Plastic article or earthenware shaping or treating: apparatus – Means feeding fluent stock from plural sources to common... – Extrusion shaping means
Patent
1992-03-30
1993-10-26
Chiesa, Richard L.
Plastic article or earthenware shaping or treating: apparatus
Means feeding fluent stock from plural sources to common...
Extrusion shaping means
425381, 425467, 425532, B29C 4720
Patent
active
052560490
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a storage head for a blow molding machine for the discontinuous production of plastic hollow bodies, comprising at least one extruder, connected to the storage-head housing, for feeding at least one liquid plastic melt into the storage head; a centrally disposed shaft; and a distributor element, formed as a spiral channel and enclosing the shaft concentrically, to distribute the plastic melt over a circular circumference and conducting it into an annular storage space underneath the ejector piston, which is mounted in the storage-head housing so as to be movable axially, and by means of which the plastic melt stored in the storage space can be ejected by an annular nozzle gap which connects underneath to the storage space.
A comparable storage head is previously known, e.g., from the DE-OS 30 00 444, and is described in detail there. The spiral-channel distributor to distribute the liquid plastic melt is here disposed on the outside wall of the ejector piston. The spiral-shaped channel is supplied with liquid plastic melt through two axial grooves that are disposed in the outside wall of the ejector piston above the spiral channel. These axial grooves are connected to appropriate radial borings in the storage housing so as to feed in material from the extruder. A disadvantage here is that, when the plastic is distributed over the circumference, such that the storage space is filled up and the ejector piston moves slowly and steadily into its upper ejector position, the spiral-channel distributor is bounded by two outside walls that move relative to one another, and the inflowing plastic material is constantly subject to a shear effect. Furthermore, during the ejection process, there is no defined ejector edge present at the outside circumference of the ejector piston, so that the entire plastic ring column in the storage space adheres on its outside to the inside wall of the storage housing and is not ejected uniformly over the entire cross-section but rather is displaced to the outside in the manner of a wedge, adheres to the storage housing, and is sheared off or smeared off. This causes undesirable material displacements and excessive internal friction as well as a non-uniform pressure build-up within the liquid melted plastic material. The result is a disturbed layer build up in the hose-shaped parison that is ejected through the annular-gap nozzle of the storage head, or in the blown plastic hollow body or in the end product.
These disadvantages should be avoided.
SUMMARY OF THE INVENTION
It is consequently an object of the present invention to improve the quality of the blown hollow bodies, such as, e.g., barrels or canisters, and for this purpose to create a favorable layer build-up with multiple overlaps of the plastic material in the storage head through a distributor element that is designed as a spiral-channel distributor, and to be able to eject this plastic ring column completely and uniformly without disturbing the interior layer build-up.
According to the invention, this object is achieved as follows: The ejector piston is formed of at least two cylindrical tubular pieces, and the spiral channels of the spiral-channel distributor are formed on one tubular piece and are covered by the other tubular piece, such that the plastic which is distributed on the circumference of the cylinder exits from a annular gap that is formed on the front face in the ejector piston.
By constructing the ejector piston in this favorable fashion, the spiral-channel distributor is formed, so to speak, within the ejector piston itself with a stationary outer boundary of the spiral-channel gap. The plastic material is uniformly distributed along the circumference and it flows into the storage space on the front side from the oscillating ejector piston and the distributor space of the spiral-channel distributor is not formed by boundary walls that are in constant relative motion with respect to one another. A shear effect and internal friction on the plastic mate
REFERENCES:
patent: 3909183 (1975-09-01), Hsu
patent: 3985490 (1976-10-01), Kader
patent: 4063865 (1977-12-01), Becker
patent: 4182603 (1980-01-01), Knittel
patent: 4201532 (1980-05-01), Cole
patent: 4305902 (1981-12-01), Uhlig
patent: 4422838 (1983-12-01), Iwawaki et al.
patent: 4424178 (1984-01-01), Daubenbuchel et al.
patent: 4548569 (1985-10-01), Pitigliano et al.
patent: 4609340 (1986-09-01), Irwin et al.
patent: 4731216 (1988-03-01), Topolski
patent: 4802833 (1989-02-01), Shapler
patent: 5116215 (1992-05-01), Hsu
Langos Peter
Lehmann Manfred
Chiesa Richard L.
Mauser-Werke GmbH
LandOfFree
Storage head for a blow molding machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Storage head for a blow molding machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Storage head for a blow molding machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-954864