JPH069836Y2 - Extrusion die cooling device for synthetic resin molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an extrusion die cooling device for molding synthetic resin, specifically, various types of thermoplastic resin pellets such as 6 nylon, polyacetal, polybutylene terephthalate, and polyethylene terephthalate. The present invention relates to an extrusion die cooling device capable of easily forming a molded body having a small warp and excellent surface smoothness when molding a molded body having the above shape.

(Prior Art) Generally, a screw extruder used to extrude a thermoplastic resin pellet into a rod shape, a plate shape, or an irregular shape is
Cylinder equipped with material supply hopper and heating device,
It is composed of a screw extruder including a screw inserted into the cylinder and rotating, and an extrusion die device with a heating device attached to the tip of the screw extruder. Then, a sizing former part that can be cooled by using a cooling jacket or a water tank is attached to the tip of the die device as an accessory. In addition, at the tip of the extruded product and a sizing former part, a water tank for maintaining the shape by water cooling, and a back pressure take-up rubber roll or a rubber caterpillar for eliminating sink marks at the center of the extruded product. It is arranged.

(Problems to be Solved by the Invention) When a resin is extruded using the above extruder, if a water cooling jacket is adopted as a cooling device for the sizing former, a cooling jacket must be made for each sizing former. In particular, with a water cooling jacket for a small size sizing former, it is difficult to process the inlet and outlet of cooling water, and when multiple pipes are taken, there is an increased risk of troubles due to defective piping.

For this reason, particularly in the case of small-size multi-stretching extrusion, it is common to use a water tank to cool the sizing former. This is a method in which the sizing former is inserted into a hole on the wall surface of the water tank that is sufficiently larger than the outer diameter of the sizing former, and water is stopped by a packing having a hole smaller than the outer diameter of the sizing former. However, also in this method, when the extrusion axis of the extrusion-molded product shifts, the rubber sheet-shaped packing locally locally deforms largely in the extrusion direction of the extrusion-molded product.
The ring-shaped contact line between the tip of the packing and the sizing former portion (the boundary line between the air-cooled area and the water-cooled area of the sizing former portion) may not necessarily be orthogonal to the extrusion direction of the extruded product and may be inclined. It was

Therefore, an extruded product that travels straight is divided into a region that is quickly water-cooled and a region that is slowly water-cooled even at the same circumferential position. In other words, due to the occurrence of uneven cooling in the extruded product, a region that solidifies quickly and a region that solidifies slowly are generated, which causes warpage of the extruded product. Further, the position of the sizing former from which water cooling is performed is closely related to the surface smoothness of the extruded product. Since it is difficult to freely set this position in packing, it often happens that only extruded products with poor surface conditions can be obtained.

An object of the present invention is to improve such problems and to provide a molded product having a small warp and an excellent surface smoothness by taking advantage of the cooling jacket even in a sizing former part having a small size and a large number of pieces.

(Means for Solving Problems) The present invention allows a sizing former to be equipped with a cooling jacket having a structure to stop water so that the boundary between the air cooling area and the water cooling area of the sizing former can be set freely and accurately. In addition, the end of the cooling jacket on the side of the take-up machine is opened so that the cooling water in the jacket naturally replaces the cooling water in the water tank.

That is, the extrusion die cooling device for molding synthetic resin according to the present invention comprises a die body having a resin passage inside and a heating device on the outside, and a sizing former portion having a cooling member connected to the die body for molding synthetic resin. In the extrusion die cooling device,
A cooling jacket with one side open is attached to the outside of the sizing former in a water-stopped state, and one packing is attached to the cooling jacket and the other packing is brought into close contact with the sizing former or the outer peripheral surface of the extruded resin molded body. A water tank is provided to cool the sizing former portion and the extruded resin molded body by a cooling medium in the water tank.

(Operation) In the extrusion die cooling device as described above, the cooling jacket can be used even in the sizing former part of small size and multi-strand where cooling water piping is difficult, and moreover, the cooling jacket has an air cooling region and a water cooling region. The boundary line of the extrusion molded article is orthogonal to the extrusion direction of the extruded molded article to eliminate uneven cooling of the extruded molded article to reduce warpage of the extruded molded article, and the cooling jacket controls the air-cooling region and the water-cooling region to provide the extruded product. A temperature gradient of cooling is applied to improve the surface smoothness of the extruded product.

(Example) Next, the Example of this invention is described using drawing. FIG. 1 is a vertical sectional view of an extrusion die cooling device for molding synthetic resin according to the present invention. The die device (1) is composed of a die body (2) and a sizing former part (3) connected to the die body (2). The die body (2) is provided with a heating device (4) on the outer surface and has a resin passage (5) inside.

On the other hand, on the outside of the sizing former part (3), a cooling jacket (6) with one side open is attached in a water-tight state by an O-ring (7) as a cooling device, and the outside in the longitudinal direction of the extruded resin molding. The water tank (9) is installed on the support base (8).

In this case, sheet-like packings (11a) (11b) are attached to both side walls (10) (10) of the water tank (9), while the packing (11a) is in close contact with the surface of the cooling jacket (6), The other packing (11
b) is in close contact with the outer peripheral surface of the extruded resin molded body (12).

The water tank (9) is filled with cooling water, which is a cooling medium of a predetermined temperature, so that the sizing former (3) and the extruded resin molding (12) inside and outside the cooling jacket (6) can be cooled uniformly. Has become. Of course, in this case one packing (11b)
It is also possible to shorten the length of the water tank (9) by contacting the outer peripheral surface of the extruded resin molded body (12) with the outer peripheral surface of the sizing former part (3). In addition, in the present invention, the cooling jacket (6) is attached at a predetermined distance (1) from the die device (1), so that the air cooling area (14) and the water cooling area (16) of the sizing former part (3) are attached. It is important to freely set the ratio so that the extruded resin molded body (12) has a temperature gradient of air cooling, indirect water cooling, and direct water cooling and cooling, which can improve the surface smoothness during cooling. Then, the cooling jacket (6) makes the boundary line between the air-cooled region (14) and the water-cooled region (16) orthogonal to the extrusion direction of the extruded product (12) to eliminate uneven cooling of the extruded product (12). The warp of the extruded product (12) is reduced.

When polyacetal pellets were molded into a round bar with a diameter of 20 mm by using the cooling device shown in Fig. 1, a conventional cooling jacket was not used and the packing of the water tank was in direct contact with the sizing former part. The smoothness of the surface was remarkably improved as compared with the above case, and a round bar with a small warp was obtained.

(Effect) As described above, the extrusion die cooling device of the present invention adjusts the air cooling area and the water cooling area by using the cooling jacket having a simple structure,
Moreover, by eliminating the uneven cooling of the extruded product, it is possible to obtain an extruded product having a high surface smoothness and a small warpage relatively easily even when a sizing former having a small size and a large number of pieces is used.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an extrusion die cooling device for molding synthetic resin according to the present invention. (2) …… Die body (3) …… Sizing former (6) …… Cooling jacket (7) …… O ring (9) …… Water tank (11a) (11b) …… Packing (12) …… Extrusion Resin molding

Claims (1)

[Scope of utility model registration request] 1. An extrusion die cooling apparatus for molding synthetic resin, comprising: a die body having a heating device on the outside and a resin passage inside; and a sizing former portion connected to the die body and having a cooling member. A cooling jacket with one side open is attached to the outside of the mar section in a water-tight state, and one packing is attached to the cooling jacket and the other packing is brought into close contact with the sizing former section or the outer peripheral surface of the extruded resin molded body to form a water tank. An extruding die cooling device for molding synthetic resin, which is arranged and cools a sizing former part and an extruded resin molded product by a cooling medium in a water tank.