KR100929775B1 - Extruder with extrusion head with improved resin flow - Google Patents

Abstract

The present invention relates to an extruder having an extruded head portion in which the resin flow is improved so as to optimize the flow characteristics of the molten resin in the extruded head portion to reduce the closed end such as premature crosslinking of the molten resin and contribute to the improvement of the quality of the molded article.

The extruder of the present invention is an extruder which transfers the raw material resin to the extrusion head part in front of the barrel 100 by the screw 200 installed inside the barrel 100 and supplies it to the molding part. The tapered tape is gradually reduced in diameter toward the outlet. A reducer assembly 300 coupled to the front end of the barrel 100 with an inner wall surface 301 and an extrusion port 302 from the inner wall surface 301 toward the molding portion, and an inner wall surface of the reducer assembly 300. A screen mesh 400 installed at the 301 or the extrusion hole 302, and a breaker plate 500 installed at the reducer assembly 300 to support the screen mesh 400, wherein the screw 200 The tapered cone portion 210 is formed at the tip end of the tapered cone portion 210, the outer diameter of which gradually decreases toward the outlet side, and the tip of the tapered cone portion 210 is in close contact with the central surface of the screen mesh 400 or the screen mesh 400. Of) Through the hem it is disposed so close to the central surface of the breaker plate 500.

Extrusion, barrel, screw, resin, flow, screen, reducer, breaker

Description

EXTRUDER HAVING AN EXTRUDING HEAD PART IMPROVED RESIN FLOW}

The present invention relates to an extruder, and more particularly, to improve the flow characteristics of the molten resin in the extrusion head portion to reduce the closed end, such as early crosslinking phenomenon of the molten resin and to improve the quality of the molded article is improved An extruder having an extrusion head portion.

The extruder supplies the raw material resin (mainly thermoplastic resin) into the barrel through a hopper provided at the rear of the barrel, and the supplied raw resin is transferred to the front extrusion head part by the rotation of the screw installed in the barrel. It is melted and kneaded and supplied to a molding part (e.g., molding die, cross head, etc.).

Figure 1 schematically shows the structure of an extrusion head of a conventional general extruder. A reducer assembly 30 is installed at the end of the barrel 10 while a screw cone 21 formed at the end of the screw 20 is located inside the head portion in front of the barrel 10. A screen mesh 40 and a breaker plate 50 are installed at the outlet side of the reducer assembly 30. The screen mesh 40 is for filtering out foreign substances mixed in the resin, and the breaker plate 50 is for tightly fixing and fixing the screen mesh 40. The breaker plate 50 is formed with a plurality of holes (not shown) for the molten resin to pass through.

Since the head portion of the barrel 10 is a portion which is the final step of supplying the molten resin to the molding portion, the flow characteristics of the molten resin have a significant influence on the quality of the molded article.

For example, looking at the flow of molten resin in the conventional barrel 10 head portion, as can be seen in Figure 1, the melting in the 'A' region between the central end of the screw cone 21 and the breaker plate 50 The resin is stagnant in the process of meeting, and in the 'B' area, which is the front center portion of the breaker plate 50, the stagnation is affected by the flow of the 'A' area. In addition, as the cone inner wall 31 of the reducer assembly 30 is closer to the breaker plate 50, such as the region 'C', stagnation occurs due to frictional resistance with the inner wall 31. This results in an abnormal phenomenon such as unintended imbalance in the entire flow of the passage through which the molten resin exits, and thus the quality of the molded product is deteriorated because the required characteristics of the molten resin cannot be maintained.

In addition, the cone inner wall 31 of the reducer assembly 30 has a low temperature due to the cooling action on the wall side, but the resin temperature is higher toward the center, and 'D' adjacent to the breaker plate 50 is affected. There is a risk of temperature overheating in the region.

The above problems are particularly serious in the process of extruding and coating crosslinked polyethylene such as power cables and optical cables. For example, a cross-linked polyethylene (XLPE) coating process for power cables is well known by the US Patent No. 5,239,813 and Korean Patent Application No. 2008-0007389. It is a process of coating the insulator which has excellent heat resistance and mechanical performance by causing crosslinking reaction under high pressure and changing polyethylene molecules into three-dimensional network structure. In this coating step (insulation step), the polyethylene to which the crosslinking agent is added is extruded and coated on a conductor through an extrusion head (more specifically, a triple coextrusion crosshead) of an extrusion device, and the cable exiting the extrusion device is crosslinked. And a crosslinking reaction and cooling through a cooling tube.

In this way, particularly in the extrusion process of a resin containing a crosslinking agent, the crosslinking reaction must proceed in the crosslinking tube after passing through the extrusion head, but as described above, the extruder is caused by an imbalance in the flow rate or temperature of the molten resin in the extruder. There is a fear that the 'early crosslinking' phenomenon in which the crosslinking reaction proceeds in advance in the head portion of the film. Premature crosslinking in the insulation manufacturing process of power cables, such as high voltage cables, results in dielectric breakdown.

For example, the conditions under which premature crosslinking occurs are when the resin temperature is higher than the required value or the resin flow rate is slower than the required value.

In light of this, when looking at FIG. 1, a large part of the risk of early crosslinking is mainly near the front and rear of the breaker plate 50 (eg, 'A' region, 'B' region, 'D' region and 'C' region). And near the inner wall 31 of the reducer assembly 30 close to the breaker plate 50 (eg 'C' region).

The present invention was developed to solve the above problems, by improving the extruded head portion to a structure that can optimize the flow characteristics of the molten resin can reduce the closed end, such as premature crosslinking of the molten resin can contribute to the improvement of the quality of the molded article It is an object to provide an extruder having an extrusion head portion with improved resin flow.

In order to achieve the above object, an extruder having an extruded head portion with improved resin flow according to the present invention is an extruder for transferring a raw material resin to the head portion in front of the barrel by a screw provided in the barrel, and feeding it to the molding portion. A tapered cone portion is formed at the tip of the tape, and the tip of the tapered cone portion is arranged to be in close contact with the center surface of the screen mesh or the center surface of the breaker plate, thereby eliminating the space between the screw tip and the breaker plate, thereby eliminating the molten resin from the screw. Instead of stagnating in the space between the screw tip and the breaker plate, it is to pass straight through the breaker plate.

Specifically, the extruder of the present invention, the reducer assembly coupled to the front end of the barrel having a tapered inner wall surface of the tapered shape gradually toward the exit and the extrusion port toward the molding portion from the inner wall surface, the inner wall surface of the reducer assembly Or a screen mesh installed in the extrusion port, and a breaker plate installed in the reducer assembly to support the screen mesh, wherein the tip portion of the screw is formed with a tapered cone portion whose outer diameter gradually decreases toward the outlet side. The tip of the cone portion is configured to be in close contact with the central surface of the screen mesh or through the center of the screen mesh to be in close contact with the central surface of the breaker plate.

In the extruder of the present invention, the breaker plate is rotatably coupled to the reducer assembly, the tip of the tapered cone portion of the screw is integrally coupled to the breaker plate in a detachable state, the screw and the breaker plate When the unit rotates integrally, the phenomenon of stagnation of the molten resin on the inner wall surface of the reducer assembly can be reduced, and the flow characteristics of the molten resin can be improved in any zone.

In the extruder of the present invention, a cutting plane portion may be formed at the front end of the tapered cone portion of the screw for close contact with the screen mesh or the breaker plate.

In the extruder of the present invention, the reducer assembly may be configured to be divided into a reducer ring and reducer support, in which case the reducer ring is formed with the inner wall surface and the screen mesh and breaker plate Is installed, the reducer support may be configured to form the extrusion hole.

Here, the extrusion port may comprise a tapered inlet portion whose inner diameter gradually decreases toward the outlet side, and an outlet portion extending from the inlet portion to the outlet side by a constant diameter.

The extruder of the present invention has a structure in which the cone portion of the screw tip is in contact with the center of the screen mesh or the breaker plate, so that the molten resin stagnates near the center of the front and rear surfaces of the breaker plate while inducing the molten resin smoothly and constantly to the breaker plate. This phenomenon is reduced, thereby improving the flow characteristics of the molten resin.

In addition, according to the structure in which the screw and the breaker plate are integrally coupled and rotated, the flow of the molten resin and the kneading of the molten resin are more smoothly maintained by maintaining the flow of the molten resin coming out while rotating by the screw, and at the inner wall surface of the reducer assembly. Stagnant phenomena of the molten resin can be reduced to optimize the flow characteristics of the molten resin, thereby improving the quality of the molded article.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Example 1)

2 is a cross-sectional view showing the extrusion head portion of the extruder according to the first embodiment of the present invention.

As shown in FIG. 2, the extruder according to the present invention is an extruder that transfers a raw material resin to a head part in front of the barrel 100 by a screw 200 installed inside the barrel 100 and supplies the same to the molding part.

In the present invention, the reducer assembly 300 is coupled to the head portion in front of the barrel 100. The reducer assembly 300 has a tapered inner wall surface 301 which gradually decreases in diameter toward the outlet, and an extrusion hole 302 which faces the molding part from the inner wall surface 301.

The reducer assembly 300 is provided with a screen mesh 400 for filtering foreign substances contained in the molten resin and a breaker plate 500 for supporting the screen mesh 400 thereof. The screen mesh 400 is installed near the tapered inner wall surface 301 of the reducer assembly 300 or the extrusion hole 302, and the breaker plate 500 supports the screen mesh 400 closely. Is installed. As the breaker plate 500 is well known, a plurality of through holes 501 are densely formed so that the molten resin having passed through the screen mesh 400 can easily flow to the outlet side.

A tapered cone portion 210 is formed at the tip end of the screw 200, the outer diameter of which gradually decreases toward the outlet side. In particular, the tip of the tapered cone portion 210 is disposed to be in close contact with the central surface of the screen mesh 400 or through the center of the screen mesh 400 to be in close contact with the central surface of the breaker plate 500. . If the tip of the tapered cone portion 210 and the breaker plate 500 of the screw 200 is spaced apart as in the prior art, the molten resin and the tip of the tapered cone portion 210 before reaching the breaker plate 500 Gathered in the space between the breaker plate 500 will be stagnant. However, when the tip of the tapered cone portion 210 of the screw 200 is in close contact with the breaker plate 500 as in the present invention, molten resin flows directly into the breaker plate 500 along the tapered cone portion 210 to break the plate. By exiting the through hole of 500, the phenomena of the molten resin do not occur anywhere near the inlet side center or near the outlet side center of the breaker plate 500. As such, when the stagnation phenomenon near the front and rear centers of the breaker plate 500 disappears, the overall flow characteristics of the molten resin are also improved, and thus, there is no temperature increase in the vicinity adjacent to the center of the passage of the extrusion port 302.

On the other hand, the reducer assembly 300 may be formed to be divided into a reducer ring 310 and a reducer support 350. The reducer ring 310 is formed with an inner wall surface 301 having a tapered passage, and the screen mesh 400 and the breaker plate 500 are installed at an outlet portion of the passage. The reducer support 350 is formed with the above-described extrusion hole 302. The reducer support 350 is coupled to the rear end of the barrel 100 while closely supporting the breaker plate 500 and the reducer ring 310.

3 is an enlarged view showing two examples of the close contact between the tapered cone portion 210 and the breaker plate 500 of the screw 200. In the above description of FIG. 2, that the 'tip of the tapered cone portion 210 is in close contact with the breaker plate 500' means that the tip of the tapered cone portion 210 is in close contact with the screen mesh 400 or the breaker plate ( Close to 500). Since the screen mesh 400 and the breaker plate 500 are in close contact with each other, the screen mesh 400 and the breaker plate 500 are representative of only one of the breaker plates 500. In practice, as shown in (a) and (b) of FIG. 3, the tip of the tapered cone portion 210 of the screw 200 may be formed as shown in (a) of FIG. 3. It may be in close contact with the center surface, or may be in close contact with the center surface of the breaker plate 500 through the center of the screen mesh 400 as shown in (b) of FIG. When the tip of the tapered cone portion 210 of the screw 200 passes through the screen mesh 400 as shown in FIG. 3B, the tapered cone portion 210 passes through the center of the screen mesh 400. It is good to form the hole 401 for this in advance.

(Example 2)

4 is a cross-sectional view showing the extrusion head portion of the extruder according to the second embodiment of the present invention.

Extruder according to the present embodiment is different from the configuration of the tip of the tapered cone portion 210 of the screw 200 in the extruder of the first embodiment described above, the rest is the same as the extruder according to the first embodiment.

The screw 200 in this embodiment is formed with a cutting plane portion 211 at the distal end of the tapered cone portion 210. The cutting plane portion 211 helps face-to-face contact with the screen mesh 400 or the breaker plate 500.

In the structure in which the cutting plane portion 211 passes through the screen mesh 400 and closely adheres to the breaker plate 500, the tapered cone portion 210 is formed at the center of the screen mesh 400 as in the above-described embodiment. A hole 401 for the passage of is formed.

(Example 3)

5 and 6 show an extrusion head according to a third embodiment of the present invention, in which a cross-sectional view is shown in FIG. 5, and FIG. 6 is a view of the breaker plate of FIG. 5 from the outlet side toward the inlet side. It is.

The extruder according to the present embodiment has a configuration in which the screw 200 and the breaker plate 500 are integrated to rotate together. The rest of the configuration is the same as that of the extruder according to the first or second embodiment.

That is, the breaker plate 500 is rotatably coupled to the reducer assembly 300, and the tip of the tapered cone portion 210 of the screw 200 is integrally coupled to the breaker plate 500 in a detachable state. do.

In order to enable rotation of the breaker plate 500, the breaker plate 500 may be rotatably supported by the reducer assembly 300 by a bearing 510 such as an oilless bearing, a plain bearing, a bush, or the like. good.

In addition, a fastener 520 such as a bolt may be used for detachable coupling of the breaker plate 500. In this case, as shown in FIG. 6, the fastener 520 penetrates into the center of the breaker plate 500 so as to be screwed and fixed to the center of the tip of the tapered cone portion 210 of the screw 200. can do.

In this case, as shown in FIG. 5, the screen mesh 400 may be interposed between the cutting plane portion 211 of the tapered cone portion 210 and the breaker plate 500 so as to be integrally rotated.

As described above, according to the structure in which the screw 200 and the breaker plate 500 are integrally coupled and rotated, the molten resin flowing while being rotated by the rotation of the screw 200 continues to pass through the breaker plate 500. By keeping constant in a rotating form, the flow of molten resin becomes natural and the kneading becomes more perfect. Therefore, in addition to the advantages obtained in the above-described embodiments, not only the retention of molten resin at the inner wall surface 301 of the reducer assembly 300 is reduced, but also the flow characteristics of the molten resin in any region are reduced. Is improved.

(Example 4)

7 is a cross-sectional view showing the extrusion head portion according to the fourth embodiment of the present invention.

Extruder according to the present embodiment, the shape of the extrusion port 302 formed in the reducer support 350 and the above-described embodiments is different and the rest are the same.

In this embodiment, it is shown that the extrusion port 302 can be composed of an inlet 302a and an outlet 302b. The inlet 302a has a tapered shape in which the inner diameter gradually decreases toward the outlet side. The outlet portion 302b is formed to extend from the inlet portion 302a to the outlet side at a constant diameter.

When the extrusion portion requires a high extrusion speed, the tapered inlet portion 302a acts as a role of the inner wall surface 301 of the reducer ring 310 described above, that is, reduces the passage cross-sectional area to reduce the extrusion speed. Ascends.

1 is a cross-sectional view schematically showing the extrusion head structure and the flow of the raw material resin of the conventional general extruder.

2 is a cross-sectional view showing the extrusion head of the extruder according to the first embodiment of the present invention.

FIG. 3 is an enlarged view showing two examples of the contact form of the tapered cone portion of the screw and the breaker plate in FIG. 2.

4 is a cross-sectional view showing the extrusion head of the extruder according to the second embodiment of the present invention.

5 is a cross-sectional view showing the extrusion head of the extruder according to the third embodiment of the present invention.

FIG. 6 is a view of the breaker plate of FIG. 5 from the outlet side toward the inlet side. FIG.

7 is a cross-sectional view showing the extrusion head of the extruder according to the fourth embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: barrel 200: screw

210: tapered cone portion 211: cut-out plane portion

300: reducer assembly 301: inner wall surface

302: extrusion port 302a: inlet

302b: outlet 310: reducer ring

350: reducer support 400: screen mesh

401: hole 500: breaker plate

501: through hole 510: bearing

520: fastener

Claims (6)

As an extruder for transferring the raw material resin to the head portion in front of the barrel 100 by the screw 200 provided inside the barrel 100 to supply to the molding portion, Reducer assembly 300 coupled to the front end of the barrel 100 having a tapered inner wall surface 301 of the tapered shape toward the exit and an extrusion port 302 from the inner wall surface 301 toward the molding portion and , Screen mesh 400 is installed on the inner wall surface 301 or the extrusion port 302 of the reducer assembly 300, A breaker plate 500 installed in the reducer assembly 300 to support the screen mesh 400, The tip portion of the screw 200 is formed with a tapered cone portion 210 is gradually reduced in outer diameter toward the outlet side, The tip of the tapered cone portion 210 is arranged to be in close contact with the central surface of the screen mesh 400 or through the center of the screen mesh 400 to be in close contact with the central surface of the breaker plate 500. An extruder having an extrusion head portion with improved resin flow. The method of claim 1, The breaker plate 500 is rotatably coupled to the reducer assembly 300, and the tip of the tapered cone portion 210 of the screw 200 is integrally coupled to the breaker plate 500 in a detachable state. And an extruder head having an improved resin flow, wherein the screw 200 and the breaker plate 500 are integrally rotated. The method according to claim 1 or 2, Resin flow, characterized in that the cutting plane portion 211 is formed on the front end of the tapered cone portion 210 of the screw 200 to face-to-face contact with the screen mesh 400 or the breaker plate 500 An extruder having an improved extrusion head. The method according to claim 1 or 2, The reducer assembly 300 is divided into a reducer ring 310 and a reducer support 350, The inner wall surface 301 is formed on the reducer ring 310 and the screen mesh 400 and the breaker plate 500 are installed. Extruder having an extrusion head portion is improved resin flow, characterized in that the reducer support 350 is formed with the extrusion port (302). The method of claim 4, wherein The extrusion port 302 is characterized by consisting of the inlet portion 302a of the tapered form that the inner diameter gradually decreases toward the outlet side, and the outlet portion 302b extending from the inlet portion 302a to the outlet side at a constant diameter. Extruder having an extrusion head portion with improved resin flow. As an extruder for transferring the raw material resin to the head portion in front of the barrel 100 by the screw 200 provided inside the barrel 100 to supply to the molding portion, Reducer ring 310 coupled to the front end of the barrel 100 having a tapered inner wall surface 301 gradually decreases toward the exit, A screen mesh 400 and a breaker plate 500 rotatably installed at an exit side of a passage formed by an inner wall surface 301 of the reducer ring 310, Extruder 302 is formed to be connected to the passage of the reducer ring 310 and the reducer coupled to the rear end of the barrel 100 to block the breaker plate 500 and to support the reducer ring 310 Including support 350, The tip portion of the screw 200 is formed with a tapered cone portion 210 is gradually reduced in outer diameter toward the outlet side, The tip of the tapered cone portion 210 of the screw 200 is integrally coupled to the breaker plate 500 in a detachable state, and the screw 200 and the breaker plate 500 rotate integrally. Extruder having an extrusion head portion with improved resin flow.

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