JPH039829A - Method for forming resin product equipped with projecting body having whole continuous periphery - Google Patents

Abstract

PURPOSE:To produce a continuous projecting body on the outer periphery of a resin product by a method wherein parison is hung down by resin born on air stream under such condition that an insert, which is turned to be he projecting body having whole continuous periphery, is fittingly fixed to split molds so as to face in advance its inner peripheral part to the interior of a molding space. CONSTITUTION:A projecting body 7 having whole continuous periphery as an insert 8 is fittingly fixed to the interior of split molds 1 and 1 so as to face in advance its inner peripheral part 8a to the interior of a molding space 4. Under such state that upper molds 1b and 1b and lower molds 1c and 1c are opened, parison 3 is hung down from a die 2, which is provided above the molds. At this time, air flow running downwards is generated by connecting a suction pipe to the molding space 4. The air stream flows so as to surround the periphery of the parison 3 and the parison 3 hangs down at the center part of the molding space 4 without touching the surface of the surrounding split molds 1 as they are closed. By blasting air in the interior of the parison 3, where the upper and lower ends are closed by closing the upper molds 1b and 1b and the lower molds 1c and 1c, the parison 3 is expanded so as to be pushed against the inner peripheral surface of the split molds 1 and 1 in order to form the required shape.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention involves simultaneously molding continuous protrusions around the entire circumference of a resin product to diversify its shape or to reinforce it. The present invention relates to a method of molding a resin product with continuous protrusions all around the circumference.

[Conventional technology]

Conventionally, when attaching continuous protrusions to the outer periphery of a resin product, the only method was to fit and weld the protrusions after the resin product was molded. Therefore, not only were they unsatisfactory in terms of strength and cost, but they were also limited to materials of the same type.

[Problem to be solved by the invention]

This was due to the molding method unique to blow molding, in which the split mold must not be closed when the parison is allowed to hang (because the parison hits the mold, resulting in poor hanging properties).

However, recently, a molding method has been proposed in which an airflow is caused to flow inside the mold and the parison is made to hang down on this airflow (
According to Japanese Patent Publication No. 5B-47337), it is no longer necessary to open the 10% mold when hanging the parison.

This invention makes it possible to form continuous protrusions on the outer periphery of a resin product at the same time as molding, by effectively utilizing such a molding method.

[Means to solve the problem]

That is, in this invention, an airflow is caused to flow in a mold space formed by two split molds that are joined together (closed), and the parison is suspended by this airflow, and then the upper and lower ends of this parison are closed. In addition, in the molding method for resin products in which air is blown into the parison and molded into a shape that follows the split mold, an insert, which will become a continuous protrusion around the entire circumference of the molded product, is placed inside the mold space in advance. The insert is fitted into the split mold with the periphery exposed, and after the parison is allowed to hang down, air is blown into the parison so that the insert is continuously fitted to the outer periphery of the product. The present invention provides a method for molding a resin product with continuous protrusions all around the circumference.

[Effect]

By taking the above measures, in other words, the split mold can be kept closed when hanging the parison.
By fitting the insert, which is a continuous protrusion all around the mold, into the mold in advance, these protrusions can be formed on the outer periphery of the molded product at the same time as molding.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 is a cross-sectional view showing how the parison hangs down into the split molds. They are constructed so that they can be opened and closed independently. Now, only the main molds 1a and la are closed, and the upper molds 1b and lb and the lower molds 1c and l are closed.
The parison 3 is suspended from the die 2 above with the c open.

In addition, at this time, the mold space 4 composed of the main molds 1a and la
An air intake pipe 5 is connected to the mold space 4 to generate a downward airflow in the mold space 4. therefore.

The airflow surrounds parison 3.

Even if the mold space 4 is bent like this.

Keep the split mold 1.1 closed and do not touch the surface of the surrounding split mold 1.1 (do not let the center part hang down).

By the way, in this case, after molding, the protrusions 7 which are to be formed on the outer periphery of the product 6 and which are continuous over the entire periphery are placed inside the split molds 1, 1 in advance as inserts 8, so that the inner periphery 8a thereof faces into the mold space 4. In this case, it is inserted in the horizontal position. Note that "facing" here refers to whether the inner end of the inner circumferential portion 8a protrudes into the mold space 4, or whether it is set to have approximately the same diameter. That is, the inner circumference 8a of the insert 8 is located in the mold space 4.
If the protrusion protrudes into the inner part, when molded by blowing air, the continuous protrusion 7 will be partially embedded in the outer periphery of the product 6, and if it is of the same diameter, it will be simply molded. It becomes a state where it is externally fitted.

FIG. 2 is a cross-sectional view when the parison 3 reaches the lower molds 1c, lc. When this state is reached, the suction pipe 5 is removed to stop the supply of the parison 3, and at the same time the upper molds 1b, 1b and the lower molds are removed. The molds 1c and lc are closed, and the upper and lower ends of the parison 3 are closed. Next, the air pins 9 were passed through the upper molds Ib, Ib or the lower molds 1c, lc to form the upper molds 1b, lb in this example.

Therefore, pin holes 10 are pre-formed at required locations in the upper molds 1b, 1b), and air is blown into the parison 3 from the air pins 9 to form the parison 3 on the inner peripheral surface of the split mold 1.1. It is inflated by pressing and molded into the desired shape.

FIG. 3 is a partially sectional front view of the product 6, and the insert 8 was fitted in advance into the split molds 1, 1 with the inner peripheral part 8a facing the mold space 4 as described above. Therefore, when molding is performed by blowing air, the parison 3 expands so as to embed the inner circumference 8a of the inserter 1-8 in its outer circumference. As a result, continuous projections 7 are formed on the outer periphery of the product 6.
will be integrally molded. From this point of view, it is preferable to form the inner circumferential portion 8a into a block with a large diameter to prevent the inner circumferential portion 8a from being pulled out.

FIG. 4 is a sectional view showing the hanging state of the parison 3 when the continuous protrusion 7 is fitted all around the trough of the bellows of the bellows-shaped product 6, but this case is similar to the above. Then, the parison 3 may be allowed to hang down while the split molds 1, 1 into which the insert 8 is fitted in advance are closed.

FIG. 5 is a front view of the product 6 molded in this manner, in which the continuous projections 7 all around the circumference are fitted into the valleys of the bellows of the product 6. In this case, the inner circumference 8a of the insert 8
If the projecting body 7 is made to protrude into the mold space 4, the entire circumference continuous protrusion 7 will be partially embedded in the outer periphery of the product 6 (a) L, and if the diameter is the same, it will be simply externally fitted (b ) state is as described above. FIG. 6 is also a front view of the product 6, but in this case, the bellows are in a continuous spiral shape,
Along with this, the continuous protrusion 7 all around the circumference is also fitted in the same (Il!l!) spiral shape.In addition, if such a continuous protrusion 7 is fitted in the valley of the bellows, .

It is significant because it can suppress deformation due to positive pressure and negative pressure.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to integrally mold the continuous protrusion 7 all around the outer periphery of the resin product 6. Therefore, it is stronger than conventional products in which separate parts are welded or semicircular parts are butted and welded together. In particular, in the past, it was not possible to attach something like a flange whose entire circumference was continuous to the valley of a bellows body in which the peaks and valleys alternated; however, according to the present invention, it is possible to It has also become possible. Furthermore, the material of the continuous protrusion 7 all around the circumference may be different from that of the product 6, for example, it may be made of metal. It should be noted that the continuous protrusion 7 all around the circumference may be not only a single leaf extending over 360° as described above, but also a continuous spiral as shown in FIG. 6. Furthermore, since the continuous protrusions 7 all around the circumference can be formed at the same time as the blow molding of the product 6, there is no increase in cost.

[Brief explanation of the drawing]

Figures 1 and 4 are cross-sectional views of the parison in its hanging state;
The figure is a sectional view of the air blowing state, FIG. 3 is a partially sectional front view of the product, and FIGS. 5 and 6 are front views of other products. (Symbol) ・Split mold ・Parison ・Mold space ・Product ・Continuous protrusion all around ・Inner periphery of inserter I・a ・・〃

Claims (1)

[Claims] [1] Airflow is caused to flow in the mold space (5) formed by the joined split molds (1) and (1), and the parison (3) is suspended on this airflow. In the molding method for resin products, in which the upper and lower ends of the parison (3) are closed, and air is blown into the parison (3) to mold it into a shape that follows the split molds (1), (1), after molding. products (6
) into the split molds (1), (1) with the inner peripheral part (8a) facing the mold space (5) in advance. After fitting and hanging the parison (3), air is blown into the parison (3) so that the insert (8) is connected to the product (6).
A method for molding a resin product with continuous protrusions all around the circumference, which are formed so as to fit continuously around the outer periphery of the resin product.