U.S. patent application number 16/808556 was filed with the patent office on 2020-07-09 for method for delivering safety and disposal instructions to personnel who are removing coatings with laser processing.
This patent application is currently assigned to Surclean, Inc.. The applicant listed for this patent is Surclean, Inc.. Invention is credited to Kevin Hagedorn, Donald Sprentall.
Application Number | 20200215588 16/808556 |
Document ID | / |
Family ID | 56887218 |
Filed Date | 2020-07-09 |
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United States Patent
Application |
20200215588 |
Kind Code |
A1 |
Hagedorn; Kevin ; et
al. |
July 9, 2020 |
Method for Delivering Safety and disposal Instructions to Personnel
Who are Removing Coatings with Laser Processing
Abstract
A laser coating removal system includes a detector and a
controller. The detector detects wavelengths associated with
radiative emission of elements in laser-induced plasma generated by
the laser coating removal. The controller generates concentration
data based on the wavelengths, the concentration data indicating
concentration of the elements in the laser-induced plasma, and
notifies a user of the laser coating removal system in response to
concentration of one of the elements in the laser-induced plasma
being greater than or equal to a predetermined threshold.
Inventors: |
Hagedorn; Kevin; (Ann Arbor,
MI) ; Sprentall; Donald; (South Lyon, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Surclean, Inc. |
Brighton |
MI |
US |
|
|
Assignee: |
Surclean, Inc.
Brighton
MI
|
Family ID: |
56887218 |
Appl. No.: |
16/808556 |
Filed: |
March 4, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15069036 |
Mar 14, 2016 |
10583468 |
|
|
16808556 |
|
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62133360 |
Mar 14, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23K 26/03 20130101;
B23K 2101/34 20180801; B23K 26/361 20151001; B23K 37/006 20130101;
B23K 26/352 20151001; B23K 26/362 20130101; B23K 26/0622 20151001;
B08B 7/0042 20130101; B23K 26/0884 20130101 |
International
Class: |
B08B 7/00 20060101
B08B007/00; B23K 26/361 20060101 B23K026/361; B23K 26/0622 20060101
B23K026/0622; B23K 37/00 20060101 B23K037/00; B23K 26/08 20060101
B23K026/08; B23K 26/03 20060101 B23K026/03; B23K 26/362 20060101
B23K026/362; B23K 26/352 20060101 B23K026/352 |
Claims
1. A method for laser coating removal comprising: detecting
wavelengths associated with radiative emission of elements in
laser-induced plasma generated by a laser coating removal system;
generating concentration data based on the wavelengths, the
concentration data indicating concentration of the elements in the
laser-induced plasma; and notifying a user of the laser coating
removal system in response to concentration of one of the elements
in the laser-induced plasma being greater than or equal to a
predetermined threshold.
2. The method of claim 1 further comprising setting the
predetermined threshold based on toxicity of the one of the
elements in the laser-induced plasma.
3. The method of claim 1 wherein: the notification includes one or
more of health hazards posed by the one of the elements in the
laser-induced plasma, safety instructions regarding the one of the
elements in the laser-induced plasma, and instructions to dispose
waste ash generated by the laser coating removal system; the
notification includes one or more of audio, visual, or both types
of notifications; and the notification is based on one or more of
safety and disposal guidelines stored in the laser coating removal
system.
4. The method of claim 1 further comprising: stopping the laser
coating removal system in response to the concentration of the one
of the elements in the laser-induced plasma being greater than or
equal to the predetermined threshold; and continuing operation of
the laser coating removal system in response to receiving
confirmation from the user.
5. The method of claim 1 further comprising calibrating the laser
coating removal system to compensate for background radiation at
the wavelengths associated with the radiative emission of the
elements in the laser-induced plasma.
6. The method of claim 1 further comprising recording light
intensity associated with the radiative emission as a function of
wavelength.
7. The method of claim 1 further comprising calibrating the laser
coating removal system so that light intensity at different
wavelengths corresponds to a concentration of one of the
elements.
8. The method of claim 1 further comprising identifying when
removal of one layer of coating is complete and removal of another
layer begins based on the wavelengths associated with the radiative
emission of the elements in the laser-induced plasma.
9. The method of claim 1 further comprising: identifying when
removal of one layer of coating is complete; and beginning removal
of another layer or stopping the laser coating removal system based
on the wavelengths associated with the radiative emission of the
elements in the laser-induced plasma.
10. The method of claim 1 further comprising: correlating one of
the wavelengths associated with the radiative emission to a
concentration of one of the elements in the laser-induced plasma;
and indicating a change of layer of coating based on a change in
the concentration.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of U.S. patent application
Ser. No. 15/069,036 filed on Mar. 14, 2016, now U.S. Pat. No.
10,583,468, issued on Mar. 10, 2020, which claims the benefit of
U.S. Provisional Application No. 62/133,360, filed on Mar. 14,
2015. The entire disclosures of the applications referenced above
are incorporated herein by reference.
FIELD
[0002] This disclosure relates to laser processing and chemical
waste disposal.
BACKGROUND
[0003] The background description provided here is for the purpose
of generally presenting the context of the disclosure. Work of the
presently named inventors, to the extent it is described in this
background section, as well as aspects of the description that may
not otherwise qualify as prior art at the time of filing, are
neither expressly nor impliedly admitted as prior art against the
present disclosure.
[0004] Laser processing is becoming a competitive alternative to
media blasting and chemical solvents for stripping coatings from
parts and vehicles. Examples of vehicles that need to have the
paint periodically stripped and reapplied include aircraft and
naval vessels. Removing paint from vehicles and metal parts is
often done with solvents or media blasting. But solvents create
excessive chemical waste, and media blasting can damage aluminum.
However, lasers can remove individual coating layers without
damaging the aluminum. Other applications for laser coating removal
include mold cleaning, graffiti removal, and oxide removal from
metal parts.
[0005] Laser-induced breakdown spectroscopy (LIBS) is used to
determine the elemental composition of materials. In this
technique, a laser is used to deliver enough energy to the surface
of a material to ignite plasma. As the plasma cools, the
composition of the material can be determined from the intensity of
characteristic atomic emission lines.
SUMMARY
[0006] A method for delivering safety guidelines to personnel who
may be involved with removing unknown coatings from vehicles or
other parts with a laser coating removal system is disclosed.
During laser removal of a coating, the atomic emission lines for
toxic elements may be monitored with a broad band spectrometer or
may be monitored with a series of photodiodes which measure
emission at individual wavelengths or a small range of wavelengths,
to determine if the toxic elements are present above a programmed
threshold. If the toxic elements are present above a programmed
threshold, the software can select the relevant text from a
preprogrammed library and deliver the relevant text regarding waste
handling and safety to the personnel operating the system.
[0007] The method also detects heavy elements in materials being
processed with a laser coating removal system and using this
information to direct laser processing. During laser removal of a
coating, the atomic emission lines for elements in the coating may
be monitored by a detector, where the detector is a device which
can record light intensity as a function of wavelength and where
examples include a broad band spectrometer or a series of
photodiodes which measure emission at individual wavelengths or a
small range of wavelengths. A calibration is done on the detector
so that the signal intensity at different wavelengths corresponds
to a metal concentration. These metal concentrations may then be
used to determine when one layer has been removed and the layer
underneath is being etched. For example, if a material has two
layers and a particular element or elements are present in the
bottom layer but not in the top layer then it can be determined
when the bottom layer is being processed by the presence of those
elements in the plasma. Alternatively, the atomic emission from a
particular element or elements in the top layer disappearing may
also indicate that the top layer has been removed. An example would
be removing yttria stabilized zirconia from the surface of PtAl. In
this example, when platinum appears in the spectra, the bottom
layer is being processed. If it is desirable to avoid damaging the
PtAl layer, then when Pt appears in the spectra, processing is
stopped.
[0008] In sum, a method for delivering relevant waste disposal and
safety information to operators of a laser surface cleaning
apparatus is disclosed. The apparatus uses a detector, controller,
and alert system to collect data on the plasma emission spectra
created during ablation, convert the spectral data to elemental and
composition data, and deliver the relevant safety and waste
disposal guidelines to a user from a preprogrammed database. This
apparatus can be used in conjunction with a laser cleaning system
to remove unidentified coatings from vehicles, buildings, and parts
safely and in accordance with waste disposal guidelines. The
detector may further be used to aid in directing laser processing
by monitoring the composition of the material being removed.
[0009] Further areas of applicability of the present disclosure
will become apparent from the detailed description, the claims and
the drawings. The detailed description and specific examples are
intended for purposes of illustration only and are not intended to
limit the scope of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present disclosure will become more fully understood
from the detailed description and the accompanying drawings,
wherein:
[0011] FIG. 1 is a schematic of a system for monitoring the
presence of toxic elements in coatings;
[0012] FIG. 2 is a flowchart of a process for using data generated
by the system illustrated in FIG. 1 to display relevant safety
information to an operator of a laser coating removal system;
and
[0013] FIG. 3 is a flowchart of a process for using data generated
by the system illustrated in FIG. 1 to control the laser coating
removal system based on detection of elements.
[0014] In the drawings, reference numbers may be reused to identify
similar and/or identical elements.
DETAILED DESCRIPTION
[0015] Laser removal of coatings is becoming more common because
high brightness laser diodes have reduced the cost of high power
lasers so that bulk surface treatment applications have become more
affordable. As laser surface treatments become more common, it is
desirable to be able to identify heavy metals in coatings so that
workers can take appropriate safety measures, the waste can be
disposed of properly, or the process can be stopped after a
particular coating is removed.
[0016] Unlike media blasting and chemical etching with solvents,
laser coating removal may be easy to automate and program and can
produce less waste. As the laser etches the coating, some part of
the material may be heated to plasma. As the atoms in the plasma
cool, atomic emission occurs at characteristic wavelengths. For
example, there is a platinum emission peak at 214.42 nm. These
emission peaks may be monitored to report on the composition of the
material being removed. This data may be useful in notifying
workers of safety hazards if the metal is carcinogenic, or this
data may be useful in stopping or slowing laser processing when one
layer is removed and the next layer is being processed. For
example, if there are three layers including a substrate, a primer,
and a top coat, the top coat can be removed while leaving the
primer undamaged by stopping the coating removal process when
certain elements are detected.
[0017] As laser coating removal becomes more common, systems can be
configured to alert users to potential health hazards and suggests
disposal instructions. For example, many older structures, like
bridges, have been painted over many times and older coats may
still contain lead. Furthermore, many primers on old vehicles and
naval ships may contain a particularly carcinogenic form of
chromium called hexavalent chrome. Users should be notified if they
reach a section of the structure or metal part where the coating
contains carcinogenic metals. Furthermore, workers removing unknown
coatings from derelict structures and vehicles may be inadvertently
exposed to carcinogenic heavy metals if limited data on the
coatings is available.
[0018] One aspect of the present invention is a method for
identifying toxic metals in an unknown coating by monitoring
wavelengths associated with radiative emission of those elements in
laser induced plasma. Most metals pose significant health risks at
high concentrations, some metals like mercury, arsenic, beryllium,
cadmium, lead, and chromium are health risks even at very low
concentrations. In this method, wavelengths associated with atomic
emission of metals in laser induced plasma at the material surface
are monitored by a detector to determine the composition of the
waste ash. The detector can be a broadband spectrometer, a scanning
monochromatic spectrometer, or one or more photodiodes which
monitor a single or multiple wavelengths and may use light filters.
For example, Cd and Pb have atomic emission lines at 214 nm and 220
nm, respectively. An example of the detector would be a broad band
spectrometer that monitors the light intensity at 214 nm and 220 nm
simultaneously or a photodiode with a bandpass filter placed in
front of it such that only 214 nm, 220 nm, or 214 nm and 220 nm
light is detected.
[0019] There may be background radiation at the wavelengths of
interest due to blackbody radiation of the plasma that may be
compensated for by calibrating the system. The intensity data may
be converted to concentration data by software which uses this
calibration. For example, a photodiode with a 214 nm bandpass
filter placed in front of it, which allows 214 nm light to pass the
filter and may allow a range from 214.+-.5 nm to pass the filter,
which would generate a voltage in the photodiode depending on the
amount of light incident on the detector. For example, a voltage of
1V may indicate a low concentration of Cd, and a voltage of 10V may
indicate a high concentration of Cd. The system may be calibrated
empirically so that each of the voltages reports a concentration.
For example, 1V may be background and may correspond to a
concentration of 0 ppm Cd, and 10V may correspond to a
concentration of 100 ppm Cd in the waste ash.
[0020] Another aspect of the disclosed invention is a method for
quickly delivering relevant information to workers using data
collected by the detector. In this aspect of the invention, a
library of safety instructions and waste disposal guidelines are
programmed into the system. The appropriate guidelines are called
and displayed to the user based the concentration of metals as
calculated from the wavelengths being monitored by the detector.
For example, the software may convert the intensity of the
radiative emission to a metal mass concentration. For example, the
threshold for mercury may be set to 1 microgram, and the threshold
for cobalt may be set to 100 micrograms. Further, during the
cleaning process, radiative emission from mercury atoms may be
detected in the plasma which has been previously determined to
correspond to a concentration of mercury above 1 ppm. Then the
software interrupts the cleaning process and pulls relevant safety
information from a preprogrammed database which notifies the user
of the health hazards posed by mercury and suggests safety
guidelines for mercury at the detected concentration. Similarly,
the software also pulls disposal instructions for the waste ash
from the database.
[0021] One aspect of the present invention is a method for
identifying when one coating has been completely removed and
another layer is being processed by monitoring wavelengths
associated with radiative emission of specific elements in laser
induced plasma. In this method, wavelengths associated with atomic
emission of metals in laser induced plasma are monitored by a
detector to determine the composition of the waste ash. The
detector can be a broadband spectrometer, a scanning monochromatic
spectrometer, or one or more photodiodes which monitor a single or
multiple wavelengths using light filters. The emission at a
particular wavelength is correlated to the concentration of a
metal. When the concentration of a metal changes, for example from
being present to absent, this can be used to indicate that a
coating layer has changed, in which case the laser is directed to
process a different area or stop processing. For example, if
emission at 214.42 nm is being monitored and this emission is
reduced, this may indicate that processing of one coating is
complete, and the laser coating removal system might be directed to
stop etching that area.
[0022] FIG. 1 shows a system 100 for collecting compositional
information on a coating being removed by laser processing. The
system 100 includes a laser 102 that emits a pulsed or continuous
laser beam 104 under the control of a controller 120. The laser 102
can be an Ytterbium fiber laser, for example, but may also be YAG
or CO.sub.2 laser. The controller 120 can be a computing device
having a CPU and memory, the CPU operative to execute instructions
stored in the memory to direct the system 100 and to collect and
interpret data and may deliver relevant information to the user 180
based on the results.
[0023] The laser beam 104 can be directed to a specimen 112 by
laser optics 106. For example, the laser optics 106 can include
beam and pulse shaping optics that shape laser beam pulses
temporally and spatially to direct the pulsed laser beam 104 to a
focal point at or near the surface of the specimen 112. The laser
optics 106 may also include a scanner. The specimen 112 can be
comprised of more than one material, for example, a coating 112a
over a substrate 112b. The pulsed laser beam 504 creates plasma 130
when removing the coating material 112a from the substrate 112b.
The material which composes the hot plasma emits radiation 131
which is detected by a detector 132. The controller 120 analyses
the data from the detector 132 and delivers the relevant safety and
waste disposal data to the user 180 if the preprogrammed conditions
for doing so are met.
[0024] Aspects of disclosed implementations provide for the
delivery of safety and waste disposal documentation to laser
processing technicians. FIG. 2 is a flowchart of a process 200 for
delivering the relevant information. Implementations of this
disclosure may change the order of execution of steps of FIG. 2
without departing from the meaning and intent of this disclosure.
At 201, the process 200 ablates a small amount of material and
interprets the data from the detector to determine if there is a
significant amount of dangerous materials (e.g., greater than or
equal to a predetermined threshold amount) in the coating to be
removed. If there are no toxic materials in the coating (e.g., less
than the predetermined threshold amount), the process proceeds to
205. However, if there are toxic materials (e.g., greater than or
equal to the predetermined threshold amount), the system first
notifies the user and optionally asks for confirmation before
proceeding at 203. As the laser is scanned across the surface and
the coating is removed at 205, the detector continuously collects
data on the radiative emission from the plasma, and the computer
determines if the data indicates the presence of toxic materials at
207 (e.g., greater than or equal to the predetermined threshold
amount). If toxic materials are detected at any point during the
process, then the software notifies the user and optionally
requests confirmation before continuing at 203. This loop continues
until the part is fully stripped at 209 and the process terminates
at 211. The frequency of monitoring the plasma may vary. For
example, the plasma may only be examined once at the beginning of
the process at 201, and loops between 205 and 207 may occur at a
frequency between 0.01 Hz and 1 THz.
[0025] Aspects of disclosed implementations provide for directing a
coating removal process. FIG. 3 is a flowchart of a process 300 for
directing a laser process. Implementations of this disclosure may
change the order of execution of steps of FIG. 3 without departing
from the meaning and intent of this disclosure. The system may
ablate material and measure the light intensity at different
wavelengths to establish a baseline at 301. Once the baseline is
established, the process 300 proceeds to 305. As the laser is
scanned across the surface and the coating is removed at 305, the
detector continuously collects data on the radiative emission from
the plasma, and the computer determines the elemental composition
at 307. If the elemental composition changes, then a new area is
processed at 303. This loop continues until the part is fully
stripped at 309 and the process terminates at 311. The frequency of
monitoring the plasma may vary. For example, the plasma may only be
examined once at the beginning of the process at 301, and loops
between 305 and 307 may occur with a frequency between 0.01 Hz and
1 THz.
[0026] The foregoing description is merely illustrative in nature
and is in no way intended to limit the disclosure, its application,
or uses. The broad teachings of the disclosure can be implemented
in a variety of forms. Therefore, while this disclosure includes
particular examples, the true scope of the disclosure should not be
so limited since other modifications will become apparent upon a
study of the drawings, the specification, and the following claims.
It should be understood that one or more steps within a method may
be executed in different order (or concurrently) without altering
the principles of the present disclosure. Further, although each of
the embodiments is described above as having certain features, any
one or more of those features described with respect to any
embodiment of the disclosure can be implemented in and/or combined
with features of any of the other embodiments, even if that
combination is not explicitly described. In other words, the
described embodiments are not mutually exclusive, and permutations
of one or more embodiments with one another remain within the scope
of this disclosure.
[0027] Spatial and functional relationships between elements (for
example, between modules, circuit elements, semiconductor layers,
etc.) are described using various terms, including "connected,"
"engaged," "coupled," "adjacent," "next to," "on top of," "above,"
"below," and "disposed." Unless explicitly described as being
"direct," when a relationship between first and second elements is
described in the above disclosure, that relationship can be a
direct relationship where no other intervening elements are present
between the first and second elements, but can also be an indirect
relationship where one or more intervening elements are present
(either spatially or functionally) between the first and second
elements. As used herein, the phrase at least one of A, B, and C
should be construed to mean a logical (A OR B OR C), using a
non-exclusive logical OR, and should not be construed to mean "at
least one of A, at least one of B, and at least one of C."
[0028] In this application, including the definitions below, the
term "module" or the term "controller" may be replaced with the
term "circuit." The term "module" may refer to, be part of, or
include: an Application Specific Integrated Circuit (ASIC); a
digital, analog, or mixed analog/digital discrete circuit; a
digital, analog, or mixed analog/digital integrated circuit; a
combinational logic circuit; a field programmable gate array
(FPGA); a processor circuit (shared, dedicated, or group) that
executes code; a memory circuit (shared, dedicated, or group) that
stores code executed by the processor circuit; other suitable
hardware components that provide the described functionality; or a
combination of some or all of the above, such as in a
system-on-chip.
[0029] The module may include one or more interface circuits. In
some examples, the interface circuits may include wired or wireless
interfaces that are connected to a local area network (LAN), the
Internet, a wide area network (WAN), or combinations thereof. The
functionality of any given module of the present disclosure may be
distributed among multiple modules that are connected via interface
circuits. For example, multiple modules may allow load balancing.
In a further example, a server (also known as remote, or cloud)
module may accomplish some functionality on behalf of a client
module.
[0030] The term code, as used above, may include software,
firmware, and/or microcode, and may refer to programs, routines,
functions, classes, data structures, and/or objects. The term
shared processor circuit encompasses a single processor circuit
that executes some or all code from multiple modules. The term
group processor circuit encompasses a processor circuit that, in
combination with additional processor circuits, executes some or
all code from one or more modules. References to multiple processor
circuits encompass multiple processor circuits on discrete dies,
multiple processor circuits on a single die, multiple cores of a
single processor circuit, multiple threads of a single processor
circuit, or a combination of the above. The term shared memory
circuit encompasses a single memory circuit that stores some or all
code from multiple modules. The term group memory circuit
encompasses a memory circuit that, in combination with additional
memories, stores some or all code from one or more modules.
[0031] The term memory circuit is a subset of the term
computer-readable medium. The term computer-readable medium, as
used herein, does not encompass transitory electrical or
electromagnetic signals propagating through a medium (such as on a
carrier wave); the term computer-readable medium may therefore be
considered tangible and non-transitory. Non-limiting examples of a
non-transitory, tangible computer-readable medium are nonvolatile
memory circuits (such as a flash memory circuit, an erasable
programmable read-only memory circuit, or a mask read-only memory
circuit), volatile memory circuits (such as a static random access
memory circuit or a dynamic random access memory circuit), magnetic
storage media (such as an analog or digital magnetic tape or a hard
disk drive), and optical storage media (such as a CD, a DVD, or a
Blu-ray Disc).
[0032] The apparatuses and methods described in this application
may be partially or fully implemented by a special purpose computer
created by configuring a general purpose computer to execute one or
more particular functions embodied in computer programs. The
functional blocks, flowchart components, and other elements
described above serve as software specifications, which can be
translated into the computer programs by the routine work of a
skilled technician or programmer.
[0033] The computer programs include processor-executable
instructions that are stored on at least one non-transitory,
tangible computer-readable medium. The computer programs may also
include or rely on stored data. The computer programs may encompass
a basic input/output system (BIOS) that interacts with hardware of
the special purpose computer, device drivers that interact with
particular devices of the special purpose computer, one or more
operating systems, user applications, background services,
background applications, etc.
[0034] The computer programs may include: (i) descriptive text to
be parsed, such as HTML (hypertext markup language) or XML
(extensible markup language), (ii) assembly code, (iii) object code
generated from source code by a compiler, (iv) source code for
execution by an interpreter, (v) source code for compilation and
execution by a just-in-time compiler, etc. As examples only, source
code may be written using syntax from languages including C, C++,
C#, Objective C, Haskell, Go, SQL, R, Lisp, Java.RTM., Fortran,
Perl, Pascal, Curl, OCaml, Javascript.RTM., HTML5, Ada, ASP (active
server pages), PHP, Scala, Eiffel, Smalltalk, Erlang, Ruby,
Flash.RTM., Visual Basic.RTM., Lua, and Python.RTM..
[0035] None of the elements recited in the claims are intended to
be a means-plus-function element within the meaning of 35 U.S.C.
.sctn. 112(f) unless an element is expressly recited using the
phrase "means for," or in the case of a method claim using the
phrases "operation for" or "step for."
* * * * *