Liquid purification or separation – With repair or assembling means
Reissue Patent
2002-03-04
2004-04-13
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
With repair or assembling means
C210S360100, C210S380100, C029S527100, C029S527200, C029S527300, C156S172000, C156S430000, C264S603000, C494S043000, C494S081000
Reissue Patent
active
RE038494
ABSTRACT:
BACKGROUND—CROSS REFERENCES TO INVENTORS' ADDITIONAL PATENTS
This application is a reissue patent application of U.S. patent application Ser. No.
09
/
156
,
171
filed Sep.
17
,
1998
, now U.S. Pat. No.
6
,
033
,
564
; which is a continuation
-
in
-
part application of U.S. patent application Ser. No.
09
/
115
,
527
filed Jul.
13
,
1998
, now U.S. Pat. No.
6
,
312
,
610
.
BACKGROUND—FIELD OF INVENTION
The pertinent field of the invention is the “imperforate bowl,” related to prior art under “fluid separation,” especially “Disk Centrifuges,” “Nozzle Centrifuges,” and “Split Bowl Centrifuges”
BACKGROUND—DESCRIPTION OF PRIOR ART
Within the scope of this application, prior art is taken to mean conventional methods of construction for the outer walls of centrifuges. One such method for such design, fabrication and assembly predominates for all major types or classes of imperforate bowl centrifugal devices, including notably: (1) those used to separate small volumes of materials, such as Test Tube, Tubal, Preparatory and Zonal Centrifuges; and (2) those used to process industrial volumes of materials, including Decanting Centrifuges, and Disc Centrifuges. Disk type imperforate bowl devices further break down into Manual Discharge, Intermittent Discharge (Split Bowl and Valve Nozzle), and Continuous Discharge (Open Nozzle) models.
To put the conventional methods of centrifuge outer wall construction into perspective, this application refers to one particular reference work regarding methods of manufacture, which is: Fundamental Principles of Manufacturing Processes, by Robert H. Todd, Dell K. Allen and Leo Alting, Industrial Process, Inc., New York, N.Y., 1994.
For nearly 100 years, the one highly predominant method of centrifuge fabrication for all three types of imperforate bowl devices has been their fabrication in steel, stainless steel, and various other steel alloys. Such metal construction requires fabrication methods including “shaping” via “mass-reducing”, primarily through “mechanical reducing,” techniques such as turning, carving, lathing, milling and drilling. (See
FIGS. 3 and 4
, which are reproductions of page 8 and 9 of the referenced work).
This often-cited reference work places each means of construction, as of 1994, into a hierarchical taxonomy of manufacturing methods. In its introduction to this taxonomy, the authors state:
The Manufacturing Processes Taxonomy, based on the process classification method initially developed at Brigham Young University and later adapted by members of the Manufacturing Consortium, provides a precise roadmap of some 300 processes used for modifying geometry or properties of engineering materials. It has been said that students can learn twice as much in half the time when the material to be studied has been classified and the critical attributes have been clearly identified. In this text we attempt to do both. Processes used for modifying workpiece geometry [italics from the authors] are called “shaping processes.” Processes used for modifying properties [italics from the authors] are called “nonshaping” processes. (Page 6).
Thus, the objective of this book is to assist industrial designers by informing them of all possible construction avenues, and of the tradeoffs inherent in each type of material and method of construction, so as to pro-actively achieve maximum appropriateness and cost-effectiveness in their finished goods. Or, as stated in Chapter 1.
In manufacturing, the actual materials and equipment used are costly, but these costs are substantially determined by those responsible for product design before manufacturing even begins. By virtue of decisions made early in the production process, designers determine up to 70 percent of manufacturing costs.” (Page 1).
Not surprisingly, many long-established industrial goods still being produced today were originally designed using the material choices and manufacturing methods developed during the industrial revolution. This is true in general of products fashioned in metal, and specifically of imperforate bowl centrifuge.
Because of the century-long tradition of building centrifuges in metal, one can accurately describe the metal manufacturing techniques used by imperforate bowl device builders as the “tried and true” fabricating methods for this industry.
As interesting “tried and true” phenomenon occurs in manufacturing. If, at any given point in time, you only have certain ways to build something, then the things you can build in those ways are what get built. Then, because of the things you have gotten used to building, you cease looking for different ways to build, because you already have a successful product, done “the way you already do it.” This phenomenon goes to the heart of the patent issue of non-obviousness. If the many advantages of other-than-metal construction were obvious to experts in the field of imperforate bowl centrifuges, such constructions would be patented, commercially available, and, in view of their claimed cost and performance superiority, even prevalent in the field. By contrast, what we see instead in the field of the industrial-volume imperforate bowl is steel and alloy centrifuges.
The inventors do not claim that conventional centrifuge construction via conventional metal-crafting has no place in many traditional products. But it is clear that a wealth of superior new material and fabrication methods for the highly stressed outer walls of centrifuges has become available, particularly since the 1970's, and that this wealth to date has been all but ignored by centrifuge makers, particularly by manufacturers building industrial-volume devices. Such manufacturers are busy building existing steel and alloy walled devices, “the way they are used to building them.” They do not appear to be exploring radical new hybrid or composite construction methods for their imperforate bowl products.
These realizations led to a key design decision on the part of the inventors of the Density Screening outer wall transport system pending U.S. patent application Ser. No. 09/115,527. This decision was to explore the possible benefits to be obtained from a complete rethinking of the materials and methods of construction for the outer, collecting walls of centrifuges, from the point of view of works such as Fundamental Principles of Manufacturing Processes.
This decision posed the initial manufacturing philosophy question: “If you were inventing centrifuge afresh, today, and you had the entire breadth of old and new manufacturing processes at your disposal, what materials and what manufacturing methods would you select?” Again, this is not a question the traditional device builders appear to have asked. When the benefits of such a rethinking become apparent, it is clear that the traditional metal fabrication mindset of centrifuge builders has prevented them from seeing the obvious: that selected new materials offer extraordinary new benefits and advantages, including both greatly increased strength and far lower cost.
As research and design work continued, several related secondary questions emerged. These were: (1) Is it possible to conceptually filet a centrifuge outer wall into different layers, and then define the unique physical functions and properties ideal to achieve in early layer? (2) Would it then be desirable and practical to employ radically different materials and manufacturing methods for each such individual filet or layer of a centrifuge outer wall, so that each such member provided the ideal mix of physical characteristics and cost performance for that layer? And, (3) Might it then also occur that all of said ideally fabricated individual layers, when combined together, yield an overall design strategy far superior, both in physical characteristics and cost performance, to traditional design and construction methods, for centrifuge outer collecting walls?
The rich, multiple answers to the first question led the inventors to discard conventional manufacturing wisdom and techniques for the pr
Fuller Berkeley F.
Kirker Curtis
Phase Inc.
Reifsnyder David A.
LandOfFree
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