Abrading – Abrading process – Utilizing fluent abradant
Reexamination Certificate
2002-04-12
2003-09-30
Morgan, Eileen P (Department: 3723)
Abrading
Abrading process
Utilizing fluent abradant
C062S320000, C062S605000
Reexamination Certificate
active
06626737
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the production and propelling of solid sublimable particles. The machine comprises at least:
a system for producing or calibrating sublimable solid particles; and
a system for receiving said sublimable solid particles and for moving said particles to an outlet for ejecting or blasting sublimable particles.
Such a system is suitable for an easy cleaning of inaccessible parts without additional residues.
THE PRIOR ART
In the present specifications, the wording “sublimable solid particles” means particles made of a material that permits sublimation at the temperature and pressure of the object to be cleaned, on which said particles are propelled or blasted. These particles are advantageously made of solidified gas at a temperature lower than 20° C., in particular lower than 0° C., preferably at a temperature lower than −20° C. Those particles are for example particles of CO
2
or containing solid CO
2
.
EP-A-07689334 (corresponding to U.S. Pat. No. 5,520,572) discloses a machine to produce and propel sublimable solid particles on demand. The machine comprises a horizontal chamber containing CO
2
blocks, a mechanical pushing mechanism, a granulation system with long knives, a transmission to have them turning in a vertical plane, a mechanical feeding system pushing CO
2
pellets on the granulation system, a duct to bring the particles to a distributor conveying the particles in a duct provided with a propelling gas feeding, and an exhaust nozzle mounted on the end of the latter duct.
In this machine, knives act on blocks of solid CO
2
, for cutting solid CO
2
slices which are converted or broken into granules of variable size or length. This machine is also very expensive, as it required a system for pushing horizontally the blocks of CO
2
on the knives. This machine is also too heavy to be carried by a person on his back.
Furthermore, the EP-A-0768934 machine also cannot work in a continuous way, as the pushing system must be removed for refilling the chamber with CO
2
. For limiting the refilling problem, the chamber has a high volume so as to have a sufficiently long working time, this rendering the machine heavy.
Finally, as only slices of material are cut during the working of said machine, it means that a large portion of the particles do not have a sharp edge, such an edge being advantageous, for example, for a specific cleaning operation, such as the cleaning of paint.
U.S. Pat. No. 5,071,289 (corresponding to WO9109800) discloses a system for moving particles by means of a blasting gas, said particles issuing from a hopper provided with a stirring means. Such a system can be used for propelling sublimable solid particles. This document does not disclose the preparation of the solid particles to be blasted out.
BRIEF DESCRIPTION OF THE INVENTION
The present invention relates to a machine having one or more advantages with respect to the system of the state of the art. Said advantages will be disclosed hereinafter.
A first object of the invention is a system for producing and propelling solid sublimable particles, said system comprising at least:
a first means for producing solid sublimable particles;
a second means connected to said first means, said second means receiving solid sublimable particles produced by said first means and propelling said solid sublimable particles towards an outlet, and
at least one duct extending between the first means and the second means for conveying solid sublimable particles produced by the first means to the second means,
In the system of the invention, the first means for producing solid sublimable particles comprises:
a container with a first opening adapted for receiving solid sublimable material and a second opening associated to a cutting plate having a face indented to be directed towards the solid sublimable material present in the container and intended to be in contact with said solid sublimable material present in the container, said face being provided with at least one line of teeth associated to at least one passage extending through the cutting plate,
means for driving into rotation the cutting plate;
whereby the cutting teeth of the cutting plate driven into rotation are adapted for producing, when contacting solid sublimable material present in the container, solid sublimable particles with an average diameter smaller than 6 mm.
Advantageously, the plate forms at least partly a bottom for the recipient intended to receive sublimable material, so that said sublimable material present in the recipient is at least moved towards the plate by gravity.
Preferably, the plate is provided with teeth adapted for shaving the sublimable material present in the container into sublimable particles with an average size comprised between 0.1 mm and 5 mm, for example an average particle size between 0.5 and 4 mm.
Preferably, the plate is provided with a series of independent teeth or teeth which are distant from each other, whereby a better control of the size of the particles can be obtained. The maximum size of the particles can thus be controlled by selecting teeth with appropriate cutting edge and section of passage through the plate.
By using two or more different types of teeth, it is possible to produce a mixture of particles comprising two or more different fractions of particles, said fractions having different mean particle sizes.
According to an embodiment, the plate forms at least partly a bottom for the recipient intended to receive sublimable material, so that said sublimable material present in the recipient is at least moved towards the plate by gravity, and in which the plate is provided with teeth adapted for shaving the sublimable material present in the container into sublimable particles with an average size comprised between 0.1 mm and 3 mm. Most preferably, the solid sublimable material is substantially only moved towards the plate by the force of gravity. In the preferred embodiment, there is no mechanical means for pushing the solid sublimable material towards the plate, whereby during the working of the system, the container can be refilled, making continuous work possible.
According to a detail of an embodiment, the plate is substantially circular and is provided with a series of lines with teeth, each line of teeth extending substantially along a radial direction of the substantially circular plate.
According to another detail of an embodiment, the teeth have a free cutting line extending above the face of the plate intended to be in contact with the sublimable material present in the container, said free cutting line having a shape selected among the group consisting of U-shape, V-shape, a triangle, a square, a rectangle, a half hexagon, a half trapeze, a half octagon, a half pentagon, a half ellipse and combination of these shapes, said teeth being provided with means for guiding the formed particles towards the passages provided in the plate.
Preferably, the plate has at least one line of teeth adapted to form particles with a shape having at least one sharp edge.
According to a specific embodiment, the plate is provided with at least a first series of teeth and a second series of teeth, the teeth of the first series defining a first series of circular working paths during the driving into rotation of the plate, while the teeth of the second series defines a second series of circular working paths, at least one circular path of the second series being located between two adjacent circular working paths of the first series.
Preferably, in this embodiment, the plate is provided with sufficient teeth with different circular working paths, whereby the plate has a substantially continuous teeth working zone corresponding to a major portion of the face of the plate intended to be in contact with the sublimable material present in the container.
According to an advantageous detail of an embodiment, the system further comprises at least a scraping means working with the plate. For example, the system further comprises at least a scraping means working
Hovey & Williams, LLP
Morgan Eileen P
LandOfFree
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