Symmetrical flow extrusion manifold

Details Symmetrical flow extrusion manifold Symmetrical flow extrusion manifold

1999-01-14

2001-03-27

Vargot, Mathieu D. (Department: 1732)

Plastic article or earthenware shaping or treating: apparatus

Preform severing means

Means forming from bulk and downstream severing means

C264S142000, C425S311000, C425S313000, C425S463000

Reexamination Certificate

active

06206678

ABSTRACT:

DESCRIPTION
1. Technical Field
The present invention relates generally to a method and apparatus for extruding generally cylindrical, multi-layered materials and more particularly to a manifold with multiple-extrusion orifices for coextrusion, such as may be used in the manufacture of center-filled food products and methods of using the same.
2. Background of Invention
There are numerous desirable products made by extruding two or more substances together so that the substances become generally radially-layered. The process for making such products is generally referred to as coextrusion. In other words, a product is formed by extruding a first substance which circumferentially surrounds a second substance and, where desired, the second surrounds a third, and so on. Others have proposed methods and apparatus for making such products. For example, U.S. Pat. Nos. 4,402,898 and 4,208,175 disclose methods and apparatus for extruding radially layered plastic tubing. U.S. Pat. Nos. 5,124,161; 5,120,554; 5,110,276; 4,900,572; 4,882,185; and, 4,648,821 disclose methods and apparatus for extruding center-filled food products.
Generally coextrusion involves a separate extruder for each substance to be combined into the multi-layered extrusion product. Each of these extruders flows the extrudable substance or “extrudate” into an apparatus such as a manifold. This apparatus presents flow paths to the various substances to direct them ultimately to a means which combines them and extrudes them as a multi-layered (usually radially-layered) product through an extrusion orifice. While not disclosed by some, others in the art cited above recognize a need for the apparatus or manifold to have multipleextrusion orifices for higher production output.
However, problems arise in connection with producing radially-layered products, especially when multiple orifices are employed. For example, it can be difficult to achieve a product which is uniform from orifice to orifice. A primary reason for this is that the extrudable substance flowing from any given extruder must be divided in some manner to distribute the substance along a flow path to each extrusion orifice. With conventional apparatus, achieving uniform distribution to each orifice, requires separate adjustment to vary the flow path or flow rate leading to each given orifice. Such adjustments must be checked, and perhapsrepeated whenever a new batch of extrudate is supplied from the extruder. Adjustments may also be required upon conditions changing, such as temperature or flow rate from the extruder. These adjustments are not desirable as they require the purchase, installation and maintenance of the flow varying apparatus. Also, valuable production time is consumed in making the adjustments and scrap may be generated until the adjustments are complete. For example, U.S. Pat. Nos. 5,120,554 and 5,110,276 teach the use of valves interposed in the flow path of the extrudates to vary and adjust volumetric flow.
Uniform distribution of extrudate is also impeded by the inherent necessity of introducing the flow path of inner extrudable substances within the flow path of the outer extrudable substances. To address this problem, others have proposed complex manifold structures employing spider plates and the like which attempt to uniformly divide outer substance by flowing into additional flow paths temporarily while the flow path of the inner substance can be interposed and brought into coaxial alignment, with the outer substance flow path. In these embodiments, the outer substance is generally then recombined before it proceeds to the extrusion orifice. The apparatus proposed for this dividing and recombining flow is complex and further impedes uniform distribution. The complexity also increases equipment capital and maintenance costs. Examples of these structures are disclosed in the above-cited patents.
While presenting an improvement over the above discussed approaches and while enjoying significant commercial success, U.S. Pat. No. 4,900,572 to Repholz nonetheless discloses, among other things, the need for adjustment of flow and distribution of extrusion. For example, in Repholz, the extrudate flow and uniformity are adjusted by separately turning individual eccentric sleeves in each of the extrusion orifices.
Generally uniform distribution of extrudable substance is also frustrated by non-symmetrical and nonequal flow paths presented by conventional apparatus from the extruders to each of the multiPle extrusion orifices.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for high volume, cost efficient extrusion of a generally radially-layered product. According to one aspect of the invention, a plurality of extruders are provided and a flow path between an extruder and each of a plurality of multiple-extrusion orifices is sufficiently equal to obviate the need for individual adjustment apparatus, such as valves or eccentric sleeves in the orifices, to obtain a substantially uniform distribution and volumetric flow at each extrusion orifice. The use of symmetry in a multiple-orifice extrusion manifold is contemplated as another aspect of the invention. Thus, a plurality of radially-layered substances are produced by providing an extrudable substance for each layer of product, extruding each extrudable substance to a plurality of extrusion orifices through an equal and symmetrical flow path.
More specifically, one aspect of the invention contemplates a multiple-orifice extrusion manifold including a housing with a symmetrical chamber and a plurality of orifices in the housing adapted to extrude a first substance from the symmetrical chamber. The orifices are generally symmetrically spaced from each other. A plurality of tubes, adapted to carry a second substance, extend through the chamber in a generally symmetrical relationship to each other and the symmetrical chamber. Each tube has a terminal end cooperatively aligned with an extrusion orifice to extrude a second substance within the first substance. Thus, each extrudate substance is flowed to an extrusion orifice through a flow path, which is symmetrical with all other flow paths for that substance.
According to another aspect of the invention, a multiple-orifice extrusion manifold is employed, which includes a first housing defining an outer chamber and one or more extrusion walls. A plurality of orifices, adapted for extruding a first substance from the outer chamber, extend through the extrusion walls. An inlet is provided in the first housing for flowing the first substance into the outer chamber. The inlet is located so as to permit flow of the first substance symmetrically within the outer chamber. A second housing which defines an inner chamber is provided within the first housing. The second housing is located symmetrically within the outer chamber. A plurality of tubes extend from the second housing. Each tube has a first end opening into the inner chamber and a second open end cooperatively aligned with an orifice for extruding a second substance from the inner chamber through the tube and to within the first substance.
According to another aspect of the invention, a multiple-orifice extrusion manifold includes a plurality of extrusion orifices and a means for flowing an outer layer substance from a first extruder output symmetrically to the extrusion orifices. The means for flowing an outer layer substance provides a fixed and equal flow path from the first extruder output to each of the extrusion orifices. A means for flowing an inner layer substance from a second extruder output to the extrusion orifices is provided. The means for flowing an inner layer substance also provides a fixed and equal flow path from the extruder output to each of the extrusion orifices.
According to another aspect of the invention, a multiple-orifice, multiple-layer extrusion apparatus, which includes a plurality of means for combining a plurality of extrudable substances and for extruding them as a continuous, radially-layered, generally cylindrical body. A plurality o

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