Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Making porous product
Reexamination Certificate
1999-09-30
2001-03-13
Jenkins, Daniel J. (Department: 1742)
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Making porous product
C419S004000, C419S048000
Reexamination Certificate
active
06200523
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field Of The Invention
This invention relates to sintering and more particularly to the process of sintering a matrix of elements such as fibers or particles with electromagnetic radiation such as infrared radiation.
2. Background Of The Invention
Various means and methods have been provided in the past for sintering materials such as ceramic fibers, metallic fibers or powders. In general, these sintering processes included placing a matrix of fibers or the powder into an oven. The oven was raised to temperatures sufficient to at least melt a portion of the surfaces of each of the fibers or the particles of powder of the matrix. Upon the melting of the surfaces of each of the fibers or the particles of powder, the fibers or the particles of powder were sintered into a unitary mass.
In some instances, the sintering process was accomplished within a vacuum, a reactive or a non-reactive atmosphere. In such instances, the sintering process may utilize a vacuum oven or a continuous process oven which is purged with a desired atmospheric gas.
In general, the sintering ovens of the prior art utilized conventional heating elements for heating the walls of the oven. The heated wall of the oven heated the matrix of the fibers or the powder through a convection process. Although the sintering ovens of the prior art have operated satisfactorily, the sintering ovens of the prior art were costly to operate. In addition, the sintering ovens of the prior art required a substantial time to heat up the ovens to an operational temperature as well as a substantial time to cool down from the operational temperature after completion of the sintering process. In a vacuum oven, this time for heating up and cooling down contributes substantially to the overall time required to sinter the material in the vacuum oven.
Therefore, it is an object of this invention to provide an improved apparatus and method of sintering a web of elements which overcomes the problems encountered by the prior art and provides a significant advancement in the pertinent art.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements incorporating an infrared heating source for sintering the web of elements.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements wherein the infrared heating source may be used when the sintering material is fixed relative to the infrared heating source.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements wherein the infrared heating source may be used when the sintering material is moving relative to the infrared heating source.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements wherein the web of elements is rolled into a compressed web concurrently with the sintering process.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements which provides for an efficient heat transfer from the infrared heating source to the web of elements.
Another object of this invention is to provide an improved apparatus and method for sintering a web of elements having a low sintering time of two (2) to five (5) minutes.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements which provides for a more rapid heat up and cool down time.
Another object of this invention is to provide an improved apparatus and method for sintering a web of elements having superior repeatability of process and consistency of sintered properties such as porosity.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements which allows for more economical operation.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements which substantially reduces the cost of power for sintering the material.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements which provides for a cleaner sinter bonded material.
Another object of this invention is to provide an improved apparatus and method for sintering a web of elements which eliminates the need for refractory materials.
Another object of this invention is to provide an improved apparatus and method for sintering a web of elements which eliminates the need for refractory materials and uses a transparent material which does not stick to the sintered web.
Another object of this invention is to provide an improved apparatus and method of sintering a web of elements with a decrease of gas and power consumption.
Another object of this invention is to provide an improved apparatus and method for sintering a web of elements with low capital expenses on equipment.
Another object of this invention is to provide an improved apparatus and method for sintering a web of elements wherein the temperature of the web may be monitored for controlling the output of an infrared source heating the web of elements.
Another object of this invention is to provide an improved apparatus and method for sintering a web of elements wherein the web of elements may be sintered with a predetermined quantity of infrared energy.
Another object of this invention is to provide an improved apparatus and method for sintering a web of elements wherein the web of elements is a composite of metallic fibers and non-metallic particles.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention with in the scope of the invention. Accordingly, other objects in a full understanding of the invention may be had by referring to the summary of the invention, the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
The present invention is defined by the appended claims with specific embodiments being shown in the attached drawings. For the purpose of summarizing the invention, the invention relates to an improved apparatus and method for sintering a web of elements. The apparatus and method comprises irradiating the web with infrared energy for a period of time sufficient to sinter bond each of the elements to adjacent elements of the matrix randomly oriented elements.
In a more specific embodiment of the invention, each of the elements of the matrix randomly oriented elements may be a metallic fiber such as a stainless steel fiber. In the alternative, each of the elements of the matrix randomly oriented elements may comprise a plurality of metallic elements and a plurality of non-metallic elements. The plurality of metallic elements may entrap the plurality of non-metallic elements therein.
In one embodiment of the invention, the invention relates to an apparatus and a method of forming a sintered web of elements. The apparatus and method comprises arranging the elements into a matrix randomly oriented elements to form a web and irradiating the web with infrared energy for a period of time sufficient to sinter bond the elements each of the elements to adjacent elements of the matrix randomly oriented elements.
In a more specific embodiment of this invention, the apparatus and method includes the step of rolling the web between a first and a second roller for at least partially compressing the web. This step of irradiating the web may include simultaneously rolling the web between a first and a second roller for at least partially compressing the web and irradiating the web from opposed first and second sides of the web. Furthermore, the step of irradiating the web may include simultaneously
Li Tao
Liberman Michael
Malanga Robert
McGrath James A.
Quick Nathaniel R.
Frijouf Rust & Pyle P.A.
Jenkins Daniel J.
USF Filtration and Separations Group Inc.
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