis in a close contact portion between the lower member and the upper member, through which the molten resin passes. And a circular passage that is connected to the forward direction of the spiral passage and discharges the annular resin upward, and the spiral passage is formed on the lower spiral groove formed on the upper end surface and the lower end surface. A spiral die, which is formed in a substantially circular cross-sectional shape from the formed upper spiral groove and has an inflow hole through which molten resin flows in, which is opened downward. 3. A lower member comprising an inner member having a taper projection protruding upward and an outer member arranged outside the inner member and having a receiving portion for fitting and receiving the taper projection, and the lower member. An upper stage composed of a lower member formed above the member and having a flat upper end surface, and an upper member having a lower end surface in close contact with the upper end surface and arranged above the lower member. A resin extrusion die for use in extrusion molding, comprising: a member, wherein the lower member is formed in a spiral shape extending upward about an extrusion direction axis at a fitting portion of the inner member and the outer member. And has a lower spiral passage through which the molten resin passes, wherein the upper member has a spiral shape that extends radially inward around the extrusion direction axis at the close contact portion between the lower member and the upper member. Is formed on the top of the molten resin A step-side spiral passage is provided, and an annular passage that is connected to the forward sides of the both spiral passages in the extrusion direction and discharges the annular resin upward is provided. The lower-step spiral passage is formed on the outer peripheral surface of the taper protrusion. The inner spiral groove and the outer spiral groove formed on the inner peripheral surface of the receiving portion are formed into a substantially circular cross-sectional shape, and an inflow hole for allowing the molten resin to flow into the lower spiral passage is opened downward. The upper spiral groove is formed in a substantially circular cross-sectional shape from the lower spiral groove formed in the upper end surface and the upper spiral groove formed in the lower end surface, and the upper spiral passage is formed. A spiral die, wherein an inflow hole for allowing a molten resin to flow into the passage is formed by opening at an outer peripheral surface of the upper stage member. 4. An inner member having a taper projection protruding upward and an outer member having a receiving portion for fitting and receiving the taper projection and arranged outside the inner member.
A resin extrusion die used for extrusion molding, wherein a spiral passage formed in a spiral shape extending upward around an extrusion direction axis at a fitting portion between the inner member and the outer member and through which the molten resin passes. And an annular passage that is connected to the front of the spiral passage in the extrusion direction and discharges the annular resin upward, wherein the spiral passage has an inner spiral groove formed on the outer peripheral surface of the taper protrusion and the receiving portion. The outer spiral groove formed on the inner peripheral surface of the inner peripheral surface of the inner member has an inflow hole formed in a substantially circular cross-section, and the molten resin flows into the spiral passage below the inner spiral groove on the outer peripheral surface of the inner member. A spiral die characterized by being formed with openings. 5. A lower member having a flat upper end surface, and an upper member having a lower end surface in close contact with the upper end surface and arranged above the lower member, and used for extrusion molding. A single-layer resin extrusion die, which is a spiral passage formed in a spiral shape extending radially inward around an extrusion direction axis in a close contact portion between the lower member and the upper member, through which the molten resin passes. And an annular passage connected to the forward direction of the spiral passage for ejecting the annular resin upward, the spiral passage being formed on the lower spiral groove formed on the upper end surface and the lower end surface. An inflow hole that is formed in a substantially circular cross-section from the upper spiral groove and that allows molten resin to flow into the spiral passage, is formed on the outer peripheral surface of the lower member below the lower spiral groove. Spiral die characterized by being. 6. A lower member comprising an inner member having a taper projection protruding upward and an outer member arranged outside the inner member and having a receiving portion for fitting and receiving the taper projection, and the lower member. An upper stage composed of a lower member formed above the member and having a flat upper end surface, and an upper member having a lower end surface in close contact with the upper end surface and arranged above the lower member. A resin extrusion die for use in extrusion molding, comprising: a member, wherein the lower member is formed in a spiral shape extending upward about an extrusion direction axis at a fitting portion of the inner member and the outer member. And has a lower spiral passage through which the molten resin passes, wherein the upper member has a spiral shape that extends radially inward around the extrusion direction axis at the close contact portion between the lower member and the upper member. Is formed on the top of the molten resin A step-side spiral passage is provided, and an annular passage that is connected to the forward sides of the both spiral passages in the extrusion direction and discharges the annular resin upward is provided. The lower-step spiral passage is formed on the outer peripheral surface of the taper protrusion. The inner spiral groove and the outer spiral groove formed on the inner peripheral surface of the receiving portion are formed into a substantially circular cross-sectional shape, and the inflow hole for allowing the molten resin to flow into the lower spiral passage is the inner spiral groove. Formed on the outer peripheral surface of the inner member below the upper spiral passage, the upper spiral passage is formed from a lower spiral groove formed on the upper end surface and an upper spiral groove formed on the lower end surface. A spiral die, which has a circular cross-sectional shape, and has an inflow hole through which molten resin flows into the upper spiral passage, which is formed in an outer peripheral surface of the upper member. 7. An inner member having a taper projection protruding upward, and an outer member having a receiving portion for fitting and receiving the taper projection and arranged outside the inner member,
A resin extrusion die used for extrusion molding, wherein a spiral passage formed in a spiral shape extending upward around an extrusion direction axis at a fitting portion between the inner member and the outer member and through which the molten resin passes. And an annular passage that is connected to the front of the spiral passage in the extrusion direction and discharges the annular resin upward, wherein the spiral passage has an inner spiral groove formed on the outer peripheral surface of the taper protrusion and the receiving portion. And an outer spiral groove formed on the inner peripheral surface of the outer peripheral member, and an inflow hole for allowing molten resin to flow into the spiral passage is formed on the outer peripheral surface of the outer member. A spiral die characterized by.