Plastic article or earthenware shaping or treating: apparatus – With apparatus assembly or dismantling means or with idle part – For extrusion or injection type shaping means
Reexamination Certificate
1998-09-14
2001-03-27
Pyon, Harold (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With apparatus assembly or dismantling means or with idle part
For extrusion or injection type shaping means
C425S380000, C425S467000, C264S177120, C264S209100, C264S209800
Reexamination Certificate
active
06206675
ABSTRACT:
This invention relates to an apparatus for the manufacture of monolithic tubes, containing equally distributed tunnels, by extrusion of an extrudable material through a novel extrusion die.
BACKGROUND OF THE INVENTION
Monolithic tubes having tunnels along the length thereof are useful for a variety of purposes. Thus, for example, thus, for example, monolithic tubes made of an adsorbent material and having parallel tunnels along the length thereof for the passage of gas may be used for the separation or purification of gases from gas mixtures. Similar structures made from other materials, such as cement, may be used for withdrawing and storing heat from fluids passing through the tunnels. Furthermore, in the fabrication of elongated monolithic structures, such as rods, the incorporation of a desired amount of void space in the form of parallel tunnels may be used to achieve a balance between strength and weight may be achieve a balance between strength and weight.
The use of adsorption materials for the separation or purification of gases from gas mixtures is known. Thus, for example, gases to be purified or gas mixtures to be separated with the aid of an adsorbent may be passed through vessel filled with particles of the adsorbent (particle bed). When the gas contacts the adsorbent, some is adsorbed. The selectivity of the adsorbent will allow some gases to pass through readily but will preferentially adsorb other gases. For example, silica gel will adsorb water vapor in preference to the other components of air and the air will therefore be dried. Some adsorbents will adsorb nitrogen much more readily than oxygen and, therefore, the gas emerging from the adsorbent vessel will have a higher concentration of oxygen than the air entering the vessel. When the adsorbent becomes filled or saturated with the gases that are preferentially adsorbed, the gas will pass through without changing its concentration. The adsorbent must then be desorbed to remove the adsorbed gases. The adsorbent may then be used again.
There are difficulties associated with the use of particle bed-type adsorbent vessels. For example, gas velocity must be very carefully controlled to avoid lifting of the particles or channeling of the gas through the particle bed. Furthermore, the bed must be maintained in a position for vertical flow of the gas. If the flow of gas is horizontal, the particles will tend to settle and the gas will be able to flow above the bed without particle contact. Moreover, the adsorbent particle distribution (by size) is important to the quality and capacity of the system. If, on settling, the smaller particles migrate and settle near the circumference of the vessel, it will cause a higher gas flow rate to occur at the vessel center where adsorption will take place preferentially and as that region becomes saturated, gases will pass through without adsorption and the particles near the circumference will be unused or underused.
The problems associated with the particle bed-type adsorbent vessels may be overcome with the use of monolithic adsorption tubes that may be formed by extrusion techniques and, in particular, with the use of the method and novel extrusion die of the present invention.
Various techniques and extrusion dies are disclosed in the literature for the extrusion of ceramic batches, plastics, cement, clay, adsorbents and similar materials which have the property of being able to flow or plastically deform during extrusion while being able to become sufficiently rigid thereafter so as to maintain structural integrity. Such techniques and dies have been used for the manufacture of various monolithic or honeycomb type of structures having a plurality of openings or passages extending therethrough.
U.S. Pat. No. 1,849,431 discloses the manufacture of clay conduits using a die assembly wherein a cross-head positions a plurality of spaced bells are mounted on longitudinal stems, which secured to bridges spanning the die side wall. The bells are of non-circular shape corresponding to the shape of the various passages to be formed in the conduit.
U.S. Pat. No. 3,406,435 discloses apparatus for manufacturing ceramic elements having a honeycomb structure wherein a plurality of elongated thin-walled sleeve members having extensions with closed end portions are connected to an extruder cylinder. The material to be extruded is forced through the elongated sleeve members and outwardly through orifices formed in side walls of the extensions attached thereto. The sleeve extensions are spaced from each other to provide channels in which the material from the orifices becomes reshaped into a honeycomb structure.
U.S. Pat. No. 3,905,743 discloses an extrusion die for forming thin-walled honeycomb structures. The extrusion die is of unitary construction having a plurality of interconnected discharge slots provided with uniform openings in the outlet face of the die.
Although a variety of extrusion dies and methods of use are set forth in the prior art, it will be apparent to those skilled in the art that need exists for an extrusion die apparatus that is less expensive and conveniently adaptable for the extrusion of monolithic tubes, such as, monolithic adsorption tubes and the like having variable numbers and sizes of longitudinal openings for the passage of fluids.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide an extrusion die suitable for the manufacture of monolithic adsorption tubes having a solid body portion with a multiplicity of tunnels for the passage of fluids therethrough.
It is a further object of this invention to provide a relatively simple and inexpensive apparatus for the manufacture of monolithic adsorption tubes.
It is still another object of this invention to provide an extrusion apparatus for the manufacture of monolithic adsorption tubes having a solid body portion with a multiplicity of tunnels for the passage of gases therethrough wherein the extrusion apparatus may be conveniently adapted to produce various numbers and sizes of the tunnels therein.
These and other objects are accomplished in accordance with the present invention by an extrusion die comprising
a) an outer housing having an entrance end and an exit end for the entrance and exiting of extrudable material;
b) at least two sub-assemblies, each comprising an outer ring rib collar holding a set of ribs, that is, a multiplicity of ribs forming a geometric pattern and oriented perpendicular to the outer housing and positioned approximate the entrance end thereof
c) a multiplicity of rods positioned within the housing and rib collars and oriented parallel to the housing and passing through the ribs so that each rod is supportedly contacted by at least three ribs in at least two rib collars.
In practice, as the material to be extruded is forced through the extrusion die, the rods in the die will result in the formation of corresponding tunnels in the extruded monolith. The rods may be of various cross-sectional shapes, depending on the shape desired for the tunnels. Since the tunnels in the monolith are preferably circular in cross-section, the preferred rods are also circular in cross-section. The number, size and spacing of the tunnels may similarly be varied by selecting the appropriate number, size and spacing of the rods. In a preferred embodiment, the rods are substantially circular in cross-section, of uniform diameter and substantially evenly spaced within the die. The ribs are preferably arranged in a geometric pattern and each rib may be slotted at points along its length so that two or more ribs may be conveniently interlocked to provide stability to the die assembly.
REFERENCES:
patent: 1849431 (1932-03-01), Mayhew
patent: 3406435 (1968-10-01), Dietzsch
patent: 3905743 (1975-09-01), Bagley
patent: 4743191 (1988-05-01), Chao
patent: 4846657 (1989-07-01), Chao
patent: 5407442 (1995-04-01), Karapasha
patent: 5807590 (1998-09-01), Ishikawa et al.
patent: 5972427 (1999-10-01), Muhlfield
Cookfair Arthur S.
Del Sole Joseph S.
Pyon Harold
Ralabate James J.
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