JP3407154B2 - Method and apparatus for molding plastic molded articles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for molding a plastic molded product, and more particularly to a method and a device for molding a molded product having a special shape such that a liquid circulates in a cylindrical shape and has a bulge in the middle thereof. Regarding

[0002]

2. Description of the Related Art In medical equipment such as a Ringer's solution injector, a plastic molded product having a special shape is used in which a liquid circulates inside and has a bulge in the middle thereof. As shown in FIG. 5, this plastic molded product has a pipe-shaped main body 51 through which a liquid flows, and a hollow bulge portion 52 is formed in the center thereof. Both ends 53 of the pipe-shaped main body 51 are formed in a taper shape in which the outer diameter gradually becomes smaller toward the ends in order to insert and connect them into a flexible pipe (not shown) such as a rubber tube. . A mounting seat 54 having a flat surface is formed on the outer peripheral portion of the pipe-shaped main body 51 opposite to the bulging portion 52.

Such a plastic molded product is called an octopus pipe, and conventionally, the following three types of molding methods have been known as its molding method.

1. Direct Blow Molding Method As shown in FIG. 6 (A), a parison 61 (shown in cross section for convenience) constituted by a plastic hollow pipe is continuously extruded by an extruder (not shown), and each is molded. In this method, the parison 61 is sandwiched by two blow molds 63 (only one is shown in the figure) in which the concave portion 62 is formed, and air is blown into the hollow portion of the parison 61 to blow.
This manufacturing method is often used for forming containers for detergents.

2. Injection Blow Molding Method As shown in FIG. 7, a bottomed parison 71 is molded by injection molding, the bottomed parison 71 is transferred to a blow mold (not shown), and the bulging portion 72 is blow molded. .

3. Injection molding method Since it is impossible to integrally mold the required shape by injection molding, as shown in FIG.
1 and the bulge portion 52 are divided into two parts, each of which is manufactured by injection molding, and then, as shown in FIG. 8B, bonded by a welder to obtain a finished product.

[0007]

However, each of the above-mentioned conventional methods has the following drawbacks.

1. In the direct blow molding method, the internal shape of the molded product becomes a natural shape due to the blow, and the internal shape cannot be controlled accurately, so it is difficult to satisfy the predetermined product performance. In addition, the tapered ends 5
3 is a method in which the parison 61 is sandwiched between two dies 63 to cut it, and as shown in FIG. 6 (C), burrs 64 remain in the cut marks, which causes a problem in using the molded product. That is,
Since both ends 53 of the molded product body are inserted and connected to a flexible hose (not shown) during use, if a parting line caused by the mold 63 remains, a gap is formed between the part and the hose. Liquid leakage may occur. Therefore, in the direct blow method, it is necessary to remove this burr in the secondary processing, but it takes time and effort for the secondary processing, not only is the plastic material wasted due to the removal of the burr, but also the plastic material powder produced by the deburring processing, etc. There is a possibility that the dust of the above may adhere to the inside of the molded product and cause a sanitary problem.

2. On the other hand, in the injection blow molding method as well as the direct blow molding method, the internal shape becomes a natural transitional shape, so it is difficult to mold it into a predetermined required shape, and therefore, it is possible to obtain a predetermined molded product performance. It was difficult.

3. In the molded product manufactured by the injection molding method, liquid leakage accidents often occur from the bonding portion between the main body and the bulging portion, which may cause a serious defect in performance. Further, there is a risk that contaminants may enter the inside of the main body during the bonding work between the pipe-shaped main body 51 and the bulging portion 52.

Therefore, the object of the present invention is to solve the problems in the conventional molding method as described above, and to make it possible to accurately mold the internal shape, so that a predetermined product performance can be obtained, and deburring processing can be performed. It is an object of the present invention to provide a molding method and a molding apparatus for a plastic molded product which is free from contamination due to.

[0012]

SUMMARY OF THE INVENTION The present invention is a method for molding a plastic molded product having a bulge portion in a portion of a tubular portion, wherein the portion corresponding to the bulge portion is an open tubular body. Prepare a primary molded article, heat the tubular body of this primary molded article to raise the temperature to a blow moldable temperature, and sandwich the temperature raising section with a split mold having a space defining the bulge portion, A method for molding a plastic molded product, characterized in that air is sent from a part of the tubular portion into the molded product body to form the bulging portion by blow molding.

The present invention is also directed to a primary molded product in which a portion corresponding to the bulge is an open tubular body in order to mold a plastic molded product having a bulge in a part of the tubular portion. In the blow molding apparatus described above, in order to accommodate a mounting table in which a hole through which the cylindrical body is formed and a cylindrical portion of the primary molded product mounted on the mounting table, the mounting table is mounted on the mounting table. A pair of molded product pressing split dies that can be moved toward and away from each other and communicates with one of the molded product pressing split dies,
A blower port for blowing air from one end of the primary molded product, and a cylinder of the primary molded product having a space that defines the bulge portion and is arranged so that they can approach and separate from each other along the lower surface of the mounting table. A pair of blow split molds that are formed into a predetermined bulge shape by sandwiching the cylindrical body, and below the pair of blow split molds are arranged so as to be able to reciprocate in the vertical direction, and the tubular body of the primary molded product is formed. A blow molding apparatus comprising a blow stand including a heater for heating to a blowable temperature.

The pair of molded product pressing dies are reciprocally driven by a pair of molded product pressing cylinders provided on both sides of the blow stand, and the pair of blow molded dies are installed on both sides of the blow stand. Further, the heater is reciprocally moved by a pair of blow mold cylinders, and the heater is vertically reciprocally driven by the heater cylinder. The heater is formed with a recess into which the tip end of the tubular body of the primary molded product is fitted. .

[0015]

1 to 4 are views for explaining an embodiment of a method for molding a plastic molded product according to the present invention. FIG. 1 is a vertical sectional view showing the structure of an injection-molded product 11 as a primary molded product before blow molding. The injection-molded product 11 has a pipe-shaped main body 12 through which a liquid flows, and a cylinder (cylindrical body) 13 for forming a portion similar to the bulge portion 52 described in FIG. Is a pipe-shaped body 12
Is formed substantially orthogonal to. The tip of the cylinder 13 is open, and the length of the cylinder 13 is formed longer than the length of the bulge portion by the amount of burr due to the cutting process in the later blowing process. Both end portions 14 of the pipe-shaped main body 12 are formed in a taper shape in which the outer diameter gradually becomes smaller toward the end portions, as in the final molded product of FIG. A mounting seat 15 similar to the mounting seat 54 of FIG. 5 is formed at the center of the pipe-shaped main body 12.

FIG. 2 is a vertical sectional view showing the overall construction of the blow molding apparatus used in the molding method according to the present invention, which is constructed as follows. A pair of molded product pressing dies 23-1, 23- are provided on the molded product mounting table 22 of the blow stand 21.
The two are mounted reciprocally between a position where they contact each other and a spaced position. A pair of molded product pressing cylinders 24-1 and 24-2 are provided on both sides of the blow stand 21, and by these, the pair of molded product pressing split dies 23-
1, 23-2 are reciprocally moved on the molded product mounting table 22.
Spaces capable of accommodating the pipe-shaped main body 12 are formed on the lower surfaces of the molded product pressing split molds 23-1 and 23-2 in a state where they are in contact with each other. In this space, a packing 25 for sealing blow air introduced into the pipe-shaped main body 12 is fixed to the end wall of the molded product pressing mold 23-2, as will be described later. Split mold 23
A perforated packing 26 is fixed to the end wall of -1.
Further, the molded product pressing split mold 23-1 is provided with an air blowing port 27 in communication with the perforated packing 26.

On the lower surface of the molded product mounting table 22 of the blow stand 21, a pair of blow split molds 28-1 and 28-2 are reciprocally arranged between a position where they contact each other and a spaced position. A pair of blow mold cylinders 29-1 and 29 are provided on both sides of the lower surface of the molded product mounting table 22 of the blow stand 21.
-2 is provided, and by these, the pair of blow split molds 28-1 and 28-2 are reciprocally moved. The pair of blow split molds 28-1 and 28-2 have a concave surface that defines the bulge portion 52 of the molded product shown in FIG. 5 in a state where they are in contact with each other, and form a joint with a burr left. A closing portion 30 for That is, a burr space is formed below the closing portion 30.

A heater 31 is arranged below the pair of blow split molds 28-1 and 28-2 so as to be vertically reciprocable, and is vertically reciprocated by a heater cylinder 32. A cylindrical concave portion 33 into which the cylinder 13 of the injection molded product 11 shown in FIG. 1 can be fitted is formed on the upper surface side of the heater 31. Further, in the molded product mounting table 22 of the blow stand 21, a central hole 22a through which the cylinder 13 of the injection molded product 11 shown in FIG.

Next, a blow molding process using the blow molding apparatus thus constructed will be described with reference to FIGS. 3 and 4. As shown in FIG. 3, a pair of molded product pressing split dies 23-
1, 23-2 and a pair of blow split dies 28-1, 28-2
Is a cylinder 24-1 for holding the molded article attached to them,
24-2 and blow mold cylinders 29-1, 29-2
The injection molded product 11 is set on the molded product mounting table 22 of the blow stand 21 in a state of being separated from each other by the cylinder 1
3 is inserted into the central hole 22a.

After the injection molded product 11 is set, the pair of molded product pressing split dies 23-1 and 23-2 are moved to positions where they are brought into contact with each other by the molded product pressing cylinders 24-1 and 24-2, and injection molding is performed. Hold item 11. In this state, one end side of the pipe-shaped main body 12 is closed by the packing 25, and the perforated packing 26 abuts on the other end side.

Next, the heater 31 is raised and the injection molded product 1 is
The tip of the cylinder 13 of No. 1 is heated. When the tip of the cylinder 13 of the injection-molded product 11 is heated to a temperature at which blow molding can be performed, the heater 31 is lowered as shown in FIG.
The pair of blow molds 28-1 and 28-2 are moved to a position where they are brought into contact with each other by a pair of blow mold cylinders 29-1 and 29-2. As a result, the injection molded product 1
The cylinder 13 of No. 1 is closed so as to form the bulge portion 52 of FIG. 5, and at the same time, blown air is fed into the injection-molded product 11 from the air-blowing port 27 through the perforated packing 26, and the injection-molded product 11 is It is blown up into the shape of the final molded product as shown in FIG. The packing 25 seals blow air so that the blow air does not leak. Also,
When the cylinder 13 of the injection molded product 11 is closed, a burr 34 is formed in the conical space, which will be separated from the final molded product in a later step.

Next, a pair of molded product pressing split dies 23-1, 2
3-2 and a pair of blow split molds 28-1, 28-2 are driven to their separated positions by a cylinder associated therewith,
The final molded product is taken out.

Although the present invention has been described with reference to the embodiments in which the present invention is applied to a plastic molded product as shown in FIG. 1, the molded product applied to the present invention is not limited to that shown in FIG. However, it can be applied to all molded products having a bulge in a part of the tubular portion, and the blow split mold 28-
The spaces 1 and 28-2 are arbitrarily changed according to the shape of the bulge.

[0024]

According to the present invention described above, the main body of a plastic molded product is molded by injection molding (injection) to form a primary molded product, and the bulge portion is formed by blow molding. The effect like is obtained.

1. Since both ends of the pipe-shaped body are formed by injection molding, there are no parting lines in the molding, so burrs do not remain, and there is no problem in connection with the rubber hose. In addition, since the secondary processing for removing burrs has a small capacity of the cutting part, there is little wasteful burrs, and the molded product and burrs are separated from the bulging part after the bulging part is formed, so there is a risk of contamination intrusion. It is good for hygiene.

2. Since the internal shape of the pipe-shaped body is also formed by injection molding, the inside can be formed into a good flow shape of the fluid, and it becomes easy to achieve the desired performance of the molded product.

3. The mounting seat integrally formed with the pipe-shaped main body requires a certain size in view of the function of the molded product because the mounting becomes unstable if the width D shown in FIG. 5 (B) is small. In the invention, since this portion is formed by injection molding, it can be formed in a sufficient size.
By the way, in the conventional direct blow molding method, if an attempt is made to increase this width, an air pocket is created at the position inside the main body (the position indicated by 65 in FIGS. 6B and C) corresponding to the mounting seat, which is a malfunction of the molded product. There was a defect that occurred.

4. Since the bulge portion of the molded product is formed by the blow molding device, it can be molded arbitrarily according to the function of the molded product such as the shape of the tip portion, the length of the bulged portion and the like.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an injection-molded product before blow molding, which is used in an example of a method for molding a plastic molded product of the present invention.

FIG. 2 is a vertical cross-sectional view showing the overall configuration of a blow molding device used in an example of a method for molding a plastic molded product of the present invention.

FIG. 3 is a vertical cross-sectional view of a main part of a blow molding device for explaining a molding step of a method for molding a plastic molded product of the present invention.

FIG. 4 is a vertical cross-sectional view of a main part of a blow molding device for explaining a molding step of a method for molding a plastic molded product of the present invention, which follows the step of FIG.

5A and 5B are views showing the constitution of a final molded product to be manufactured by the method for molding a plastic molded product of the present invention, in which FIG. 5A is a longitudinal sectional view thereof, and FIG. A plan view and the same figure (C) are bottom views.

FIG. 6 is a view for explaining a method for molding a plastic molded product by a conventional direct blow molding method, and FIG. 6 (A) is a blow in which a concave portion for molding a parison made of a hollow plastic pipe is formed. FIG. 3B is a vertical cross-sectional view showing the structure of a molded product obtained by this manufacturing method, and FIG. 3C is a vertical cross-sectional view of the bulge portion, as viewed from the side along with the mold.

FIG. 7 is a vertical cross-sectional view showing the structure of a molded product obtained by a conventional injection blow molding method, where FIG. 7A shows a parison before blow-up and FIG. 7B shows a molded product after blow-up. Indicates.

FIG. 8 is a vertical cross-sectional view showing a structure of a molded product obtained by a conventional injection molding method, FIG. 8 (A) is a view showing components of the molded product, and FIG. 8 (B) is a view showing a finished product. is there.

[Explanation of symbols]

11 injection molded products 12 Pipe-shaped body 13 cylinder 14 both ends 15 Mounting seat 21 Blow stand 22 Molded product mounting table 23-1, 23-2 Mold presser split mold 24-1, 24-2 Cylinder for holding molded products 25 packing 26 Perforated packing 27 Air inlet 28-1, 28-2 blow split type 29-1, 29-2 Blow type cylinder 30 Closed part 31 heater 32 Heater cylinder 33 recess

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) A61M 3/00 B29C 49/00-49/80 B29B 11/14

Claims (3)

(57) [Claims] 1. A method for molding a plastic molded product having a bulge part in a part of a tubular part, wherein a part corresponding to the bulge part is made into an open tubular body and a primary molded product is prepared. The cylindrical body of the primary molded product is heated to raise the temperature to blow moldable temperature, and the temperature rising part is sandwiched by split molds having a space defining the bulge portion, and from a part of the cylindrical part. A method for molding a plastic molded article, characterized in that air is blown into the molded article body to form the bulging portion by blow molding. 2. A blow molding targeting a primary molded product in which a portion corresponding to the bulge portion is an open tubular body for molding a plastic molded product having a bulge portion in a part of the tubular portion. An apparatus, wherein a mounting table having a hole through which the cylindrical body penetrates is formed, and a cylindrical portion of the primary molded product mounted on the mounting table is accommodated on the mounting table so as to approach each other. , A pair of molded product pressing split dies that are separable from each other, and a blowing port that communicates with one of the molded product pressing split molds and blows air from one end of the primary molded product, and on the lower surface of the mounting table. A pair of blow split molds, which are arranged so as to be able to approach and separate from each other along the space, have a space that defines the bulging portion, and are molded into a predetermined bulging shape by sandwiching the tubular body of the primary molded product, and these. Vertical direction below the pair of blow split molds A blow molding apparatus comprising a blow stand, which is arranged so as to be reciprocally movable in a cylindrical shape and is heated to a temperature at which the cylindrical body of the primary molded product can be blown. 3. The blow molding device according to claim 2, wherein the pair of molded product pressing split dies are reciprocally driven by a pair of molded product pressing cylinders provided on both sides of the blow stand, and the pair of blow molded split molds are reciprocally driven. The mold is reciprocally moved by a pair of blow mold cylinders provided on both sides of the blow stand, the heater is reciprocally driven in the vertical direction by a heater cylinder, and the heater has a cylindrical body tip portion of the primary molded product. A blow molding device, characterized in that a concave portion for fitting with is formed.