JPH0469537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of blow molding a synthetic resin hollow product which is bent in two or three dimensions and has a ring-shaped insert fitted around its outer periphery.

(Prior Art) Conventionally, as a blow molding method for an L-shaped or S-shaped synthetic resin hollow bent product with a piece-shaped insert component attached to the outer surface, a pair of split molds each having a half side of a bent mold cavity is used. In the open state, the required piece-shaped insert parts are removably attached to the bent half of the split mold, and then a tubular parison with a diameter slightly larger than the maximum left and right width of the bent half of the split mold is attached to the split mold. A method is known in which a hollow bent product with an insert part is obtained by extruding the parison between the molds, then closing the split molds with the parison in between, and then blowing air into the parison to inflate it. However, with this conventional method, it is impossible to mold a hollow bent product in which a ring-shaped insert is fitted around the outer periphery all at once, and the development of a new molding method has been desired.

(Problems to be Solved by the Invention) An object of the present invention is to provide a new blow molding method that enables blow molding of a synthetic resin hollow bent product in which a ring-shaped insert part is fitted around the outer periphery. do.

(Means for Solving the Problems) In order to achieve the above object, the method of the present invention is to close a curved mold cavity half face having an upwardly opening mold cavity entrance half face at one end and a mold cavity exit half face at the other end. Using a pair of split molds on the molding surface, close the pair of split molds to form an open bent mold cavity having an upwardly opening mold cavity entrance at one end and a mold cavity exit at the other end. , a ring-shaped insert part is removably attached to a predetermined position within the bent cavity along the transverse inner circumferential surface of the cavity; A parison with a diameter smaller than the inner diameter of the part is inserted from the mold cavity entrance, and an airflow is provided inside the bent mold cavity from the flow mold cavity outlet, and the airflow causes the parison to pass through the ring-shaped insert part and form the bent mold. The parison is introduced into the cavity, and then the tip of the parison is sealed and air is blown into the parison to form the parison.

The ring-shaped insert component in the present invention may be circular, triangular, square, or polygonal depending on the purpose, and may be made of metal, synthetic resin, or various other materials.

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

(Example) First, a pair of split molds 1, 1 to form a bent nest
As shown in the first and second figures, in this example, L-shaped curved nest half surfaces 2, 2 are formed on the closing surfaces, respectively,
The mold cavity half surfaces 2, 2 have a mold cavity inlet half surface 3, 3 that opens on the upper side of the split molds 1, 1 at one end, and a mold cavity exit half surface that opens on the left and right side surfaces of the split molds 1, 1 on the other end. 4 and 4 respectively. Further, semi-circular insert part holding grooves 12, 12 are formed at the positions where the ring-shaped insert parts of the double bent mold cavity halves 2, 2 are to be fitted, and are recessed along the transverse inner circumferential surface of the mold cavity halves.
has been formed.

As shown in the first diagram, the extruder 5 to which the parison is to be supplied is movable up and down above the mold cavity entrance formed by the pair of mold cavity entrance halves 3, 3 when the pair of split molds 1, 1 are closed. The extrusion die 6 has an annular parison extrusion hole 7 on its lower surface and an air blow nozzle 8 in its center.
has been established.

The insert part 13 to be insert-molded is made of synthetic resin and has an eye 14 protruding from a circular ring-shaped body, as shown in FIG.

The blow molding method for a bent product with a ring-shaped insert part is as follows. First, insert the insert part 1 into the semi-annular insert holding groove 12 of one split mold 1.
3 is fitted and held, and then the pair of split molds 1, 1 are closed to form an open L-shaped bent nest with open ends at both ends, consisting of a pair of bent nest halves 2, 2.
A ring-shaped insert component 13 is held in an annular holding groove formed by a pair of insert holding grooves 12, 12.

Next, as shown in the third figure, with the extrusion die 6 slightly raised from the upper surface of the closed split molds 1, 1, the extrusion molding hole 7 is opened to a diameter smaller than the minimum inner diameter of the bent mold cavity and the inner diameter of the insert part 13. A parison P having a circular cross section is extruded and inserted and lowered into the bent mold cavity from the mold cavity entrance consisting of the mold cavity entrance halves 3, 3, and at the same time, a vacuum device is inserted into the mold cavity exit consisting of the mold cavity exit half faces 4, 4. A suction cup 11 connected to the parison P is brought into contact with the suction cup 11, and a suction action is applied to the inside of the mold cavity through the cup 11, so that it flows into the mold cavity from the mold cavity entrance, flows outside the parison P, and flows from the mold cavity outlet to the cup 11.
In addition to creating an airflow that flows out to the outside through
Air is blown out from the air blow nozzle 8 of the extrusion die 6, thereby creating an airflow that flows inside the parison P and flows out from the mold cavity exit via the cup 11, and these airflows cause the parison P to
is guided through the ring-shaped insert part 13 and introduced into the mold cavity. In this case, it is desirable that the air pressure inside and outside the parison P be approximately equal.

The tip of the parison P is connected to the cup 11 from the mold cavity exit.
When the parison protrudes slightly inward, the extrusion of the parison and the suction by the vacuum device are stopped, and then the extrusion die 6 is lowered as shown in Figure 4 to almost close the mold cavity entrance, and the tip of the parison P is inserted into the above-mentioned cup. 11
A pair of seal shutters 9, 9 provided in the mold cavity are closed by air cylinders 10, 10 to provide a clamping seal, and the mold cavity outlet is closed by closing the shutters 9, 9 and the cup 11. In this way, as shown in Figure 5, the parison P is blown up by the air continuously blown out from the air blow nozzle 8, and a bent product with the desired ring-shaped insert part 13 fitted on the outer periphery is formed. . After molding, the extrusion die 6 is raised slightly and the parison between the extrusion die and the split mold is cut and separated, and the shutters 9, 9 are opened and the cup 11 is retracted, and then the split molds 1, 1 are opened to remove the molded product. Take out.

(Effects of the Invention) According to the method of blow molding a bendable product with a ring-shaped insert of the present invention, it is now possible to form a bendable product with a ring-shaped insert all at once by blow molding, which was previously impossible. , its use value is extremely high.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a partially cutaway schematic side view at the split mold closing stage, FIG. 2 is an enlarged sectional view taken along the - line in FIG. 1, and FIG. 3 is a parison introduction stage. FIG. 4 is a top side view of the parison tip at the sealing stage, FIG. 5 is a top side view of the blow molding stage, and FIG. 6 is an enlarged perspective view of the ring-shaped insert part. P...parison, 1...split type, 2...bent nest half side,
3...Half surface of the mold cavity entrance, 4...Half surface of the mold cavity exit, 13...Ring-shaped insert part.

Claims (1)

[Scope of Claims] 1. A pair of split molds each having a closing surface having a mold cavity inlet half face opening upward at one end and a bent mold cavity half face having a mold cavity outlet half face at the other end as a closing face, The split mold is closed to form an open bent type cavity having an upwardly opening mold cavity inlet at one end and a mold cavity outlet at the other end, and a ring-shaped insert part is placed at a predetermined position within the bent cavity. A parison is detachably attached along the transverse inner peripheral surface of the mold cavity, and then a parison having a diameter smaller than the minimum inner diameter of the mold cavity and the inner diameter of the ring-shaped insert part is inserted into the bent mold cavity from the mold cavity entrance. At the same time, an airflow is applied to the inside of the bent nest from the outlet of the flow shaped nest, and the airflow causes the parison to be introduced into the bent nest through the ring-shaped insert part, and then the tip of the parison is sealed. At the same time, this is a blow molding method for bendable products with ring-shaped inserts, in which air is blown into the inside of the parison.