JPH0683329U - Sizing die for synthetic resin pipe molding - Google Patents

Abstract

(57) [Summary] [Purpose] By reducing the sliding resistance when a soft parison immediately after extrusion passes through the sizing die, it allows the parison to pass smoothly and has a good-looking tube with no irregularities on the outer surface. Mold. [Structure] Inner wall surface 11 of cylindrical sizing die body 11
1 has a suction hole 113 formed therein, a cooling ring 12 is installed at one end of the sizing die body 11, and a plurality of rings running in an annular shape in the circumferential direction are provided on the inner surface of the cooling ring 12 having a water cooling jacket 123. The sizing die 1 in which the narrow ridges 126 are formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sizing die for molding synthetic resin pipes (hereinafter simply referred to as “sizing die”), and more particularly to a sizing die that is preferably used by being installed in a vacuum cooling water tank.

[0002]

[Prior art]

 Conventionally, as shown in FIG. 4, a sizing device for extruding a synthetic resin tube (hereinafter simply referred to as “tube”) has been extruded from an extrusion mold (hereinafter simply referred to as “mold”). A sizing die is widely used that shapes the parison immediately after being formed into a predetermined shape and dimension from the outer surface side.

The sizing die 100 has a cylindrical sizing die main body 101 formed on an inner surface (shape-imparting surface) for shaping a pipe to have a correct outer surface shape and size. There is provided a spiral slit 103 for extracting air between the outer surface of the parison P and the inner surface of the sizing die body 101 to make a negative pressure. Further, a water tank 104 for cooling the outer surface of the sizing die body 101 is attached.

Further, on the die D side of the sizing die body 101, the outer surface of the parison P extruded from the die D is in close contact with the inner surface of the sizing die body 101 and slides smoothly on the inner surface. An oil plate 102 is provided at the inlet of the sizing die body 101 so as to be cooled.

A method of forming a tube with the sizing die 100 will be described. The sizing die 100 is installed close to the die D. The parison P 1 is extruded from the die D and taken by a take-off machine to pass through the sizing die 100. At this time, the oil plate 102 is always filled with oil. Air is extracted from the spiral slit 103 of the sizing die main body 101, and cooling water is allowed to flow through the water tank 104.

When the parison P passes through the oil plate 102, the oil in the oil plate 102 is applied to the outer surface thereof, and then enters the sizing die body 101. Since air is extracted from the slit 103 of the sizing die main body 101 to be a negative pressure, the outer surface of the parison P passes while closely adhering to the inner surface of the sizing die main body 101, and at the same time, the water in the water tank 104 from the outer surface. It is cooled, solidified, and molded into a predetermined shape and dimension.

At this time, since oil is applied to the outer surface of the parison P as described above, the sliding resistance between the inner surface of the sizing die body 101 and the outer surface of the parison P is small, and the parison P is smooth. Can pass through.

However, in the sizing die 100, the oil plate 102 is heated by the heat of the parison P that passes while being used for a long time, and the oil in the oil plate is burned and clogging occurs, so that the oil plate 102 and the sizing die body 101. There was a problem that the sliding resistance between the and Parison P increased, and smooth pick-up was not possible, and as a result, the outer surface of the product pipe had ring-shaped irregularities, reducing the product value.

Therefore, as a means for solving such a problem, the present applicant has previously proposed that an inlet such as described in Japanese Utility Model Publication No. 2-28039 should be used so that water is used instead of oil. We proposed a sizing die with a cooling annulus having a cooling water passage on the inner surface of the part.

[0010]

[Problems to be solved by the device]

 However, when a pipe was manufactured using the sizing die described in Japanese Utility Model Publication No. 2-28039, no oil was used, so no seizure occurred as a result. It should be noted that some annular irregularities were generated.

The reason is that, in the case of the sizing die described in Japanese Utility Model Publication No. 2-28039, the inner surface of the portion connecting the cooling annulus to the main body is formed into a continuous long tubular shape, so that the high temperature soft parison is formed. There is a large sliding resistance when and pass, so the parison sticks to the inner surface of the cooling annulus and stops momentarily, and then the sliding resistance advances due to the pulling force of the pulling machine. This is considered to be due to "stick-slip" (a kind of "chattering vibration", which is a phenomenon in which sticking and sliding due to a large sliding resistance proceed like peristalsis).

The present invention has been made in view of the problems of the conventional device as described above, and solves the problems of the conventional device and obtains a synthetic resin pipe having a good appearance without unevenness on the outer surface. The purpose of the present invention is to provide a sizing device that can be used.

[0013]

[Means for Solving the Problems]

 In order to achieve the above object, the synthetic resin pipe forming sizing die of the present invention is a synthetic resin pipe forming sizing die that passes through a parison extruded from an extrusion molding die to form a tubular shape. It consists of a sizing die body and a cooling ring body attached to one end of the sizing die body and having a cooling water passage.Suction die holes are provided on the inner surface of the sizing die body. The gist is that multiple narrow ridges running in the direction are formed.

[0014]

[Action]

 A plurality of narrow ridges running in the circumferential direction are formed on the inner surface of the cooling ring of the sizing die of the present invention, and the plurality of narrow ridges are in sliding contact with the outer surface of the parison. Therefore, as compared with the conventional sizing die formed into a continuous long tubular shape, the inner surface area of the cooling ring body that is in sliding contact with the outer surface of the parison is small, and thus the sliding resistance is small.

When a pipe is formed using this sizing die, the sizing die main body is installed in a true-type cooling water tank, and the cooling ring body is installed at the end of the sizing die main body on the mold side. The cooling water is supplied to the cooling water passage of the body, and the cooling water is supplied while maintaining the negative pressure in the water tank to pass the parison through the inner surface of the cooling ring and the inner surface of the sizing die body.

As described above, the sliding resistance between the inner surface of the cooling annulus and the outer surface of the parison is small, and the outer surface of the parison is rapidly cooled to reduce the outer diameter slightly. (However, regarding the reduction of the parison outer diameter by rapid cooling, the same applies to the sizing die described in Japanese Utility Model Publication No. 2-28039.) Therefore, the above-mentioned "stick-slip" is unlikely to occur, and it passes smoothly. Therefore, it is considered that the outer surface of the parison does not have unevenness.

Next, the parison passes through the body of the sizing die, but since the air is sucked from the intake holes to create a negative pressure, the outer surface of the parison is adhered to the inner surface of the body of the sizing die and further cooled with cooling water. It is cooled and molded to a predetermined outer diameter. Then, when passing through the sizing die body, the outer surface of the parison is considerably cooled and solidified, so that the unevenness no longer occurs.

[0018]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a vertical sectional view showing a usage state of a sizing die according to an embodiment of the present invention. As shown in FIG. 1, a water tank W is installed close to the mold D, and a sizing die 1 of the present invention is installed at the front end of the water tank W on the mold D side.

The water tank W is a vacuum type cooling water tank and has a closed structure, and can be maintained at a reduced pressure of 200 to 500 mmHg by an attached vacuum pump, and the cooling water is spouted from the shower device S in a mist state. can do.

FIG. 2 is an explanatory view showing the structure of the sizing die of the embodiment. As shown in FIG. 2, the sizing die 1 is composed of two main parts, a sizing die body 11 and a cooling ring body 12, the sizing die body 11 is mounted inside the water tank W, and the cooling ring body 12 is attached. It is attached to the die side end of the sizing die body 11 (outside the water tank W in the example shown in FIG. 1).

The sizing die body 11 has a cylindrical inner surface 111, and its inner diameter is slightly smaller on the outlet side than on the inlet side in consideration of contraction during the passage of the parison P.

In addition, a plurality of annular suction grooves 112 are engraved on the inner wall surface 111 of the sizing die main body 11, and the bottom of the suction grooves 112 penetrates the wall of the sizing die main body 11 and receives a large number of suction holes. A hole 113 is provided. The suction groove 112 and the suction hole 113 eliminate the air between the inner wall surface 111 of the sizing die body 11 and the outer surface of the parison P by the negative pressure inside the water tank W, and at the same time, cool the cooling water to the outer surface of the parison P. It also plays the role of making direct contact with.

FIG. 3 is an enlarged view of the Y portion of FIG. 2A, and is an enlarged vertical sectional view of a part of the cooling ring 12. As shown in FIG. 3, the cooling ring body 12 has an inner cylindrical portion 121 formed by extending the sizing die body 11 and an outer cylindrical member 121 fitted to the outer surface thereof and having an opening portion on the inner surface side and having a U-shaped cross section. It is composed of a cylindrical portion 122. The outer cylinder part 122 is watertightly attached to the sizing die body 11 via the O-rings 2 and 3, and the inner cylinder part 121 and the outer cylinder part 122 form an annular water cooling jacket 123, and the water supply port 124 ( The structure shown in FIG. 2A) indirectly cools the parison P with the cooling water supplied from

On the inner surface of the inner tubular portion 121 of the cooling annulus 12, three annular grooves 125 are engraved, and by this, four narrow grooves running in the circumferential direction in sliding contact with the outer surface of the parison P are provided. The ridges 126 are formed at a distance. The inner diameter of the narrow ridge 126 is slightly larger than the inner diameter of the inner wall surface 111 of the sizing die body 11.

In order to allow the parison P to pass smoothly, the corner portion between the inner wall surface 111 of the sizing die body 11 and the suction groove 112, and the narrow ridge 126 of the cooling ring body 12 and the annular groove 125 are formed. It is preferable to add r (roundness) to the corners and to subject the inner surface of the sizing die body 11 and the inner surface of the cooling ring body 12 to a plating treatment such as hard chrome plating.

Next, a situation in which a pipe is molded using the sizing die 1 will be described. The parison P extruded from the mold D is passed through the inner surface of the sizing die 1 and is taken by a take-up machine (not shown), while cooling water is supplied from the water supply port 124 of the cooling ring body 12 and circulated in the water cooling jacket 123. Then, the water is drained from a drain port (not shown). Further, the inside of the water tank W is made to have a negative pressure by a vacuum pump (not shown), and the cooling water is sprayed from the shower device S in a mist state.

In the above state, the high temperature and soft parison P immediately after extrusion first passes through the cooling ring 12. Since a plurality of narrow ridges 126 are formed on the inner surface of the cooling ring 12, the sliding resistance between the inner surface of the cooling ring 12 and the outer surface of the parison P is reduced, and the parison P Since the outer surface is rapidly cooled by the cooling water circulating in the water cooling jacket 123, and the outer diameter is slightly reduced, the parison P passes smoothly without any unevenness on the outer surface.

Subsequently, the parison P passes through the sizing die main body 11, but since the pressure inside the water tank W is negative, the air in the suction groove 112 is formed in the bottom of the suction groove 112. It is sucked out of 113 and removed, and the inside of the suction groove 112 becomes negative pressure. Therefore, the parison P passes while being pressed against the inner wall surface 111. During the passing, the shower of cooling water indirectly passes through the sizing die main body 11 and the cooling water that enters the suction groove from the suction hole 113. It is directly cooled and solidified to obtain a tube having a predetermined outer diameter. When the parison P passes through the sizing die body 11, the outer surface of the parison P is considerably cooled and hardened, so that the surface of the tube no longer becomes uneven.

Although the embodiments of the present invention have been described in detail above, the specific configuration is not limited to the above-mentioned embodiments, and design changes and the like within the scope of the present invention are also included in the present invention. . For example, in the embodiment, when passing through the cooling ring 12, the parison P is indirectly cooled with the inner cylindrical portion 121, but the bottom of the annular groove 125 is connected to the water cooling jacket 123. It is also possible to provide holes or slits for cooling and to allow direct cooling by touching the parison P with cooling water.

Further, in the embodiment, the four narrow ridges 126 are annularly provided on the inner surface of the cooling ring body 12, but the number of the narrow ridges may be increased or the width may be narrowed. It is also possible to form a narrow ridge in a spiral shape by engraving continuous spiral grooves.

Further, in the embodiment, the suction hole 113 having a round hole is provided at the bottom of the suction groove 112 formed on the inner surface of the sizing die body 11. However, for example, a slit that penetrates the sizing die body and is long in the circumferential direction is formed. It is also possible to arrange the objects in a staggered pattern.

[0032]

[Effect of device]

 As is clear from the above explanation, by using the sizing die for molding a synthetic resin pipe of the present invention, it is possible to reduce the sliding resistance between the sizing die and the parison immediately after being extruded. Since it can pass through the body smoothly, it is possible to obtain a synthetic resin pipe having a good appearance with no unevenness on the surface.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a usage state of a sizing die according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing the structure of the sizing die of the embodiment, in which (A) is a vertical sectional view. (B) is a cross-sectional view taken along line XX.

FIG. 3 is an enlarged view of a Y portion in FIG.

FIG. 4 is a vertical cross-sectional view showing a usage state of a conventional sizing die.

[Explanation of symbols]

 1 Sizing Die 11 Sizing Die Main Body 111 Inner Wall Surface 112 Suction Groove 113 Suction Hole 12 Cooling Ring Body 121 Inner Cylinder 123 Water Cooling Jacket 125 Annular Groove 126 Narrow Convex D Mold P Parison

Claims (1)

[Scope of utility model registration request] 1. A sizing die for forming a synthetic resin pipe, which is formed by allowing a parison extruded from an extrusion molding die to pass therethrough, wherein the sizing die body is cylindrical and is attached to one end of the sizing die body and cooled. It consists of a cooling annulus having water passages, suction holes are provided on the inner surface of the sizing die body, and a plurality of narrow ridges running in the circumferential direction are formed on the inner surface of the cooling annulus. A sizing die for molding synthetic resin tubes, which is characterized in that