Abrading – Machine – Sandblast
Reexamination Certificate
1999-08-25
2002-03-26
Morgan, Eileen P. (Department: 3723)
Abrading
Machine
Sandblast
C451S087000, C451S456000, C210S767000
Reexamination Certificate
active
06361416
ABSTRACT:
TECHNICAL FIELD
This invention relates to apparatus and methods for recovering abrasive from an abrasive-laden fluid for use with abrasive jet cutting systems.
BACKGROUND OF THE INVENTION
Abrasive-jet cutting systems are used for cutting a wide variety of materials and for the production of a wide variety of products. In a typical abrasive-jet cutting system, abrasive particles are mixed with an ultra-high pressure fluid (e.g. water), and the resulting ultra-high pressure abrasive fluid is flowed through a cutting nozzle which directs an abrasive cutting jet onto a workpiece. The cutting nozzle may then be controllably moved across the workpiece to cut the workpiece into the desired shape. After the ultra-high pressure abrasive jet passes through the workpiece, the energy of the abrasive jet is dissipated and the abrasive fluid is collected in a catcher tank for disposal. Abrasive-jet cutting systems of this type are shown and described, for example, in U.S. Pat. No. 5,643,058 issued to Erichsen et al and assigned to Flow International Corp. of Kent, Wash., which patent is incorporated herein by reference, corresponding to Flow's Bengal 4×4 and Paser 3 abrasive-jet cutting systems.
One abrasive material commonly used in abrasive-jet cutting systems is garnet. Garnet is well-known for its hardness, resiliency, and overall performance in abrasive-jet cutting systems for a wide variety of workpiece materials. The cost of garnet, however, is not insubstantial. In existing abrasive-jet cutting systems the consumable garnet particles represent 60 to 75 percent of the operating costs of the system. Research into the recovery and recycling of garnet particles indicates, however, that between 40 and 60 percent of the garnet particles are typically large enough to be recovered and recycled after initial use depending upon the material properties of the workpiece being cut. This fact makes abrasive recycling commercially viable.
Currently, abrasive recovery apparatus for use with abrasive-jet cutting systems may be divided into two broad categories. In a first category, the abrasive-laden fluid contained within the jet catcher of the abrasive jet cutting system is simply removed to a heater and subjected to heat to evaporate the fluid, leaving a mixture of abrasive particles and cuttings (or “fines”) from the workpiece. This mixture of abrasive particles and cuttings is then sifted, such as through a system of successive screens, to remove the desirable abrasive particles from the undesirable cuttings and unusable particles.
In a second category, the abrasive-laden fluid is removed from the jet catcher and is separated by a wet separation process known as “classification” into a low-concentration abrasive flow and a wet recovered abrasive. The wet recovered abrasive is then heated to evaporate the fluid, leaving a mixture of dry recovered abrasive and cuttings for segregation. The low-concentration abrasive flow may simply be disposed of, or may be transported to a fine-separation tank to allow the fine particulates to settle and be recovered. In this second category of abrasive recovery systems, energy savings may be achieved because the low-concentration abrasive flow is not heated, with correspondingly lower operational costs. An abrasive recycling system of this type is shown and described, for example, in DE 19645142 issued to Hering et al and assigned to Intrec Ges Innovative Technologien MbH of Berlin, Germany, which patent is incorporated herein by reference.
FIG. 1
is a schematic view of an existing abrasive recovery apparatus
10
of the type that uses classification. First, an abrasive-laden fluid
22
is pumped through the cutting head
12
to form an abrasive jet
14
. The abrasive jet
14
is passed through a workpiece and collected in a catcher tank
16
. A pump
18
draws the abrasive-laden fluid
22
from the catcher tank
16
and pumps it through a bypass
20
to a hydro-classifier
34
.
The abrasive-laden fluid
22
enters into an upper portion
36
of a hydro-classifier
34
. A clear-fluid pump
38
draws a clarified fluid
30
from a reserve tank
32
and pumps it into a lower portion
40
of the hydro-classifier
34
. The abrasive-laden fluid
22
passes downwardly through a middle portion
42
of the hydro-classifier
34
, while the clarified fluid
30
passes upwardly through the middle portion
42
. The resulting mixing in the middle portion
42
of the hydro-classifier
34
causes the abrasive-laden fluid
22
to separate into a recovered abrasive
44
and a fine-particle flow
46
. The recovered abrasive
44
collects in the bottom portion
40
of the hydro-classifier
34
. The fine-particle flow
46
is routed to a clearing tank
26
for separation as described below.
The recovered abrasive
44
exits from the hydro-classifier
34
to a wet abrasive storage receptacle
47
. If the wet abrasive storage receptacle
47
becomes filled to capacity, the bypass
20
directs the abrasive-laden fluid
22
directly to the clearing tank
26
. An auger
48
transports the recovery abrasive
44
from the wet abrasive storage receptacle
47
to a dryer
50
. In the dryer
50
, the recovered abrasive
44
is heated to remove any remaining moisture, and is shaken and sifted through screens to separate the recovered abrasive
44
from any non-reusable particulates. The recovered abrasive
44
is then deposited into a collection tank
52
for reuse in the abrasive jet cutting system.
The fine-particle flow
46
is shunted to the clearing tank
26
where the particles are permitted to settle to the bottom. A sediment
27
which collects at the bottom of the clearing tank
26
includes cuttings from the workpiece as well as fine, non-reusable abrasive particulates. The sediment
27
is collected in a receptacle
28
for disposal or subsequent processing. Clarified fluid
30
exits from the settling tank
26
and is collected in the reserve tank
31
. From the reserve tank
31
, the clarified fluid
30
may be pumped by a filter pump
32
through a filter
33
and into a waste disposal system (not shown). Alternately, the clarified fluid
30
may be pumped by a return pump
35
from the reserve tank
31
back to the catcher tank
16
as necessary.
Although desirable results may be achieved using the abrasive recovery apparatus
10
, certain characteristics may be improved. For example, the energy costs associated with the dryer
50
remain high and the throughput of the dryer
50
is low. Furthermore, the hydro-classifier
34
is typically extremely large. These characteristics tend to make the abrasive recovery apparatus
10
economically non-viable and it impractical for most cutting environments.
SUMMARY OF THE INVENTION
This invention relates to apparatus and methods for recovering abrasive from an abrasive-laden fluid for use with abrasive jet cutting systems. In one aspect, an apparatus in accordance with the invention includes an abrasive-laden fluid handling device coupled to a catcher tank of an abrasive jet cutting system, a pre-classifier fluidly coupled to the abrasive-laden fluid handling device, a hydro-classifier fluidly coupled to the pre-classifier, a fine-particle separation tank fluidly coupled to a clarified-fluid flow outlet of the hydro-classifier, a wet abrasive receptacle positioned to receive a wet recovered abrasive discharged from the hydro-classifier, a de-watering device engageable with the wet recovered abrasive in wet abrasive receptacle, and a dryer unit.
In operation, the abrasive-laden fluid handling device provides an abrasive-laden fluid from the catcher tank without requiring mechanical agitators. The pre-classifier separates the abrasive-laden fluid into a high concentration abrasive flow that enters the hydro-classifier, and a low concentration abrasive flow that is shunted back to the catcher tank, advantageously allowing a smaller, more economical and practical hydro-classifier to be used. Further, the de-watering device removes a residual, interstitial fluid content from the wet recovered abrasive, thereby reducing the energy
Chin Daniel
Devine Daniel
Hopkins Jordan J.
Massenburg John
Sciulli Felice M.
Flow International Corporation
Morgan Eileen P.
Seed Intellectual Property Law Group PLLC
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