JPH0270421A - Blow molding device - Google Patents

Abstract

PURPOSE:To bond a parison and a film with insert dies sufficiently and prevent a projected screw section from getting thin-walled by providing the insert dies for forming a projected screw section on a film facing section of a mold more recessed than the regular position and manufacturing the same to the regular position at the end of blowing process. CONSTITUTION:Insert dies 17 and 18 are in the recessed position more recessed that the regular position in a mold 6 at the sites facting a film 10 of the mold 6 by the control of an insert die transfer mechanism to form an expanded space 26 necessarily on the film 10 side of the insert dies 17 and 18. Main blowing is started by blowing compressed air from a blow pin into a preblown parison 5, and the film 10 and the parison 5 are sufficiently oriented in the expanded space 26 at the time of recessing the insert dies, and then insert dies 17 and 18 are moved forward to the regular position at the end of blowing process. The parison 5 and the film 10 can be bonded with insert dies 17 and 18 by said arrangement to prevent securely a projected screw section of a mold product from getting thin-walled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a blow molding apparatus for blow molding a plastic fuel tank having a liquid-impermeable film such as a nylon resin film attached to its outer peripheral surface.

(Prior Art) In recent years, in order to reduce cost and weight of vehicle fuel tanks, there has been a tendency to use plastic tanks instead of conventional tanks made of press-formed steel sheets.

When storing fuel such as gasoline for a long period of time, the above-mentioned plastic fuel tank has a liquid-impermeable material such as a nylon resin film on the outer circumferential surface to prevent the fuel from permeating the tank wall and leaking out of the tank. Blow molding means is used to attach a so-called barrier film.

That is, as described in JP-A No. 61-89025, a parison extruded from an extrusion
By supplying a film from the side of the mold between the mold and the mold that molds the parison into a predetermined shape, the heat retained in the parison is used to melt the adhesive on the film side. This is a hot parison blowing means (direct blowing means) for obtaining a blow-molded product with a film attached to the outer circumferential surface of the parison.

When such a blow molding means is used to blow mold a plastic fuel tank provided with a protruding thread for attaching a pump or a protruding thread for attaching a level gauge, a structure as shown in FIG. 8 can be considered.

That is, a protruding thread forming insert 83 is disposed in a portion of the mold 81 facing the film 82, and the parison 84 and film 82 are brought into close contact with the above-mentioned insert 83 during blow molding. This is a means for forming a threaded portion.

However, with this configuration, the following problems occur.

That is, with only the internal space of the insert 83 described above, as shown in FIG. 9, the film 82 and the parison 84 are not sufficiently stretched during blow molding, and the adhesion between these two is insufficient, and the molded product is heated to the mold 81°. 10th when taken out from 81
As shown in the drawings and FIG. 11, there was a problem in that a lack of thickness 87 occurred in the protruding threaded portion 86 of the molded product 85.

(Object of the Invention) The present invention provides blow molding that can sufficiently adhere the parison and film to the insert during blowing, and that can prevent underfilling of the protruding threaded portion of the molded product. The purpose is to provide equipment.

(Structure of the Invention) The present invention provides blow molding by supplying a film from the side of the mold between the parison extruded from an extrusion head and a mold for molding the parison into a predetermined shape. A blow molding device for producing a blow molded product by pasting a film on the outer circumferential surface, wherein an insert for forming a protruding threaded portion is recessed in the film-opposed portion of the mold, and the insert is molded with metal before blowing. It is installed in a position recessed from the normal position in the mold,
The blow molding apparatus is characterized in that it is provided with insert moving means for moving the insert to a regular position at the end of the blowing process.

(Effects of the Invention) According to the present invention, the above-mentioned insert moving means controls the retreat of the above-mentioned insert to a position retracted from the normal position in the mold before blowing, and the retreat of the insert causes the inevitable At the end of the blowing process after the film and parison are once stretched by making effective use of this expansion space, the concave portion formed by the
The insert is moved forward to the normal position by the insert moving means described above.

As a result, the protruding threaded part is formed after the film and parison have been stretched sufficiently, so that the parison and film are brought into close contact with the insert, and there is no lack of thickness in the protruding threaded part of the molded product. This has the effect of reliably preventing this from occurring.

(Example) An embodiment of the present invention will be described in detail below based on the drawings.

The drawings show a blow molding device, and in FIGS. 1 and 2, this blow molding device 1 is configured such that an extruder 3 and a parison die 4 are provided on the upper part of a frame 2, and a parison 5 is extruded in a hanging shape. are doing.

Further, a pair of left and right molds 6, 6 are provided at positions symmetrical with respect to the center line of the parison 5, and the parison 5 is
is configured to be molded into a predetermined shape.

Furthermore, a blow pin 7 is provided at the lower part of the above-mentioned parison 5, and is configured to blow about 3 to 10 kg/- of compressed air into the above-mentioned parison 5 during the pre-blow process and the main blow process.

Furthermore, a vertical movement device 11F (not shown) for vertically moving the above-mentioned blow bin 7, and molds 6, 6 after blow molding are provided.
A molded product take-out device 9 for taking out the molded product 8 from the molded product 8, and a film supply section 11.11 that supplies films to from the side of the mold between the parison 5 and the molds 6, 6. We are prepared.

The above-mentioned molded product removal device 9 is connected to the frame 2 of the blow molding device 1.
A guide rail 13 having one end fixed to the support column 12 and extending in the front-rear direction perpendicular to the opening/closing direction of the molds 6, 6 and having the other end fixed to the support 12;
It is provided with a take-out part 14 that is slidably provided along the taking-out part 14, and a chain drive part 15 that slides and operates this take-out part 14.

Here, the above-mentioned extraction section 14 is arranged parallel to the guide rail 13 as shown in FIG. 1, and is opened and closed by an arm opening/closing cylinder (not shown) as shown in FIG. arm 16.16.

As shown in FIG. 3, inserts 17 and 18 are recessed in a portion of the mold 6 facing the film 10 to form a protruding threaded portion of the molded product 8.

Here, one insert 17 forms a protruding threaded part for attaching a pump to a plastic fuel tank as a molded product 8, and the other insert 18 forms a protruding threaded part for attaching a level gauge to the same tank. It forms the

Each of the above-mentioned inserts 17 and 18 includes these inserts 17 and 18.
．． Insert moving mechanism 19 that controls the movement of 18 from outside the mold 6
．． 20 is installed.

As shown in FIG. 4, the above-mentioned nesting moving mechanism 19.20
A first hydraulic cylinder 22 for driving the nested rotating rod 21 forward and backward, and a second hydraulic cylinder 23 for rotating the nested body disposed in a direction perpendicular to the axial direction of the piston rod of the first hydraulic cylinder 22. A rack member 24 fixed to the piston rod of the second hydraulic cylinder 23 is engaged with the binion portion 25 of the rotary insert rod 21 described above.

The insert moving mechanism 19.20 described above causes each insert 17.18 to be retracted from the normal position in the mold 6 before blowing, while at the end of the blowing process, each of the inserts 17. The inserts 17 and 18 are configured to be moved forward to their normal positions.

The illustrated embodiment is constructed as described above, and its operation will be explained below.

First, as shown in Fig. 5, a thermoplastic resin is placed between the left and right molds 6 and 6 in the open state (in Figs. 5 to 7, only one mold is shown for convenience of illustration). For example, a parison 5 made of polyethylene as a base material is extruded from a parison die 4 in a hanging shape, and this parison 5 and a mold 6.
A film 10.10 is interposed between the two.

Before this blowing, as shown in the same figure, each of the aforementioned inserts 17 and 18 is controlled by the insert movement n ellipses 19 and 20, and the mold 6 is
The expansion space 26 is inevitably formed on the film 10 side of these inserts 17 and 18.

Next, a pre-pinch device (not shown) is driven to clamp the lower ends of the parison 5 and the film 10, and the blow pin 7 is inserted into the parison 5 from this clamping part.

Next, just before mold clamping, compressed air (compressed air at a lower pressure than the pressure during normal blow molding) from a blowing device (not shown) is blown into the parison 5 through the blow pin 7 for pre-blowing.

Next, as shown in FIG. 6, the molds 6, 6 are clamped,
After this mold clamping process is completed, compressed air is supplied from the blowing device to the blow pin 7 at the pressure normally used for blow molding, and the compressed air is blown from the blow pin 7 into the parison 5 that has undergone one rib blow to start main blowing.

At the start of the main blow, as shown in the figure, the aforementioned inserts 17 and 18 are in the retracted position retracted from the normal position, and the aforementioned expansion space is located on the film 10 side of these inserts 17 and 18. 26 is formed, so that the film 10 and the parison 5 described above are fully stretched within this expansion space 26.

Next, as shown in FIG. 7, at the end of the main blowing process, the aforementioned nest moving mechanisms 19 and 20 are driven to
7.Move 1.8 forward to the normal position and insert these inserts 1.
7. Bring the film 10 and the parison 5 into close contact with the shaped surface for forming the protruding screw portion of 18.

After the main blow is completed, the rack member 24 is operated to rotate the inserts 17 and 18 via the pinion portion 25 and the insert rotating rod 21 in the direction in which the screws are loosened.
The above-mentioned nested rotating rod 21 is controlled by the first hydraulic cylinder 22.
Each insert 17° 18 is retracted through.

In this way, after each of the inserts 17 and 18 described above is retreated, the molds 6 and 6 are opened and the pinch is released by the pre-pinch device, and the blowbin 7 is separated downward from the lower end of the molded product 8. Then, the molded product removal device 9
is driven, the upper end of the molded product 8 is held between the pair of arms 16.16 of the take-out part 14, and the molded product 8 is taken out. After all the above steps are completed, deburring and trimming are performed to remove the plastic fuel tank ( Molded product) Complete step 8.

In summary, at the end of the blowing process after the film 10 and the parison 5 have been sufficiently stretched in the expansion space 26 that is inevitably formed when the insert is retracted, the inserts 17 and 18 are advanced to the normal position. Since it is moved, it is possible to achieve sufficient adhesion of the parison 5 and the film 10 to the inserts 17 and 18, and it is possible to reliably prevent underfilling from occurring in the protruding threaded portion of the molded product 8. There is.

In the correspondence between the structure of the present invention and the above-described embodiments, the blow-molded product of the present invention corresponds to the plastic fuel tank of the embodiment, and similarly, the extrusion head corresponds to the parison die 4, and the blow-molded product corresponds to the plastic fuel tank of the embodiment. Although the means correspond to the telescoping mechanism 19, 20, the invention is not limited to the configuration of the embodiments described above.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is a schematic side view of a blow molding device, FIG. 2 is a schematic plan view of the same device, FIG. 3 is a sectional view showing the arrangement structure of the insert, and FIG. Figure 4 is a perspective view of the nest moving mechanism, Figure 5 is an explanatory diagram showing the state before blowing, Figure 6 is an explanatory diagram showing the main blow starting process, and Figure 7 is an explanatory diagram showing the state at the end of the blowing process. , Fig. 8 is a cross-sectional view showing the nest arrangement structure in a conventional blow molding device, Fig. 9 is a cross-sectional view showing the conventional blowing process, and Fig. 10 is a section of a molded product taken out from a conventional mold. 11 is an enlarged sectional view of section A in FIG. 10. 4...Parison die 5...Parison agent
Patent Attorney Nagai 1) Ryo Akira 7th Cause Figure 8 Figure 10 Figure 19 Figure 11

Claims (1)

[Claims] (1) A film is supplied from the side of the mold between the parison extruded from the extrusion head and a mold that molds the parison into a predetermined shape, and blow molding is performed to attach the film to the outer peripheral surface. A blow molding device for obtaining a blow molded product consisting of a mold, wherein an insert for forming a protruding screw portion is recessed in the film-opposing part of the mold, and the insert is moved from its normal position in the mold before blowing. A blow molding device provided with an insert moving means that is provided in a retracted position and moves the insert to a normal position at the end of the blowing process.