JP2000301589A - Mold for extrusion molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate a flow rate regulation at a resin channel and to reduce a time and a cost required for manufacturing by providing a core at a position for generating resin flows in an extruding direction and a vertical direction in the channel of a throttling plate. SOLUTION: A core 2 is provided near a boundary between an enlarged portion 111 in a resin channel 11 and a contracted portion 112, and an engaging portion for supporting the core 2 is engaged with a recess 12 recessed on a throttling plate. Since the core 2 is provided in the mold for extrusion molding, a resin flow of a vertical direction to the extruding direction of the resin generated near a boundary between the portion 111 and the portion 112, that is, the resin flow from the portion 112 to the portion 111,..., a cross sectional flow is prevented by the core 2 to prevent a turbulence of a flow rate balance, and the balance can be regulated according to a size, a shape of the core 2. Thus, various shapes of the core 2 is suitably replaced to regulate the balance, to prevent the turbulence, to reduce unevenness of a designing size of the molding, and to improve dimensional accuracy, thereby reducing a time and a cost of mold designing and manufacturing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion die, and more particularly to an extrusion die suitable for use in forming a molded article.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Publication No.
As described in Japanese Patent Application Laid-Open Publication No. H10-163, there is known an extrusion molding die in which a resin flow path is provided inside and an extrusion port is provided at a tip end.

[0003] Conventionally, profiled extrusions such as rain gutters and sashes usually have different thicknesses at each portion. For this reason, the resin flow resistance in the resin flow path of the land plate at the tip of the extrusion mold of such a modified extrusion molded product is different in each portion, and the resin is more likely to flow to the one with less flow resistance.

As shown in FIG. 12, in a mold for extrusion molding of a deformed extruded product, several narrowing plates (c) and (d) connected to a nozzle (b) at the tip of an extruder (a).
It is constituted by a land plate (f) at the tip via (e). Nozzle (b), deployment plate (c),
The cross-sectional shapes of the resin flow paths in the plurality of narrowing plates (d) and (e) and the land plate (f) are changed as shown in FIGS.

For example, as shown in FIG. 17, when there is a difference in thickness between the extruded products (g), a small thickness portion is formed in a resin flow path of a mold for molding a thick portion (h). Since the resin flow resistance is smaller than that of the resin flow path of the mold for forming (i), the resin is more likely to flow to the one having the lower flow resistance.

By the way, in order to obtain an extruded product having a desired cross-sectional shape, it is necessary to uniformly extrude the resin from the extrusion port at the tip of the land plate at the tip of the extrusion mold. It is necessary to adjust the flow rate balance according to the cross-sectional shape of the flow path of the throttle plate reaching the path.

In the case of a molded product shape as shown in FIG. 17, a thick portion (h) and a thin portion (f)
When the pressure drop is calculated for each portion, it can be understood that the flow path (nu) of the narrowing plate should be shaped as shown in FIG. However, FIG.
In the flow path shown in FIG. 8, there is a possibility that the resin may stay at the corners of the flow path, and therefore it is necessary to smooth the corners of the flow path as shown in FIG. Note that, in FIG.
Indicates the extrusion direction.

As shown in FIG. 19, the resin flow balance is improved to some extent by improving the flow path of the mold.

However, since the flow in the extrusion direction and the vertical direction, that is, the cross flow, actually occurs, the resin flow rate in the flow path is not completely uniform. In particular, when molding a shaped article having a large difference in thickness between the portions, the influence of the cross flow is large, the flow rate balance is disturbed, and it is difficult to obtain a uniform flow.

As described above, it is extremely difficult to theoretically clarify and design and manufacture an extrusion mold in which the resin is uniformly extruded from the extrusion port at the tip of the land plate. Based on experience and accumulated technology, similar shapes are referred to.

[0011] Alternatively, the publication "Extrusion Dies for Pl" by Walter Michele
A three-dimensional resin flow analysis is performed with reference to “a static and rubber” to determine an optimal resin flow path shape.

[0012]

However, in the case of the conventional design of a mold for extrusion molding, selection of a reference model and correction of resin flow such as build-up and cutting are based on the experience and intuition of the mold designer. It depends a lot. In addition, there is a drawback that a great deal of labor and calculation time are required for designing a mold by analysis. In any case, there is a problem that it takes a long time and a large amount of cost to start using the mold.

The present invention has been made in view of such a problem in a conventional extrusion mold.
The purpose of the extrusion is to solve the above problems, to easily adjust the flow rate in the resin flow path of the mold, and to reduce the time and cost required for designing and manufacturing the mold. To provide a metal mold.

[0014]

In order to attain the above object, according to the present invention, there is provided an extrusion molding die according to the present invention, wherein a land plate is provided at a tip of a narrowing plate for narrowing a resin flow path in an extrusion direction, In an extrusion molding die having an extrusion port provided at a tip of a land plate, a core is provided at a position where a resin flow in a direction perpendicular to an extrusion direction in a resin flow path of a narrowing plate is provided. It is.

According to a second aspect of the present invention, there is provided the extrusion molding die according to the first aspect, wherein the core is supported by a fitting portion, and the fitting portion is formed in a recess of the drawing plate. It is characterized by being fitted.

In the present invention, regarding the material of the core,
The material is desirably the same as the material of the mold body, but may be another material.

In the present invention, the core and the fitting portion may be connected by a spider, or may be directly connected without providing a spider. When a spider is provided, the cross section of the spider is desirably streamlined so that the flow resistance of the resin is small, but may be rectangular or circular.

[Operation] In the extrusion molding die according to the first aspect of the present invention, the core is provided in the resin flow path of the narrowing plate at a position where a resin flow occurs in a direction perpendicular to the extrusion direction. Resin flow in the extrusion direction and vertical direction,
That is, the cross flow is prevented, and the disturbance of the flow rate balance is prevented.

In the extrusion molding die according to the present invention, the core is supported by the fitting portion, and the fitting portion is fitted into the recess of the drawing plate. Is easy. Further, the flow rate balance can be adjusted by preparing cores of various shapes in advance and replacing them appropriately.

[0020]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing a main part of an example of an extrusion molding die of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG.

1 and 2, reference numeral 1 denotes a narrowing plate of the extrusion molding die according to the present invention, 11 denotes a resin flow path provided in the narrowing plate 1, and 111 denotes a resin flow path.
Reference numeral 1 denotes an enlarged portion, and 112 denotes a reduced portion of the resin flow path 11. 1
Reference numeral 2 denotes a recess provided in the aperture plate.

Reference numeral 2 denotes a core provided in the resin flow path 11, and the core 2 includes an enlarged portion 111 and a reduced portion 1 in the resin flow channel 11.
12 is provided near the boundary. Reference numeral 21 denotes a fitting portion, and the core 2 and the fitting portion 21 are, as shown in FIG.
They are connected by a spider 22. The fitting portion 21 is fitted into a recess 12 formed in the narrowing plate 1.

In the extrusion molding die of the present invention shown in FIGS. 1 and 2, the core 2 is provided near the boundary between the enlarged portion 111 and the reduced portion 112 in the resin flow path 11. The extrusion direction generated in the vicinity of the boundary between the 111 and the reduced portion 112 is a resin flow in a vertical direction, that is, a resin flow from the reduced portion 112 to the enlarged portion 111, that is, a cross flow is prevented by the core 2, so that the core 2 prevents flow. Disturbance is prevented. Also, core 2
The flow rate balance can be adjusted by changing the size and shape of each of them into various ones.

FIG. 4 is a front view showing a main part of another example of the extrusion mold of the present invention. In FIG. 4, reference numeral 1a denotes a narrowing plate of the extrusion molding die according to the present invention, 11a denotes a resin flow path provided in the narrowing plate 1a,
1a is an enlarged portion of the resin flow path 11a, and 112a is a resin flow path 1
1a is a reduction section.

2a is a core provided in the resin flow path 11a, and the core 2a is an enlarged portion 111a in the resin flow path 11a.
It is provided in the vicinity of the boundary between the image and the reduction unit 112a. 2
1a is a fitting portion provided on the core 2a, and the fitting portion 21a is a recess 12a formed in the narrowing plate 1a.
It is fitted in.

FIG. 5 is a sectional view of an extruded product formed by the extrusion mold of the present invention shown in FIG.

The molded product 3 shown in FIG. 5 is specifically a weatherstrip for an automobile.
3, 34 exist. The height H1 of the left half of the molded product 3 is H1.
Is 17 mm, the height H2 of the right half is 9 mm, and the width W is 8 mm
It is. The thickness and the draw ratio of each part of the molded product 3 are as shown in Table 1.

[0028]

[Table 1]

FIGS. 6 and 7 are perspective views of the resin flow paths 11a and 11b provided in the narrowing plate 1a. The resin flow path 11b shown in FIG. 7 is provided downstream of the resin flow path 11a shown in FIG. As shown in FIGS.
The portions 1a and 11b having different sizes of the flow paths are connected by a surface as smooth as possible in order to prevent stagnation of the resin. In FIGS. 6 and 7, the arrow a indicates the resin extrusion direction.

As shown in FIG. 8, the core 2a is a quadrangle provided with oblique sides, and the height H3 of the long side is equal to the height of the inlet of the resin flow path of the narrowing plate 1a.

[Embodiment] A single screw extruder (Ikegai FS65) using the extrusion molding die of the present invention shown in FIGS.
The screw shaft diameter is 65mm, compression ratio is 3,
L / D of 22 was used, and an external lubricant, an internal lubricant, a filler, etc. were blended with polypropylene as an extruded material.
A molded product 3 shown in FIG. 5 was formed using a material having a shear rate and a shear viscosity characteristic as shown in FIG.

The height H4 of the short side of the core 2a is equal to the height of the outlet of the resin flow path of the narrowing plate 1a. The thickness T of the core 2a is 0.2 mm, the height H4 of the core 2a is 10 mm, the width W1 is 89 mm, the width W2 of the fitting portion 21a is 20 mm, and the thickness T1 is 12 mm. Extrusion conditions are as shown in Table 2.

[0033]

[Table 2]

[Comparative Example] A molded product shown in FIG. 3 was molded.

[Evaluation] In the case of the comparative example, the flow rate balance was disturbed in the thick portion due to the influence of the cross flow, and a large amount of resin flowed in the thick portion where the flow resistance was small. Variations in the thickness of the surface appear to be wavy. In the embodiment, no change in the thickness of a portion having a large thickness is observed. Table 3 shows the results of measuring the thickness of each part shown in FIG.

[0036]

[Table 3]

As shown in Table 3, the thickness deviation rate of the thickness of the molded article 3 is 8% in the example and 19% in the comparative example. I understand.

Although the embodiment of the present invention has been described with reference to the drawings, the specific configuration of the present invention is not limited to the illustrated embodiment, and the design change within a scope not departing from the gist of the present invention. Are included in the present invention.

[0039]

According to the first aspect of the present invention, the core prevents the resin flow in the extrusion direction and the vertical direction, that is, the cross flow, and prevents the flow rate from being disturbed. The variation in the thickness with respect to the design dimensions of the substrate is reduced, and the dimensional accuracy is improved.

In the second aspect of the present invention, the core is supported by the fitting portion, and the fitting portion is fitted in the recess of the drawing plate. Is easy. Further, the flow rate balance can be adjusted by preparing cores of various shapes in advance and replacing them appropriately.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a main part of an extrusion molding die according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a perspective view of a core and a fitting portion used in the extrusion molding die according to the present invention shown in FIGS.

FIG. 4 is a front view showing another example of the main part of the extrusion molding die according to the present invention.

5 is a side view of a molded product formed by the extrusion molding die according to the present invention shown in FIG.

FIG. 6 is a perspective view of a flow path of the extrusion molding die according to the present invention shown in FIG.

FIG. 7 is a perspective view of a channel of the extrusion molding die according to the present invention shown in FIG.

FIG. 8 is a front view of a core and a fitting portion used in the extrusion molding die according to the present invention shown in FIG.

FIG. 9 is a left side view of the core and the fitting portion shown in FIG. 8;

FIG. 10 is a graph showing viscosity characteristics of an extruded material.

FIG. 11 is a side view showing a part of a molded product.

FIG. 12 is a front view of a conventional extruder and a die for extrusion molding.

FIG. 13 is a sectional view taken along line XIII-XIII in FIG. 12;

FIG. 14 is a sectional view taken along line XIII-XIII in FIG. 12;

FIG. 15 is a sectional view taken along line XIII-XIII in FIG. 12;

FIG. 16 is a sectional view taken along line XIII-XIII in FIG. 12;

FIG. 17 is a perspective view showing an example of a profile-extruded product.

FIG. 18 is a perspective view showing a main part of a conventional extrusion molding die.

FIG. 19 is a perspective view showing a main part of a conventional extrusion molding die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Narrowing plate 11, 11a Resin channel 111, 111a Enlarged part 112, 112a Reduced part 12 Concave part 2, 2a Core 21, 21a Insertion part 22 Spider 3 Molded part 31 Thin part 32, 33 34 Thickness Big part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F207 AA11 AB07 AB11 AG09 AH47 KA01 KA20 KL57 KL62 KL98 KL99

Claims (2)

[Claims] In a die for extrusion molding, wherein a land plate is provided at a tip of a narrowing plate for narrowing a resin flow path in an extrusion direction, and an extrusion port is provided at a tip of the land plate, the resin flow path of the narrowing plate in the resin flow path is reduced. An extrusion molding die, wherein a core is provided at a position where a resin flow in a direction perpendicular to the extrusion direction occurs. 2. The extrusion mold according to claim 1, wherein the core is supported by a fitting portion, and the fitting portion is fitted into a recess of the drawing plate.