JPS6059853B2 - Injection blow molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection blow molding method characterized by Parylin's female mold method.

In injection blow molding, Parilynn is injected and then blown in a blow mold, but if Parylynn adheres to the core, the strength of the adhesion varies in the circumferential and longitudinal directions of the core, depending on the resin. Therefore, it begins to swell from the weakly bonded area first, and the wall thickness becomes thinner in that area.

In addition, at that stage, the surface of Parylin has cooled to some extent, so wrinkles occur on the surface of the molded product as the bulge moves. Therefore, in the past, a preliminary blowing process was added before the blowing process (see Japanese Patent Publication No. 53-30731),
Injection blow molding methods have been developed that are modified from the female mold method for Parilyn, such as by adding a female mold process to mechanically lift the Parilyn from the core (see Japanese Patent Publication No. 47-34827).

However, the former method, which uses two-stage blowing, has drawbacks such as requiring a pre-blowing mold and making the process complicated, while the latter method, which uses a mechanical female mold, requires a female mold mechanism. There were some drawbacks, such as the Parilynn scraping over the surface of the core and causing scratches on the Parylynn surface, and the need for positioning in two stages because the Parylynn position shifted.

The present invention was devised to solve the above-mentioned conventional problems, and involves attaching injection-molded Parilynn with a bottom to a core, and then applying ultrasonic vibration to the core to separate Parylynn from the core. The object of the present invention is to provide an injection blow molding method in which expansion of Parylin is uniformly performed by blow molding. Hereinafter, an example of an injection blow molding apparatus for carrying out the present invention will be explained with reference to FIGS. 1 to 3 showing the steps of the method of the present invention. A core holder, 5 is a void for parylin molding made up of these, 6 is a blowing slit for blowing non-adhesive fluid such as air into the void from the side of the core 3, and 7 is a core that penetrates the core holder 4 and is fixed thereto. 3 is an ultrasonic oscillator such as a crystal oscillator installed at the fixed end, 8 is an injection nozzle that can be brought into close contact with the gate 1a of the cavity 1, and 9 is a blow-in type.

When carrying out the present invention using such an injection blow molding apparatus, the resin is first filled into the cavity 5 through the injection nozzle 8 as shown in FIG. As shown, a load is applied to the ultrasonic vibrator 7 to generate ultrasonic waves of a predetermined frequency into the core 3, thereby causing the core 3 to vibrate. At this time, the parison 10 attached to the core 3 also vibrates, but due to the difference in the resonance waveform, a slight deviation occurs in the contact surface, the parison 10 separates from the core 3, and a gap is created between the parison 10 and the core 3. A non-adhesive fluid is blown into this gap 11 through the slit 6 to form an anti-adhesion layer between the parison 10 and the core 3. Next, as shown in FIG. 3, the core 3 is removed from the cavity 1 and placed in a blow mold 9, followed by blow molding. At this time, the parison 10, which is separated from the core 3, uniformly expands within the blow mold 9 due to the interposition of the anti-adhesion layer of the non-adhesive fluid. Incidentally, if the parison 10 is cooled to such an extent that it does not adhere again after leaving the core 3, the anti-adhesion layer may not be formed.

As described above, the present invention is configured to apply ultrasonic vibration to the core prior to blow molding and separate the parison from the core without changing its relative position, so molded products without scratches, wrinkles, or uneven thickness can be easily produced. , can be manufactured reliably.

[Brief explanation of the drawing]

1 to 3 are schematic diagrams showing the injection, mold release, and blowing steps of the present invention. 1... Cavity, 2... Screw type, 3... Core,
4...Core holder, 5...Gap for parison molding, 6
...Blowing slit, 7...Ultrasonic vibrator, 8...
Injection nozzle, 9...Blowing type, 10...Parison, 1
1... Gap.

Claims (1)

[Claims] 1. An injection blow molding method, characterized in that an injection molded bottomed parison is attached to a core, and the core is subjected to ultrasonic vibration to separate the parison from the core, followed by blow molding.