JPS6151527B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a multilayer hollow molded article by blow molding.

(Prior art) Two-layer blow molding, which has recently started to be widely used, is basically the same as conventional blow molding, and as shown in FIGS. It is molded by discharging both inside and outside.

In addition, in order to obtain a blow molded product with a two-layer structure on only one side, conventionally the outer layer of the two-layer structure is formed in advance by injection molding operation, and then manufactured using a blow molding mold ( Japanese Patent Publication No. 1979-97965
(Japanese Patent Application Laid-Open No. 49-88970).

(Problems to be Solved by the Invention) In the above-mentioned two-layer blow molding method, the entire circumference is two layers and it is not possible to partially form a single layer. Even if you wanted to do this, it would be impossible to do this, and there would be a lot of wasted material.

Furthermore, the method of combining injection molding and blow molding requires manufacturing equipment and man-hours for injection molding, and cannot be manufactured at low cost.

The present invention improves the drawbacks of the prior art and provides a method for manufacturing a multilayer hollow molded product, in which only the necessary portions are multilayered and the unnecessary portions are left as a single layer.

(Means for solving the problem) The method for manufacturing a multilayer hollow molded product of the present invention includes discharging an annular parison from a nozzle and simultaneously discharging a sheet parison from the nozzle parallel to the parison on one side of the parison. supplying the parison between the molds, then clamping the lower end of the sheet parison, and then performing mold clamping while blowing air into the annular parison and applying tension to the sheet parison as the mold moves; Next, the annular parison and the sheet parison are expanded by blowing air into the annular parison, and integrally molded so that only one side of the mold parting line forms two layers.

(Function) The annular parison and the sheet parison are simultaneously fed between the molds in a parallel state, the lower end of the sheet parison is clamped, and tension is applied as the mold moves, while air is blown into the annular parison. By clamping the mold while compressing the sheet parison, an appropriate tension is applied to the sheet parison, and the abutment against the annular parison is performed accurately.Next, air is blown into the annular parison to separate the annular parison and the sheet parison. By stretching, a good multilayer hollow molded product can be obtained.

(Example) Next, an example of implementation of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a guide frame provided parallel to the upper and lower positions, and a pair of die plates 2 and 3 are provided on this upper and lower guide frame 1 so as to be able to move forward and backward in opposing directions. Molds 4 and 5 are attached to the opposing surfaces of a pair of die plates 2 and 3, a blow pin 6 is attached to the opposing surface of one of the die plates 4, and a blow pin 6 is attached to the upper part of the other die plate 3 via a support frame 7. A guide roller 8 is mounted on the mold 5 side.

Further, a nozzle 9 for a parison having an annular cross section and a nozzle 10 for a sheet parison are provided adjacent to each other at one position above the pair of molds 4 and 5, and the other nozzle 10 for a sheet parison.

Further, a clamp device 11 is provided at a lower position between the pair of molds 4 and 5. In this clamp device 11, a sliding table 13 is slidably provided on a base 12 via rollers, and a piston 1 of a cylinder 14 fixed to the base 12 is attached to the sliding table 13.
5 are connected via a piston rod 16. A fixed piece 17 is erected on the sliding table 13,
A bell clamp-shaped rotating piece 18 is rotatably mounted on the fixed piece 17 at an intermediate portion thereof, and a long hole 19 is formed at the base of the rotating piece 18.
A piston 21 of a cylinder 20 fixed to the slide table 13 is connected via a piston rod 22.

The piston 15 of the cylinder 14 is moved forward and backward by pneumatic pressure, the slide table 13 is moved forward and backward along the base 12 via the piston rod 16, and the piston 21 of the cylinder 20 is moved forward and backward by pneumatic pressure. The rotary piece 18 is actuated to rotate the rotary piece 18 through the piston rod 22 and the elongated hole 19, thereby opening and closing the rotary piece 18 with respect to the fixed piece 17.

In such an apparatus, first, the pair of die plates 2 and 3 are moved in a direction away from each other along the guide frame 1, and the molds are opened. Then, the nozzles 9 and 10 simultaneously start discharging between the pair of molds 4 and 5, and one nozzle 9 discharges a parison 23 having an annular cross section, for example, a cylindrical shape, and a sheet parison 24 is discharged from the other nozzle 10 in parallel. Discharge in the condition. Next, the lower end portion of the sheet parison 24 discharged to a predetermined length is clamped by the fixed piece 17 and the rotating piece 18 of the clamp device 11.

Next, the pair of die plates 2 and 3 are moved in a direction toward each other, and the parisons 23 and 24 are clamped by the pair of molds 4 and 5. When this mold clamping is performed, the sheet parison 24 has its lower end fixed by the clamp device 11, is pushed by the guide roller 8 provided on the die plate 3, and moves in synchronization with this. The clamp device 11 applies tension to the outer surface of the cylindrical parison 23, while air is blown into the cylindrical parison 23 by the blow pin 6, so that the parison 23 comes into contact with the sheet parison 24 during the mold clamping process. to keep it from collapsing.

Then, after clamping with the pair of molds 4 and 5,
Air is blown into the cylindrical parison 23 using the blow pin 6 to inflate the cylindrical parison 23 so that it comes into pressure contact with the system 24, stretching both parisons 23 and 24, and completing the molding with the pair of molds 4 and 5 pressing against each other. .

Next, the pair of die plates 2, 3 and the pair of molds 4, 5 are separated and the product is taken out. As shown in FIG. 3, in this product, the molded body of the cylindrical parison 23 and the molded body of the sheet parison 24 are fused together, with a cut-off burr 25 protruding outward. Cut one side into 2 pieces with the parting line as the border, as shown in Figure 4.
A hollow molded product is obtained with one layer on the other side and a single layer on the other side.

In addition, in implementation, the cylindrical parison 23 is
It may be oval or any other shape as long as it is continuous in the circumferential direction in cross section.
Further, the sheet parison 24 is not limited to a flat plate shape, but may also be an arc shape.

Further, if both parisons 23 and 24 are made of a material that cannot be fused, for example, the guide roller 8
An adhesive application roller may be disposed on the opposite side of the parisons 23 and 24 to apply adhesive to both or one of the parisons 23 and 24, and to integrate them by adhesion.

Furthermore, as the clamp device 11, an appropriate device can be used. Furthermore, in the above embodiment, the clamping device moves in synchronization with the mold, but if the stroke of the mold is small, the clamping device is fixedly installed and the sheet parison 2 is moved by the movement of the mold.
4 may be used to generate tension.

According to the present invention, only the necessary portion side is multi-layered,
It is possible to obtain a molded product with unnecessary parts left in a single layer. Therefore, in the case of products such as lids, there is no need to create unnecessary parts on the back side, which eliminates wasted material and makes it possible to create separate parts. When installing, it is possible to easily form a portion according to the installation state.

Furthermore, there is no need for an injection molding operation to preform the outer layer of the double layer on one side as in the conventional technology, and two layers can be continuously formed on only one side with only one blow molding operation. Products can be mass-produced at low cost.

In addition, if the lower end of the sheet parison is not clamped, the lower end of the sheet parison will be lifted up due to contact between the moving mold and the sheet parison during mold clamping, resulting in the sheet parison being insufficient in length. In addition, the sheet parison may wrinkle, which may cause air bubbles to be interposed between the sheet parison and the annular parison, resulting in defective products. However, in the present invention, since the lower end of the sheet parison is clamped, the lower end of the sheet parison is not pushed up during mold clamping, thereby preventing the sheet parison from being insufficient in size, and furthermore, air bubbles are interposed between the sheet parison and the annular parison. Since an appropriate tension is applied to the sheet parison without any friction, the sheet parison can be brought into precise contact with the annular parison, which has the advantage that a good multilayer hollow molded product can be manufactured.

[Brief explanation of the drawing]

1 and 2 are partially cutaway front views of the apparatus showing the molding state of the method of the present invention, FIG. 3 is a partially cutaway perspective view of the molded product, and FIG. 4 is one of the parts. 5 is a sectional view showing a conventional molding method, and FIG. 6 is a sectional view of the molded product. 4, 5... Mold, 9, 10... Nozzle, 23...
...Cylindrical parison as annular parison, 24...
sheet parison.

Claims (1)

[Claims] 1 At the same time as the annular parison is discharged from the nozzle, a sheet parison is discharged from the nozzle parallel to the parison on one side of the parison, both parisons are supplied between the molds, the lower end of the sheet parison is clamped, and then the annular parison is The mold is clamped while blowing air and applying tension to the sheet parison as the mold moves.Next, air is blown into the annular parison to stretch the annular parison and the sheet parison. A method for manufacturing a multilayer hollow molded product, characterized by integrally molding the two layers.