JP2554592B2 - Die equipment for extrusion molding of resin moldings - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die device for extrusion molding of resin moldings, and more specifically, it maintains the surface smoothness of a thick resin molding obtained by the solidification extrusion method and suppresses the occurrence of burns. The present invention relates to a die device for extrusion molding of a resin molding that can be extruded.

[0002]

2. Description of the Related Art Generally, extrusion of a resin molding having a continuous shape is often carried out by a vacuum sizing method. However, when the wall thickness of the molded body is large, or when the shrinkage rate of the resin used during solidification is large, defects easily occur in the molded body. In such a case, a solidification extrusion method is used in which a sizing former equipped with a cooling device is placed in close contact with the mold, the molded product is held down by a take-up machine, the brake is applied, and sizing is performed under pressure. It had been. That is, in this method, the molten resin extruded from the mold attached to the extruder is cooled and solidified in a sizing former equipped with a cooling device, and the extruded thick molded body is pressed by a take-up machine. ing. On the other hand, since the resin before solidification has a constant pressure, the molten resin was solidified while being dimensionally regulated while being pressed by the sizing former.

[0003]

However, in this method, when the molten resin begins to solidify in the sizing former, that is, when a thin solidified resin film is formed on the inner surface of the sizing former, this film is formed. is pressed against the sizing former inner surface, working strong frictional force, and to the formed film or stretched or torn without being extruded continuously, the molded surface was not smooth. Further, the torn film stayed on the inner surface of the former for a long time, and what was colored due to oxidation and the like gradually adhered to the surface of the molded product, causing a so-called burn phenomenon.

In order to solve this problem, conventionally, the shape of the resin passage in the mold is made thin at the portion in contact with the extruder, and gradually approaches the internal shape of the sizing former toward the outlet, and the die outlet is provided. Then, it was considered that the resin flow would be smooth by matching the internal shape of the sizing former. However, even with this method, since the molten resin is slowly cooled from the vicinity of the die exit into the sizing former, a thin solidified resin film is likely to be formed at this portion, and the problem cannot be solved. As another method, a method of coating the inner surface of the sizing former with Teflon has been proposed. However, the effect is not sufficient as expected, and since the surface of the sizing former receives a large frictional force, the Teflon layer easily peels off, which is not practical. The present invention solves these problems, and provides a die apparatus for extrusion molding of a resin molded product, which improves the surface smoothness of the resin molded product by solidification extrusion and reduces the occurrence of burns.

[0005]

That is, a feature of the present invention is that a mold having a resin passage for a molten resin therein and a resin passage inside which is connected to the mold to be cooled are coolable. In an extrusion molding die device consisting of a sizing former, the cross section of the resin passage of the die is made smaller than that of the resin passage of the sizing former, and the outlet of the resin passage provided in the die is projected into the sizing former. In the die device for extrusion molding of the resin molded body, the resin heated and melted by the above extruder is introduced into the sizing former which is directly cooled through the passage in the mold, and the molten resin is solidified by rapid cooling. .

FIG. 1 is a cross-sectional view of an extrusion molding die apparatus of the present invention, and FIG. 2 is a schematic view of an extrusion molding apparatus for resin moldings using this die apparatus. Here, the extrusion molding die apparatus 1 comprises a mold 2 and a sizing former 3 connected to the mold 2. The mold 2 is provided with a heating device 4 on the outer surface and has a molten resin passage 5 inside. On the other hand, the sizing former 3 is a tubular body having a resin passage 7 in the shape of a product, has a cooling device 6 such as a water cooling jacket, and a flange 8 provided at the end thereof is screwed into the mold 2. It is fixed.

The cross section of the resin passage 5 of the mold 2 is smaller than the cross section of the resin passage 7 in the sizing former,
The exit portion projects into the sizing former. The protrusion angle θ is less than 180 °. The protrusion angle θ needs to be determined in consideration of factors such as the resin extrusion rate, the cooling rate, and the shape of the resin passage 7 in the sizing former. If this portion does not project, that is, if θ exceeds 180 °, the effect of the present invention is not recognized as described later.

If the resin passage 5 in the die 2 is thinner than the resin passage 7 in the sizing former and the outlet portion of the die 2 protrudes into the resin passage 7 in the sizing former, the die 2 is used. The molten resin extruded from the outlet portion of 2 is rapidly cooled and solidified by directly touching the inner surface of the sizing former 3 without being cooled.
At this time, since the molten resin is cooled at a high rate, it is difficult to form a thin film of the solidified resin on the surface of the molded body 9.
This smoothes the surface of the molded body 9 and reduces the occurrence of burn phenomenon.

As shown in FIG. 2, the die device 1 is provided with heating devices 15 and 16 on the surface, and a screw 19 is inserted into a cylindrical cylinder 18 having a hopper 17 for charging a raw material at an end thereof. It is connected to the outlet of the screw extruder 20 with a bolt or the like. The breaker plate 2 having a plurality of holes at the inlet of the molding die device 1
1 is inserted to control the flow of molten resin. In addition, the pair of upper and lower caterpillars 22, 22 are the screw extruder 20.
It is located in front of the outlet of the molding die device 1 connected to, and gives an appropriate back pressure to the thick molded body 9 to enable continuous extrusion. Incidentally, the resin material of the molded body of the present invention,
Relatively high crystallinity polyacetal, polyamide, polyethylene terephthalate, PEEK (polyether A)
Terketone) and the like.

[0010]

As described above, in the present invention, the resin passage 5 in the mold 2 is
Is thinner than the resin passage 7 in the sizing former, and when the die 2 whose outlet portion protrudes into the resin passage 7 in the sizing former is used, the molten resin extruded from the outlet portion of the die 2 is sized. Touch the Mar 3 directly
Is maintained at a high temperature due to the absence Rukoto, and soon is slowly cold <br/> and is, in particular solidified quenched supposed to touch directly cooled inner surface of the sizing former 3
Become. As a result, a thin film of solidified resin is unlikely to be formed on the surface of the molded body 9, the surface becomes smooth, and the occurrence of a burn phenomenon is reduced.

[0011]

EXAMPLES Next, specific examples using the die apparatus of the present invention will be shown below. Example 1 FS having a screw with a diameter of 30 mm and L / D = 25
A 30-25 (made by Ikegai Tekko Co., Ltd.) extruder was equipped with a die (protruding angle θ of outlet part = 120 °, inner diameter of resin passage 8 mm)
And a sizing former (internal diameter of the resin passage: 50 mm) were connected to a molding die device, and two tracks were arranged in front of the molding die device. Using this screw extruder, under the extrusion conditions shown in Table 1, nylon 6 pellets (cast nylon crushed pellets manufactured by Mitsuboshi Belting Co., Ltd.) were extruded into a round bar having a diameter of 50 mm. The extrusion results are shown in Table 2.

COMPARATIVE EXAMPLE 1 The shape in which the outlet portion is not protruded and is recessed (θ = 300
The same equipment was used under the conditions shown in Table 1 except that the mold of (°) was mounted, and the same extrusion was performed. The extrusion results are shown in Table 2.

[0013]

[Table 1]

[0014]

[Table 2]

According to these results, the surface of the molded product of this example is smooth and there is no burning or discoloration, but the surface of the molded product of the comparative example is uneven due to the occurrence of graininess and crisping, and It was slightly discolored due to the occurrence of burns.

[0016]

As described above, in the present invention, the resin passage in the mold is made thinner than the resin passage in the sizing former,
Further, by using a die device having a shape in which the passage outlet is projected into the sizing former, the molten resin is directly cooled by the sizing former without being gradually cooled, which results in a good surface smoothness and a scorch. There is an effect that it is possible to extrude a resin molding having a large thickness without causing the occurrence of

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a die device for extrusion molding of a resin molding of the present invention.

FIG. 2 is a schematic view of an extrusion molding device for a resin molded product using the molding die device shown in FIG.

[Explanation of symbols]

 1 Extrusion Molding Die Device 2 Mold 3 Sizing Former 4 Heating Device 5 Resin Passage 6 Cooling Device 7 Resin Passage

Claims (1)

(57) [Claims] 1. A die apparatus for extrusion molding, comprising: a die having a resin passage for a molten resin therein, and a coolable sizing former connected to the die and having a resin passage therein Extrusion molding of a resin molding characterized in that the cross section of the resin passage of is made smaller than that of the resin passage of the sizing former, and the outlet of the resin passage provided in the mold is protruded into the sizing former. Die equipment.