JP2024011564A - Die plate for extruder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die plate for an extruder, which increases durability of an orifice through which molten resin plasticized during extrusion molding passes and simplifies a component replacement operation, and to provide a die plate for an extruder, which reduces occurrence of eye stains and the like during an extrusion molding operation.

SOLUTION: A die plate for an extruder comprises: a die plate main body 10 attached to a discharge side of molten resin R in the extruder; and an orifice pin 20 that is fitted into an orifice pin holding hole provided in the die plate main body 10 from an inflow direction of the molten resin R, in which an orifice 21 with a predetermined inner diameter having a tapered surface 22 on an inflow side through which the molten resin R passes and is discharged is formed in an axial direction.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a die plate for an extruder, which is provided at the tip of an extruder used for extrusion molding of thermoplastic resin, and improves the durability of the orifice through which plasticized resin passes, and also prevents eye stains etc. The present invention relates to a die plate for an extruder that can reduce the

Conventionally, as a method for manufacturing resin pellets for molding, a manufacturing method is known in which a molten thermoplastic resin is extruded to form a cord-like strand, and the strand is cut into short lengths to form pellets. At this time, in order to form a strand with a desired diameter, a die plate having an orifice (nozzle) with a predetermined diameter is attached to the tip of the extruder. As the plasticized molten resin passes through the orifice continuously, a string-like strand is extruded.

It is necessary to have a plurality of die plates each having orifices of different diameters and numbers depending on the resin type and composition specifications of the strand to be manufactured. Furthermore, if the orifice of the die plate becomes worn, contaminated, etc., the entire die plate must be replaced.

In addition, during the extrusion molding process, when the molten resin composition is continuously extruded from the orifice, resin lumps and carbide called tar will grow near the exit of the orifice due to abrasion and staining of the inner wall surface of the orifice, forming strands. There was also the problem that the quality of the pellets produced from the strands deteriorated due to the adhesion of streaks and dirt to the strands.

To solve these problems, by using a die plate that has a nozzle piece with nozzle holes formed, maintenance can be performed without replacing the entire die plate, and the occurrence of eye stains can be reduced. A strand die for an extruder has been proposed (Patent Document 1).

In the strand die for an extruder disclosed in Patent Document 1, as shown in each figure in FIG. A threaded nozzle hole with a small diameter is formed at the tip side of the flow path 7, and a nozzle piece 6, which is a feature of the invention, is attached by screwing from the downstream side of the die plate 5. In the extruder to which this die plate 5 is attached, the resin plasticized in the extruder passes from the wide resin channel 7 in the die plate 5 to the small diameter nozzle hole and the nozzle hole 9 of the nozzle piece 6. It is discharged from the tip of the nozzle hole 9 to the outside of the extruder. If the inner surface of the nozzle hole is damaged, it can be repaired at low cost by simply replacing the nozzle piece without replacing the entire die plate, and it is also possible to reduce the amount of eye stain that occurs at the exit of the nozzle hole. has been done.

Japanese Patent Application Publication No. 2000-52403

However, in the die plate of the strand die disclosed in Patent Document 1, a small diameter nozzle hole is formed in the die plate main body, and the nozzle hole of the nozzle piece is positioned so as to communicate with this nozzle hole. Therefore, the inner wall surface on the nozzle hole side formed in the die plate main body, into which the molten resin flows under high pressure in a manner that it is squeezed from the wide resin channel 7 where the molten resin is once stored, is most likely to wear out. If this part becomes worn or soiled, it cannot be solved by replacing the nozzle piece, so there is a problem in that the entire die plate must be replaced.

SUMMARY OF THE INVENTION Therefore, the purpose of the present invention is to solve the above-mentioned problems of the conventional technology, have an orifice that does not easily deteriorate, can be used for a long period of time, and has a size (inner diameter) that is suitable for changing the diameter of the strand to be formed. To provide a die plate for an extruder which can be used simply by replacing an orifice pin.

The die plate for an extruder of the present invention includes a die plate main body that is attached to the discharge side of the molten resin in the extruder, and a die plate that is fitted into an orifice pin holding hole provided in the die plate main body from the inflow direction of the molten resin. and an orifice pin in which an orifice of a predetermined inner diameter through which the molten resin passes and is discharged is formed in the axial direction.

Preferably, the orifice pin holding hole is provided in a recess in the die plate main body in which molten resin is stored.

Preferably, the orifice pin has a collar portion whose diameter is enlarged from the main body via a haunch portion, and is formed on the inlet side of the molten resin, and is held in position within the orifice pin holding hole by the haunch portion.

It is preferable that the orifice pin has a tapered surface that guides the molten resin to the orifice formed on an end surface of the collar portion on the molten resin inlet side.

It is preferable that the orifice has a land of a predetermined length continuously provided on the tapered surface.

It is preferable that the material strength of the orifice pin is higher than the material strength of the die plate main body.

Preferably, the tapered surface has a taper angle of about 120°.

It is preferable that the length of the land of the orifice is set to be 10 to 20 mm.

According to the present invention, it is possible to increase the durability of the orifice through which plasticized molten resin passes during molding, simplify parts replacement work, and reduce the occurrence of eye stains etc. that occur during molding. It has the effect of being able to do it.

The front view and Ib-Ib sectional line diagram which showed the box main body of the die plate for extruders of this invention. FIG. 1 is a front view, an end view, and a longitudinal cross-sectional view showing the overall shape of an orifice pin of a die plate for an extruder according to the present invention. FIG. 3 is a partially enlarged sectional view showing a state in which the orifice pin is attached to the pin accommodating portion of the box body of the die plate. The front view and IVb-IVb sectional line diagram showing the state where the orifice pin is attached to the pin accommodating part of the box body of the die plate, and the molten resin flow path in the die plate is formed.

EMBODIMENT OF THE INVENTION Hereinafter, as one embodiment of the die plate for extruders of the present invention, its structure will be described with reference to the accompanying drawings.

EMBODIMENT OF THE INVENTION Hereinafter, the structure of one embodiment of the die plate for extruders of this invention is demonstrated with reference to an accompanying drawing. FIG. 1(a) is a front view of a die plate 10 for an extruder (hereinafter simply referred to as die plate 10) of the present invention, viewed from the front end side of the extruder. This die plate 10 has four mounting bolt holes 11 formed therein when viewed from the front, and is attached to the downstream end surface of the extruder main body via the mounting bolt holes 11 using fixing bolts (not shown), and then molded. A die section is configured as an outlet for the resin. High hardness stainless steel (SUS440C) is used for the die plate 10 of this embodiment. Further, as other materials, chromium molybdenum steel (SCM material), aluminum chromium molybdenum steel (SACM material), alloy tool steel material (SKD material), etc. can also be used as appropriate.

The molten resin heated and plasticized in the extruder continuously passes through an orifice (described later) with a predetermined inner diameter formed in the die plate 10 of this die section, and is discharged out of the extruder. A cord-like strand (FIG. 4(b)) is formed. In this embodiment, the orifice is a small diameter through hole formed in an orifice pin 20 (described later in FIG. 2) that is incorporated as a separate member from the die plate 10 main body. In addition, in the die plate 10 of this embodiment, as shown in FIG. 1(a), four orifice pins 20 are provided on the die plate 10 so that, for example, four strands can be formed in parallel at the same time. They are installed side by side at a predetermined interval (after installation: Fig. 4(a)).

As shown in FIGS. 1(a) and 1(b), the inner surface of the die plate 10 (upstream side in the resin flow direction) to which the orifice pin 20 is attached has a flat horizontally elongated shape in which the inner part 12a is semicircularly convex. A recess 12 is formed. This flat and horizontally elongated recess 12 functions as a buffer section for temporarily storing the molten resin transported by a screw or the like (not shown) and uniformly flowing the molten resin into each orifice. Furthermore, four orifice pin holding holes 13 are formed in the semicircular convex inner part 12a along the longitudinal direction of the flat oblong recess 12 at predetermined intervals. The orifice pins 20 (FIG. 2(a)) are attached so as to be tightly fitted into each orifice pin holding hole 13, as shown in FIGS. 3(a) and 3(b). Therefore, the inner wall shape of the orifice pin holding hole 13 is set to follow the overall outer shape of the orifice pin 20. Note that the diameter of the orifice through which the plasticized resin passes can be set arbitrarily according to the characteristics of the various thermoplastic resins to be extruded, and the size of the die plate 10 and the size of the die plate 10 can be set according to the scale and specifications of the molding machine. It goes without saying that the number of orifice pins 20 installed can be set as appropriate.

Furthermore, since the extruder of the present invention is intended to extrude super engineering plastics (such as PEEK resin), a heater (not shown in the figure) is installed in the die plate 10 to prevent the resin temperature from decreasing when passing through the die plate 10. ) is equipped. The heater is stored in a circular hole-shaped heater storage part 14 that runs vertically through the die plate 10, is heated by electricity from an external power source, and is passed through the die plate 10 by raising the die plate 10 to a predetermined temperature. The temperature of the molten resin can be kept at a predetermined temperature. It goes without saying that the present invention can be applied to the efficient production of high-quality molded products of various engineering plastics and filler-filled general-purpose plastics, in addition to the molding of the above-mentioned super engineering plastics.

Here, the configuration of the orifice pin 20 attached to the die plate 10 shown in FIG. 1 will be explained with reference to each figure in FIG. 2. The orifice pin 20 of this embodiment includes a main body part 20a (length 11 mm, outer diameter Φ7 mm) with a total length of 15 mm, a haunch part 20b (length 1 mm, haunch angle 45°) that widens the outer diameter of the main body part 20a, It has a substantially cylindrical shape that is integrated with a collar part 20c (length 3 mm, outer diameter Φ9 mm) whose outer diameter is enlarged with respect to the main body part 20a, and a through hole 21 (inner diameter Φ3 mm) is formed along the central axis direction. It is formed. This through hole 21 functions as an orifice (nozzle) through which the molten resin passes. Further, a gentle taper portion is formed on the end surface of the through hole 21 on the molten resin inlet side. Hereinafter, this through hole will be referred to as the "orifice 21" as a functional name. In order to form a homogeneous strand, the length of the land is set to about 13.6 mm out of the total length of the orifice 21 in order to define the diameter of the strand and maintain its shape.

Of the overall shape of the orifice pin 20, the haunch portion 20b connecting the main body portion 20a and the collar portion 20c is set to have a taper angle of 90° (haunch angle of 45°). The haunch portion 20b and the collar portion 20c having an enlarged diameter are brought into close contact with the haunch portion 13b and the enlarged diameter portion 13c formed on the inner wall surface of the orifice pin holding hole 13 formed in the die plate 10. This can prevent the orifice pin 20 fitted into the die plate 10 from rotating and falling off during resin molding.

Further, by setting the length (thickness) of the collar portion of the orifice pin 20 to about 3 mm, it is possible to sufficiently withstand the internal pressure of molten resin (resin pressure) acting on the orifice pin 20 during resin molding.

Furthermore, a gently tapered surface 22 is formed on the molten resin inlet side of the orifice 21. In this embodiment, the angle θ formed by the tapered surface 22 is set to θ=120°. By providing this gently tapered surface 22 on the end face on the resin inlet side, it is possible to prevent a sudden pressure increase of the molten resin that has reached the orifice 21 and the accompanying decomposition of the resin. Thereby, the generation of gas due to resin decomposition, which causes corrosion of the orifice 21, can also be suppressed. It is preferable that the taper angle θ to obtain this effect is approximately 90° to 150°.

In addition, it is preferable to set the land length of the orifice 21 in the orifice pin 20 to 10 to 20 mm, and within this range, the shear rate applied to the molten resin passing through the orifice 21 is moderated, and the temperature rise of the molten resin is suppressed. can do. The dimensions of each part of the orifice pin 20 mentioned above (total length, collar thickness, taper angle, land length, etc.) are set as appropriate depending on the characteristics of the thermoplastic resin used and the specifications (size, material) of the strand to be molded. It is preferable to do so.

The orifice pin 20 of this embodiment is made of cemented carbide (approximately VM 10 to 50). Furthermore, instead of cemented carbide such as WC-Co alloy, cemented carbide steel or the like having equivalent strength may be used. For example, the strength of cemented carbide is higher than that of the die plate 10, has high resistance to abrasion, corrosion, staining, etc., and is less susceptible to deterioration than the die plate 10. Therefore, roughness is less likely to occur due to abrasion caused by generated cracked gas and molten resin passing through the orifice 21, and the smoothness of the inner wall surface of the orifice 21 can be maintained. This makes it possible to ensure a uniform flow of the thermoplastic resin passing through the orifice 21, and to significantly reduce the occurrence of eye stain at the outlet of the orifice 21, which impairs the stability of manufacturing and the quality of the obtained product. . The specifications of the molded product include reinforcing fibers, fillers, additives, flame retardants, etc. in the thermoplastic resin, making it possible to effectively deal with cases where eye stains are likely to occur.

As described above, the material of the orifice pin 20 in this embodiment has sufficient durability and has a slower deterioration rate than the die plate 10, so the orifice pin 20 has a long life and can be used for a long period of time. , the time for replacing the orifice pin 20, etc. can be extended.

Each figure in FIG. 3 is a partially enlarged view showing a state in which the orifice pin 20 is attached to the flat, horizontally elongated recess 12 of the die plate 10. As shown in FIG. 3(a), the overall external shape of the orifice pin 20 is approximately the same as the inner wall surface shape of the orifice pin holding hole 13 formed in the flat oblong recess 12 of the die plate 10. Become. As a result, the orifice pin 20 installed in the orifice pin holding hole 13 on the die plate 10 side is held in close contact with the inner wall surface of the orifice pin holding hole 13 (FIG. 3(b)).

FIG. 4 shows a longitudinal section of the orifice pin 20 installed in the flat, horizontally elongated recess 12 of the die plate 10. As shown in FIG. As shown by the arrow in the figure, the molten resin R smoothly flows from the flat oblong recess 12 along the resin path formed in the die plate 10 via the tapered surface 22 of the orifice pin 20. The strand S flows into the orifice 21 and is discharged from the discharge side with a predetermined diameter.

As described above, in the extrusion molding operation using the orifice pin 20 of the present invention, if the inner wall surface of the orifice 21 deteriorates as a result of the long-term molding operation, or if the diameter of the strand to be molded changes. Even in this case, it is sufficient to leave the die plate 10 as it is and replace it with a new orifice pin 20 or an orifice pin 20 with an inner diameter of the orifice 21 that corresponds to the change, which greatly simplifies and streamlines the maintenance work.

Note that the present invention is not limited to the embodiments described above, and various changes can be made within the scope of each claim. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included within the technical scope of the present invention.

10 Die plate 12 Recess 13 Orifice pin holding hole 14 Heater storage hole 20 Orifice pin 21 Orifice 22 Tapered surface R Molten resin S Strand

Claims (8)

A die plate body attached to the molten resin discharge side in the extruder;
an orifice pin that is fitted into an orifice pin holding hole provided in the die plate main body from the inflow direction of the molten resin, and has an orifice of a predetermined inner diameter formed in the axial direction through which the molten resin passes and is discharged;
A die plate for an extruder characterized by being equipped with. The die plate for an extruder according to claim 1, wherein the orifice pin holding hole is provided in a recess in the die plate main body in which molten resin is stored. 2. The orifice pin according to claim 1, wherein a collar portion whose diameter is enlarged from the main body portion through a haunch portion is formed on the inlet side of the molten resin, and the collar portion is held in position within the orifice pin holding hole by the haunch portion. Die plate for extruder. 4. The die plate for an extruder according to claim 3, wherein the orifice pin has a tapered surface that guides the molten resin to the orifice, and is formed on an end surface of the collar portion on the molten resin inlet side. The die plate for an extruder according to claim 1, wherein the orifice is provided with a land of a predetermined length continuously on the tapered surface. The die plate for an extruder according to claim 1, wherein the material strength of the orifice pin is higher than the material strength of the die plate main body. The die plate for an extruder according to claim 4 or 5, wherein the tapered surface has a taper angle of about 120°. The die plate for an extruder according to claim 5, wherein the land length of the orifice is set to 10 to 20 mm.

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