JPH0428213B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a mold cavity formed by a pair of split molds, in which the upper end of the mold cavity is opened as an inlet, and the other end of the mold cavity is opened as an outlet. The present invention relates to a parison tip sealing device used in blow molding in which a parison is introduced into an open mold cavity by suction air, the tip of the parison is sealed, and then blowing is performed.

(Prior Art) As a parison tip sealing device used in the above-mentioned blow molding, the present inventor has previously developed a parison tip sealing device configured to clamp the parison tip with seal shutters (Japanese Patent Application No. 129161/1982); the tip of the parison,
We have proposed a structure in which the material is squeezed and sealed by pressing against a pinching surface that gradually squeezes outward (Japanese Patent Application No. 129162/1983), and each has achieved excellent effects.

(Problems to be Solved by the Invention) The present invention aims to enrich the technology of the parison tip seal device used in blow molding as described above.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a structure in which a large number of ventilation holes are formed at least around the periphery of the plate in the passage through which the tip of the parison is introduced by the intake air flowing outside the parison. A sealing plate is provided through the parison, and the sealing plate prevents the inside of the parison from expanding when the open end of the parison is pressed against the sealing plate and spread on the inner and outer sealing plate surfaces of the parison. The diameter is larger than that of the tip of the parison so that the spread resin on the outside of the parison does not cover the seal plate surface in a manner that prevents ventilation until the spread resin closes the opening of the parison. Embodiments of the present invention will be described below with reference to the drawings.

In Figures 1 and 2, surface plates 2, 2 are fixed standing upright and parallel to each other at appropriate intervals on a base plate 1, and four slide rods 3 are supported horizontally between both surface plates 2, 2. At the same time, a pair of movable plates 4, 4 are horizontally slidably supported by the rod, and a pair of split molds 5, 5 are attached to opposing surfaces of both movable plates. 6,
Reference numeral 6 denotes a hydraulic cylinder for driving the opening and closing of the split mold horizontally fixed to the surface plates 2, 2, whose rams 7, 7 are fixed to the back surfaces of the movable plates 4, 4, and the cylinders 6, 6
By driving, the pair of split molds 5, 5 can be moved relatively in the horizontal direction for closing and opening.

The split molds 5, 5 have an L shape on their opposing closing surfaces, for example, to form an L-shaped bent product.
When forming symmetrical L-shaped bent cavity half surfaces 8, 8 on which a letter-shaped bent cavity is to be formed, and looking at one of the split molds 5, as shown in the second figure, the upper end of the bent cavity half surface 8 is An inlet half face 9 is opened from the upper side of the split mold 5, and an outlet half face 10 is opened from the lower end of the bent half mold half 8 to the side face of the split mold 5 in an approximately extending direction thereof. Reference numeral 11 denotes a parison extrusion die of the extruder, which is disposed appropriately above the inlet formed by the inlet half faces 9, 9 when the split molds 5, 5 are closed, and an air blow nozzle 12 (the second 1), and in this example, the extrusion die 11 is constructed to be able to be raised and lowered from the raised position shown in FIG. 2 to a position in contact with the upper surface of the split mold.

The parison tip sealing device is as follows. The above exit half surface 1 when the pair of split molds 5, 5 are closed
A seal cylinder 13 is supported on the outside of the axis of the outlet formed by 0 and 10 so as to be able to move forward and backward toward the outlet. It has a circular hole-shaped lumen 14 with the front end of the side opening facing, and a sealing plate 15 is fixed at an intermediate position within the lumen 14 facing in the transverse direction of the lumen.
An intake hole 16 is opened at the closed rear end of the inner cavity 14,
A hose 17 connected to a vacuum device (not shown) is connected to the intake hole 16. In this example, the seal plate 15 is a circular flat plate with a large number of ventilation holes 18 evenly distributed throughout the plate, and the effective diameter of the seal plate 15 is still in a fluid state. When the opening end of the pipe-shaped parison is pressed against the seal plate 15 surface and spread on the seal plate surface to the inside and outside of the parison, the spread resin on the outside of the parison continues until the spread resin on the inside of the parison closes the opening of the parison. The diameter is suitably larger than the diameter of the tip of the parison so that it does not cover the ventilation holes 18 of the seal plate 15 and make ventilation impossible. The sealing plate 15 is preferably a silicone-based synthetic resin plate or a plate coated with a silicone-based synthetic resin that has a mold release effect on the parison resin.

The support structure of the seal cylinder 13 is such that a T-shaped guide groove 20 is provided on a stand 19 fixed to the base plate 1, and a T-shaped slide plate 21 provided at the bottom of the seal cylinder 13 can freely slide into the guide groove 20. At the same time, the ram 23 of the forward/backward driving air cylinder 22 fixed on the stand 19 is connected to the seal cylinder 1.
3, and when advanced by the drive of the cylinder 22, the seal cylinder 1
The front end of the opening of 3 is the exit half side 1 when the split mold 5 and 5 are closed.
It abuts in communication with the outer end of the outlet opening formed by 0 and 10, and separates from it as shown in the second figure when retracted.

The operation of the above example will be explained next along with blow molding.
First, a pair of split molds 5, 5 are closed, and a mold nest consisting of mold cavity half surfaces 8, 8, an inlet consisting of inlet half surfaces 9, 9, and an outlet consisting of exit half surfaces 10, 10 are formed, respectively. Next, the seal cylinder 13 is advanced by driving the air cylinder 22, and its opening front end contacts the outer end of the outlet. In that state, extrusion die 1
When the parison P is pushed out from the mold cavity 1 and lowered into the mold cavity from the entrance, and the vacuum device is started to start suction from the inside of the seal cylinder 13 to the outside, the mold cavity passes from the mold cavity entrance through the outside of the parison P. An airflow is generated that flows from the inside to the exit, enters the seal cylinder inner cavity 14, flows through the small ventilation holes 18 of the seal plate 15, and flows out from the intake hole 16, and the parison P is guided by this airflow into a bent shape. The tip of the parison is then introduced from the outlet into the seal cylinder inner cavity 14 and comes into contact with the seal plate 15.

When the extrusion and suction of the parison is continued after the tip of the parison comes into contact with the seal plate 15, the open tip of the parison is pressed against the seal plate 15 and spreads inside and outside the parison in a flange shape on the seal plate surface. Then, the inner spread resin a
When the opening at the tip of the parison is sufficiently closed as shown by the chain line in FIG. 3, extrusion and suction of the parison are stopped. Note that it is desirable to supply an appropriate amount of air from the blow nozzle 12 into the parison P during the extrusion and suction so that the parison maintains its pipe shape.

Next, the extrusion die 11 is lowered to close the inlet of the split mold with its lower end face, and then air is blown into the parison from the blow nozzle 12 to perform blow molding. After molding, the seal cylinder 13 is moved back, and the extrusion die 1
1 is raised, then the split molds 5, 5 are opened and the molded product is taken out.

Another embodiment of the present invention shown in FIG. 4 has a structure in which the seal plate 15a is curved backward into a conical shape, and the other structures are substantially the same as those in FIGS. 1, 2, and 3.

Furthermore, as another embodiment, for example, the first, second, third
The semicircular part of the circular seal plate 15 is fixed to the outlet half surface 10 of one of the pair of split molds 5, 5 in the example shown in the figure, and when the split molds 5, 5 are closed, the seal plate 15 is closed. The other semi-circumferential part is fitted into the other outlet half surface 10, or semicircular seal plate halves are respectively fixed to the outlet half surfaces 10, 10 of the pair of split molds 5, 5. , 5 There is also an example of a configuration in which both seal plate halves are brought together to form a circular seal plate when closed, and the seal cylinder 13 is moved toward and away from the mold outlet as a suction cylinder with the seal plate 15 removed. can get.

Another embodiment of the present invention shown in FIG.
The other structures are substantially the same as in FIGS. 1, 2, and 3.

(Effects of the Invention) According to the parison tip sealing device of the present invention, when the parison tip guided by intake air comes into pressure contact with the sealing plate, the parison tip expands and automatically seals the opening of the parison. be.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a partially omitted front view of the molding machine, Fig. 2 is a partially cutaway sectional view taken along the line - - in Fig. 1, and Fig. 3 is a seal cylinder portion in Fig. 2. FIGS. 4 and 5 are partially omitted enlarged longitudinal sectional views of other embodiments of the seal cylinder. P...Parison, 15, 15a, 15b...Seal plate, 18, 18a, 18b...Vent hole.

Claims (1)

[Scope of Claims] 1. A seal plate having a large number of small ventilation holes extending through at least the peripheral portion of the plate is provided in a passage through which the tip of the parison is introduced by the intake air flowing outside the parison, and the above-mentioned seal When the opening tip of the parison is pressed against the seal plate and spread on the inner and outer seal plate surfaces of the parison, the plate is applied to the outside of the parison until the spread resin inside the parison closes the opening of the parison. A parison tip sealing device, which is formed to have a diameter larger than the diameter of the parison tip so that the spread resin does not cover the seal plate surface in a manner that makes it impossible to ventilate the seal plate surface.