JP2826426B2 - Granulation dies for resin extruders - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a granulating die for a resin extruder provided in a resin pelletizer (granulating device) for cutting a thermoplastic resin into pellets with a cutter while extruding a thermoplastic resin in a heated and molten state. , Which can granulate relatively small pellets.

[0002]

2. Description of the Related Art As one type of a resin granulating apparatus, a thermoplastic resin melted in an extruder is heated at a nozzle end of a granulating die (hereinafter simply referred to as a die) provided at a terminal end of the extruder. A method is known in which the extruded resin is cut and granulated at the outlet end surface (extruded surface) of the nozzle hole by a cutter which is brought into sliding contact with the nozzle while rotating or moving. .

[0003] The diameter of a nozzle hole of a die provided in such a resin granulating apparatus is generally 1 mm or more, and the resin extruded therefrom is released from a pressurized state and expands. And usually 2 mm or more.

[0004]

In recent years, however, there has been a strong demand for reducing the diameter of the resin to be granulated as much as possible for reasons such as convenience in the regeneration process. Generally, when a viscous fluid such as a molten resin is extruded from a fine hole (nozzle hole), its diameter becomes larger than the diameter of the nozzle hole as described above, but the degree of expansion may become smaller as the nozzle hole becomes longer. Are known. That is, as schematically illustrated in FIGS. 4 and 5, two nozzle holes 100 and 200 having the same hole diameter and having a length a and a length b longer than a are provided.
When the molten resin is extruded from the same under the same condition, the diameter of the resin P extruded from the short nozzle hole 100 becomes relatively large Da due to the difference in the peripheral surface resistance and the like in the nozzle holes 100 and 200. The long nozzle hole 20
The diameter of the resin P extruded from 0 becomes Db which is considerably smaller than Da.

Accordingly, in order to reduce the diameter of the resin extruded from the nozzle hole and granulated, the diameter of the nozzle hole may be reduced and the length of the resin may be increased. However, in the die body in which the nozzle hole is formed, the blade of a cutter such as a rotary cutter is slid into contact with the extruded surface in order to cut the extruded resin. It is made of extremely hard metal material with excellent wear resistance such as steel and carbide tool steel. for that reason,
It is extremely difficult to mechanically drill a relatively long nozzle hole having a diameter of less than 1 mm in such a die body with a normal drill or the like. If the diameter of the nozzle hole is about 1 mm, the length is 4 to 4 mm. The limit was about 5 mm.

[0006] It is possible to make the diameter and length of the nozzle hole smaller and longer than the above-mentioned values, respectively, by using an advanced technique such as electric discharge machining. In addition to the necessity of equipment, a large amount of labor and time are required for drilling work, and it is inevitable that the production cost of the dies increases significantly. In view of the above, the present invention is capable of making the diameter and length of the nozzle hole smaller and longer than the conventional one, respectively, without significantly increasing the manufacturing cost of the die, and granulating smaller pellets. It is an object of the present invention to provide a granulating die for a resin extruder, which is capable of performing the following.

[0007]

In order to achieve the above-mentioned object, a granulating die for a resin extruder according to the present invention comprises a nozzle hole formed of a material having good cutting workability in a die body having a nozzle hole. By attaching the extension member, the diameter and the length of the nozzle hole can be easily made small and long, respectively.

Specifically, a resin extruder is provided for an extruder that extrudes a thermoplastic resin in a heated and molten state, and a blade portion of a cutter is slidably contacted with the extruded surface to cut the extruded resin into pellets. A granulating die, wherein a first nozzle hole is formed in a die main body forming the extrusion surface and penetrates in a thickness direction and is opened on the extrusion surface side; A nozzle hole extending member made of a material having a better cutting workability than the die main body having the second nozzle hole having the same hole diameter is formed such that the second nozzle hole is on the same center line as the first nozzle hole. The extruder is fixed such that the distal end thereof is in contact with the die main body so as to be positioned, and the molten resin inside the extruder is extruded toward the extrusion surface through the second nozzle hole and the first nozzle hole. That has been It is characterized in.

The material of the nozzle hole extending member used in the granulating die for a resin extruder according to the present invention is made of a copper-based material such as brass or the like, which is more easily cut than the die body to which the blade of the cutter is slid. It is characterized by being made of an aluminum-based metal material. The method of fixing the nozzle hole extension member to the die body is not particularly limited, but also includes pressure bonding, welding,
Known methods such as bonding, screwing, fitting, and screwing can be used.

Further, the nozzle hole extending member may be manufactured separately for the number of the first nozzle holes in which the die body is formed, and may be individually fixed to the die body.
A plurality of second nozzle holes are formed in the nozzle hole extension member corresponding to the first nozzle holes formed in the die body, and the first nozzle holes and the second nozzle holes match. A plurality of nozzle hole extension members may be fixed to the die body.

[0011]

In the granulating die for a resin extruder according to the present invention having the above-described structure, the die body in which the first nozzle hole is formed is made of a material having better cutting workability. In other words, a nozzle hole extending member made of a material that can easily drill a small-diameter nozzle hole with a drill or the like is fixed.

Therefore, when viewed from the whole die, the length of the nozzle hole is not only the length of the first nozzle hole formed in the die body but also the length of the second nozzle hole formed in the nozzle hole extending member. It will be extended by that amount. This means that the thickness of the nozzle hole forming portion in the die body portion which needs to be made of a hard material having excellent wear resistance because the blade portion of the cutter is brought into sliding contact can make a small diameter nozzle hole. This means that the entire length of the nozzle hole can be increased by the nozzle hole extending member even if the thickness is reduced.

By doing so, it is possible to relatively easily make the diameter and length of the nozzle hole smaller and longer than the conventional one, respectively, without significantly increasing the manufacturing cost of the die. Can be granulated.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a bottom view of one embodiment of a granulating die for a resin extruder according to the present invention as viewed from the extrusion surface side, and FIG. 2 is a sectional view of the die shown in FIG. In the figure, a die body 20 is formed in a substantially short cylindrical shape entirely from an extremely hard metal material having excellent wear resistance, such as a hardened carbon steel or an alloy steel. A shaft hole 21 through which the rotary shaft of the rotary cutter 50 is inserted is formed, and a bolt insertion hole 22 through which a bolt for attaching the die main body 20 to the extruder is formed at a predetermined angular interval on the outer peripheral side. ing.

The bottom surface of the die body 20 is formed as an annular extrusion surface 20a on which the blade portion 50a of the rotary cutter 50 is brought into sliding contact.
A large number of first nozzle holes 25 in a direction orthogonal to
Are perforated. The first nozzle holes 25 are arranged as shown in FIG.
As can be clearly understood from the above, they are arranged in a zigzag pattern at regular intervals so as to go around the extrusion surface 20a.

Above each first nozzle hole 25, a concave portion 28 having a circular cross section which opens upward is provided with the first nozzle hole 25.
The nozzle hole extension member 30 having a circular cross-sectional outer shape is pressed into the concave portion 28 by pressure. The nozzle hole extending member 30 is made of an aluminum alloy having a better machinability than the die main body portion 20, and has a second hole diameter equal to that of the first nozzle hole 25 so as to pass through the center thereof and penetrate in the longitudinal direction. A nozzle hole 35 is formed.

Therefore, the nozzle hole extending member 30 has a second nozzle hole 35 formed on the same center line as the first nozzle hole 25 formed in the die body 20, and a tip end thereof. That is, the die body 20 is fixed by being brought into contact with the bottom surface of the concave portion of the die body 20. Here, in this embodiment, the first nozzle hole 25 has a diameter of 0.6.
mm, the length is 3 mm, and the diameter of the second nozzle hole 35 is the same as that of the first nozzle hole 25.
The length is 6 mm and the length is 7 mm.

In such a configuration, the molten resin inside the extruder passes through the combined nozzle hole 32 composed of the second nozzle hole 35 and the first nozzle hole 25 as shown by a dashed line in FIG. It is extruded to the 20a side, cut by the rotary cutter 50, and granulated. In this case, the diameter of the extruded resin P was about 1.0 to 1.1 mm, and the extruded resin cut by the cutter 50 was spherical.

On the other hand, as shown in FIG. 3, when the molten resin was extruded from the die (comparative example) from which the nozzle hole extending member 30 was removed under the same conditions as described above, the diameter of the extruded resin P was The resin extruded and cut by the cutter 50 was 1.4 to 1.5 mm, and was a lens-shaped irregular thing which could not be said to be spherical. As described above, in the present embodiment, the nozzle main body 20 in which the first nozzle holes 25 are formed is easily formed with a nozzle having a smaller diameter by using a material having a better cutting workability, in other words, a drill. Since the nozzle hole extension member 30 made of a material that can be pierced is attached, the length of the nozzle hole (32) in the entire die is equal to the length of the first nozzle hole 25 formed in the die body. In addition, the length is extended by the length of the second nozzle hole 35 formed in the nozzle hole extension member 30.

For this reason, since the blade portion 50a of the cutter 50 is slidably contacted, the thickness of the nozzle hole forming portion in the die main body portion 20 which needs to be made of a hard material having excellent wear resistance is reduced. Even when the nozzle hole is relatively thin so as to obtain the same, the entire length of the nozzle hole can be increased by the nozzle hole extending member 30, so that the diameter and length of the nozzle hole can be relatively easily reduced without significantly increasing the manufacturing cost of the die. Can be made smaller and longer than conventional ones, and smaller pellets can be granulated.

In the above-described example, the nozzle hole extending members 30 are individually formed for the large number of the first nozzle holes 25, and these are individually pressed to the concave portions 28, but they are not necessarily required. You don't have to do that, for example
A nozzle hole extension member having a size sufficient to cover all or some of the first nozzle holes 25 is prepared, and a number of second nozzle holes 35 corresponding to the first nozzle holes 25 are pierced therein. It goes without saying that various changes may be made, such as fixing the nozzle hole extending member to the die body 20 with screws or the like.

[0022]

As is clear from the above description, according to the granulating die for a resin extruder according to the present invention, the diameter and the length of the nozzle hole can be reduced without increasing the production cost of the die. An excellent effect can be obtained in that the pellets can be made smaller and longer than the ones, and smaller pellets can be granulated.

[Brief description of the drawings]

FIG. 1 is a bottom view of one embodiment of a granulating die for a resin extruder according to the present invention.

FIG. 2 is a sectional view of the die shown in FIG. 1;

FIG. 3 is a sectional view of a die body of a comparative example.

FIG. 4 is a diagram for explaining the relationship between the length of a nozzle hole and the diameter of extruded resin.

FIG. 5 is a diagram for explaining the relationship between the length of the nozzle hole and the diameter of the extruded resin.

[Explanation of symbols]

 Reference Signs List 20-die body portion 20a-extrusion surface 25-first nozzle hole 28-recess 30-nozzle hole extension member 32-coalesced nozzle hole 35-second nozzle hole 50-rotary cutter P-extruded resin

Claims (1)

(57) [Claims] 1. A granulating die for a resin extruder, which is provided in an extruder that extrudes a thermoplastic resin in a heated and molten state, and in which a blade portion of a cutter is slidably contacted with an extruded surface to cut the extruded resin into pellets. Wherein a first nozzle hole is formed in a die main body portion forming the extrusion surface and penetrates in a thickness direction thereof and opens to the extrusion surface side, and a second nozzle hole having the same hole diameter as the first nozzle hole is formed. The nozzle hole extending member made of a material having a better cutting workability than the die body portion having the nozzle hole formed therein such that the second nozzle hole is located on a common center line with the first nozzle hole. The tip of the extruder is fixed to the die body so that the tip of the extruder contacts the second nozzle hole and the first nozzle.
Through the nozzle hole to a granulating die for the resin extruder that is to be extruded in the extrusion face, said nozzle
The hole extension member is made of copper or aluminum, such as brass.
For resin extruders characterized by being made of metal material
Granulation dies.