JPH057434U - Inner die support arm in extruder - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] The present invention aims to provide an extruder capable of producing a plastic molded product of uniform quality and excellent quality. Concerning the design of the support arm. [Structure] A structure is provided in which support arms 3 that come into contact with or fit into the die body 1 are provided at a plurality of locations on the outer peripheral surface of the inner die 2, and the support arms 3 are formed in a spiral shape. [Effect] The thickness unevenness and the like caused by the structure of the conventional linear support arm are prevented, and thus a molded product having a uniform quality is obtained.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to the shape of a support arm (spider; hereinafter the same) of an inner die (mandrel, core; hereinafter the same) in an extruder.

[0002]

[Prior Art]

 Extrusion machines that make long objects with complicated cross-sectional shapes such as window frames, table board edging, handrails for stairs, gutters for electrical wiring, etc., knead molten resin to form a die lip with the desired cross-sectional shape. It is extruded from the opened die and molded.

It is important to keep the die lip intervals constant in order to obtain a molded product having a constant shape and wall thickness with this extruder.

Therefore, in the inner die installed in the die main body, supporting arms provided at a plurality of locations around the inner die are projected toward the die main body and contacted or fitted into the die main body. Holds the inner die in the center of the die body.

As seen in the schematic view of FIG. 4, the support arm of the conventional inner die is arranged in parallel (straight line) with the longitudinal direction of the inner die (flow direction of molten resin; the same applies hereinafter). Has become.

Therefore, most of the extruded molten resin flows linearly.

Therefore, the kneading of the molten resin is not sufficient, which causes unevenness in the thickness of the molded product and a line mark (or a spiral mark in the spiral system; the same applies hereinafter).

Further, when the resin has a high melt viscosity, the pressure loss of the die body may increase.

In order to solve this problem, many registered utility models have been made, and for example, the following technical documents are listed.

First, there is an annular extrusion die of Japanese Utility Model Publication No. Sho 63-37231. The gist of the annular extrusion die is to expand the flow path of the resin tip portion in the range of 30 to 90 degrees with respect to the die center axis. However, the vicinity of all mold outlets of the tip flow path is formed so as to form an acute angle in the range of 10 to 70 degrees, and the effect is to prevent the adhesion and deposition of resin and to produce a tubular film without scratches. Is the content.

However, this registered utility model has the following problems.

That is, since it is due to the adjustment of the angle of the resin flow path, there is still room for improvement in kneading the resin and preventing the non-uniformity of the flow.

Secondly, there is an uneven thickness preventing alignment die of Japanese Utility Model Publication No. 1-8348.

This registered utility model has a structure using a spiral mandrel die.

However, this registered utility model cannot be adopted in the present invention because of its complicated structure and the structure utilizing the overflow (land flow) phenomenon.

[0016]

[Problems to be solved by the device]

 The structure is such that the support arm is linearly arranged in the conventional flow path for molten resin (hereinafter referred to as the molten resin path).

Therefore, the uniform flow rate of the molten resin cannot be ensured. Alternatively, the molten resin is not sufficiently kneaded, which causes unevenness in the thickness of the molded product and a line mark.

Further, when the resin has a high melt viscosity, the pressure loss of the die body may increase.

The purpose of the present invention is to solve the above problems, to achieve sufficient kneading of the molten resin at the time of extrusion molding, and to prevent the molten resin from flowing in the molten resin path. It is to obtain a flow along the spiral direction (also called the circumferential direction; the same applies below) and to obtain a support arm for the inner die that can secure a uniform flow rate.

[0020]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the supporting arm of the inner die according to the present invention has the following structure.

That is, in an extrusion molding machine in which a molten resin is kneaded and extruded from a die lip having a desired cross-sectional shape, in order to keep a constant gap between the die lips, it is provided at a plurality of locations around the inner die, A supporting arm that projects toward the die body and contacts or fits into the die body, wherein the supporting arm is formed in a spiral shape in the longitudinal direction of the inner die.

[0022]

[Action]

 The molten resin extruded from the extruder becomes a so-called spiral flow through the spiral-shaped inner die supporting arm in the molten resin passage, where it is sufficiently kneaded and a uniform flow rate is secured. Meanwhile, they are pushed out one by one.

After that, the flow becomes a substantially linear flow and is extruded from the die lip to be formed into a desired shape.

The molded product can be a product having a desired shape and wall thickness and excellent quality.

[0025]

【Example】

 An embodiment of this invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a relationship between a die body, an inner die and a supporting arm in an extruder, FIG. 2 is an enlarged cross sectional view of the supporting arm according to the present invention, and FIG. 3 is an example of a shape of the supporting arm according to the present invention. And FIG. 4 is an enlarged schematic diagram showing an example of the shape of a conventional support arm.

In the extrusion molding apparatus, an inner die 2 having a circular outer peripheral surface is arranged inside a die main body 1 having a circular inner peripheral surface.

Support arms 3 are provided at a plurality of locations on the outer peripheral surface of the inner die 2, and the support arms 3 are projected toward the die body 1 to come into contact with or be inserted into the die body 1. Hold and maintain the dimension of the die lip 4 that regulates the shape of the molded product to a constant value.

Further, a heater 5 for heating the molten resin is provided outside the die body 1.

The cross-sectional shape of the support arm 3 is preferably a plate shape, a wing shape, or the like. Although not shown, the support arm 3 may have a tapered shape in the rising direction, for example, to facilitate fitting or division.

In the figure, 6 is a bolt for adjusting the molten resin, and 7 is an extruder.

As shown in FIGS. 2 and 3, since the support arm 3 according to the embodiment is formed in a spiral shape, the molten resin flowing in the molten resin path is exposed on the outer peripheral surface of the inner die 2. The flow in the spiral direction is secured.

As can be seen from FIG. 4, the molten resin in the molten resin path provided by the conventional linear support arm 13 has a straight flow direction, which is different from the spiral flow of the present invention. , It is a completely different aspect.

In the figure, 12 is an inner die having a conventional structure.

Next, the operation of the embodiment will be described.

The molten resin extruded from the extruder enters a resin melting passage formed by the die body 1 and the inner die 2 held at the central position by the supporting arm 3.

A spiral motion (vortex motion) is imparted to the molten resin flowing in the molten resin path by the spiral shape of the support arm 3 and the molten resin flows in the direction of the sequential die lip in a state where a constant flow rate is secured. To do.

Then, in this flow process, the heater 5 is constantly heated.

After that, after being formed into a predetermined cross-sectional shape by the die lip 4 kept at a constant opening size, it is sent to the next stage such as cooling and cutting.

[0040]

[Effect of the device]

 Since the inner die supporting arm is configured to add a spiral motion to the resin flow, it has the following effects.

That is, according to this invention, various defects such as unevenness in thickness of molded products, line marks, and other deterioration of strength due to the interposition of the linear support arm in the prior art are eliminated.

Further, this makes it possible to manufacture a molded product that is uniform and has excellent quality.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a relationship between a die body, an inner die, and a support arm in an extrusion molding machine.

FIG. 2 is an enlarged cross-sectional view of a support arm according to an embodiment of the present invention.

FIG. 3 is an enlarged schematic view showing an example of the shape of a support arm of the present invention.

FIG. 4 is an enlarged schematic view showing an example of the shape of a conventional support arm.

[Explanation of symbols]

 1 die body 2 inner die 3 support arm 4 die lip 5 heater 6 bolt 7 extruder

Claims (1)

[Claims for utility model registration] 1. In an extrusion molding machine for kneading molten resin and extruding it from a die lip having a desired cross-sectional shape, in order to keep a constant gap between the die lips, Support arms that are provided at a plurality of locations and that protrude toward the die body to contact or fit into the die body, and that the support arms are formed in a spiral shape in the longitudinal direction of the inner die. Inner die support arm characterized by.