JPH07276481A - Molding method for resin products with all-round continuous protrusions - Google Patents

Abstract

(57) [Summary] [Purpose] To integrally form a projection with a continuous whole circumference on the outer circumference of a resin product. [Structure] The parison 3 is suspended in a substantially vertical mold space 4 formed by the split molds 1 and 1 in a bonded state.
In the method of molding a resin product in which the upper and lower ends are closed and air is blown into the parison 3 to form the shape along the split molds 1 and 1, an insert which becomes the continuous projection 7 around the entire circumference of the product after molding. 8 is mounted on the split molds 1 and 1 in a state where the inner peripheral portion 8a of the insert 8 is exposed in advance in the mold space 4, and the parison 3 holds the inner peripheral portion 8a of the insert 8 around the entire circumference. Molding method for resin products with body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin with a continuous projection for the entire circumference, in which a projection that is continuous over the entire circumference is simultaneously formed on the outer periphery of the resin product at the same time when molding the resin product in order to diversify the shape or reinforce. The present invention relates to a method of molding a product.

[0002]

2. Description of the Related Art Heretofore, in the case of fixing a continuous protrusion over the entire circumference of a resin product, there has been no choice but to externally fit and weld the protrusion after molding the resin product. Therefore, they are unsatisfactory in terms of strength and cost, and are limited to the same kind of materials.

[0003]

This is due to the molding method peculiar to blow molding in which the split mold must not be closed when the parison is hung (since the parison hits the mold, resulting in poor hanging performance). there were. However, recently, a molding method has been proposed in which an air flow is flown into a mold and the parison is hung down on the air flow (Japanese Patent Publication Sho 58.
According to this, when the parison droops,
You don't have to open the split mold.

Therefore, the applicant of the present invention has proposed a case in which a continuous projection can be formed simultaneously with molding on the outer periphery of a resin product by effectively utilizing such a molding method. Proposed as No. 144925. However, since the air flow is made to flow in the mold space, this device complicates the device and increases the cost. The present invention solves such a problem, and in short, it is possible to form a continuous protrusion on the outer periphery without flowing an air flow.

[0005]

Under the above problems, according to the present invention, a parison is hung in a substantially vertical mold space formed by a split mold in a bonded state to close the upper and lower ends of the parison. ,
In a method of molding a resin product in which air is blown into a parison to mold it into a shape along the split mold, an insert that becomes a continuous projection of the entire circumference of the product after molding is exposed in advance in the mold space to its inner peripheral portion. The present invention provides a method for molding a resin product with a continuous projection having an entire circumference, which is mounted in a split mold in a state where the parison holds the inner circumference of the insert.

[0006]

By using the above means, that is, since the split mold is kept closed when the parison hangs down, it is possible to previously insert the insert, which is a continuous projection of the entire circumference, into the mold. These projections can be formed on the outer periphery of the molded product at the same time as the molding. Further, in this case, since the airflow does not flow in the mold space, the device is simplified.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a state where the parison hangs in the split mold. The split molds 1 and 1 have upper molds 1b and 1b and lower molds 1c and 1c above and below the central main molds 1a and 1a, respectively. Each has a structure that can be opened and closed independently. And
Now, with only the main dies 1a and 1a closed, and the upper dies 1b and 1b and the lower dies 1c and 1c opened, the upper die 2 to the parison 3
Droop.

Incidentally, in the conventional case, an intake pipe 5 is continuously connected to the mold space 4 constituted by the main molds 1a and 1a, and the air is sucked by the intake pipe 5 to generate an airflow flowing downward in the mold space 4. Is common. However, when the mold space 4 has a substantially vertical shape as in this example, even if the split molds 1 and 1 are left in the closed state, the parison 3 does not contact the surrounding split molds 1 and 1 surface. Without touching, hang the central part. Therefore, in this example, the intake mechanism including the intake pipe 5 is unnecessary.

By the way, at this time, after the molding, the projection 7 which is to be formed on the outer circumference of the product 6 and is continuous to the entire circumference is used as the insert 8 in advance in the split molds 1 and 1 with the inner peripheral portion 8a of the mold space 4 formed therein. It is fitted so that it faces inside.
Incidentally, the term "faced" here means whether the inner end of the inner peripheral portion 8a projects into the mold space 4 or is set to have substantially the same diameter. That is, as long as the inner peripheral portion 8a of the insert 8 is projected into the mold space 4, when the molding is performed by blowing air later, the entire circumference continuous protrusion 7 is partially embedded in the outer periphery of the product 6. In this state, if they have the same diameter, they are simply fitted.

FIG. 2 is a sectional view when the parison 3 reaches the lower molds 1c and 1c. In this state, the supply of the parison 3 is stopped, and at the same time, the upper molds 1b, 1b and the lower mold 1 are stopped.
c and 1c are closed, and the upper and lower ends of the parison 3 are closed. Then, the air pin 9 is placed in the upper mold 1b, 1b or the lower mold 1c, 1c.
(In this example, the upper molds 1b and 1b are used. Therefore, pin holes 10 are formed in advance in the required positions of the upper molds 1b and 1b), and air is blown from the air pins 9 into the parison 3. The parison 3 is inflated so as to be pressed against the inner peripheral surfaces of the split molds 1 and 1 to be molded into a desired shape.

FIG. 3 is a partial sectional front view of the product 6.
As described above, since the inner peripheral portion 8a of the insert 8 is fitted in the split molds 1 and 1 in advance so as to face the mold space 4,
When air is blown in for molding, the parison 3 swells so that the inner peripheral portion 8a of the insert 8 is embedded in the outer periphery thereof. As a result, the entire circumference continuous projection 7 is integrally formed on the outer circumference of the product 6. From this point of view, it is preferable to make the inner peripheral portion 8a in the shape of a large diameter block so that the inner peripheral portion 8a can be prevented from coming off.

FIG. 4 is a cross-sectional view showing a suspended state and an air blown state of the parison 3 when the all-round continuous protrusion 7 is fitted in the valley portion of the bellows-shaped product 6, but in such a case. The same applies to the above, and the parison 3 may be suspended with the split molds 1 and 1 to which the inserts 8 have been fitted in advance closed.

FIG. 5 is a front view of the product 6 molded in this manner, but the entire-circumferential continuous projection 7 is fitted in the bellows valley of the product 6. In this case, if the inner peripheral portion 8a of the insert 8 is projected into the mold space 4, the entire circumferential continuous protrusions 7 are partially embedded in the outer periphery of the product 6 (a), and have the same diameter. If so, it will be in a state of being simply fitted (b)
Is as described above.

FIG. 6 is also a front view of the product 6. In this case, the bellows have a continuous spiral shape, and accordingly, the entire circumference continuous projection 7 is also fitted in a spiral shape. Will be done. If such a full-circumferential continuous projection 7 is fitted in the valley portion of the bellows, it is possible to suppress the deformation due to both positive pressure and negative pressure, which is significant.

FIG. 7 is a cross-sectional view showing the air blowing state of the parison 3 when the continuous protrusions 7 are fitted around the bellows of the bellows-shaped product 6, and the molding in this case is also the same as the above. It is the same. However, since the insert 8 is embedded in the parison 3, holes 8b are formed at the center, and the parison 3 is continuous through the holes 8b so that the continuous projection 7 is fixed all around. We are trying to strengthen it. This is particularly effective in suppressing deformation against negative pressure.

[0016]

As described above, according to the present invention, it is possible to integrally form a continuous projection on the outer circumference of a resin product. Therefore, the strength is higher than that of a conventional product in which separate ones are welded or a semicircular one is butted and welded. In particular, conventionally, it was not possible to attach something like a flange whose entire circumference is continuous to the valleys or peaks of the bellows body in which the peaks and valleys alternate, but according to the present invention , It became possible to do such a thing.

Further, it is possible to use a material of the continuous circumferential projection which is different from that of the product, for example, metal. It should be noted that, as this all-round continuous projection,
Not only the uniform shape over 60 ° but also the continuous spiral shape as shown in FIG. 6 is possible. And
The continuous projections having the entire circumference can be formed at the same time as the blow molding of the product, and at this time, it is not necessary to flow the air flow into the mold space, so that the cost reduction effect is great.

[Brief description of drawings]

FIG. 1 is a sectional view of a split mold showing a suspended state of a parison.

FIG. 2 is a cross-sectional view of the split mold in an air blown state.

FIG. 3 is a partial sectional front view of a semi-finished product.

FIG. 4 is a sectional view of a split mold showing a hanging state and an air blowing state of a parison when a full-circumferential continuous protrusion is attached to a valley portion of a bellows.

FIG. 5 is a front view of the product.

FIG. 6 is a front view of the product.

FIG. 7 is a sectional view of a split mold showing an air blowing state of a parison when a continuous projection having a full circumference is attached to a mountain portion of a bellows.

[Explanation of symbols]

 1 split type 3 parison 4 type space 6 product 7 all-round continuous protrusion 8 insert 8a inner peripheral part of insert

Claims (1)

[Claims] 1. A parison is hung in a substantially vertical mold space formed by a split mold in a bonded state to close upper and lower ends of the parison, and air is blown into the parison to follow the split mold. In the method of molding a resin product that is molded into a shape, insert the insert that will be the entire circumferential continuous protrusion of the molded product into the split mold with its inner periphery facing the mold space in advance, and insert the parison with the insert. A method for molding a resin product with an entire circumference continuous protrusion characterized by holding an inner peripheral portion.