Core pins, injection molds

In injection blow mol ding, a parison is injection molded onto a core pin the parison is then rapidly transferred via the core pin to a blow mold, where it is blown by air into an article. This process is appHed to smad and intricate bottles. 

Unstable state of plastic as evidenced by changes in physical )roperties not caused by the surroundings. Example is the temporary flexible condition some plastics display after molding. Assembly of all parts making up an injection mold, excluding cavity, cores and pins. 

Mold base Assembly of all parts making up an injection mold, excluding cavity, cores, and pins. 

First station usually has multiple preform injection molds where preforms are formed over core pins. The preforms have hemispherical closed ends (resembles a laboratory test tube). The other ends have an open bore, formed by the core pin. External details, such as the thread and neck flange for a screw-top container, are directly produced by injection molding. While the preform is still hot, the injection split mold is opened and the preforms, still on the core pins, are rotated to the blowing station two. Here the preforms are enclosed within the blow mold, and introducing blowing air through the core pins followed with cooling produces the BM. Blow molds opened and the finished products, still on the core pins, are rotated to an ejection station where they are stripped off mechanically and/or air. 

The injection molding with rotation (MWR) is an example of processing at lower temperatures, pressure, etc. It is also called injection spin molding or injection stretched molding. This BM process combines injection molding and IBM, as performed in IBM reviewed, except it has the additional step of with melt orientation (Dow patent). The equipment used is what is commercially available for IM except the mold is modified so that either the core pin or outside cavity rotates. The rotated melt on its preform pin is transferred to a blow mold. The end product can come directly from the I MM mold or be a result of two-stage fabrication malting a parison and BM the parison.164... 

There are many considerations in specifying the shape of the counterbore. In molding, every hole in a plastic piece is created by a pin (the core pin). The core pins are often subjected to unbalanced side forces, caused by high injection pressures and poor flow conditions in the mold as a result of the gate location, which will deflect these pins. 

Figure 1.4 Three Station Injection Blow Molding Machine [Miller, 1983]. The parison is injection molded on a core pin (instead of as a tube in free air, as with extrusion blow molding) at the preform mold station (1). The parison and neck finish of the container are formed there. The parison is then transferred on the core pin to the blow mold station (2) where air is introduced through the core pin to blow the parison into the shape of the blow mold. The blow container is then transferred to the stripper station (3) for removal.

Retainer plate n. In injection molding, a plate that reinforces the cavity block against the injection pressure, and also serves as an anchor for the cavities, ejector pins, guide pins, and bushings. The retainer plate is usually cored for circulating water or steam. 

In injection blow molding, the parison is injected into a preform cavity and around a core pin in the exact quantity required to form a container. The preform mold is kept at a precisely controlled temperature, which is just a little cooler than the melt temperature. After injection, the mold opens, and the core pin and the still warm preform are rotated 120°. A blow mold then closes over the preform, and air is injected through the core pin. After the container is blown, it is rapidly cooled by contact with the walls of the blow mold, which are kept at around 102-122°C by cold air or fluid circulating through the mold passageway. The mold then opens, a second 120° rotation occurs, and the part is stripped from the core pin. Then a third 120° rotation of the transfer head returns the core pin to the preform injection mold, and the cycle is repeated. 

Injection blow molding injects molten or thermally softened polymers into one or more heated preform cavities around a given core pin (Fig. 9-5). The preform mold is then opened. Heated polymer is then moved by using the core pin to the blow-mold station, where it is inflated and then ejected. Figure 9-8 is a schematic of a three-station unit. The injection blow-molding cycle is shown in Fig. 9-9. 

Blow molding can be divided into three major processing categories 1) extrusion BM (EBM), which principally uses an unsupported parison 2) injection BM (IBM), which usually uses a preform supported by a metal core pin and 3) stretch BM, for either EBM or IBM, to obtain bioriented products, providing significantly improved cost-to-perfor-... 

Figure 7-66. An integral carrying handle for an injection blow-molded product. 1) The precision neck mold, including a solid handle 2) the preformed core and blow pin 3) the basic water-cooled bottle female mold and 4) the injection nozzle of the injection-molding machine.

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