JPS63260423A - Extrusion nozzle and its manufacture - Google Patents

Abstract

PURPOSE:To enable a plastic material to solidify up to a state where the same is cuttable by removing tackiness by cooling the same rapidly during its passing through an extrusion nozzle, by a method wherein inlet side opening parts of through holes formed in large numbers in a flat plate of a predetermined thickness are rounded and a plurality of grooves, where the closer a depth of the groove comes to an outlet side opening the deeper it becomes, are engraved radially extending to an outlet side opening part from a position deflected to an inlet side then the middle point. CONSTITUTION:A nozzle fitted to the tip of an extruding machine is one obtained by forming a large number of through holes 2 in a flat plate 1 of a predetermined thickness. An opening part 3 of the surface facing on the extruding machine is rounded, the smallest point A in relation to an area of a through hole is possessed at a position deflected to an inlet side from the middle point M of a thickness of the flat plate and a plurality of grooves 5...5 are engraved radially extending to an outlet side opening part 4 of a material from the smallest point A, in a form of the through holes 2. A trough line runs along an axial direction, and the closer a depth of the through comes to the outlet side opening part 4 the deeper it becomes, in a from of a lined groove 5. With this construction, as the material passes through the nozzle while it is being cooled, it is solidified to appropriate viscosity suitable for cutting process.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an extrusion nozzle used in extrusion molding of plastics, and is particularly applied to the production of plastic pellets.

<Prior Art> In the production of plastic pellets, a soft string-like plastic extruded from an extrusion nozzle is immediately cut into predetermined dimensions, or after being cooled in phlegm or cold air, it is cut into predetermined dimensions.

<Problems to be Solved by the Invention> When cutting a string-like plastic extruded from a nozzle into pellets, it is preferable to cut the string-like plastic immediately after it comes out of the nozzle. However, the plastic material inside the extruder is still in a liquid state at high temperatures, and even though the nozzle has a predetermined thickness, it is still sticky immediately after passing through the nozzle, even if it is cut with a cutter. However, there is a problem in that the cut pieces stick together again due to their own stickiness.

Further, when the nozzle material is worn out over many years of use, the dimensional accuracy decreases, so a wear-resistant material is required. However, although hard materials generally have excellent wear resistance, they are difficult to cut and have a high melting point or firing temperature.

For example, ceramic is hard, but cutting after firing is extremely difficult and requires a long time to grind. Furthermore, materials with high firing or casting temperatures require high temperature resistance in their molds, and such materials are not easy to process and difficult to obtain into complex shapes.

In addition, in casting technology, the "r core" must be extracted after casting, and usually has a tapered draft angle, but if there is a minimum point of cross-sectional area between the two ends, it is necessary to extract it. The problem is that it is not possible.

Therefore, the first object of the present invention is to provide an extrusion nozzle in which a plastic material is rapidly cooled while passing through the extrusion nozzle, and when it exits the nozzle, it is no longer sticky and solidifies to a state where it can be cut. It is.

A second object of the present invention is to provide a method for manufacturing an extrusion nozzle that can be manufactured easily and at low cost even when such an extrusion nozzle is made of ultra-hard material such as ceramics.

<Means for solving the problems> The configuration of the extrusion nozzle of the present invention is a device that is attached to the tip of an extruder and has a large number of through holes formed in a flat plate of a predetermined thickness. The entrance side opening of the through hole is rounded, and a valley line runs along the axis from a position offset toward the entrance side from the midpoint of the predetermined thickness to the exit side opening, and the depth of the valley is the same as the exit side. It is characterized by a plurality of radial grooves that become deeper as they get closer to the opening.

In addition, the method for manufacturing an extrusion nozzle of the present invention has a minimum point (B) of the cross-sectional area at a position offset from the midpoint CM), and the cross-sectional area is A plurality of protrusions that expand in a trumpet shape and whose ridge line runs along the axis toward the far end from the minimum point (B), and the height of the ridge line increases as it approaches the far end. is formed radially and has a holding part extending outward in the axial direction from both ends,
In addition, a core made of a material with a melting point higher than the temperature during molding is used, and the cores are arranged in the same direction at a predetermined position in the mold to constitute a mold or mold, and the extrusion nozzle is molded. After that, the core is removed.

Methods for removing the core include heat melting, tensile fracture, melting with chemicals, and a method of dividing the core into two.

<Example> FIG. 1 shows a sectional view of an extrusion nozzle according to an example of the present invention, and FIG. 2 shows a side view as seen from the material outlet side.

The nozzle attached to the tip of the extruder is a flat plate 1 of a predetermined thickness with a large number of through holes 2 formed therein. The shape of the through hole 2 is such that the opening 3 on the material inlet side, that is, the face facing the extruder, is rounded, and the minimum penetration area A is located at a position deviated toward the inlet side from the midpoint M of the thickness of the flat plate. A plurality of grooves 5...5 are radially carved from the minimum point A to the opening 4 on the exit side of the material. - Groove 5
The shape is such that the valley line runs along the axial direction, and the depth of the valley becomes deeper as it approaches the outlet opening 4. Further, the inner diameter of the portion where no groove is formed is tapered so that it gradually increases as it approaches the outlet opening 4. Note that piping 6...6 is provided for each groove of the outlet opening 4, through which cooling water or cold air can be sent into the groove.

The material entering the through hole 2 having such a shape has a rounded entrance, so the resistance when entering the through hole is small, and after passing the minimum point A, the contact area is reduced due to the groove, and furthermore, Because the inner diameter gradually increases, the material passes through the through hole without resistance, and the material is rapidly cooled while passing through the nozzle by cooling water or cold air supplied into the groove, changing from a liquid state to a solid state. It is ejected outside the nozzle.

Next, an example of a manufacturing method when the extrusion nozzle of the present invention is made of ceramics will be described.

FIG. 3 shows a core 10 used in the manufacturing method of the present invention.

This core 10 has a minimum point (B) of cross-sectional area at a position offset from the midpoint (M), and expands in a trumpet shape toward the end 11 near the minimum point (B). However, a taper is formed that gradually expands toward the end 12 far from the minimum point (B), and a plurality of protrusions 18 . . . 18 are formed radially. - The shape of the protrusion 18 is such that the ridge line runs along the axial direction, and the height of the protrusion increases as it approaches the end portion 12.

Also, a holding portion 13. which extends outward from both ends 11.12.
14 is formed. This core 10 is held by a lower mold 15 and an upper mold 16, as shown in FIG. 4, and arranged side by side in the same direction to form a mold. Using this mold, a ceramic material mixed with alumina powder, a sintering aid, an organic binder, and a solvent is cast and formed.

After the molded product is taken out of the mold, the core is melted and removed by heating, and then the ceramic is fired to obtain the product of the present invention. The melted and removed core material can be remolded and reused.

As another manufacturing method of the present invention, after the ceramic material is molded, a tensile load may be applied to both ends of the core 10 to cause tensile fracture and removal.

In addition, as yet another manufacturing method, a removable fitting portion may be provided at the minimum point B of the core to form a two-part structure, and the core may be removed non-destructively.

FIG. 5 shows a side view of another embodiment of the core.

The radial protrusion of this core is 2 along a plane P passing through the axis.
A striped protrusion 19a and two upper and lower protrusions 19b perpendicular to it
It consists of Therefore, it can be molded using a two-part mold.

The core of the present invention can be made of various materials. Above all, glass is easy to mold with a mold,
It has the advantages of being able to withstand high pressure during ceramic formation, having a smooth surface, easy regeneration after melting and removal, and low material cost.

The extrusion nozzle of the present invention is not limited to ceramics, but can also be made of castable metal.

<Effects of the Invention> According to the extrusion nozzle of the present invention, the material passes through the nozzle without being cooled by direct contact with cooling water or cold air, so the material is cooled in a very short time before reaching the nozzle outlet. It solidifies to a viscosity suitable for cutting.

In addition, in the method of the present invention, the core is removed after molding by melting, tensile fracture, etc., so it can be manufactured easily and at low cost.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the extrusion nozzle of the present invention, Fig. 2 is a side view seen from the exit side of Fig. 1, and Fig. 3 shows a 1° core used in the manufacturing method of the present invention. 4 is a sectional view showing a mold used in the manufacturing method of the present invention, and FIG. 5 is a side view showing a modified example of the core used in the manufacturing method of the present invention. 1... Flat plate 2... Through hole 3... One end of the through hole 4... Other end of the through hole 5... Groove 10... Core 18... Protrusions 19a, 19b... protrusion

Claims (8)

[Claims] (1) A device used by being attached to the tip of an extruder, in which a large number of through holes are formed in a flat plate of a predetermined thickness, each of the through holes having a rounded inlet opening, and a flat plate of a predetermined thickness. A plurality of grooves are carved radially from a position offset toward the inlet side from the point to the outlet side opening, with the valley line running along the axis, and the depth of the valley becoming deeper as it approaches the outlet side opening. An extrusion nozzle characterized by: (2) The extrusion nozzle according to claim 1, which is made of ceramics. (3) The minimum point (B) of the cross-sectional area is located at a position offset from the midpoint (M), and it expands in a trumpet shape toward the end near the minimum point (B), and the minimum point A plurality of protrusions are formed in a radial manner toward the far end from (B), the ridge line extending along the axial direction, and the height of the ridge line increasing as the distance approaches the far end. A core made of a material that has a holding part that extends outward in the axial direction from the outside and has a melting point higher than the temperature at which the ceramic is molded is used, and this core is placed in a predetermined position in the mold. A method for manufacturing an extrusion nozzle, which comprises forming ceramic materials in parallel in the same direction, removing the core, and then firing the ceramic molded product. (4) The method for manufacturing an extrusion nozzle according to claim 3, wherein the core is made of glass. (5) The method for manufacturing an extrusion nozzle according to claim 3, wherein the core is melted and removed after the ceramic material is molded. (6) The method for manufacturing an extrusion nozzle according to claim 3, wherein after molding the ceramic material, the core is removed by tensile fracture. (7) The method for manufacturing an extrusion nozzle according to claim 3, wherein the core is divided into two at the minimum point (B). (8) The minimum point (B) of the cross-sectional area is located at a position offset from the midpoint (M), and it expands in a trumpet shape toward the end near the minimum point (B), and the minimum point A plurality of protrusions are formed in a radial manner toward the far end from (B), the ridge line extending along the axial direction, and the height of the ridge line increasing as the distance approaches the far end. A core having a holding part extending outward in the axial direction is used, the cores are arranged in a predetermined position in the mold in parallel in the same direction to form a mold, and this mold is used to cast metal. A method for manufacturing an extrusion nozzle, in which the core is removed after casting.