JPH0242654B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for partially secondary injection molding a synthetic resin molded product into a hollow molded product such as a thin-walled packaging container manufactured by stretch blow molding. It is something.

[Prior art] When attaching other parts to a blow-molded product, insert molding and heat welding are used. When the part is a handle, etc., a part of the parison is blow-molded. Sometimes it is molded integrally with a bulge on the side of the main body.

In addition, in the case of a hollow molded product made by stretch blow molding, everything else in the bottomed parison except for the neck is stretched and expanded, so handles and other parts are integrally molded in advance on the neck, which remains molded. The parts are installed by inserting them into a blow mold.

[Problems to be Solved by the Invention] However, in stretch blow molding, the wall thickness of the bottomed parison that is injection molded therein is thinner than the wall thickness of the parison formed by extrusion molding, and furthermore, the bottomed parison is Because the material is stretched and then expanded in the lateral direction, it is extremely difficult to form parts by applying the partial deformation that is carried out in blow molding.

In addition, in the case of inserts, there were problems such as not being able to achieve heat welding as in blow molding, and because the inserts do not bite into the main body shallowly, they are easy to remove later, and the inserts require time and effort.

Furthermore, as the uses of thin-walled containers expand, there is a demand for containers with external shapes that match the contents.
In line with this, some molded products are fitted with handles and base caps for reinforcing the parts using adhesives, but it takes time to fit them in, and there is also loss when fitting them. There were also problems such as high costs due to the use of adhesives.

This invention was devised to solve the above problems, and its purpose is to use a thin-walled hollow molded product as an injection core, and to secondary mold a synthetic resin molded product at any location of the thin-walled hollow molded product. The purpose of the present invention is to provide a new injection molding method that can be integrated.

[Means for Solving the Problems] The secondary injection molding method of the present invention for the above purpose is as follows:
A thin-walled hollow molded product with an opening at the top formed by stretch blow molding is housed in a secondary processing mold.

This secondary processing mold consists of a pair of split molds each having a cavity with the same dimensions as the cavity of the blow mold used when the thin-walled hollow molded product was stretch blow molded from the bottomed parison. Furthermore, recesses for secondary molding are partially provided at required locations on the circumferential surface of the cavity.

The above-mentioned thin-walled hollow molded product is placed in the center of the split mold that has been opened, and when the mold is closed, the entire body, including the neck part, is accommodated in the mold, and the part of the main body that has fit into the cavity is shown above. It is positioned so as to close the opening of the secondary molding recess.

After the mold is closed, compressed air is blown into the main body from the blowing core inserted into the neck through the upper opening.
As a result, the thin-walled hollow molded product expands and is brought into pressure contact with the cavity surface, and an internal pressure higher than the injection pressure is applied to the product to form an injection core.

After that, when the molten resin is injected from the injection device into the secondary processing mold and injected into the secondary molding recess,
The recess allows the molten resin to form a secondary molded product attached around the main body of the thin-walled hollow molded product that serves as the injection core.

This secondary molded product is a synthetic resin molded product that can be injection-molded using a thin-walled hollow molded product as an injection core that has been given internal pressure, and can be attached to the container body. Alternatively, it can be provided arbitrarily depending on the shape.

Further, the present invention will be explained with reference to a case where a base cup is injection molded as a secondary molded product on the bottom peripheral surface of a bottle-shaped thin-walled container.

[Embodiment] In the figure, reference numeral 1 denotes a board provided above a machine stand 2 at a required interval, and a drive device 3 is fixed at the center of the top surface.

This drive device 3 intermittently rotates a horizontal rotary disk 4 provided close to the lower side of the substrate 1, and is operated by electric or hydraulic power.The drive shaft portion 5 of the drive device 3 is Although not shown in the drawings, it communicates with the rotary disk 4 via a transmission means.

Further, around the lower surface of the rotary disk 4, five neck molds 6, 6 are attached at regular intervals by the action of springs 7, 7 so as to be able to open and close freely in the radial direction of the rotary disk 4.

The positions at which this neck mold 6 stops are five operation stations: parison forming station A, temperature adjustment station B, stretch blowing station C, secondary processing station D, and take-out station E, and the portion corresponding to each station is Although not shown in the figure, the substrate 1 and rotary disk 4 have a required number of holes 8, 8a for guiding downward, respectively, various cores and mold opening members that are moved up and down by a lifting device provided on the substrate in that part. It has been drilled.

The parison molding station A is equipped with an injection device 9, an injection mold for molding a bottomed parison, and a mold clamping device, and the stretch blow molding station C is equipped with an injection mold and a mold clamping device.
A blow mold 10 and hydraulically operated mold opening/closing devices 11, 11 are provided in the radial direction on the machine stand.

As shown in FIG. 2, this blowing mold 10 is composed of a pair of split molds each having a neck-shaped holding part in the upper part of the cavity. The blowing core 13 inside the stretching rod 14 is formed into a thin-walled container 15.
It is designed so that it can be inserted from above the board through the holes 8, 8a.

A secondary processing mold 16 and a hydraulically operated mold opening/closing device 17 are installed on the machine floor plate 2a of the secondary processing station D, and a secondary injection device 18 is installed below the machine table floor plate 2a. It is set facing the direction.

As shown in FIG. 3, the secondary processing mold 16 is composed of a pair of split molds that hold the thin-walled container 15 formed by the blow mold 10 together with the neck mold 6. A pneumatic core 19 is inserted into the neck mold 6 through the holes 8 and 8a from above the board.

Furthermore, a secondary molding recess 22 for molding a base cup 22a is formed between the bottom die 21 and the bottom peripheral surface of the holding cavity, which has the same dimensions as the blow molding cavity.

The secondary injection device 18 is mounted on an elevating device 23 from the side of the machine base 2 into the interior, and has a nozzle 20 protruding from the hot runner block 19.
The nozzle touches the central gate of the secondary forming recess 22 through the machine floor plate 2a.

The lifting device 23 includes a seat plate 26 connected to a piston rod 25 of a hydraulic cylinder 24, and a seat plate 26 connected to a piston rod 25 of a hydraulic cylinder 24.
4 and a seat plate guide rod 28 supported by an integral fixed plate 27, and together with the seat plate 26, the secondary injection device 18 is raised and lowered in accordance with the opening and closing operations of the secondary processing mold 16.

In such a molding machine, a parison molding station A performs injection molding of a bottomed parison 12, and a stretch blow molding station C continuously molds the bottomed parison 12 into a thin-walled container 15.

This thin-walled container 15 is held by the neck mold 6 and transferred to the secondary processing station D, where it is set in the center of the secondary processing mold 16 which is in an open state. By closing the mold, the thin-walled container 15 is held in the mold together with the neck mold 6, and the air press-fitting core 19 is inserted into the neck mold 6, so that high-pressure compressed air is pressurized into the inside of the thin-walled container 15. Due to this press-fitting, the thin-walled container 15 expands and comes into pressure contact with the cavity surface.
A part of the opening of the secondary molding recess 22 is closed, and
The internal pressure is maintained higher than the injection pressure during secondary injection molding to form an injected core. After such a step, when the molten resin is injected from the secondary injection device 18 into the secondary molding recess 22 using the thin walled container 15 as an injection core, the base cup 22a is integrally molded on the bottom surface of the thin walled container 15.

The thin-walled container 15 that has undergone secondary processing is held in the neck mold 6 and transferred to the take-out station E.
It is removed from the network mold 6 and taken out of the machine.

Note that since the injected molten resin is immediately cooled, the thin-walled container side will not melt due to the resin temperature and the secondary molding will not be impaired. Furthermore, since the resin in the recesses contracts due to cooling, if the secondary molded product is annular, the thin hollow molded product will be tightened.

Furthermore, in the above embodiment, the thin-walled hollow molded product and the injection molded secondary molded product are continuously performed in the same molding machine, but both can be performed separately. The present invention is not limited to the above embodiments.

[Effects of the Invention] As described above, the present invention provides a thin-walled hollow molded product with an opening at the top formed by stretch blow molding, which has the same cavity as the blow mold of the thin-walled hollow molded product, and has two molded parts on the circumferential surface of the cavity. The thin-walled hollow molded product is placed in a secondary processing mold consisting of a pair of split molds that partially have recesses for subsequent molding, and after the mold is closed, an internal pressure higher than the injection pressure is applied to the thin-walled hollow molded product, and then the thin-walled hollow molded product is injected. As the core, molten resin is injected into the recess for secondary molding, and the required synthetic resin molded product is partially molded around the outer periphery of the thin-walled hollow molded product, so even if the molded product is thin, Any part can be injection molded, and the design of the recess for secondary molding allows parts suitable for the purpose and shape of the thin-walled hollow molded product to be reliably attached by injection molding.

Furthermore, since the secondary molding of the part is performed by directly injecting molten resin into the thin-walled hollow molded product, the bond between the two parts becomes tighter, and compared to insert molding, there are fewer steps and less processing loss, resulting in cost savings. It has many advantages such as:

[Brief explanation of the drawing]

The drawings show an embodiment of the secondary injection molding method for thin-walled blow molded products according to the present invention, and FIG. 1 is a schematic plan view of an injection stretch blow molding machine equipped with a secondary processing station, and FIG. The figure is a longitudinal sectional view of the stretch blow molding station, and FIG. 3 is a longitudinal sectional view of the secondary processing station. 12...Bottomed parison, 15...Thin-walled container, 1
6...Secondary processing mold, 18...Secondary injection device, 2
0... Nozzle, 22... Recessed portion for secondary forming, 22a
...Base cup.

Claims (1)

[Claims] 1 A thin-walled hollow molded product with an upper opening formed by stretch blow molding is divided into a pair of parts having the same cavity as the blow mold of the thin-walled hollow molded product and partially having a recess for secondary molding on the circumferential surface of the cavity. Secondary processing by a mold The thin-walled hollow molded product is housed in a mold, and after the mold is closed, an internal pressure higher than the injection pressure is applied to the thin-walled hollow molded product.
Then, using the thin-walled hollow molded product as an injection core, the recess for secondary molding is injected and filled with molten resin, and the desired synthetic resin molded product is partially molded around the outer periphery of the thin-walled hollow molded product. A secondary injection molding method for thin-walled hollow molded products.