JPH01247135A - Method for blow molding of hollow molded product having interior part integrally molded along therewith - Google Patents

Abstract

PURPOSE:To easily perform the integral molding of an interior part, by allowing the interior part to be present in a mold in a state made small as compared with the size at the time of the use in a hollow molded product and surrounding the said part by the parison extruded from a core to place the same under heating. CONSTITUTION:Two hooks 9 are fixedly provided to the core 4 of a blow molding machine to respectively fix one ends of ropes 10 and other ends of said ropes 10 are connected to a buffle plate 11 as an interior part to support said plate in the air from above. The buffle plate 11 is molded from a shape memory alloy or resin and made small in a state bent into an almost L-shape at room temp. Next, when the heated molten thermoplastic resin is extruded to the outer peripheral part in a predetermined length from the conical mold gap A formed between the core 4 and die 5 of the blow molding machine to mold a parison 6, the buffle plate 11 suspended in the parison is returned to a flat state by the heat of the parison 6 and, two split molds 12, 13 are allowed to approach the parison 6, the parison 6 is successively brought into contact with the outer peripheral part of the buffle plate 11. Therefore, the thickness of the molded product becomes stable and molding becomes easy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a blow molding method for a hollow molded product in which interior parts such as a puffy board are integrally molded.

2. Description of the Related Art For example, when manufacturing a hollow molded product such as a plastic fuel tank, a method of integrally molding interior parts installed inside the tank is sometimes adopted.

An example of this molding method will be described in the case where a baffle plate is used as an interior component.

The baffle plate is used to improve the mechanical strength of the product and stabilize the capacity of the molded product, and also to partition the interior space in order to prevent abnormal noises caused by the movement of fuel and the like while the vehicle is running.

Conventionally, the blow molding method for plastic hollow molded products with a baffle plate integrally molded inside has been carried out by heating and melting thermoplastic resin such as polyethylene, polypropylene, polycarbonate, vinyl chloride resin, ABS resin, etc., and then blowing it. A parison 6 of a predetermined length is formed by extruding it through the mold gap A between the core 4 and die 5 of the molding machine (see FIG. 11),
As shown in FIG. 12, this parison 6 is clamped from the left and right sides as shown in the figure by a molding die 1.2 in which one molding die 2 is provided with a jetty portion 2a, and then air is sent into the inside of the parison 6. The parison 6 was expanded and brought into close contact with the inner surface of the molding die 1.2, and after cooling, the molding die 1.2 was opened to take out the hollow molded product 3 (fuel tank body).
(See Publication No. 5-20157).

In this way, a part of the parison 6 is pressed against the outer peripheral surface of the jetty portion 2a, and a baffle plate 3a is formed in the internal space B.

Note that 7 in FIG. 12 indicates cooling holes drilled in the molding die 1.2.

Problems to be Solved by the Invention However, in such a conventional blow molding method, the baffle plate 3a is made of the same material as the hollow molded product 3.
Since the parison 6 is molded from the baffle plate 3a, the elongation rate of the parison 6 in the baffle plate 3a portion is much larger than that in other parts, resulting in unstable wall thickness after molding, and there is a problem in that it is difficult to set the molding conditions. Ta.

Further, in cases where the baffle plate 3a is required to have a different thickness from other parts, it is extremely difficult to set the molding conditions, and the total internal capacity of the hollow molded product 3 is reduced.

Furthermore, in terms of appearance, grooves are formed in the baffle plate 3a portion, and depending on the molding conditions, wrinkles may occur on the outer surface, which may impair the aesthetic appearance.

Therefore, the present invention provides a blow molding method for integrally molding interior parts, which is easy to mold, has little effect on appearance quality, and is not limited by the diameter of the parison to be extruded. It is something to do.

Means for Solving the Problem The interior parts, which return to the shape they were in use by the shape deforming means when heated, are made smaller in size than when used in the blow molding machine. A parison placed between the molds and extruded from the core of a blow molding machine surrounds the interior component, the interior component is heated with the parison, and the mold is clamped to connect the interior component and the parison. Molded in one piece.

Function: The interior parts placed in a reduced size between the molding molds of the blow molding machine are surrounded by the parison and heated by the extrusion of the parison, so that the interior parts return to the shape in use by the shape deforming means. Then, when the mold is clamped, a part of the outer periphery of the interior part is joined to the parison,
The interior parts and the parison are integrally molded.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, with the same reference numerals assigned to the same parts as in the conventional structure.

A first embodiment is shown in FIGS. 1-4.

FIG. 1 shows a preparatory stage for molding according to the present invention. Two hooks 9 are fixed to the core 4 of the blow molding machine, and one end of the rope IO is fixed to each of the hooks 9. Incidentally, hooks 9 may also be provided on the floor portion 8 of the blow molding machine or on the plywood floor on which the molding machine is placed to support it from above and below.

The other end of each rope 10 is connected to a baffle plate 11 as an interior component bent into an oval shape, and this baffle plate 11 is supported from above in the air by the rope 10.

Here, the baffle plate 11 is molded from, for example, a shape memory alloy or shape memory resin having shape memory properties, and is made small by bending it into an abbreviated shape at room temperature (as shown by the solid line in Fig. 1). (shown), the parison heat causes it to return to its flat state, which is the shape in use (
(shown in dashed lines in Figure 1).

Therefore, in this embodiment, the baffle plate II itself constitutes the shape deforming means.

Next, the heated and melted thermoplastic resin is poured through the conical mold gap A formed between the core 4 and die 5 of the blow molding machine.
A parison 6 is formed by extruding the rope 10 and the baffle plate 11 around its outer periphery to a predetermined length.

At this time, since the baffle plate 11 is bent and made small, the diameter of the parison 6 can be small, which is advantageous in that the extrusion pressure can be low.

It is generally desirable to select the same material for the rope 10 as the parison 6 for integration after molding, but the rope 10 does not necessarily need to be made of the same material as long as it can be integrated by molding.

Next, a process for forming a hollow molded product in which a baffle plate is integrally molded using a molding die from the state shown in FIG. 1 will be described with reference to FIG. 2.3.

Due to its shape memory property, the baffle plate ll suspended inside the parison 6 returns to its flat state due to the heat of the parison 6, and the molding die 12° 13, which is divided into two parts, is turned into a flat state as shown in FIG. As the parison 6 gradually approaches the direction indicated by the arrow, the parison 6 forming the main body of the hollow molded product sequentially comes into contact with a part of the outer periphery of the baffle plate II which has returned to its flat state.

And the pinch portion 12a of the molding die 12.13.

When air is sent into the internal space B by the blow pin P in a mold-clamped state in which the lobes IO are in contact with each other, the state shown in FIG. 3 is achieved, and the baffle plate 11 is integrally molded inside the hollow molded product, and the baffle The lobe lO supporting the plate 11 is completely and easily integrated at the joint of the parison 6.

After cooling, when the molding die 12.13 is opened, a hollow molded product 20 (fuel tank body) with a high quality appearance as shown in FIG. 4 is completed.

In the above embodiment, two lobes 10 for supporting the baffle plate 11 are provided at the top, but the number can be set depending on the baffle plate 11 to be supported.

Next, a second embodiment will be explained with reference to FIGS. 5 to 7.

In this embodiment, a thread 14 made of thermoplastic resin is used as the shape deforming means.

The thread 14 is stretched between arc-shaped attachment pieces 15 on the side edges of the baffle plate +1 made of resin and curved within the limit of elastic deformation, and is used to reduce the size of the baffle plate II.

In this way, when the parison 6 is pushed out while the baffle plate 11 (see Fig. 5.6), which has been curved and reduced in size by the thread 14, is suspended by the lobe lO in the same manner as in the embodiment described above, the parison 6 The thread 14 is melted and cut by the heat (as shown by the solid line in FIG. 7). Hence the thread! The baffle plate 11 released from the tension of 4 returns to its used shape as shown by the broken line in FIG. be.

Note that the other configurations and operations are the same as those of the above-described embodiment, so explanations thereof will be omitted.

Therefore, in this embodiment as well, a product that is easy to mold and has a high quality appearance can be obtained, and the diameter of the parison 6 can be small, which is advantageous in manufacturing.

Next, a third embodiment will be explained with reference to FIGS. 8 to 10.

In this embodiment, a thermal expansion part I6 extending in the diametrical direction of the parison 6 provided on the baffle plate 11 and a bellows part 17 formed in a direction crossing this are used as shape deforming means.

Specifically, the baffle plate I+ has arc-shaped mounting pieces 1 on both side edges.
A thermal expansion section 16 filled with an inert gas 18 is provided in the diametrical direction of the parison 6 across each of the mounting pieces 15, and a bellows section 17 is provided across the thermal expansion section 16. is installed.

When the parison 6 is pushed out with this baffle plate II suspended by the lobe IO (as shown in FIG. 8.9), the inert gas 18 in the thermal expansion section 16 expands due to the heat of the parison 6, and the bellows section 17 The baffle plate 11 is expanded to the size in use through the baffle plate 11, and the mounting piece 15 is welded to the parison 6, so that the baffle plate +1 becomes integral with the parison 6 (see FIG. 10).

Note that the other configurations and functions are the same as those of the first embodiment described above, so explanations thereof will be omitted.

Therefore, this embodiment is also advantageous in terms of manufacturing, since it is easy to mold and a product with high appearance quality can be obtained, and the diameter of the parison 6 can be small.

Each embodiment has been described using the baffle plate 11 as an example of an interior component, but it is also possible to apply it to a rotating tank or a tube such as a filler neck in addition to the baffle plate 11. It can be applied to resin products other than tank bodies. Furthermore, the shape of the baffle plate 11 can be set arbitrarily.

Furthermore, in each of the above embodiments, a rope was used as a means for placing the interior parts between the molding molds, but the rope is not limited to this. It may be made to exist in

As explained in detail, according to this invention, the thickness of the molded product is stable compared to the conventional molding method in which interior parts such as baffle plates are molded by rolling out a part of the parison. This has the effect of making molding easier.

In addition, since the interior parts are pre-molded, the wall thickness can be set arbitrarily regardless of the thickness of the outer wall of the hollow molded product, and the volume of the interior parts does not have to be as large as in the past. This has the effect of increasing the internal capacity of the hollow molded product.

Furthermore, since grooves, wrinkles, etc. do not appear on the outer surface, it is possible to manufacture products with good appearance quality.

Then, the interior parts are set in a smaller state through the shape deforming means, and when the parison is extruded, the heat of the parison is used to restore the shape to the used state, so the diameter of the parison can be reduced, and therefore the extrusion pressure is It is advantageous in that it can also be small.

[Brief explanation of the drawing]

Figures 1 to 4 show a first embodiment of the present invention, Figure 1 is a perspective view showing the preparation stage for molding, Figures 2 and 3 are sectional views showing the molding situation, and Figure 4 is a perspective view of the product. Figures 5 to 7 show the second embodiment, Figure 5 is a perspective view showing how the baffle plate is hung, and Figures 6 and 7 are respectively ■(■) - ■( of Figure 5).
■) Cross-sectional explanatory diagram showing the return status of the baffle plate along the line,
8 to 10 show the third embodiment, FIG. 8 is a perspective view showing the hanging condition of the baffle plate, and FIG.
A cross-sectional explanatory diagram showing the return status of the baffle plate along line IX(X)-1X(X) in the figure, Figures 1I and 12 are respectively a perspective view showing the molding preparation stage of the prior art and a cross-section showing the mold clamping completion status. It is a diagram. 4... Core, 6... Parison, II... Pubful board (interior parts, shape deforming means), 12.13... Molding mold, 14... Thread (shape deforming means), 16. ... Expansion part (shape deformation means), 17 ... Bellows part (shape deformation means), 18 ... Inert gas (shape deformation means), 2o..
・Hollow molded product (fuel tank body). Engraving of drawings (no changes in content) Figure 4 Figure 5 Figure 14 series (modified HF scale) Figure 6 Figure 7 Figure 9 Figure 10 Figure 8 Figure 11 Figure 12 Procedure amendment (, Display of phantom matter Patent application No. 75305 of 1988 Name of blow molding of hollow molded products integrally molded with interior parts Subject of 2 master craftsmen outside the Risekai Building, 1-29 Akashi-cho, Chuo-ku, Tokyo 6. Contents of amendment (I) Submit an engraving of the specification (no changes in content) as shown in the attached sheet. (2) Submit an engraving of the specification (with one change in content) as shown in the attached sheet. (None). 2 people other than the above.

Claims (1)

[Claims] (I) An interior component that returns to its used shape by shape deformation means when heated is placed between the molds of a blow molding machine in a smaller size than when used in a blow molded product. , surrounding the interior component with a parison extruded from a core of a blow molding machine, heating the interior component with the parison, and clamping the molding die to integrally mold the interior component and the parison. A blow molding method for hollow molded products in which interior parts are integrally molded.