U.S. patent number RE45,501 [Application Number 10/309,777] was granted by the patent office on 2015-05-05 for low pressure dryer.
The grantee listed for this patent is Stephen B. Maguire. Invention is credited to Stephen B. Maguire.
United States Patent |
RE45,501 |
Maguire |
May 5, 2015 |
Low pressure dryer
Abstract
A low pressure dryer for granular or powdery material includes a
plurality of hoppers rotatable about a common vertical axis
serially among material filling and heating, vacuum drying and
material discharge positions; pneumatic piston-cylinder means for
rotating the hoppers about said axis among said filling and
heating, vacuum drying and discharge positions; means for heating
contents of a hopper at said filling and heating positions; means
for sealing a hopper at said vacuum and drying positions; means for
drawing vacuum within a hopper at said vacuum drying position and
means for selectably permitting downward flow of dried granular or
powdery material out of a hopper at said discharge position where
said hoppers move collectively and unitarily one with another.
Inventors: |
Maguire; Stephen B. (West
Chester, PA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Maguire; Stephen B. |
West Chester |
PA |
US |
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|
Family
ID: |
22023897 |
Appl.
No.: |
10/309,777 |
Filed: |
December 4, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60059579 |
Sep 19, 1997 |
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Reissue of: |
09157238 |
Sep 18, 1998 |
6154980 |
Dec 5, 2000 |
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Current U.S.
Class: |
34/370; 34/92;
34/408; 34/168 |
Current CPC
Class: |
F26B
25/002 (20130101); F26B 5/04 (20130101); F26B
5/042 (20130101); B29B 13/065 (20130101); F26B
3/08 (20130101); F26B 9/063 (20130101); B29B
9/16 (20130101) |
Current International
Class: |
F26B
3/08 (20060101) |
Field of
Search: |
;34/289,290,291,292,293,294,295,326,327,361,402,403,406,407,408,418,423,427,446,538,559,92,491,484 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
417596 |
|
Jun 1971 |
|
AU |
|
1100402 |
|
May 1981 |
|
CA |
|
688217 |
|
Jun 1997 |
|
CH |
|
318127 |
|
Jan 1920 |
|
DE |
|
421770 |
|
Nov 1925 |
|
DE |
|
623 000 |
|
Jun 1937 |
|
DE |
|
3541532 |
|
Nov 1985 |
|
DE |
|
3541532 |
|
May 1986 |
|
DE |
|
3923241 |
|
Jan 1991 |
|
DE |
|
43 00 060 |
|
Jul 1994 |
|
DE |
|
4323295 |
|
Feb 1995 |
|
DE |
|
0466362 |
|
Jan 1992 |
|
EM |
|
0132482 |
|
Feb 1985 |
|
EP |
|
0318170 |
|
May 1989 |
|
EP |
|
0507689 |
|
Oct 1992 |
|
EP |
|
0587085 |
|
Mar 1994 |
|
EP |
|
0743149 |
|
Nov 1996 |
|
EP |
|
0997695 |
|
May 2000 |
|
EP |
|
802618 |
|
Sep 1936 |
|
FR |
|
2109840 |
|
May 1972 |
|
FR |
|
22357753 |
|
May 1972 |
|
FR |
|
2235775 |
|
Jan 1975 |
|
FR |
|
2517087 |
|
Sep 1982 |
|
FR |
|
2517087 |
|
May 1983 |
|
FR |
|
2695988 |
|
Mar 1994 |
|
FR |
|
479090 |
|
Jan 1938 |
|
GB |
|
671085 |
|
Apr 1952 |
|
GB |
|
849613 |
|
Sep 1960 |
|
GB |
|
2081687 |
|
Feb 1982 |
|
GB |
|
1235604 |
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Sep 1989 |
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JP |
|
01286806 |
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Nov 1989 |
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JP |
|
6114834 |
|
May 1991 |
|
JP |
|
4201522 |
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Jul 1992 |
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JP |
|
06114834 |
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Apr 1994 |
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JP |
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WO 99/37974 |
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Jun 1999 |
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WO |
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WO 01/49471 |
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Jul 2001 |
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WO |
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Other References
Thirty-nine page brochure entitled "Maguire Low Pressure Dryer:
Sep. 7, 2000: Installation Operation Maintenance". cited by
applicant .
Two-sided color-brochure entitled "NovaDrier.TM. N Series Dryer"
published by Novatec Inc., undated. cited by applicant .
Two-sided color brochure entitled "Convey, Blend, Dry" published by
Novatec, Inc., undated. cited by applicant .
Forty-four page two-sided brochure including cover and back pages
entitled "Maguire: Auxiliary equipment for the plastics industry"
of Maguire Products, Inc., Oct. 2000. cited by applicant .
Two page two-sided color brochure entitled "LPD Series Dryers: New
Directions in drying technology" of Maguire Products, Inc., May
2000. cited by applicant .
One page two-sided color brochure entitled "Drying Systems: WGAR
Gas Dryer Retrofit" AEC Whitlock, 1997. cited by applicant .
Two page two-sided color brochure entitled "Drying Systems: Mass
Flow.TM. Series Drying Hoppers" of AEC Whitlock, 1998. cited by
applicant .
Four page color brochure entitled "Speedryer Thermodynamic Hopper
Dryer" of Canam Manufactured Products Inc., Dec. 10, 2001. cited by
applicant .
Two page two-sided color brochure entitled "WDMR Series Compact
Dryers" of AEC Whitlock, 1998. cited by applicant .
Two page two-sided color reprint entitled "10 most frequently asked
questions about Dryers" by Joseph Dziediz, AEC/Whitlock, from
Plastics Technology, Jan. 1998. cited by applicant .
Two page two-sided color brochure entitled "Drying Systems: WD
Series High Capacity Dehumidifying Dryers" of AEC Whitlock, 1997.
cited by applicant .
Three page two-sided color brochure entitled "Portable Drying and
Conveying Systems: Nomad.TM. Series Portable Dryers", AEC Whitlock,
1998. cited by applicant .
Two page two-sided color brochure entitled "Drying Systems: WD
Series Dehumidifying Dryers" of AEC Whitlock, 1997. cited by
applicant .
Five page two-sided color brochure entitled "AEC Auxiliaries As
Primary", AEC, Inc., 1999. cited by applicant .
Two page two-sided color brochure entitled "LPD Vacuum Dryers" of
Maguire Products, Inc. Jun. 6, 2000. cited by applicant .
19 page document entitled "Model MLS--Clear Vu Eight Component
Vacuum Loading System: Operation Manual" of Maguire Products, Inc.
dated May 4, 1999. cited by applicant .
One page two-sided color brochure entitled "Maguire Clear-VU.TM.
Loading System" of Maguire Products, Inc. cited by applicant .
One page color advertisement entitled "this little vacuum dryer can
do in 40 minutes what it takes your desiccant dryer to do in 4
hours.", Plastic News dated Nov. 19, 2001. cited by applicant .
One page color article entitled "Dryer Competition Heats Up With
New Designs", Modern Plastics, Jul. 2001, p. 68. cited by applicant
.
One page advertisement of Frigomeccanica Industriale, Modern
Plastics, Jul. 2001, p. 70. cited by applicant .
16 page Low Pressure Dryer Technical Information Specifications
Features of Maguire Products, Inc. dated Nov. 29, 2000. cited by
applicant .
One page article entitled "New Dryer Technologies at NPE Aren't
Just Hot Air", Plastics Technology, Aug. 2000, p. 19. cited by
applicant .
One page article entitled "Tech Preview", Automatic Plastics, Aug.
2000, p. 66. cited by applicant .
One page article entitled "Maguire expands Low Pressure Dryer
commercialization" from www.specialchem.com dated Mar. 30, 2001.
cited by applicant .
One page article entitled "Smaller Resin Dryer", Plastics
Engineering, Aug. 2001, p. 28. cited by applicant .
Five page brochure entitled LPD.TM. Series Dryers of Maguire
Products, Inc. dated Jan. 29, 2001. cited by applicant .
Two page press released entitled "Maguire.RTM. LPD.TM. 30, Smaller
Model Of Breakthrough Resin Dryer, Will Make World Debut at K 2001
Show" of Maguire Products, Inc. dated Jun. 29, 2001. cited by
applicant .
Three page press release entitled "In Commercial Use by Wide Range
of Plastic Processors, Maguire.RTM. LPD.TM. Resin Dryer Yields Big
Savings in Energy Costs" of Maguire Products, Inc. dated May 14,
2001. cited by applicant .
Two page press release entitled "Maguire Obtains Patent On
Fundamentally New Resin Dryer and Steps Up Program for Worldwide
Commercialization" of Maguire Products, Inc. dated Dec. 18, 2000.
cited by applicant .
Six page press release entitled "Fast, Low-Cost Process Transforms
Resin Drying, Promising Dramatic Advance in Industry Productivity
and Quality" of Maguire Products, Inc. dated Jun. 20, 2000. cited
by applicant .
Two page press release entitled "New-Concept Resin Dryer Enables
Custom Molder To Eliminate Reject Parts--And Once More Enjoy Sunday
Evenings" of Maguire Products, Inc. dated Jun. 20, 2000. cited by
applicant .
One page color article entitled "Maguire LPD unit nets positive
marks", Plastic News, Oct. 3, 2001, p. 3. cited by applicant .
International Search Report for related application No.
PCT/US2005/021851. cited by applicant .
Written Opinion of the International Searching Authority for
related application No. PCT/US2005/021851. cited by applicant .
European Search Report for related application No. EP 05076911.
cited by applicant .
Sheet of 2 photographs of Mould-Tek gravimetric blender, circa
1993. cited by applicant .
Sheet of 2 photographs of Motan gravimetric blender and feeding
system with Maguire Products, Inc. controls, circa 1993. cited by
applicant .
Sheet of 3 photographs of UNA-DYN gravimetric blender, circa 1993.
cited by applicant .
Sheet of 2 photographs of Maguire Producs, Inc. gravimetric blender
with Conair hoppers and feeding system, circa 1993. cited by
applicant .
Sheet of 1 photograph of Hydracolor gravimetric blender, circa
1993. cited by applicant .
Advertisement entitled "Machinery and Systems for Extrusion is Our
Only Business" by Process Control Corporation, circa 1993. cited by
applicant .
Advertisement entitled "Weigh Blender Delivers Unmatched Accuracy"
by Universal Dynamics, Inc., circa 1993. cited by applicant .
Advertisement entitled "A Full Line-up of Blender Solutions . . .
Priced Right" by HydReclaim, circla 1993. cited by applicant .
Advertisement entitled "New From HydReclaim--Now Processors Can
Economically Achieve Continuous Gravimetric Blending" by
HydReclaim, circa 1993. cited by applicant .
Article entitled "Control Loading Systems" from Plastics
Technology, Oct. 1995, p. 41. cited by applicant .
Advertisement "Introducing our 400 VME-II Gravimetric Blender" by
HydReclaim Corporation, circa 1993. cited by applicant .
Four page brochure entitled "Gravimix Better Quality through
Research", circa 1993. cited by applicant .
Four page brochure entitled "Conomix Plus Volumetric Blender" dated
Aug. 1993. cited by applicant .
Four page brochure entitled "Conair Franklin Autocolor Y Mezclador"
dated Mar. 1995. cited by applicant .
Two-sided flyer entitled "GB 140 Series Compact Auto Weigh Blender"
published by Conair Franklin in the United States, Jun. 1994. cited
by applicant .
Six page brochure entitled "Graviblend Precise Continuous Weigh
Blenders" published by Ktron Vertech, Jun. 1991, United States.
cited by applicant .
Six page brochure entitled "Piovan Gravimetric Blenders MDW"
published by Piovan Sri, Oct. 1993, Venezia, Italy. cited by
applicant .
One page flyer entitled "Gravimix, The New Gravimetric Blending
Generation" published by Ferlin, De demsvaard, Holland, circa 1993.
cited by applicant .
Four page brochure entitled "When you Weigh it All Up . . ."
published by Ferlin Trading, Holland, circa 1993. cited by
applicant .
Thirty-two page catalog entitled "Maguire Color Blending Equipment"
published by Maguire Products, Inc., 1993, United States. cited by
applicant .
Two page brochure entitled "Mould-Tek Bulk Handling Systems"
published by Mould-Tek Industries, Inc. in Canada, circa 1993.
cited by applicant .
Brochure entitled "Plastic Molders and Extruders: published by
Maguire Products, Inc., 1995". cited by applicant.
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Primary Examiner: Rinehart; Kenneth
Attorney, Agent or Firm: Quinn; Charles N. Fox Rothschild
LLP
Parent Case Text
.[.CROSS-REFERENCE TO RELATED PATENT APPLICATION.].
.[.This patent application is entitled to the benefit of the filing
date of provisional U.S. patent application Ser. No. 60/059,579
filed Sep. 19, 1997 in the name of Stephen B. Maguire entitled "Low
Pressure Granular Material Dryer", under 35 USC 120..].
.Iadd.CROSS-REFERENCE TO RELATED FILINGS.Iaddend.
.Iadd.This patent application is entitled to the benefit of the
filing date of provisional U.S. patent application 60/059,579 filed
19 Sep. 1997 in the name of Stephen B. Maguire entitled "Low
Pressure Granular Material Dryer", under 35 USC 119(e). More than
one application has been filed for reissue of U.S. Pat. No.
6,154,980, issued 5 Dec. 2000. The reissue applications are
application Ser. No. 10/309,777, filed 4 Dec. 2002, and this
application Ser. No. 11/474,257 filed 22 Jun. 2006, as a division
of application Ser. No. 10/309,777..Iaddend.
Claims
What is claimed is:
1. A low pressure dryer for granular or powdery material,
comprising: a. a plurality of hoppers rotatable about a common
vertical axis serially among material filling and heating, vacuum
drying and material discharge positions; b. a plurality of
pneumatic piston-cylinder combinations for rotating said hoppers
about said axis among said filling and heating, vacuum drying and
discharge positions; c. means for heating contents of a hopper at
said filling and heating position; d. means for sealing a hopper at
said vacuum drying position; e. means for drawing vacuum within a
hopper at said vacuum drying position; and f. means for selectably
permitting downward flow of dried granular or powdery material out
of a hopper at said discharge position.
2. .[.Dryer.]. .Iadd.The dryer .Iaddend.of claim 1 further
comprising: a. a vertical shaft defining said vertical axis; b.
said pneumatic piston-cylinder combinations being equiangularly
positioned about said shaft for rotating said shaft and thereby
said hoppers.
3. .[.Dryer.]. .Iadd.The dryer .Iaddend.of claim 1 wherein said
hoppers are open-ended, generally vertically oriented cylindrical
configuration and equiangularly positioned respecting a vertical
axis.
4. A hopper for use in a low pressure granular or powdery material
dryer comprising: a. a vertically-oriented cylindrical shell having
open ends, adapted to be sealingly closed by selectably contacting
top and bottom plates thereagainst, enabling vacuum to be drawn
within said shell when said shell is at a vacuum drawing position;
b. a funnel within said cylindrical shell proximate the bottom
thereof; c. an internal material flow control plate located within
said cylindrical shell beneath said funnel, pivotally connected to
said cylindrical shell for movement about said connection away from
a downwardly opening discharge orifice in said funnel to a position
permitting downward granular resin material flow from said
hopper.
5. .[.Hopper.]. .Iadd.The dryer .Iaddend.of claim .[.4.]. .Iadd.1
in which said means for sealing said hopper at said vacuum drying
position .Iaddend.further .[.comprising.].
.Iadd.comprises.Iaddend.: a. top and bottom plates for selectively
sealing .[.said.]. .Iadd.a .Iaddend.cylindrical shell .Iadd.of said
hopper .Iaddend.allowing vacuum to be drawn therein; b. pneumatic
piston-cylinder means for urging said top and bottom plates into
sealing contact with said shell; said shell being adapted to
selectively dispense granular material stored therein at a dispense
position removed from said vacuum drawing position.
6. A method for continuously drying granular or powdery material
preparatory to mixing, molding, extruding or other processing of
that material, comprising the steps of: a. supplying granular or
powdery material to a vertically-oriented cylindrical shell at a
fill and heat position and heating said material within said shell
by introduction of heated air into said cylinder; b. moving said
vertically-oriented cylindrical shell through an arc about a
vertical axis outboard of the shell periphery to a vacuum drying
position and sealing open ends of said shell thereat; c. drawing a
preselected level of vacuum within said sealed shell for time
sufficient to evaporate moisture from said heated material to a
desired degree of dryness; d. moving said shell to a discharge
position at which said shell is open; e. discharging said dried
material from said cylindrical shell responsively to a pneumatic
piston-cylinder combination actuating a material discharge gate
proximate the bottom of said shell; and f. moving said shell
through an arc about said vertical axis .[.to a fill and heat
position.]. and sequentially repeating steps (a) through .[.(d).].
.Iadd.(e) .Iaddend.for so long as .[.said.]. .Iadd.such
.Iaddend.granular .[.plastic.]. .Iadd.or powdery .Iaddend.material
is to be continuously dried.
.[.7. A method for continuously supplying dried granular resin
material for processing from a supply of material which is
excessively moist, comprising substantially simultaneously
performing the steps of: a. heating a portion said moist material
to a selected temperature at which said moisture evaporates
therefrom at a preselected level of vacuum; b. drawing and
maintaining said preselected level of vacuum for a second portion
of said material which has been heated to said selected temperature
for a time sufficient to cause said moisture to evaporate therefrom
and result in said second portion of material being at a
preselected dryness; and c. supplying to granular resin material
processing equipment a third portion of said material which has
been dried to said preselected dryness by evaporation in said
preselected level of vacuum after being heated to said selected
temperature..].
.[.8. The method of claim 7 wherein said portions are serially
supplied..].
9. A method for continuously drying granular .[.or powdery.].
.Iadd.plastic resin .Iaddend.material in batches preparatory to
.[.mixing.]., molding.[.,.]. .Iadd.or .Iaddend.extruding .[.or
other processing.]. of that material .Iadd.into intermediate or
finished products.Iaddend., comprising the steps of: a. supplying
granular or powdery material to a closeable shell at a fill
position; b. heating said material within said shell .Iadd.while at
the fill position .Iaddend.by introduction of heated air thereinto;
c. moving said shell to a vacuum drying position and sealing said
shell thereat; d. drawing a preselected level of vacuum within said
sealed shell for time sufficient to evaporate moisture from said
heated material to a desired degree of dryness; e. moving said
shell to a discharge position at which said shell is opened; f.
discharging said dried material from said shell; and g. moving said
shell to said fill position and sequentially repeating steps (a)
through (f) for so long as .[.said.]. .Iadd.such .Iaddend.granular
.[.plastic.]. .Iadd.resin .Iaddend.material is to be continuously
dried.
10. The method of claim 9 wherein said heating further comprises
introducing air into said shell at a desired material temperature,
measuring temperature of said air as it .[.exists.]. .Iadd.exits
.Iaddend.said shell, comparing said exit air temperature to said
desired temperature and halting heating when said exit air reaches
said desired temperature.
11. The method of claim 9 wherein said heating further comprises
capturing heating air leaving said shell for recycling through said
shell.
12. The method of claim 10 wherein said heating further comprises
capturing heating air leaving said shell for recycling through said
shell.
.[.13. A low pressure dryer for granular or powdery material,
comprising: a. a shell movable among material filling and heating,
vacuum drying and material discharge positions; b. means for moving
said shell serially among said filling and heating, vacuum drying
and discharge positions; c. means for heating contents of said
shell at said filling and heating position; d. means for drawing
vacuum within a said shell at said vacuum drying position; and e.
means for selectably permitting downward flow of dried granular or
powdery material out of a shell at said discharge position..].
.[.14. The dryer of claim 13 further comprising: a. means for
sealing said shell at said vacuum drying position..].
.[.15. A low pressure dryer for granular or powdery material,
comprising: a. a plurality of shells movable among material filling
and heating, vacuum drying and material discharge positions; b.
means for moving said shells serially simultaneously among said
filling and heating, vacuum drying and discharge positions; c.
means for heating contents of a shell at said filling and heating
position; d. means for drawing vacuum within a shell at said vacuum
drying position; and e. means for selectably permitting downward
flow of dried granular or powdery material out of a shell at said
discharge position..].
.[.16. The dryer of claim 15 further comprising: a. means for
sealing a shell at said vacuum drying position..].
.[.17. The dryer of claim 15 wherein said shells are collectively
movable among material filling, drying and discharge
positions..].
18. A low pressure dryer for granular .[.or powdery.].
.Iadd.plastic resin .Iaddend.material, comprising: .[.a..].
.Iadd.(a) .Iaddend.a plurality of .Iadd.sealable closeable
.Iaddend.shells .[.collectably.]. .Iadd.spaced one from another,
each being .Iaddend.movable serially among material
filling.Iadd./heating.Iaddend., drying and discharge positions;
.[.b..]. .Iadd.(b) .Iaddend.means for moving said shells among said
filling.Iadd./heating.Iaddend., drying and discharge positions;
.[.c..]. .Iadd.(c) .Iaddend.means for heating shell contents
.[.prior to arrival.]. at said .[.drying.]. .Iadd.filling/heating
.Iaddend.position .Iadd.by blowing hot air through the shell
contents.Iaddend.; .[.d..]. .Iadd.(d) .Iaddend.means for sealing
said shells at said drying position; .[.e..]. .Iadd.(e)
.Iaddend.means for drawing vacuum .Iadd.of at least about 27.5
millimeters of mercury over the shell contents .Iaddend.within said
.Iadd.sealed .Iaddend.shells at said drying position; and .[.f..].
.Iadd.(f) .Iaddend.means for .[.emptying.]. .Iadd.opening bottoms
of said sealed shells at said discharge position to permit downward
flow of .Iaddend.dried granular .[.or powdery.]. .Iadd.plastic
resin .Iaddend.material from said shells at said discharge
position.
.[.19. A low pressure dryer for granular or powdery material,
comprising; a. a plurality of shells serially movable around a
circuit along which said shells are filled emptied, heated and
vacuum dried; b. means for moving said shells around said circuit
for filling and emptying said shells and heating and vacuum drying
of material in said shells; c. means for heating said shells prior
to drying; d. means for sealing said shells for drying; e. means
for drawing vacuum within said shells during drying; and f. means
for emptying dried granular or powdery material from said shells
after drying..].
.Iadd.20. A hopper for use in a granular plastic resin material
vacuum dryer comprising: a. a shell having an opening, for
discharge of granular plastic resin from the bottom of the shell,
that is sealingly closeable by selectably movably contacting
sealing means thereagainst, enabling vacuum to be drawn within said
shell; b. a downwardly tapering funnel, the upper extremity of the
funnel contacting the shell interior, for collecting and channeling
downwardly flowing granular plastic resin material towards said
opening, positioned within said shell proximate the bottom thereof;
c. a dump flap located within said shell beneath said funnel,
pivotally connected to the shell interior for movement about said
connection away from a position blocking downward flow of granular
plastic resin material towards a downwardly opening discharge
orifice in said funnel, to a position remote from downwardly
opening discharge aperture in the funnel thereby permitting
downward granular resin material flow through the funnel and the
opening in the shell, thereby exiting said hopper..Iaddend.
.Iadd.21. The hopper of claim 20 wherein said shell is cylindrical
and further comprises concentric inner and outer tubes and a second
downwardly tapering funnel positioned above the first funnel and
having funnel angle in common therewith, the upper extremity of the
second funnel contacting the interior of the inner tube, for
collecting and channeling downwardly flowing granular plastic resin
material towards said first funnel..Iaddend.
.Iadd.22. A method for drying granular plastic resin material in
batches preparatory to molding or extruding of that material into
intermediate or finished products, without heating the material to
above a preselected desired temperature, comprising the steps of:
c. supplying granular plastic resin material to a movable closeable
shell while the shell is at a first location; d. heating said
material to a desired temperature within said movable closeable
shell while at the first location by; i. heating air to the desired
material temperature; ii. blowing the heated air through the
material in the shell; iii. measuring the temperature of the air as
it exits the shell; iv. comparing the exit air temperature to the
desired material temperature; v. capturing the heated air as it
exits the shell and recycling the air through the shell after
heating step "i", and vi. halting heating and blowing the air when
the exit air temperature equals the desired material temperature;
e. drawing a vacuum of at least 27.5 millimeters of mercury within
said movable closeable shell while at a second location at which
said shell is closed for time sufficient to evaporate moisture from
said heated material to a desired degree of dryness; f. discharging
said dried material from said shell by opening the closed shell and
permitting the dried material to flow downwardly out of the shell:
and g. sequentially repeating steps (a) through (d) for so long as
said granular plastic resin material is to be dried in batches to
thereafter be molded or extruded into intermediate or final
products..Iaddend.
.Iadd.23. A method for continuously drying granular plastic resin
material in batches preparatory to molding or extruding that
material into intermediate or finished products, comprising the
steps of: a. supplying granular plastic resin material to a movable
closeable shell while the shell is at a first location; b. heating
said material within said shell while at the first location by
recycling heated air around a closed loop of which said shell forms
at part only when at said first location; c. drawing a preselected
level of vacuum within said closeable shell while at a second
location at which said shell is closed for time sufficient to
evaporate moisture from said heated material to a desired degree of
dryness; d. discharging said dried material from said shell by
opening the closed shell and permitting the dried material to flow
downwardly out of the shell: and e. sequentially repeating steps
(a) through (d) for so long as said granular plastic resin material
is to be continuously dried in batches to thereafter be molded or
extruded into intermediate or final products..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to drying granular or powdery material,
preferably granular resin material, prior to processing thereof
into intermediate or finished products, preferably by extrusion or
molding.
2. Description of the Prior Art
Plastic resins are initially granular materials and are produced in
pellets. These pellets are processed by extrusion or other means in
which the granular resin pellets are heated until the pellets melt
and may then be molded or extruded into a desired shape. Typically
granular resins melt at elevated temperatures, for example from
300-400.degree. F., which is well above the boiling point of
water.
Many granular resins have affinity for moisture. These hydroscopic
resins absorb moisture and cannot be properly processed by molding
or extrusion until dried. If processed before dry, moisture in the
plastic boils at or approaching the high plastic molding or
extrusion process temperatures, leaving bubbles and perhaps other
imperfections in the finished product. Hence, hydroscopic granular
resins must be dried prior to molding or extrusion.
Some granular resin materials are extremely hydroscopic and become
unprocessable by molding or extrusion in ten minutes or less after
exiting a dryer, due to the rapid absorption of moisture by the
granular resin material.
It is known to dry granular resin material by placing the granular
resin material pellets on large shallow trays to a depth of one or
two inches, and putting those trays into ovens for several hours.
With this approach to granular resin material drying, resin
temperatures of 150-180.degree. F., but no higher, can be used
since many granular resin materials begin to soften at
200-210.degree. F.
During the drying process, the granular resin material cannot be
permitted to soften, since it becomes unmanageable. Once granular
resin material begins to soften, at temperatures above the boiling
point of water, the granular resin material pellets stick together
in lumps or even melt into useless masses of solid plastic, making
it impossible to further process the resin material into a useful
article.
SUMMARY OF THE INVENTION
In one of its aspects, this invention provides a low pressure
granular .Iadd.resin .Iaddend.or powdery granular material dryer.
The dryer preferably includes a rotatable preferably vertical
shaft, a plurality of preferably vertically-oriented, open-ended
preferably cylindrical hoppers which are preferably equiangularly
positioned and rotatable about a vertical axis, which is preferably
defined by the shaft, serially among material filling and heating,
vacuum drying and dispensing positions.
The dryer preferably further includes a pin extending vertically
and radially displaced from the axis, a preferably triangular
preferably horizontal plate rotatably receiving the pin proximate
the center of the plate, a preferably horizontal link pivotally
connecting said shaft and the plate, and a plurality of preferably
pneumatic piston-cylinder combinations equiangularly operatively
connected to the plate for rotating the shaft by sequentially
moving the plate relative to the shaft thereby to move the hoppers
among the filling and heating, vacuum drying and dispensing
positions.
The dryer yet preferably .Iadd.further .Iaddend.includes preferably
pneumatic piston-cylinder .[.actuated.]. .Iadd.actuating
.Iaddend.means for sealing the cylindrical hoppers at the vacuum
drying station.
In another of its aspects, this invention provides a hopper for use
in a low pressure granular resin material or powdery material dryer
where the hopper includes a preferably vertically-oriented
preferably cylindrical shell having open ends with the shell
preferably adapted to be sealingly closed by selectably contacting
top and bottom plates thereagainst, thereby enabling vacuum to be
drawn within the shell when desired. The hopper further preferably
includes a funnel within the cylindrical shell and located
proximate the shell bottom. The hopper further preferably includes
an internal material flow control plate in the form of a dump flap
located within the shell beneath the funnel. The dump flap is
preferably pivotally connected to the shell for movement about the
connection point away from a downwardly opening discharge orifice
of the funnel, thereby to selectably release granular resin
material from the hopper.
In yet a further aspect of the invention, top and bottom plates
preferably selectably seal the cylindrical shell thereby allowing
vacuum to be drawn therewithin. Pneumatic piston-cylinder means may
be provided for urging the top and bottom plates into sealing
contact with the shell.
The shell is desirably adapted to selectably dispense granular or
powdery material stored therewithin at a dispense position, when
the shell is at that position. The dispense position is preferably
removed from the vacuum drying position.
The hopper is further preferably adapted to effectuate material
dispensing upon contact by an upwardly moving rod of a pneumatic
piston-cylinder combination, thereby permitting downward flow from
the funnel of material with the material thereby flowing out of the
cylindrical shell.
In yet another of its aspects, this invention provides a method for
continuously drying granular or powdery material preparatory to
mixing, molding, extruding or other processing of that material.
The method preferably includes supplying granular or powdery
material to a vertically-oriented cylindrical shell at a fill and
heat position and heating the material within the shell by
introduction of heated air into the cylindrical shell while at the
fill and heat-position.
The method yet further preferably includes moving the
vertically-oriented cylindrical shell through an arc about a
vertical axis outboard of the shell periphery to a vacuum drying
position and sealing open ends of the shell at such position.
The method still yet further preferably includes drawing a
preselected level of vacuum within the sealed shell for a time
sufficient to evaporate moisture from the heated material within
the shell to a desired degree of dryness.
The method even yet further preferably includes bringing the shell
to a material discharge position at which the bottom of the shell
is open and then discharging the dried material from the
cylindrical shell responsively to action of a preferably pneumatic
piston-cylinder combination inserting a rod into the shell interior
from below to move a material discharge gate proximate the bottom
of the shell.
The method preferably still yet even further includes moving the
shell through an arc about the vertical axis to the fill and heat
position and sequentially repeating the steps of supplying material
to the shell, heating the material within the shell, moving the
shell to the vacuum drawing position, drawing a sufficient level of
vacuum within the shell to evaporate moisture from the material
within the shell and moving the shell to a discharge position, for
so long as the material is to be continuously dried.
In yet another of its aspects, this invention provides a method for
continuously supplying dried granular resin material for processing
from a supply of material which is excessively moist where the
method preferably includes substantially simultaneously performing
the steps of heating a portion of the moist granular resin material
to a selected temperature at which the moisture evaporates from the
granular resin material at a preselected level of vacuum, drawing
and maintaining the preselected vacuum for a second portion of the
granular resin material which has been heated to the selected
temperature for time sufficient to cause the moisture to evaporate
therefrom and result in the second portion of granular resin
material being at the preselected dryness and supplying to granular
resin material processing equipment a third portion of the granular
resin material which was dried to the preselected dryness by
evaporation in the preselected level of vacuum after having been
heated to the selected temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front elevation of part of the low pressure granular or
powdery material dryer showing a cylindrical hopper portion of the
dryer at a material filling and heating position prior to supply of
heated air to the hopper interior, in accordance with the preferred
embodiment of the invention.
FIG. 2 is a plan view of the supply plenum portion of the low
pressure dryer at the heating and filling station, taken at arrows
2-2 in FIG. 1.
FIG. 3 is a front elevation of part of the low pressure dryer
showing a hopper portion of the dryer at the material filling and
heating position, as illustrated generally in FIG. 1, configured
for supply of heated air to the hopper.
FIG. 4 is a partially sectioned, schematic elevation of a
vertically-oriented open ended cylindrical hopper, forming a part
of the low pressure dryer, showing the hopper at a vacuum drying
position with the hopper open so that pressure within the hopper is
ambient.
FIG. 5 is a partially sectioned, schematic elevation of the
vertically-oriented open ended generally cylindrical hopper
illustrated in FIG. 4, with top and bottom plates sealing the
hopper, thereby allowing vacuum to be drawn within the hopper and
further illustrating the hopper connected to a vacuum pump.
FIG. 6 is a broken front schematic elevation of the lower interior
of a vertically-oriented open ended generally cylindrical hopper as
illustrated generally in FIGS. 4 and 5, showing two material
discharge funnels within the hopper, with the hopper illustrated at
the material dispensing position.
FIG. 7 is a broken front schematic elevation of the lower interior
of a vertically-oriented open ended generally cylindrical hopper as
illustrated in FIG. 6, at the same material dispensing position
illustrated in FIG. 6, illustrating the material dispensing
piston-cylinder combination actuated, thereby actuating a discharge
flap beneath the discharge funnels within the hopper permitting
material flow out of the hopper.
FIG. 8 is a broken schematic side elevation of the lower interior
of a vertically-oriented open ended generally cylindrical hopper as
shown in FIGS. 6 and 7, taken looking from the right in FIG. 7
illustrating the material dispensing piston-cylinder combination
actuated, thereby moving a discharge flap beneath the material
discharge funnels depicted in dotted lines within the hopper, to
dispense material from the hopper.
FIG. 9 is a top view of low pressure dryer illustrated in FIGS. 1
through 8.
FIG. 10 is a front elevation the low pressure dryer illustrated in
FIGS. 1 through 9.
FIG. 11 is a top view, similar to FIG. 9, schematically
illustrating a portion of the low pressure dryer.
DESCRIPTION OF THE PREFERRED EMBODIMENT AND BEST MODE KNOWN FOR
PRACTICING THE INVENTION
Referring to the drawings in general and to FIGS. 9, 10 and 11 in
particular, a low pressure granular material dryer manifesting
aspects of the invention is designated generally 10 and includes a
plurality of cylindrical hoppers, preferably three, each of which
has been designated generally 12. Each hopper 12 preferably
includes a cylindrical shell 14 and is preferably substantially
vertically-oriented with the axis of the cylinder extending
substantially vertically in order to be rotatable preferably
unitarily with the other hoppers about a substantially vertical
axis defined by a preferably vertical shaft 24.
Dryer 10 includes a frame, designated generally 22, on and within
which vertical shaft 24 is rotatably mounted for rotation relative
to frame 22, the details of which are discussed below. Cylindrical
hoppers 12 rotating unitarily with vertical shaft 24 preferably
move serially among a material fill and heat position designated
generally 100, a material vacuum drying position designated
generally 102 and a material dispensing position designated
generally 104. Hoppers 12 move when and as required among fill and
heat position 100, vacuum drying position 102 and dispensing
position 104. The three hoppers 12 start and stop together as
required; they do not move continuously in a merry-go-round fashion
among positions 100, 102 and 104.
Referring principally to FIGS. 9 and 10, frame 22 is formed of a
plurality of vertically and horizontally extending preferably angle
iron members which collectively define what appears as the edges of
a rectangular parallelepiped. As visible in FIG. 10, frame 22
includes preferably four substantially vertical members 160, only
two of which are visible in FIG. 10; the remaining two
substantially vertical members 160 are hidden behind the two
members 160 visible in FIG. 10.
Frame 22 further includes four upper substantially horizontally
extending members 162 which collectively define the outer periphery
of a square in geometrical terms; the four upper substantially
horizontally extending members 162 are visible in FIG. 9; not all
of members 162 are visible in FIG. 10.
Frame 22 further yet preferably includes four lower horizontally
extending members 164, one of which is visible in FIG. 10. The
remaining lower members 164 lie immediately under the corresponding
upper horizontally extending members 162 illustrated in FIG. 9. The
four lower horizontally extending members 164 define the base of
frame 22 for contacting a floor or other weight supporting
structure on which dryer 10 rests.
At least one and preferably a plurality of suspension members 166
extend laterally across the upper end of dryer 10, between selected
upper horizontal members 162. One of such suspension members 166 is
illustrated in FIG. 10. A hopper top sealing piston-cylinder
combination designated generally 44, serving to seal the top of a
hopper 12 at the vacuum drying position, is supported by one of
horizontally extending suspension members 166 as illustrated in
FIG. 10. Similarly, a hopper upper closure piston-cylinder
combination 98 located at material fill and heat position 100,
which piston-cylinder combination is used to close an upper end of
a cylindrical hopper 12 at the fill and heat position 100, is
supported by one of horizontally extending suspension members 166
as also illustrated in FIG. 10.
First, second and third driving rotation piston-cylinder
combinations 34, 36, 38 are preferably pivotally connected to
selected ones of upper horizontal members 162 of frame 22 as
illustrated in FIG. 10. In the case of first driving rotation
piston-cylinder combination 34, a triangular or cantilever
extension may be provided from the proximate upper horizontal
member 162 where the triangular extension has been designated
generally 182 in FIG. 9. Connections of driving rotation
piston-cylinder combinations 34, 36 and 38 to frame 22 are denoted
as pivotal connections 180 in the drawings.
Connection of generally triangular plate 28 with
vertically-oriented shaft 24 is effectuated by means of a pin
connector 168 which is vertically-oriented and resides rotatably
slidably within an aperture formed at the center of horizontal
central portion 30 of generally triangular plate 28. Pin connector
168 fits rotatably not only within triangular plate 28 but also
fits rotatably within an aperture in one end of a plate-pin
connection arm 116 best shown in FIG. 9. While plate-pin connection
arm preferably lies under triangular plate 28 as is apparent from
FIG. 10, plate-pin connection arm 116 has been illustrated in solid
lines in FIG. 9 to facilitate understanding.
Plate-pin connection arm 116 is fixedly connected to vertical shaft
24 at the upper end thereof.
In this arrangement movement of triangular plate 28, as effectuated
by any of first, second or third driving rotation piston-cylinder
combinations 34, 36 or 38, results in pin connector 168 translating
such motion to plate-pin connection arm 116. Rotation of plate-pin
connection arm 116, being fixedly connected to shaft 24, results in
shaft 24 rotating. As shaft 24 rotates, it carries hoppers .[.16.].
.Iadd.12 .Iaddend.among the fill and heat position 100, vacuum
drying position 102 and material dispense position 104. Hoppers
.[.16.]. .Iadd.12 .Iaddend.move this way unitarily with shaft 24 as
a result of hoppers .[.16.]. .Iadd.12 .Iaddend.being fixedly
connected to shaft 24 by cantilever connecting rods 110,
illustrated in phantom lines in FIG. 10.
Shaft 24 is journaled in suitable bearings mounted on upper and
lower shaft suspension plates 112 to define upper and lower shaft
bearing assemblies 114 as indicated in FIG. 10. Upper shaft
suspension plate 112 is connected to a horizontally extending
suspension member 166 by suitable nut and bolt combinations which
have not been numbered but are clearly visible in FIG. 10; lower
shaft suspension plate 112 is connected to a lower horizontal
member 164 as indicated generally in FIG. 10, again by suitable nut
and bolt combinations which have not been numbered in the
drawings.
Referring to FIGS. 1 through 3 illustrating the fill and heat
position 100 of lower pressure dryer 10, at fill and heat position
100 a moist material supply hopper 64 has a supply of moist
granular or powdery material, which is to be dried resident
therein. A butterfly valve at the bottom of hopper 64 is within a
conduit 144 and is operated by a piston-cylinder combination 146 as
clearly visible in FIGS. 1 and 3.
Conduit 144 includes a telescoping portion 148 for connecting moist
material supply hopper 64 with a hopper top sealing plate 150 at
fill and heat position 100. Positioned around the outer periphery
of hopper top sealing plate 150 is an annular lip 152. An aperture
154 is within hopper top sealing plate 150 and facilitates
communication between telescoping portion 148 of conduit 144 and
the interior of a hopper .[.14.]. .Iadd.12 .Iaddend.when at the
fill and heat position.
.[.Still referring.]. .Iadd.Referring .Iaddend.to FIGS. .[.1 and
3.]. .Iadd.9, 10 and 11.Iaddend., a hopper .[.14.]. .Iadd.12
.Iaddend.is illustrated in position as a result of having been
rotated to that position by rotation of vertical shaft 24 in
response to first, second and third driving rotation
piston-cylinder combinations 34, 36 and 38.
At material fill and heating position 100, a blower 76 facilitates
recirculation of heated air through material 74 resident within
hopper .[.14.]. .Iadd.12 .Iaddend.to heat material 74. Blower 76
has an intake aperture 78 and an exhaust aperture 80. Exhaust
aperture 80 connects to conduit 156 within which there are a
plurality of heater elements 82 to heat air exhausted from blower
76 prior to flow through material within hopper 12. Conduit 156
includes a telescoping portion 158 connecting with and exhausting
into a supply plenum designated generally 86 via a plenum inlet 90
which is visible in both FIGS. 1 and 2.
Plenum 86 includes an outlet screen .[.88.]. .Iadd.92
.Iaddend.mounted at the upper end thereof, as illustrated generally
in FIG. 2. Outlet screen 92 has a plurality of apertures 184 formed
therein with apertures 184 concentrated towards the central portion
of outlet screen 92 as illustrated in FIG. 2. Apertures 184 serve
to concentrate upward flow of the heating air about the central
portion or central axis of hopper .[.14.]. .Iadd.12 .Iaddend.which
is desirable since this is where the majority of the material is
concentrated to the shape of dispensing funnels 94, 96. A
preferably silicon annular gasket 88 on plenum 86 provides tight
sealing between supply plenum 86 and the open bottom of hopper 12
at the material fill and heat position illustrated in FIGS. 1 and
3.
A pneumatic piston-cylinder combination 106 is mounted on a
suitable cross-member, not illustrated in the drawings but forming
a part of frame 22. When actuated, piston-cylinder combination 106
serves to close the bottom of hopper 12 in the fill and heat
position by moving supply plenum 86 vertically upwardly, from the
position illustrated in FIG. 1 to the position illustrated in FIG.
3, thereby effectuating a tight seal between outlet plenum 86 and
hopper 12 to facilitate passage of heated air through granular or
powdery material in hopper .[.14.]. .Iadd.12.Iaddend..
Heated air, having passed through granular or powdery material
within hopper .[.14.]. .Iadd.12.Iaddend., exhausts from hopper
.[.14.]. .Iadd.12 .Iaddend.via telescoping portion 148 of conduit
144. A butterfly valve 66 having closed conduit 144 so that heated
air passing through telescoping portion 148 of conduit 144 cannot
escape through supply hopper 64, causes the heated, moist air to
flow into heated air recirculator 70 at heated recirculation intake
72. A thermocouple 68 positioned at heated air recirculation intake
72 senses temperature of heated air leaving hopper .[.14.].
.Iadd.12.Iaddend.. A second thermocouple 84 is positioned proximate
the outlet of the heated air supplied by blower 76, after the
heated air has passed along heating elements 82. When the
.[.temperature.]. .Iadd.temperatures .Iaddend.sensed by
thermocouples 68 and 84 are substantially equal, this is indicative
of the granular or powdery material within hopper .[.14.]. .Iadd.12
.Iaddend.having reached the desired temperature, namely the
selected temperature of the air entering into supply plenum 86
after having been heated by heating elements 82.
During material heating at the fill and heat position, hopper top
sealing plate 150 is lowered into position against the upper
extremity of hopper .[.14.]. .Iadd.12 .Iaddend.by action of a
pneumatic piston-cylinder combination 98 which is connected to a
suitable cross-member extending across the top of frame 22.
Referring to FIGS. 4 through 8 in particular, each preferably
cylindrical hopper 12 preferably includes a cylindrical shell
designated generally 14. Each cylindrical shell 14 is preferably
defined by an inner cylindrical tube referred to as a vacuum tube
and designated 52 in the drawings and a concentric outer
cylindrical tube referred to as an insulation tube and designated
54 in the drawings. Annular space between tubes 52 and 54, which
space is designated generally 55 in the drawings, is preferably
filled with thermal insulation to minimize heat transfer and heat
loss out of cylindrical shell 14.
A pair of downwardly opening material dispensing funnels designated
94 and 96 respectively are secured within each cylindrical shell 14
of cylindrical hopper 12 proximate the bottom of hopper 12. The
higher of the two material dispensing funnels is referred to as an
upper material dispensing funnel and is designated 94 in the
drawings. The lower of the two material dispensing funnels is
referred to as the lower material dispensing funnel and is
designated generally 96 in the drawings. Material dispensing
funnels 94 and 96 are preferably fixedly secured, by suitable sheet
metal screws or other fastening means, to a lower portion of vacuum
tube 52 at the positions generally indicated in the drawings
Material dispensing funnels 94 and 96 preferably share a common
funnel angle such that the sloped sides of the respective funnels
are essentially parallel one with another. The sloped surface or
side of upper material dispensing funnel is designated generally
122 in the drawings while the sloped side of lower dispensing
funnel 96 is designated generally 124 in the drawings.
As further apparent from the drawings, particularly FIGS. 6 through
8, upper dispensing funnel 94 is configured as an extremely
truncated cone such that the downwardly dispensing opening of upper
material dispensing funnel 94, which is designated 126 in the
drawings, is substantially larger than a corresponding downwardly
dispensing opening 128 of lower material dispensing funnel 96. This
results from lower dispensing funnel 96 being less truncated in the
vertical direction than upper dispensing funnel 94, as is
illustrated in the drawings.
Use of two dispensing funnels such as dispensing funnels 94, 96
facilitates circulation of heated drying air around material in
hopper .[.14.]. .Iadd.12 .Iaddend.at filling and heating position
100 and further facilitates drying of the material in hopper
.[.14.]. .Iadd.12 .Iaddend.when the hopper is at vacuum drying
position 102.
Each hopper .[.14.]. .Iadd.12 .Iaddend.preferably further includes
a dump flap designated generally 20 located below downwardly
dispensing opening 128 of lower funnel 96. Dump flap 20 is
pivotally connected to vacuum tube 52 by suitable screw connections
which are illustrated in the drawings, particularly in FIGS. 4, 5
and 8, and are numbered 140 and 170 respectively.
Dump flap 20 includes a central portion 172 which is generally
planar in configuration as illustrated in the drawings,
particularly FIGS. 6, 7 and 8, and has a weight 130 located at one
side thereof, offset from the point of pivotal connection between
dump flap 20 and dump actuator 62, which point of pivotal
connection is denoted 132 in the drawings, and also offset from the
pivotal connection of dump flap 20 with vacuum tube 52 of hopper
shell 14 as effectuated by screw-nut connection 170 and offset from
pivotal connection 140 of pivoting arm 134 to the interior surface
of vacuum tube 52. Weight 130 helps to cause dump flap 20 to return
to the position illustrated in FIG. 6 in response to gravitational
force after material dispensing piston-cylinder combination 108 has
been deactuated.
Dump actuator 62 engages a generally vertical .[.air.].
.Iadd.pivoting arm .Iaddend.134 forming a part of dump flap 20.
Dump actuator 62 includes a vertically movable arm 136, also
illustrated in FIG. 7. Vertically movable arm 136 is mounted for
sliding, vertical movement along the interior surface of vacuum
tube 52 of horizontal shell 14. The extent of vertical movement of
vertically movable arm 136 is controlled by a pin 174 illustrated
in FIG. 7, which is preferably mounted fixedly to and extending
radially inwardly from the interior of vacuum tube 52. A vertical
slot 176, similarly visible in FIG. 7, in vertically movable arm
136 receives pin 174. Interference between pin 174 and the ends of
slot 176 limits vertical travel of movable arm 136.
Movement of arm 136 upwardly in FIGS. 6, 7 and 8 results from
actuation of material dispensing piston-cylinder combination 108,
which is preferably a pneumatically powered piston-cylinder
combination. When piston-cylinder combination 108 is actuated, a
piston rod 178 extending from piston-cylinder combination 108
contacts a horizontal tabular extension portion of vertically
movable arm 136. This horizontal tabular extension of vertically
movable arm 136 is designated 138 and is shown in FIG. 8. There
tabular extension 138 is illustrated in solid lines in the "at
rest" or unactuated position and in dotted lines in the position
assumed by tabular extension 138, and hence vertically movable arm
136, when material dispensing pneumatic piston-cylinder combination
108 has been actuated and the piston rod associated therewith
extends therefrom.
Actuation of material dispensing piston-cylinder combination 108
moves vertically movable arm 136 upwardly, to the position
illustrated in solid lines in FIG. 8; the movement of arm 136 is
from the position illustrated in FIG. 6 to the position illustrated
in FIG. 7.
Vertically movable arm 136 is pivotally connected to .[.an arm 134
portion .]. .Iadd.pivoting arm portion 134 .Iaddend.of dump flap
20.
.[.Arm.]. .Iadd.Pivoting arm .Iaddend.134 connects the horizontal
part of dump flap 20 to the inside of vacuum tube 52 via a pivotal
connection identified as 140 in FIGS. 6, 7 and 8. .[.Arm.].
.Iadd.Pivoting arm .Iaddend.134 is pivotally connected not only to
the interior vacuum tube 52 at connection 140 but is also pivotally
connected to vertically movable arm 136 at .[.a.]. pivotal
connection 132. As a result, upward movement of vertically movable
arm 136 causes pivotal movement of pivoting arm 134 about pivotal
connection 140. Since pivotal connections 140 and 170 are
horizontally aligned along a common axis, pivotal movement of
.Iadd.pivoting .Iaddend.arm 134 about this axis moves the
horizontal part of dump flap 20 away from the dispensing aperture
of lower funnel 96 thereby permitting granular or powdery material
contained within hopper 12 to float downwardly outwardly therefrom
when dump flap 20 is in the position illustrated in FIG. 7.
Once preferably pneumatic hopper dispensing piston-cylinder
combination 108 has been deactuated, gravitational force acting
with weight 130 tends to rotate dump flap 20 back to the
horizontal, hopper closed, position illustrated in FIGS. 6 and 8.
This causes vertically movable arm 136 to drop downwardly, from the
position illustrated in FIG. 7 to the position illustrated in FIG.
6. This further causes .Iadd.pivoting .Iaddend.arm 134 to rotate
counterclockwise from the position illustrated in FIG. 7 to the
position illustrated in FIG. 6, about pivotal connection point 140.
This returns dump flap 20 to the horizontal position illustrated in
FIG. 6 where granular material in hopper 12 cannot flow outwardly
downwardly therefrom through the open bottom of hopper 12.
The horizontal portion 172 of dump flap 20 is positioned
sufficiently close to and sufficiently overlaps downwardly
dispensing opening 128 of lower funnel 96 about the periphery of
dispensing opening 128 that the angle of repose of any granular or
powdery material within hopper 12 is sufficient to prevent downward
flow of material through the gap between horizontal portion 172 of
dump flap 20 and dispensing opening 128 of lower funnel 96.
Material dispensing piston-cylinder combination 108 is preferably
mounted either on a portion of frame 22 below dryer 10 or on some
other stable member such as the floor of an installation where
dryer 10 may be used. In either case, material dispensing
piston-cylinder combination 108 is stationary in the sense that
piston-cylinder combination 108 does not rotate with hoppers 12 as
they are moved among fill and heat position 100, vacuum drying
position 102 and material dispense position 104; hopper dispensing
piston-cylinder combination 108 remains at material dispense
position 104.
As apparent from FIG. 8, dump flap 20 includes two .Iadd.pivoting
.Iaddend.arms 134, 134A. .[.Arm.]. .Iadd.Pivoting arm .Iaddend.134A
which is located at the side of dump flap 20 remote from material
dispensing piston-cylinder combination 108 is pivotally connected
directly to vacuum tube 52, preferably by screw-nut combination 170
as illustrated in FIGS. 4 and 5, for pivotal movement as dump flap
20 is actuated.
In FIGS. 4 and 5 one of hoppers 12 is illustrated at vacuum drying
position 102. FIG. 4 illustrates hopper 12 at vacuum drying
position 102 prior to movement of hopper top and bottom vacuum
sealing plates 40, 42 into position to seal cylindrical shell 14 so
that a vacuum may be drawn therewithin.
Hopper top and bottom vacuum sealing plates 40, 42 are preferably
respectively connected to unnumbered piston rod extensions which
are connected to and are parts of hopper top and bottom sealing
piston-cylinder combinations 44, 46 respectively. Piston-cylinder
combinations 44, 46 are preferably pneumatically actuated; the
cylinder portions thereof are preferably fixedly connected to
horizontally extending cross-members of frame 22 as indicated
generally in FIGS. 4 and 5.
Hopper top and bottom vacuum sealing plates 40, 42 are most
preferably of dome-like shape, as illustrated in FIG. 4, and have
upper and lower vacuum sealing gaskets 58, 60 positioned running
circumferentially around the unnumbered preferably circular lips of
preferably dome-like hopper top and bottom vacuum sealing plates
40, 42 respectively.
When a hopper 12 is located at vacuum drying position as
illustrated in FIG. 4, pneumatic actuation of respective hopper top
and bottom sealing piston-cylinder combinations 44, 46 respectively
causes respective dome-like hopper top and bottom vacuum sealing
plates 40, 42 to move vertically towards cylindrical hopper shell
14. Arrows A in FIG. 4 denote the vertical movement of hopper top
and bottom vacuum sealing plates 40, 42 respectively.
When hopper cylindrical shell 14 is located at vacuum drying
position 102, actuation of respective piston-cylinder combinations
44, 46 moves top and bottom sealing plates 40, 42 downwardly and
upwardly respectively to effectuate an airtight, vacuum maintaining
seal between the preferably circular periphery of top and bottom
sealing plates 40, 42, where vacuum gaskets 58 and 60 are
preferably located and the preferably circular circumferential top
and bottom edges of vacuum tube 52. The hopper top and bottom
vacuum sealing plates 40, 42 in this position, with gaskets 58, 60
in sealing connection with the circumferential circular top and
bottom edges of vacuum tube 52, as illustrated in FIG. 5.
Top vacuum sealing plate 40 preferably includes a fitting, not
numbered in the drawings, selectably connectingly receiving a
preferably flexible vacuum line 50 which is preferably connected to
a vacuum pump depicted schematically in FIG. 5 and designated 48.
When hopper top and bottom vacuum sealing plates 40, 42 have been
engaged with cylindrical shell 14 as illustrated in FIG. 5 and
vacuum pump 48 is actuated, vacuum is drawn within hopper 12 at
this vacuum drying position. As pressure drops within hopper 12 at
this vacuum drying position, moisture rapidly evaporates from
granular resin material within hopper 12.
Once moisture has been evaporated from resin material within hopper
12 when located at vacuum drying position 102 and the resin
material has reached a desired degree of dryness, hopper top and
bottom sealing piston-cylinder combinations 44, 46 are permitted to
return to their default positions illustrated in FIG. 4. This
retracts hopper top and bottom vacuum sealing plates 40, 42 away
from and out of contact with cylindrical shell 14, thereby
permitting air once again to enter cylindrical shell 14 and
permitting cylindrical shell 14, having the now-dried granular
resin material therewithin, to be moved to the material dispensing
position.
The time during which vacuum is drawn within hopper 12 while
located at vacuum drying position 102 may be adjusted by
microprocessor control means connected to and associated with the
low pressure granular material dryer. Similarly, the level of
vacuum drawn in hopper 12 at vacuum drying position 102 may be
adjusted. Furthermore, air withdrawn from hopper 12 by vacuum pump
48 may be monitored for moisture content and vacuum pump 48 may be
halted once the desired low level of moisture of the material
within hopper 12 has been attained. The microprocessor control
means controls operation of the low pressure dryer, including
operation of the pneumatic piston-cylinder combinations, the
blower, the vacuum pump, etc.
Referring to FIGS. 9, 10 and 11, plate-pin connection arm 116 is
rotatably connected to a generally horizontal plate 28 by pin
connector 168. Pin connector .Iadd.168 .Iaddend.facilitates
rotation of plate 28 respecting plate-pin connection arm 116 and
hence respecting pin-like extension 26 and vertical shaft 24.
Plate 28 includes a horizontal central portion 30 and downwardly
projecting lips 32 extending from the periphery of plate 28.
Three preferably pneumatically actuated piston-cylinder
combinations 34, 36 and 38 are designated respectively first,
second and third piston-cylinder combinations and are pivotally
connected to frame 22, specifically to upper horizontally extending
member 162 of frame 22, as generally illustrated respecting second
and third piston-cylinder combinations 36, 38 in FIG. 9. The
pivotal connections are designated 180 in FIG. 9.
To facilitate rotation of plate 28 about an axis defined by
vertical shaft 24, first, second and third piston-cylinder
combinations 34, 36, 38 are actuated as needed. Each
piston-cylinder combination 34, 36, 38 has a piston rod extension
which fits loosely within a respective aperture formed in a
respective portion of a downwardly projecting lip 32, with the
piston rods being retained in position within those apertures by
nuts threaded on the piston rod extremities as illustrated
generally in FIGS. 9 and 11.
With this arrangement, as piston-cylinder combinations 34, 36, 38
are actuated to move their associated piston rods, from extended
positions in which the piston rods of piston-cylinder combinations
36, 38 are illustrated in FIG. 11 to the retracted position in
which the piston rod extension of piston-cylinder combination 34 is
illustrated in FIG. 11. As a result plate 28 and hence, vertical
shaft 24 and cylindrical hoppers 12 attached thereto rotate about
the axis of vertical shaft 24, thereby moving hoppers 12 serially
among the material fill and heat, vacuum drying and material
dispense positions 100, 102, 104 respectively as illustrated in
FIGS. 9 and 11.
For example, referring to FIG. 9, upon actuation of first driving
rotation piston-cylinder combination 34 to extend the piston shaft
therefrom forwardly out of the retracted position illustrated in
FIG. 9 and actuation of third driving rotation piston-cylinder
combination 38 to cause the piston shaft associated therewith to
retract to within piston-cylinder combination 38, plate 28 rotates
counterclockwise as considering FIG. 9, in the direction indicated
by arrow A, with such rotation of plate 28 being about pin
connector 168 and as illustrated in FIG. 11 and indicated by arrow
B.
As plate 28 rotates about pin connector 168 in the direction
indicated by arrow .[.A.]. .Iadd.B.Iaddend., plate 28 together with
pin connector 168 rotate with horizontally extending plate-pin
connection arm 116 pivotally about the axis defined by vertical
shaft 24 thereby rotating shaft 24. This rotation results from
plate-pin connection arm 116 being fixedly connected to shaft 24.
Hence, as first, second and third driving rotation piston-cylinder
combinations 34, 36 and 38 respectively are actuated in a
sequential manner, plate 28 rotates about pin connector 168 and
plate 28, pin connector 168 and plate-pin connection arm 116 all
rotate about the vertical axis defined by shaft 24 thereby to
rotate shaft 24.
The vertically-oriented cylindrical sides of hopper shells 14
defined by vacuum tubes 52 and insulation tubes 54 are connected to
shaft 24 for rotation therewith by cantilever connecting rods 110
as best illustrated in FIG. 10. Each cylindrical shell 14 of a
cylindrical hopper 12 may be removable from its associated
cantilever connecting rods 110 if desired; preferably two
cantilever connecting rods 110 are provided for each hopper 12,
with one rod 110 connecting hopper 12 to vertical shaft 24 at
positions relatively close to but removed from the vertical
extremities of hoppers 12, as illustrated in FIG. 10.
FIG. 9 has been drawn without depiction of moist material supply
hopper 64, exhaust plenum 142 and the structure associated
therewith, to enhance drawing clarity. Similarly, hopper dispensing
piston-cylinder 108 has been depicted in FIG. 9 even though it is
to be understood that such piston-cylinder combination would not be
visible in the view from above dryer 10 since when a hopper 12 is
at material dispense position 104, piston-cylinder combination 108
is blocked from view from above.
Arrow B in FIG. 11 depicts the preferred direction of rotation of
vertical shaft 24 and hoppers 12 so as to move hoppers 12 serially
from the material fill and heat position 100 to material vacuum
drying position 102, then to material dispense position 104 and
then to material fill and heat position 100, where this cycle may
repeat.
At the material vacuum drying position, the heated material is
preferably subjected to a vacuum of about 27.5 millimeters of
mercury or greater. This lowers the evaporation point or boiling
point of water to only 120.degree. F., thereby causing the moisture
within the heated material to evaporate and be drawn off through
the vacuum pump drawing vacuum within hopper 12 at the vacuum
drying position 102. Once the vacuum drying process is sufficiently
complete, piston-cylinder combinations 44, 46 retract hopper top
and bottom sealing plates 40, 42 so that hopper 12 may move from
the vacuum drying position to the material dispense position.
Blower 70 is preferably a one horsepower blower. Preferably two
heater elements 82 are utilized, as illustrated in the drawings.
Air flow through supply plenum 86 is preferably restricted to 4.5
ounces of pressure.
As depicted schematically in the drawings by line 74 indicating the
angle of repose of within hopper 12, an air space is permitted to
remain within hopper 12 to accommodate material spillage during
movement of hoppers 12 and cycling of the drying process.
The material fill and heat and vacuum drying functions may each
take approximately twenty minutes. Accordingly, in one hour, all
three hoppers 12 preferably cycle through material fill and heat
position 100, material vacuum drying position 102 and material
dispense position 104. If each hopper 12 is approximately 10 inches
in diameter and 24 inches high, each hopper 12 will hold about one
cubic foot of granular resin material, which is about thirty-five
pounds of granular resin material. With such configuration, dryer
10 embodying the invention can provide about 100 pounds per hour of
dried granular resin material for subsequent processing by plastic
injection molding or extrusion equipment.
As is apparent from the drawings, hoppers 12 are preferably
provided equally spaced around vertical shaft 24 with hoppers 12
120.degree. apart.
* * * * *
References