JPH0698669B2 - Extrusion nozzle manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for manufacturing an extrusion nozzle used in extrusion molding rubber or plastic. Such an extrusion nozzle is used for manufacturing a long product having a predetermined cross-sectional shape and pellets.

<Prior Art> A conventional extrusion nozzle is shown in FIG. Since the through hole 6 forming the nozzle was cut by a drill, the diameter from the inlet to the outlet was the same size and was straight. Therefore, there is a drawback that the frictional resistance when a highly viscous material such as rubber or plastic passes through is large, so that a large thrust force is required for the extruder and the nozzle is rapidly worn.

<Problems to be Solved by the Invention> Generally, hard materials have excellent wear resistance, but are difficult to cut, and have a high melting point or a high forming temperature.

For example, ceramic is hard, but it is difficult to cut it after firing and it takes a long time to grind. Further, a material having a high baking temperature or a casting temperature is required to have a high temperature resistance also in the mold, and such a material is not easy to process, and it is difficult to obtain a material having a complicated shape.

In addition, the "core" in the casting technology must be removed after casting, and usually a tapered draft is provided, but if there is a minimum cross-sectional area in the middle of both ends, remove this. There is a problem that you can not.

Therefore, an object of the present invention is to make an extrusion nozzle, which has a relatively small frictional resistance even when a high-viscosity material passes through, and therefore requires only a small extruder and thrust, and suppresses wear of the nozzle to be a ceramic material. While using a super-hard material
An object of the present invention is to provide a method for manufacturing an extrusion nozzle that can be manufactured easily and at low cost.

<Means for Solving the Problems> The method for manufacturing an extrusion nozzle of the present invention has a minimum point (B) of the cross-sectional area at a position deviated from the midpoint (M), and the minimum point (B). From the minimum point (B) to the end farther from the minimum point (B), the cross-sectional area gradually expands to form a holding portion extending to the outside of the both ends. Using a core made of a material having a higher melting point than the molding temperature, and arranging the cores in the same direction in the mold in the same direction to form a mold or mold, and after molding the extrusion nozzle The feature is that the core is removed.

Examples of means for removing the core include heating and melting, tensile fracture, dissolution by chemicals, and core splitting method.

<Example> FIG. 1 shows a sectional view of an extrusion nozzle manufactured by the method of the present invention.

The nozzle attached to the tip of the extruder is a flat plate 1 having a predetermined thickness with a number of through holes 2 formed therein. The shape of this through hole 2 is such that the minimum point A of the through area is located at a position displaced from the midpoint M of the thickness of the flat plate to the inlet side by rounding the opening 3 on the inlet side of the material, that is, the surface facing the extruder. And a taper whose cross-sectional area gradually increases from the minimum point A to the opening 4 on the material outlet side.

The material that enters the through-hole 2 having such a shape has a small resistance when entering the through-hole because the inlet is rounded, and after passing through the minimum point A, the cross-sectional area gradually expands so that the material penetrates without resistance. The material is cooled while passing through the holes and passing a predetermined thickness, and is changed from a liquid state to a solid state and is discharged to the outside of the nozzle.

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

FIG. 3 shows the core 10 used in the manufacturing method of the present invention. This core 10 has a local minimum point (B) of the cross-sectional area at a position deviated from the central point (M), and expands in a trumpet shape from the local minimum point (B) toward the end 11 closer thereto. However, a taper gradually expanding toward the end 12 farther from the minimum point (B) is formed, and holding portions 13 and 14 extending outward from the both end portions 11 and 12 are formed. This core 10 has a lower mold 15 and an upper mold 16 as shown in FIG.
And hold them in parallel and arrange them 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 molded. After taking out the molded product from 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 core material that has been melted and removed can be remolded and reused.

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

As another manufacturing method, as shown in FIG.
10A, 10B with removable fitting part 17 at the minimum point B of the core
It can also be divided into two parts and removed nondestructively.

The core of the present invention can be made of various materials. Among them, glass is advantageous in that it can be easily molded by a mold, can withstand high pressure during ceramic molding, has a smooth surface, can be easily regenerated after being melted, and has a low material cost. .

The extrusion nozzle of the present invention is not limited to ceramics, and may be made of castable metal.

<Effects of the Invention> According to the present invention, extrusion is performed using a "core" made of a material having a minimum point between the nozzle inlet surface and the outlet surface and having a higher melting point than the temperature at which the ceramic is molded. A high-viscosity material such as rubber or plastic is formed by forming the nozzle mold and removing it from the molded product by methods such as sintering, melting, and tensile fracture without extracting the "core" after temporary molding of ceramics. It is possible to easily and inexpensively manufacture an extrusion nozzle having a small frictional resistance when passing through a nozzle and having an excellent cooling and solidification of a material.

[Brief description of drawings]

FIG. 1 is a sectional view showing an extrusion nozzle manufactured according to the present invention. FIG. 2 is a sectional view showing an example of a conventional extrusion nozzle. FIG. 3 is a front view showing an embodiment of a core used in the manufacturing method of the present invention. FIG. 4 is a cross-sectional view showing a mold used in the manufacturing method of the present invention. FIG. 5 is a front view showing a modified embodiment of the core used in the manufacturing method of the present invention. 10 …… Core 11 …… End nearer to minimum point B 12 …… End farther from minimum point B ………… Holder 14 …… Holder 15 …… Lower mold 16 …… Upper mold

Claims (6)

[Claims] 1. A method for manufacturing an extrusion nozzle, which is used by being attached to the tip of an extruder and has a large number of through holes formed in a flat plate having a predetermined thickness, the method being at a position deviated from a midpoint (M). It has a minimum point (B) of the cross-sectional area, expands in a trumpet shape from the minimum point (B) toward the nearer end, and has a cross-sectional area toward the farther end from the minimum point (B). Use a core made of a material that gradually expands and has a holding portion that extends to the outside of both ends and that has a melting point higher than the temperature at which the ceramic is molded, and use this core at a predetermined position in the mold. A method for manufacturing an extrusion nozzle, in which a ceramic material is molded in parallel in the same direction, the core is removed, and then a ceramic molded product is sintered. 2. A core according to claim 1, wherein the core is made of glass.
A method for manufacturing an extrusion nozzle according to item. 3. The method for producing an extrusion nozzle according to claim 1, wherein the core is dissolved and removed after the ceramic material is molded. 4. The method for producing an extrusion nozzle according to claim 1, wherein the core is removed by tensile fracture after the ceramic material is molded. 5. The method for manufacturing an extrusion nozzle according to claim 1, wherein the core is divided into two at the minimum point (B). 6. A minimum point (B) of the cross-sectional area is provided at a position deviated from the middle point (M), and the minimum point (B) expands in a trumpet shape toward the end closer thereto, A core is used in which the cross-sectional area gradually expands toward the end farther from the minimum point (B), and the holding parts extending to the outside of the both ends are formed, and the core is placed at a predetermined position in the mold. A method for producing an extrusion nozzle, in which a mold is formed in parallel in the same direction, a metal is cast using this mold, and the core is removed after the casting.