U.S. patent application number 14/201083 was filed with the patent office on 2015-09-10 for method and system for vibratory finishing of composite laminate parts.
This patent application is currently assigned to The Boeing Company. The applicant listed for this patent is The Boeing Company. Invention is credited to Brian K. Hovik.
Application Number | 20150251291 14/201083 |
Document ID | / |
Family ID | 52669409 |
Filed Date | 2015-09-10 |
United States Patent
Application |
20150251291 |
Kind Code |
A1 |
Hovik; Brian K. |
September 10, 2015 |
METHOD AND SYSTEM FOR VIBRATORY FINISHING OF COMPOSITE LAMINATE
PARTS
Abstract
A method for vibratory finishing of a composite laminate part
includes placing particles of a vibratory media, comprising
titanium oxide abrasive in a synthetic binder, into a trough of a
vibratory finishing machine, placing a composite laminate part into
the trough and substantially immersed in the vibratory media, and
operating the vibratory finishing machine at a vibrational
frequency of 40 Hz to 50 Hz with the vibratory media and composite
laminate part disposed in the trough.
Inventors: |
Hovik; Brian K.; (Renton,
WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Boeing Company |
Seal Beach |
CA |
US |
|
|
Assignee: |
The Boeing Company
Seal Beach
CA
|
Family ID: |
52669409 |
Appl. No.: |
14/201083 |
Filed: |
March 7, 2014 |
Current U.S.
Class: |
451/35 ;
451/113 |
Current CPC
Class: |
B24B 31/06 20130101 |
International
Class: |
B24B 31/06 20060101
B24B031/06 |
Claims
1. A method for vibratory finishing of a composite laminate part,
comprising: placing particles of a vibratory media, comprising
titanium oxide abrasive in a synthetic binder, into a trough of a
vibratory finishing machine; placing a composite laminate part into
the trough and substantially immersed in the vibratory media; and
operating the vibratory finishing machine at a vibrational
frequency of 40 Hz to 50 Hz with the vibratory media and composite
laminate part disposed in the trough.
2. A method in accordance with claim 1, wherein the binder of the
vibratory media comprises synthetic acrylic.
3. A method in accordance with claim 1, wherein the particles of
vibratory media range in size from about 1/4'' to about 21/2'' and
have a specific gravity of about 1.5 to about 2.0.
4. A method in accordance with claim 1, wherein a total volume of
the particles of vibratory media in the trough have a sectional
density approximately equal to a sectional density of the composite
laminate part.
5. A method in accordance with claim 1, wherein the particles of
vibratory media comprise about 10% to 20% titanium oxide abrasive
in a binder of synthetic urea-resin.
6. A method in accordance with claim 1, further comprising
operating the vibratory finishing machine for a period of 45 to 60
minutes.
7. A method in accordance with claim 1, further comprising applying
flush water to the vibratory media at a rate of about 0.35-0.50
gallons per hour per cubic foot of volume of the finishing
media.
8. A method in accordance with claim 1, wherein operating the
vibratory finishing machine comprises rotating a drive shaft,
coupled to the trough, the drive shaft having offset counterweights
that cause an approximately 10% eccentric rotation of the drive
shaft.
9. A method in accordance with claim 1, further comprising
adjusting the vibrational frequency of the vibratory finishing
machine.
10. A method in accordance with claim 1, further comprising
refreshing the vibratory media by removing worn particles below
about 1/2'' in size and replacing the worn particles with a
comparable volume of particles of 1'' to 21/2'' in size.
11. A method for finishing composite laminate parts, comprising:
placing particles of a vibratory media, comprising titanium oxide
abrasive in a synthetic acrylic binder, into a trough of a
vibratory finishing machine; placing a composite laminate part into
the trough and substantially immersed in the particles of vibratory
media; applying flush water to the vibratory media at a rate of
about 0.35-0.50 gallons per hour per cubic foot of volume of the
finishing media; and operating the vibratory finishing machine,
with the vibratory media and composite laminate part disposed in
the trough, at a vibrational frequency of 40 Hz to 50 Hz via a
rotating shaft having an approximately 10% eccentric rotation, for
a period of 45 to 60 minutes.
12. A method in accordance with claim 11, wherein the particles of
vibratory media range in size from about 1/4'' to about 21/2'' and
have a specific gravity of about 1.5 to about 2.0.
13. A method in accordance with claim 11, wherein the particles of
vibratory media have a sectional density approximately equal to a
sectional density of the composite laminate part.
14. A method in accordance with claim 11, further comprising
refreshing the vibratory media by removing particles below about
1/2'' in size and replacing a comparable volume of particles of 1''
to 21/2'' in size.
15. A method in accordance with claim 11, further comprising
removing the part from the trough and rinsing the part with
water.
16. A system for finishing composite laminate parts, comprising: a
vibratory finishing machine, having a trough of suitable volume to
contain a composite laminate part, configured to vibrate at a
frequency of 40 Hz to 50 Hz; a volume of vibratory media particles,
disposed in the trough, comprising titanium oxide abrasive in a
synthetic binder; and a water inlet, configured to provide process
water into the trough while the vibratory finishing machine is
vibrating with the composite laminate part substantially immersed
in the vibratory media particles, whereby the composite laminate
part is substantially deburred through contact with the vibratory
media particles.
17. A system in accordance with claim 16, wherein the vibratory
media particles range in size from 1/4'' to about 21/2'' and have a
specific gravity of about 1.5 to about 2.0.
18. A system in accordance with claim 16, further comprising a
speed adjustment mechanism, configured to allow adjustment of the
vibrational frequency of the vibratory finishing machine.
19. A system in accordance with claim 16, further comprising a
rotating a drive shaft, coupled to the trough, rotatable at about
2700 RPM, having offset counterweights that cause an approximately
10% eccentric rotation of the drive shaft.
20. A system in accordance with claim 16, wherein the water inlet
is configured to apply flush water at a rate of up to about 0.5
gallons per hour per cubic foot of volume of the finishing media,
and further comprising a water outlet, disposed in the trough,
configured to drain flush water from the trough.
Description
FIELD OF THE DISCLOSURE
[0001] The present disclosure relates to the fabrication of
composite laminated parts. More particularly, the present
disclosure relates to a system and method for finishing composite
laminated parts using an automated vibratory deburring process.
BACKGROUND
[0002] In a variety of manufacturing processes, it is desirable to
deburr manufactured parts after they have been machined or
subjected to other processing steps. Parts that have been produced
by casting, machining, laminating and other fabrication techniques
frequently have burrs and surface roughness that are not considered
acceptable in the final product. Finishing of such an article can
include the removal of burrs and modification of the surface
finish. Deburring is the general term given to various processes
for rounding or smoothing the edges of parts and removing burrs
from them, in order to provide a part with the desired finish
characteristics.
[0003] Traditionally, deburring of manufactured parts has involved
significant manual labor, using grinders and other tools to smooth
the edges and surfaces of parts. More recently, vibratory deburring
processes have been developed for removing burrs and smoothing the
surfaces of mass-produced articles. In these processes, articles to
be finished are typically placed in a vibratory finishing apparatus
such as a vibratory trough or bowl, together with particles of a
finishing medium, which can be an abrasive material. The finishing
medium is agitated in the trough, causing the particles of the
finishing medium to repeatedly contact the edges and surfaces of
the articles to be finished. The finishing medium can include
particles having relatively sharp points or corners, which can work
their way into grooves and crevices of the article, thereby
smoothing the article and removing burrs and sharp edges. In some
cases, the finishing medium can have a cleaning or surface
polishing effect. In many cases, the vibratory deburring process
produces a slightly sanded looking surface.
[0004] While vibratory deburring of manufactured parts reduces
manual labor involved in deburring and can provide more consistent
results, it has primarily been applied to metal parts, and is not
believed to have been applied to laminated composite parts for a
variety of reasons. Consequently, deburring of advanced composite
laminated parts that have been machined or fabricated is still
generally performed using manual deburring tools and methods.
Unfortunately, these manual processes tend to be very labor
intensive, and can produce irregular results--leading to
over-burring of some parts and providing parts that do not meet
specifications for edge-break and surface finish.
[0005] The present disclosure is directed toward one or more of the
above issues.
SUMMARY
[0006] In accordance with one aspect thereof, the present
disclosure provides a method for vibratory finishing of a composite
laminate part. The method includes placing particles of a vibratory
media, comprising titanium oxide abrasive in a synthetic binder,
into a trough of a vibratory finishing machine, placing a composite
laminate part into the trough and substantially immersed in the
vibratory media, and operating the vibratory finishing machine at a
vibrational frequency of 40 Hz to 50 Hz with the vibratory media
and composite laminate part disposed in the trough.
[0007] In accordance with another aspect thereof, the present
disclosure provides a method for deburring composite laminate
parts. The method includes placing particles of a vibratory media,
comprising titanium oxide abrasive in a synthetic acrylic binder,
into a trough of a vibratory finishing machine, placing a composite
laminate part into the trough and substantially immersed in the
particles of vibratory media, applying flush water to the vibratory
media at a rate of about 0.35 to 0.50 gallons per hour per cubic
foot of volume of the finishing media, and operating the vibratory
finishing machine, with the vibratory media and composite laminate
part disposed in the trough, at a vibrational frequency of 40 Hz to
50 Hz via a rotating shaft having an approximately 10% eccentric
rotation, for a period of 45 to 60 minutes.
[0008] In accordance with yet another aspect thereof, the present
disclosure provides a system for finishing composite laminate
parts, including a vibratory finishing machine, having a trough of
suitable volume to contain a composite laminate part, a volume of
vibratory media particles, disposed in the trough, and a water
inlet. The trough is configured to vibrate at a frequency of 40 Hz
to 50 Hz. The vibratory media particles are titanium oxide abrasive
in a synthetic binder. The water inlet is configured to provide
process water into the trough while the vibratory finishing machine
is vibrating with the composite laminate part substantially
immersed in the vibratory media particles, whereby the composite
laminate part is substantially deburred through contact with the
vibratory media particles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Additional features and advantages of the invention will be
apparent from the detailed description which follows, taken in
conjunction with the accompanying drawings, which together
illustrate, by way of example, features of the invention.
[0010] FIG. 1 is a perspective view of a tub- or trough-type
vibratory finishing machine.
[0011] FIG. 2 is a cross-sectional view of a trough of a vibratory
finishing machine showing the drive shaft and offset
counterweights.
[0012] FIG. 3 is a close-up view of a trough-type vibratory
finishing machine loaded with finishing media and having parts
being finished therein.
[0013] FIGS. 4A and 4B are perspective views of media particles of
various sizes and shapes that can be used in a deburring process in
accordance with the present disclosure.
[0014] FIG. 5 is a partial sectional view showing the edge break of
a piece of composite material that has been subjected to a
vibratory deburring process in accordance with the present
disclosure.
[0015] FIG. 6 is a logic flowchart outlining the steps in an
embodiment of a process of deburring laminated composite parts in
accordance with the present disclosure.
[0016] While the disclosure is susceptible to various modifications
and alternative forms, specific embodiments have been shown by way
of example in the drawings and will be described in detail herein.
However, it should be understood that the disclosure is not
intended to be limited to the particular forms disclosed. Rather,
the intention is to cover all modifications, equivalents and
alternatives falling within the scope of the invention as defined
by the appended claims.
DETAILED DESCRIPTION
[0017] As noted above, mass finishing or "vibratory finishing" is a
mechanical and/or chemical process that is applied to finish
component parts. Vibratory finishing processes can remove burrs and
smooth the surfaces of mass-produced articles. However, while
vibratory deburring reduces manual labor and can provide more
consistent results than manual deburring, it has primarily been
applied only to metal parts. For example, manufacturers of
vibratory finishing equipment acknowledge that metal parts are the
major field of application for this technology, and that mass
finishing technologies are also used for wood, rubber, stone and
plastic. Notably, vibratory finishing is not believed to have been
applied to laminated composite parts. One reason is that typical
vibratory finishing media is not compatible with composite
materials. Another reason is that composite laminated parts tend to
"float" atop vibratory media, and do not naturally immerse
themselves in the media. Additionally, vibratory finishing machines
that are commercially available operate at a fixed frequency and
magnitude of vibration that is not suitable to finishing laminated
composite parts. Thus, known vibratory finishing systems and
methods not only teach away from finishing laminated composite
parts, but teach away from systems that are adjustable in a way
that they could be made suitable for finishing laminated composite
parts.
[0018] Advantageously, as disclosed herein, a system and method
have been developed for applying vibratory deburring processes to
laminated composite parts. This process utilizes automated
vibratory deburring machines with specific deburring media,
specific RPM and processing times to deburr these parts, which
eliminates the need for manual single-part deburring of many
composite parts. This saves time, money and eliminates many
ergonomic issues that can arise with manual deburring. Preliminary
testing with certain media has shown excellent results that meet
exacting specifications.
[0019] Shown in FIGS. 1 and 2 is a trough-type vibratory finishing
apparatus 100, such as are commercially available from Rosler
America, of Battle Creek Mich. and other manufacturers. Another
commercially available vibratory finishing machine that has been
used in this type of process is the model SVP-5 made by Hammond
Roto Finish of Kalamazoo Mich. The vibratory finishing machine 100
includes a large tub or trough 102 that receives finishing media,
indicated generally at 104, and the article to be treated 106. The
trough 102 is supported on springs 108 and is attached to a motor
110 that drives a drive shaft 112 that is positioned below the
trough 102. The drive shaft 112 is attached to the spring-mounted
trough 102 with bearings 114 and is provided with offset or
off-center counterweights 116, so that the drive shaft 112 vibrates
as it rotates, and thus transmits this vibration through the
bearings 114 to the trough 102. This configuration causes the
trough 102 to vibrate at a frequency that depends on the rotational
speed of the drive shaft 112, and a magnitude that depends on the
weight and offset position (i.e. how much the counterweights are
off-center) of the counterweights 116.
[0020] As shown in FIG. 2, rotation and vibration of the drive
shaft 112 causes the trough 102 to vibrate in a generally
elliptical motion, as indicated by arrow 118. This vibration of the
trough 102 causes the individual particles (136 in FIGS. 4A, 4B) of
the finishing media 104 and the part(s) 106 that are being finished
to rotate individually within the trough 102 in a small circular
motion, as indicated by arrows 120, and the whole mass of the media
104 to rotate or churn in a "rolling" motion simultaneously in one
direction about a horizontal axis, as indicated by arrows 122.
[0021] Previously, vibratory finishing machines of the general type
shown in FIGS. 1 and 2 have typically had a fixed vibrational
speed. Indeed, it does not appear that vibratory finishing machines
of this type having an adjustable speed are commercially available
at all, and those that are commercially available all operate at a
speed of 2100 RPM. Unfortunately, vibratory finishing machines of
this type that operate at that speed are largely ineffective with
composite materials, for reasons discussed above.
[0022] Advantageously, the vibratory finishing system depicted
herein is compatible with composite materials, and its operational
parameters, specifically the vibrational frequency and magnitude of
vibration, have been developed and optimized for them. In one
embodiment, the vibratory finishing machine 100 includes both a
motor RPM controller 124 and a tachometer 126 to allow a user to
adjust and verify the RPM of the motor 110, which determines the
vibrational frequency. This speed adjustment mechanism allows a
user to change the RPM to find an optimum RPM for the parts 106
that are to be finished, whether composite parts or other types of
parts. This not only allows a user to find a suitable speed for
finishing composite parts, but can also allow a single vibratory
finishing machine to be selectively adjusted for use with metal
parts, composite parts, and other types of parts, if desired.
[0023] In one embodiment, it has been found that a motor frequency
of around 2700 RPM, with the offset counterweights 116 provided on
the drive shaft 112, will vibrate the trough at a frequency in the
range of 40-50 Hz, such as a specific frequency of 45 Hz.
Frequencies in this range have been found to be effective for
composite materials, while the typical 35 Hz frequency of prior
vibratory finishing machines is not.
[0024] As shown in FIGS. 1 and 2, the vibratory finishing machine
100 can be configured to allow for the addition or subtraction of
counterweights 116 to allow a user to create a desired offset so
that the vibration has a desired magnitude (combined with the
selected RPM). Those of skill in the art will recognize that the
frequency of vibration is a function of the rotational speed of the
drive shaft 112, while the magnitude of vibration is a function of
the mass of the counterweights 116 in relation to the combined mass
of the trough 102, vibratory media 104 and part(s) 106. These
latter characteristics are, in turn, affected by the size and
volume of the trough 102. In one test embodiment, a Hammond SVP-5
vibratory finishing machine was modified according to the present
disclosure and used to finish composite parts. The modified machine
included a trough having a volume of 5 cubic feet, and was modified
to run at 2700 RPM, as discussed above. This machine included four,
41/2 pound counterweights 116. These weights were each increased by
11/2 pounds, providing four 6-pound counterweights (24 pounds
total) positioned eccentrically on the drive shaft, as shown in
FIG. 2. Imposing this additional weight on the weighting mechanism
helped provide a satisfactory magnitude for the deburring motion
with the lighter weight deburring media.
[0025] Using the modified counterweight system described, it has
been found that with the drive shaft rotating at a speed of 2700
RPM, the shaft demonstrates an eccentric rotation of about 10%
(relative to the diameter of the shaft), as indicated by the dashed
line circle 140 in FIG. 2. For example, a 3'' diameter drive shaft
112 that is provided with suitable counterweights 116 will describe
an eccentric rotational motion that is about 3.3'' (i.e. 10% larger
than the shaft diameter) when rotating. This magnitude of
vibration, at the frequency of 40-50 Hz, produces a vibration of
about 0.001'' in the individual abrasive media particles 136. It is
believed that this magnitude of vibration can be suitable for any
size of part and any size of vibratory finishing machine. It will
thus be apparent that as the size, volume and mass of the vibratory
finishing machine 100 increases or decreases, the mass of the
counterweights 116 can be increased or decreased to provide the
desired vibrational magnitude at the same vibrational
frequency.
[0026] A close-up view of the trough 102 loaded with finishing
media 104 and having parts 106 being finished therein is provided
in FIG. 3. Under the vibrating motion of the trough 102, the
finishing media 104 is agitated in the trough 102, and tends to
behave almost like a liquid. The part 106 that is immersed in the
finishing media 104 gradually rolls and tumbles within the media,
as particles of the finishing medium repeatedly contact its edges
and surfaces, gradually removing burrs and smoothing rough edges
and surfaces, and also rounding edges of the part.
[0027] The vibratory finishing machine 100 also includes one or
more water inlets 128, which provide a flow of process water to the
volume of abrasive media 104. The process water, sometimes with a
small amount of mild liquid soap (e.g. 30:1 water to soap ratio),
is slowly metered into the media 104 to provide liquidity, some
lubricity, and washing action to wash away and remove the media
swarf and abraded particles of substrate. As shown in FIG. 2, the
trough 102 includes an outlet or drain 130 at its lower extremity
and drain conduit 132, which allows the process water to drain
away. Strainers, filters, etc. (not shown) can be placed in or
associated with the drain conduit 132 to remove the media swarf and
particles of substrate that are washed away by the process water.
The machine 100 can be configured to deposit these particles into a
waste tub (not shown) before the waste water is discharged. The
system for adding the process water and the associated waste tub
can be standard components that are commonly included with
commercially available vibratory finishing systems.
[0028] As shown in FIG. 3, an individual trough 102 can be provided
with dividers 134, so that multiple parts 106 can be simultaneously
finished in separate portions of a single trough 102. A divider 134
is also shown in the trough 102 of the finishing machine 100 in
FIG. 1. Depending on the part size, shape and whether or to what
extent incidental contact of multiple parts 106 with each other
during the finishing process can be tolerated, multiple parts 106
can be simultaneously placed in a single or undivided portion or
region of a vibratory finishing trough 102, and finished
together.
[0029] As described above, the finishing media 104 comprises
individual abrasive particles 136. Perspective views of individual
finishing media particles 136, which can be used in a deburring
process in accordance with the present disclosure, are shown in
FIGS. 4A and 4B. The finishing media 104 can include particles 136
having various shapes and sizes. For example, the particles 136a
shown in FIG. 4A have a tetrahedral shape, while the particles 136b
shown in FIG. 4B have a conical shape. Other shapes can also be
used. These particles 136 can range in size from about 1/4'' to
about 21/2'' in their maximum dimension. Other sizes can also be
used. As illustrated in FIGS. 4A and 4B, the particles 136 can have
relatively sharp points or corners 138, which tend to work their
way into grooves and crevices of the part 106 that is being
finished, thereby smoothing the article and removing burrs and
sharp edges on the outer part surface.
[0030] The particles 136 of finishing media 104 are made of two
parts: an abrasive and a binder. In one embodiment, the abrasive
includes titanium oxide, and the binder is synthetic acrylic. In a
more specific embodiment the media is about 10%-20% titanium oxide,
held in a binder of synthetic urea-resin that constitutes 80%-90%
of the volume of the particle 104. Vibratory finishing media having
this general formulation is commercially available under the
product designation SY from Vibra-Finish Co. of Los Angeles,
Calif., for example.
[0031] For the vibratory finishing of composite parts, as disclosed
herein, it is considered desirable that the specific gravity of the
finishing media be from about 1.5 to 2.0, so that the sectional
density of the total volume of the particles 136 is approximately
equal to the sectional density of the composite laminate parts 106
that are to be finished. This aspect of the vibratory finishing
media 104 allows the composite part 106 to naturally "sink" in the
media, rather than "float" atop it, thus allowing the part to
become substantially immersed in the media.
[0032] This media formulation is different than the standard media
commonly used for finishing metal and other parts. Specifically,
many vibratory finishing media formulations use aluminum oxide as
an abrasive, which is generally incompatible with composite
materials. On the other hand, it has been found that titanium oxide
abrasive works well with composite parts. However, it is believed
that the suitability of this type of abrasive media for composite
materials has not previously been known. Additionally, the binder,
being a synthetic, does not require any processing compound (e.g.
soap) for the finishing process. Instead, the processing fluid can
be ordinary water, leaving the parts soap-free, receiving only a
water rinse and towel dry at the end of the process.
[0033] The abrasive particles 136 of the media 104 are of a
generally constant make-up throughout their volume, such that as
each particle 136 gradually wears down with use, its surface
retains the same abrasive quality, even as it changes shape and
size. That is, during use, the surface of the abrasive particles
136 will gradually wear away, exposing the underlying material,
which has substantially the same abrasive quality and
characteristics. In this way, the abrasive particles 136 retain
their operational characteristics as they gradually wear down
during use, until they are of a size where it is considered
desirable to replace them with new, full sized particles. Replacing
the worn particles 136 can be effectively accomplished by adding
new particles 136 periodically, so as to maintain a given
percentage of larger full-sized particles.
[0034] The vibratory deburring process with this finishing media
produces a slightly sanded looking surface on composite materials.
One additional aspect of vibrational deburring of parts using the
apparatus and method disclosed herein is the provision of an edge
break or edge relief on parts. It is well known in manufacturing
that sharp edges on mechanical parts are undesirable in many
instances, but are the natural byproduct of various fabrication
and/or machining processes. Shown in FIG. 5 is a partial sectional
view of an end portion 202 of a composite part 200. Prior to
deburring, the end 202 of the part 200 includes sharp edges 204.
After vibratory finishing in accordance with the present
disclosure, the sharp edges 204 are smoothed to a rounded profile
206. The degree of edge break or edge relief that is desired will
vary from one situation to another. Using the present system and
method, an edge break or round-over of about 0.005'' can be
provided on the exposed edges of a composite part. It will be
apparent that the magnitude of the edge break will depend at least
in part on the length of vibratory processing and the grit level of
the abrasive media 104.
[0035] A logic flowchart outlining the steps in an embodiment of a
method 500 for deburring and finishing laminated composite parts in
accordance with the present disclosure is provided in FIG. 6.
First, the trough of the vibratory machine is filled with finishing
media particles (step 502). It is considered desirable to fill the
trough no more than about 80% full, but not less than about 50%
full, by volume. Next, the process water flow is turned on (step
504). The process water can be ordinary water, without any
additives, such as soap or the like. The process water washes
debris out of the volume of finishing media particles, enhancing
the finishing process by removing residue that has been worn off of
the part, and removing abrasive dust that has been worn off of the
finishing media particles. The process water flow that is used in
this process is about double the amount of flow water that is
typically used in vibratory finishing of metal parts. In general,
it is believed that a process water flow of 0.35-0.50 gallons per
hour per cubic foot of volume of finishing media can be used. In
one embodiment, using a trough having a volume of 5 cubic feet, a
process water flow of 2 gallons per hour has been used.
[0036] After the process water is flowing, the machine can be
started (step 506)--that is, the vibration can be initiated at the
desired frequency. Next, the parts to be deburred can be placed
into the trough of the finishing machine (step 508), with the parts
being immersed in the finishing media. It has been found desirable
that the volume of parts placed into the trough not exceed about
10% of the total trough volume, in order to avoid damage from the
parts contacting each other, and/or to avoid the parts being
inadequately finished. The parts are then left in the vibrating
trough for a set time (step 510), while the process goes forward.
In one embodiment, it has been found that parts can be processed
for about 60 minutes with good results. In general, it is believed
that vibratory finishing for about 45-60 minutes is likely to be
sufficient. Those of skill in the art will be able to determine
optimal settings for any given part and media combination to
provide the desired edge-break and surface treatment.
[0037] After sufficient processing of the parts, the finished parts
can be removed from the machine (step 512). Advantageously, parts
can be removed from the trough while the machine is running, which
can help to speed up the batch processing flow. Alternatively, the
machine and the process water flow can be shut off (step 514)
either before or after removal of the parts. After processing, the
parts can be rinsed with fresh water (step 516) and dried, making
them ready for use. The entire composite laminate part will show
signs of deburring, which leaves a slightly dull, sanded appearance
on the part, and is especially noticeable on the "tool-side" of the
parts (i.e., the side of the composite part that was held against a
form or "tool" while being cured). An un-deburred tool-side of a
composite part will appear shiny compared to parts processed in the
manner disclosed herein. After a part or a batch of parts have been
finished in this manner, the process can be repeated by placing
more parts into the trough (step 508), or returning to one of the
prior steps, if needed.
[0038] As noted above, the finishing media particles 136 gradually
wear away with use. Consequently, it is desirable to periodically
refresh the vibratory media (step 518) by removing particles below
a certain lower threshold size and replacing the removed particles
with a comparable volume of new particles, so that the particle
size distribution is kept within a desired range. This can be done
by dumping all of the particles from the trough into a vibratory
sieve mechanism (not shown), which sorts out all particles below a
certain size, depending on the size of sieve that is used, thus
removing the smallest particles. The remaining particles, which are
greater in size than the sieve that was used, can be returned to
the trough for continued use, and a volume of new particles (or
particles of suitable size) can be placed into the trough to bring
the particle volume back up to a desired "full" level (step 502).
In one embodiment, refreshing of the vibratory media particles
involves removing particles below about 1/2'' in size, and
replacing them with a comparable volume of particles of 1'' to
21/2'' size.
[0039] The process disclosed herein is made possible by combining
specifically developed machine operational parameters and
processing time with a specific and unique vibratory finishing
media formulation, to allow the special deburring media to be
applied to a composite substrate. Heretofore in the composite
industry it is believed that this sort of process had not been
attempted because the technical understanding of how to use
abrasive media upon a composite substrate had not been
developed.
[0040] The apparatus and method provides for the automated batch
processing of composite parts, removing burrs occurring on the
outer part surface. The use of automated finishing allows for
batching of many parts, eliminates the human-error of over-burring,
and reduces or eliminates the possibility of ergonomic issues that
are often associated with manual deburring, such as carpal-tunnel
syndrome. The process disclosed herein has the potential to save a
tremendous amount of time and money by providing a much more cost
effective and safe way to deburr the large number of composite
parts that are and will be made. Labor cost will be highly reduced
by transferring the labor-intensive manual deburring to automated
equipment.
[0041] Although various embodiments have been shown and described,
the present disclosure is not so limited and will be understood to
include all such modifications and variations are would be apparent
to one skilled in the art.
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