JP3063953B2 - Blow molding method using expansion core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding method using a stretchable core.

[0002]

2. Description of the Related Art In blow molding for producing a hollow resin product from a parison injected or extruded into a cylindrical shape from a die head, a parison is injected or extruded from a die head, and a pre-blow is applied to a parison formed into a bag by a parison pinch. Go to inflate slightly, put in the opened mold, close the mold, evacuate the gas in the cavity formed by the mold and the parison, and then vacuum pump through the small air vent hole to the mold surface Then, high-pressure air is blown into the parison to form the parison into a predetermined shape based on the cavity, and then cooled with a mold to complete the molding. In this way, the molded resin product is opened and taken out. FIG. 10 shows a conventional blow molding machine.

FIG. 10 shows a molten resin in a die head 2.
Shows a blow molding machine 1 of a so-called side feed system, which is supplied from one side of the die, and a resin in a high-temperature molten state pressed by an extruder 4 is connected to a die head 2 and a mandrel 3 via a resin supply port 2a. Are discharged from the lowermost annular space passage 7 to form a parison P. The core 3a is connected to a paricon rod 6a penetrating the mandrel 3, and is slightly moved up and down by the operation of the paricon cylinder 6, so that the thickness of the parison P is controlled. ) Can be adjusted.

On the other hand, as shown in FIG. 11, a resin is formed into a panel shape having a bag-shaped air space inside to form a building material such as a door (gate) or a simple wall material (partition wall). However, it has been considered to use them for floors such as concrete casting formwork and simple piers, but these molded products have considerable structural strength despite their light weight.
It has the feature of being resistant to deformation.

[0005]

However, when manufacturing a panel-shaped molded product having such a bag-shaped space by blow molding, for example, if a tack-off core is used, a tack-off core is formed. A hydraulic drive device must be used for the advance and retreat of the child, which not only complicates the structure of the mold, but also increases the thickness of the mold and causes poor maintenance.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a blow molding method capable of easily obtaining a molded product having a constant thickness.

[0007]

In order to achieve the above-mentioned object, a male mold for molding the front surface of a panel having a smooth surface and a back surface of the panel having a plurality of elastic cores are formed.
Using the female mold for the shape, the parison after mold close straight parison depending from the die at the both mold while expanding in blow air, so as to shape the parison also introducing compressed gas into the expansion core did.

[0008]

[Function] A parison suspended from a die is clamped by a pair of left and right dies, and at the same time, a compressed gas is introduced into a telescopic core provided on a female mold side for molding the back surface of the panel to expand the parison. Blow air is introduced into the parison and the panel surface
When the back of the panel is gently pressed against the panel surface of the parison, which is in close contact with the cavity surface of the male mold that molds the side , the parison naturally follows the cavity surface of the female mold that molds the back surface of the panel , and there is no local stretching. A molded product having a constant thickness can be obtained.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a blow molding method using a stretchable core according to the present invention.

FIG. 1 is an overall vertical sectional view of a blow molding machine, and FIG.
Fig. 3 is a view showing a state immediately after mold clamping with the parison held between the two dies, Fig. 3 is a view showing a state in which compressed gas is introduced into the expandable core and the parison, and Fig. 4 is a cross section viewed from A to A in Fig. 3. FIG. 5 is a view showing the completed expansion of the expandable core, and FIG. 6 is a view showing BB of FIG.
FIG. 7 is a perspective view of a panel-shaped molded product, and FIG.
FIG. 9 is a plan view of a telescopic core of another embodiment according to this embodiment, and FIG.
9 is a partially enlarged plan view of a panel-shaped molded product manufactured by using the elastic core shown in FIG.

As shown in FIG. 1, in a blow molding machine 1, a parison (particularly, a flat parison) P is formed into a pair of right and left molds 8 by a die head 2, a mandrel 3, an extruder 4, and a paricon cylinder 6 which are the same as those of the conventional structure. Hang between. The blow molding machine 1 according to the present invention is different from the conventional structure in that the mold 8 has a male mold 8a for molding a panel front side having a smooth cavity surface and a panel back side provided with a plurality of elastic cores 12. To
And a female mold 8b to be molded .

The elastic core 12 is preferably made of a material having elasticity and heat resistance, such as silicon rubber or fluorine rubber.

When such a material is used, heat resistance 3
It can be up to 00 ° C and elongation of 600%.

The compressed gas (for example, 5-1)
5 kg / cm ² ) is supplied from a compressed gas source (not shown) via a conduit 14 to a female mold 8 b for molding the back side of the panel.
The compressed gas is introduced through a gas introduction hole 13 provided therein, and the expansion and contraction core 12
Is inflatable to a desired size.

Both dies 8a and 8b are connected to the back of a platen (not shown) at the back, and are configured to be openable and closable (movable forward and backward).

A blow molding method using the mold having the above configuration will be described.

In the blow molding machine 1 having the mold constructed as described above, the parison P having a circular cross section (preferably having a major axis in the width direction of the mold) is obtained by opening both molds 8a and 8b. After hanging down the substantially elliptical flat parison), the mold clamping cylinders (not shown) attached to the outside of the left and right molds 8a and 8b are operated to perform mold clamping (FIG. 2).

Immediately after the mold clamping, the blow pin
While blowing blow air 16 of 7 kg / cm ² , a compressed gas 15 such as compressed air for expanding the expandable core 12 is introduced and expanded from the inside and outside of the parison P to form the panel surface. Mold 8a and back of panel
The female mold 8b for molding the surface side is formed (FIG. 3).

When this state is further continued, the expandable core 12 expands to a predetermined size, and the panel back surface 24 is
Lightly contact the back surface of the second (FIG. 7). Compressed gas 1
Although N2 gas may be used for 5, it is possible to shorten the cooling time by introducing the compressed gas 15 which has been cooled halfway while the molding of the parison P is completed.

In this embodiment, the expandable core 12 has a cylindrical shape as shown in FIG. 4. However, the present invention is not limited to this, and a plan view as shown in FIG. The core 12 may be used, whereby the panel molded product 10 as shown in FIG. 9 is obtained.

Simultaneously with the completion of the blowing of the blow air 16, the blow air 16 in the molded product 10 is rapidly removed, and then the compressed gas 15 in the expandable core 12 is also removed.

Since the expansion and contraction core 12 from which the compressed gas 15 has been removed is reduced in size, the mold is opened as it is, and the cooled and solidified molded product 10 is taken out.

[0023]

As is apparent from the above description, the present invention comprises a male mold for molding a panel surface having a smooth surface and a plurality of extendable elastic cores. panel
Using the female mold for molding the rear surface side, while the parison depending from the die is inflated by blowing air to the parison after mold close straight at the both molds, molding the parison also introducing compressed gas into the expansion core By doing so, the front surface, the back surface, and the peripheral surface of the molded product are tacked off, so that the strength of the molded product is increased.

[Brief description of the drawings]

FIG. 1 is an overall vertical sectional view of a blow molding machine according to an embodiment of the present invention.

FIG. 2 is a view showing a state immediately after mold clamping in which a parison is held between both molds.

FIG. 3 is a view showing a state in which compressed gas is introduced into a telescopic core and a parison.

FIG. 4 is a sectional view as viewed from AA of FIG. 3;

FIG. 5 is a diagram in which the expansion of the telescopic core is completed.

FIG. 6 is a sectional view taken along line BB of FIG. 5;

FIG. 7 is a perspective view of a panel-shaped molded product.

FIG. 8 is a plan view of a telescopic core of another embodiment according to the present embodiment.

9 is a partially enlarged plan view of a panel-shaped molded product manufactured by using the elastic core shown in FIG.

FIG. 10 is an overall vertical sectional view of a conventional blow molding machine.

FIG. 11 is a perspective view of a conventional panel-shaped molded product.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 blow molding machine 2 die head 2a resin supply port 3 mandrel 3a core 4 extruder 6 paricon cylinder 7 annular space passage 8 mold 8a male mold 8b female mold 9 cavity 10 molded product 12 elastic core 13 gas introduction Hole 14 Conduit 15 Compressed gas 16 Blow air 22 Panel surface 24 Panel back P Parison

Claims (1)

(57) [Claims] 1. A panel having <br/> male mold and a plurality of stretchable elastic core for molding the panel surface side which has a smooth surface
Using the female mold for molding the rear surface side, while the parison depending from the die is inflated by blowing air to the parison after mold close straight at the both molds, molding the parison also introducing compressed gas into the expansion core A blow molding method using a telescopic core.