JP2701112B2 - Pressurized fluid injection nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized fluid injection nozzle of a mold apparatus for injection blow molding.

[0002]

2. Description of the Related Art In injection blow molding of synthetic resin, a fluid such as nitrogen gas, water or the like is injected into a resin in a mold before the resin immediately after injection and filling of a molten resin into a mold cavity has not yet solidified. It is a method of injecting, which is known as a method of reducing shrinkage deformation and sink when a resin is solidified in a mold.

As a method of injecting a pressurized fluid, there is known a method of injecting a fluid by injecting a synthetic resin into a mold, and then injecting a fluid into the resin through a mold wall through a mold wall. ing. More specifically, a method using an injection nozzle provided with a fluid injection port having a diameter of 0.02 to 0.2 mm on a surface facing the cavity at the tip of the injection nozzle (JP-A-3-2227)
13) and a method of using a pouring nozzle provided with a porous crystalline alloy which prevents gas from flowing back at the tip and allows gas to pass through (JP-A-63-165114).

[0004]

When injection molding is carried out using a conventional injection nozzle, a part of the press-fitting fluid leaks from a slight gap between the resin and the injection nozzle, so that the resulting molded product has a dimensional deviation. There are problems such as occurrence.

[0005]

Means for Solving the Problems Accordingly, the present inventors have:
In order to provide a mold device for injection hollow molding in which the leakage of the press-fitting fluid was prevented, the inventor conducted a thorough study focusing on the injection nozzle. As a result, the injection nozzle has a special structure. It has been found that the press-fitting fluid is prevented from leaking from between the resin and the desired object is achieved, and the present invention has been completed.

That is, the gist of the present invention is a nozzle for injecting a pressurized fluid into a molten resin filled in a cavity of a mold in a mold apparatus for injection blow molding. Are characterized by having pores through which the molten resin does not pass but through which the pressurized fluid can pass, and a groove along the circumferential direction of the nozzle on the outer surface near the pores of the nozzle. Located in the pressurized fluid injection nozzle.

Hereinafter, an example of the nozzle of the present invention and an apparatus using the nozzle will be described with reference to the drawings. FIGS. 1 and 2 are schematic views of an example of an injection blow molding apparatus provided with a nozzle of the present invention, and FIGS. 3, 4, and 5 are side views and FIGS. 6 is an explanatory diagram showing an enlarged view of a groove portion of the nozzle during molding.

In the figure, 1 is a nozzle, 2 is a fine hole, 3 is a groove, 4 is a connecting rod, 5 is a hydraulic device, 6 is a fixed mold, 7 is a movable mold, 8 is a cavity, 9 is a fluid introduction pipe, Numeral 10 denotes a molten resin. As shown in FIGS. 1 and 2, the nozzle 1 moves from the fixed mold 6 to the movable mold 7 with the cavity 8.
It is provided so that it can protrude in. Although the nozzle 1 can be provided on the movable mold 7 side, it is usually provided on the stationary mold 6 which does not move.

At the tip of the nozzle 1, there are provided pores 2 which do not allow the molten resin 10 to pass therethrough but allow a pressurized fluid, ie, nitrogen gas, air, water, etc., to pass therethrough. The molten resin is introduced into the mold. The rear nozzle 1 enters the molten resin and injects a pressurized fluid. The nozzle 1 may be moved forward / backward by the hydraulic device 5 or the like via the connecting rod 4, but the structure is not limited to this.

[0010] A fluid introduction pipe 9 is connected to the nozzle 1 so that fluid is supplied in a timely manner. The pores of the nozzle 1 may be sized so as not to allow the molten resin to pass therethrough but allow the pressurized fluid to pass therethrough. For example, 0.005 to 0.05 mm by laser light, preferably
Hole of about 0.01 to 0.03 mm, length of 1 to 2 mm, width of 0.005 to 0.05 mm, preferably 0.01 to 0.03 mm
Slit of about 0.03 mm, JP-A-63-16511
And a block to which a block made of a porous crystalline alloy as described in No. 4 is attached.

A groove is provided on the outer surface of the nozzle 1 near the pore 2 along the circumferential direction of the nozzle. The groove 3 is provided in a ring shape (headband shape) outside the injection nozzle 1. The shape of the groove 3 is not particularly limited as long as the molten resin 10 can enter the groove 3 and seal the gap between the molten resin 10 and the injection nozzle 1. -3, Fig.-4, Fig.-5.

The groove 3 shown in FIG. 3 shows a case in which a tapered groove 3 in which the depth of the groove 3 is gradually increased toward the base of the nozzle is formed. As shown in FIG. 6, it is desirable that the molten resin 10 easily adheres to the wall surface of the groove 3 by the pressure of the pressurized fluid and the sealing effect is enhanced. Needless to say, the shape of the groove 3 having a rectangular cross section as shown in FIG. 4 and the groove 3 having an arc-shaped cross section as shown in FIG.

The position where the groove 3 is provided is preferably such that when the nozzle 1 enters the cavity 8, the groove is within the cavity 8 and near the boundary between the cavity 8 and the mold 6. The groove 3 is usually 0.5 to 2 mm wide and 0.1 to deep.
It is preferable to provide one or two or more wires with a size of about 1 mm. The grooves are preferably provided continuously in the circumferential direction of the nozzle, but may be provided intermittently in the circumferential direction.

Using such a mold apparatus, an injection hollow molded article is manufactured as follows. For example, from the state where the nozzle 1 is housed as shown in FIG. 1, the tip of the injection nozzle 1 is inserted into the engraving of the mold cavity 8 by the hydraulic device 5 by a predetermined length (FIG. 2). It is adjusted so that the groove 3 provided in the injection nozzle 1 is exposed in the cavity 8 and near the boundary with the mold 6. Usually, the groove 3 is exposed in the cavity 8 from the fixed mold 6 by about 1 to 5 mm, preferably about 2 to 4 mm. Next, the molten resin is filled into the mold cavity 8 through an injection port (not shown).
During or after the filling of the molten resin, a gas such as nitrogen is injected into the molten resin in the mold cavity 8 from the fluid introduction pipe 9 through the fine holes 2 of the injection nozzle 1. In this way, an injection-molded hollow product can be obtained. Alternatively, after filling the molten resin into the mold cavity 8, the tip of the injection nozzle 1 is inserted into the mold cavity 8 by a predetermined length. You may.

The molten resin 10 enters the groove 3 provided outside the injection nozzle 1 by the action of the injection pressure of the molten resin 10 itself or the pressure of a gas which is a pressurized liquid, and the gap between the injection nozzle 1 and the molten resin 10 is formed. Seal. In this manner, since the pressure of the pressurized fluid is maintained at a constant level without releasing the pressure, the molded product does not have a dimensional deviation or a defective molded product.

The cooling is performed while maintaining the gas pressure in the same state as at the time of gas injection, and the gas pressure is purged on the side of a gas pressurizing device (not shown) immediately before the end of cooling. Next, the mold clamping force of the mold is released, and at the same time, the nozzle 1 is removed from the molded article, and after purging the gas pressure in the molded article, the mold is opened to obtain a target molded article.

[0017]

When the injection nozzle of the present invention is used, the gap between the cooled and solidified resin and the injection nozzle is sealed by the resin itself, and leakage of the press-in fluid is prevented. , And an injection-molded hollow molded article can be produced favorably.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of an apparatus provided with a nozzle according to the present invention.

FIG. 2 is a schematic diagram showing an operating state.

FIG. 3 is a side view of an example of a nozzle.

FIG. 4 is a side view of an example of a nozzle.

FIG. 5 is a side view of an example of a nozzle.

FIG. 6 is an enlarged view of a groove portion of the nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Micropore 3 Groove 8 Cavity 9 Fluid introduction pipe 10 Molten resin

Claims (1)

(57) [Claims] 1. A nozzle for injecting a pressurized fluid into a molten resin filled in a cavity of a mold in a mold apparatus for injection hollow molding, wherein the molten resin does not pass through a tip portion of the nozzle. A pressurized fluid injection nozzle, characterized in that it has pores through which the pressurized fluid can pass and has a groove along the circumferential direction of the nozzle on the outer surface near the pores of the nozzle.