CA1268672A - Process and apparatus for applying chilled electrostatically charged particles to the surface of a large metal article - Google Patents
Process and apparatus for applying chilled electrostatically charged particles to the surface of a large metal articleInfo
- Publication number
- CA1268672A CA1268672A CA000510001A CA510001A CA1268672A CA 1268672 A CA1268672 A CA 1268672A CA 000510001 A CA000510001 A CA 000510001A CA 510001 A CA510001 A CA 510001A CA 1268672 A CA1268672 A CA 1268672A
- Authority
- CA
- Canada
- Prior art keywords
- particles
- pores
- chilled
- large object
- crevices
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
- B05D5/08—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface
- B05D5/083—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface involving the use of fluoropolymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
- B05B5/001—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means incorporating means for heating or cooling, e.g. the material to be sprayed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
- B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
- B05B5/03—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying
- B05B5/032—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying for spraying particulate materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
- B05B5/08—Plant for applying liquids or other fluent materials to objects
- B05B5/082—Plant for applying liquids or other fluent materials to objects characterised by means for supporting, holding or conveying the objects
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/002—Processes for applying liquids or other fluent materials the substrate being rotated
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
- B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
- B05D1/06—Applying particulate materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
- B05D3/0218—Pretreatment, e.g. heating the substrate
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
- B05D5/08—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface
- B05D5/083—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface involving the use of fluoropolymers
- B05D5/086—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface involving the use of fluoropolymers having an anchoring layer
Abstract
PROCESS AND APPARATUS FOR APPLYING CHILLED
ELECTROSTATICALLY CHARGED PARTICLES TO
THE SURFACE OF A LARGE METAL ARTICLE
ABSTRACT OF THE DISCLOSURE
The process described herein comprises the application of chilled particles such as polytetrafluoroethylene generally marketed under the trade mark "TEFLON", graphite, molybdenum sulfite, boron nitride, etc., to a metal surface having crevices or pores therein. With the metal heated to expand the crevices or pores and the particles chilled to contract them, the particles will be locked into the pores when both the metal and the particles come to equilibrium temperature with the particles thereby expanding and the pores contracting. The process described herein is directed to such an application of chilled particles to expanded pores in large metal objects such as for example, large rolls. The large object is rotated on it linear axis while maintained at the desired raised temperature and the particles are given an electrostatic charge and chilled prior to their application to the metal surface. Apparatus for effecting this application of electrostatically charged chilled particles is also described.
ELECTROSTATICALLY CHARGED PARTICLES TO
THE SURFACE OF A LARGE METAL ARTICLE
ABSTRACT OF THE DISCLOSURE
The process described herein comprises the application of chilled particles such as polytetrafluoroethylene generally marketed under the trade mark "TEFLON", graphite, molybdenum sulfite, boron nitride, etc., to a metal surface having crevices or pores therein. With the metal heated to expand the crevices or pores and the particles chilled to contract them, the particles will be locked into the pores when both the metal and the particles come to equilibrium temperature with the particles thereby expanding and the pores contracting. The process described herein is directed to such an application of chilled particles to expanded pores in large metal objects such as for example, large rolls. The large object is rotated on it linear axis while maintained at the desired raised temperature and the particles are given an electrostatic charge and chilled prior to their application to the metal surface. Apparatus for effecting this application of electrostatically charged chilled particles is also described.
Description
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BACKGROUND OF THE INVENTION
Field of the Invention:
This invention relates to a process and apparatus for applying chilled Einely divided particles to the surFace of a ]arge metal object having crevices or pores therein. More specifically~ it relates to a method for chilling and applying electrostatically charged particles to such an objectO Still more speciEically it relates to a method of rotating and maintaining the large object at the desired raised temperature during the application of the chilled particles. Still more speciically it relates to apparatus for effecting this process.
Description o~ the Prior ~rt:
U.S. Patent No. 3,279,936, issued to Clarence WO Forestek on October 18, 196~, is directed to the treating of metal surfaces having crevices or pores therein with perfluorocarbon polymer particles so as to deposit such particles into the pores. By having the metal at a raised temperature to enlarge the pores and the particles chilled to contract them, the particles are interlocked in the pores when the particles and the metal come to an equilibrium temperature whereby the particles are expanded and the pores contracted.
U.S. Patent ~oO 4,051,275 issued on September 27, 1977 was also granted to Clarence W. Forestek and is directed to applying such chilled particles in a fluid stream carrying finely divided particles applied at a pressure of 30-120 psi to compact previously deposited particles and thereafter depositing additional particles in the space freed by the compaction, said additional particles being a temperature at least 100F below the ~.
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'72 temperature oE khe metal surFace so that these additional particles will also be locked into the fissures upon reaching e~uilibrium temperature.
OBJECTIVES OF TH~ INVENTION
It is an objective of this invention to aid in the deposition of such finely divided particles into crevices and pores in the surface of metal objects, particularly larqe objects, by placing an electrostatic charge on these particles.
It is also an objective oE this invention to place an opposite charge on the object to be impregnated with the particles.
It is also an objective of this invention to apply the electrostatically charged particles in a blast of Eluid medium in which the electrostatically charged particles are directed against the metal surFace and into its crevices and pores.
It is also an objective of this invention whereby the blasting of the electrostatically charged particles effects a compaction of the particles already in the crevices and pores so as ~o increase the free space therein thereby increasing space for additional particles to be deposited therein.
It is also an objective of this invention that the object, particularly large objects, can be rotated on an axis so as to expose the deposited particles to repeated compaction upon repeated revolutions so as to effect additional free space for additional deposition of chilled particlesL
It is also an objective of this invention to design an apparatus for the rotation of large objects while said electrostatically charged chilled particles are blasted thereon.
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;,UMMARY OF THE INVENTION
In accordance with the present invention it has been found that the application of finely divided chilled particles of perfluorocarbon polymer or graphite, molybdenum sulfate, boron nitride or other suitable electrostatically charged particles to the surface of a metal object, particularly large objects, having crevices or pores in said surEace can be Eacilitated and more adequately eEfected by rotating the object on it linear axis and maintaining theobjec~ at a raised temperature while applying chilled finely divided electrostatically charged particles oE
perfluorocarbon, etc., onto thesurface thereof. Advantageously the object is substantially enclosed in a hood or shield which protects heat loss from the object. While the object is maintained at the desired temperature, a stream of the chilled electrostatically charged, finely divided particles suspended in dry air or in an inert gas such as helium, nitrogren, argon~
etc., is directed against the metal surface so as to deposit and impinge such particles into the crevices orpores and to compact particles which had been previously deposited in the crevices or pores.
The electrostatic charge applied to the particles is advantageously in the range of 50-150 kilovolts, preferably about lOOkv. Preferablyr the particles are given a positive charge and the object is given a minus potential. However, while this system is preferred, the revers system of charging may be used.
Any appropriate means may be used for applying this charge, but a particularly advantageous device is described in another application being fi~ed by this inventor on the same date herewith. This device comprises a spray gun, such as used for ,,~, .
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?lectrostatically spraying paint which has an interior channel through which is p3ssed the sprayinq medium, in this case the suspension of particles dispersed in dry air or inert gas, is mi~ed with a chilled gas. A cooling medium such as liguid nitrogen or solid carhon dio~ide is maintained in an adjacent vessel so that a chil.ling effect can be imparted to the gaseous suspension medium by introducing a chilled gas, preferably the same as used in the original suspension, into the suspensin oE
electrostatically charged particles during its passage through a passageway of the chilling apparatus. Prior to the chilling of the gaseous suspending medium, electrostatic charges are applied to the particles by passing khe suspension oF particles through an electrical field effected by electrodes positioned in the chamber oE the spray gun. Appropriate electrical charge for the electrodes is maintained by a high voltage transformer and condensersO
The chilled gas introduced into the suspension is desirably maintained at -20C (-4F) to -130C (-~02~), preferably -50C
(-58F) to -120C (-184F). While the method of chilling the suspending gas and the suspended particles may comprise any : suitable means for effecting this chilling condition, a particularly effeckive means is the chilling apparatus shown hereinafter for attachment to the front of a spray gun. This preferred chilling apparatus is considered patentable per se and is claimed in a companion application filed concurrently herewith.
The spray gun may be any one oE a number of commercial spray guns suitable for spraying electrostatically charged particlesO
A particularly suitable spray gun is the one marketed under the ~r . :
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trademark "GEM~" which has a Eour electrode and high voltage generating system including a high voltage transEormer and a high voltage ~et of condensers. The cooling attachment is fitted onto the Eront or spraying end of the spray gun so that as ~he spray of suspended electrostatically charged particles emanate ~rom the spray gun they pa~s through a passageway in the chilling apparatus and out over impact spreading cone.
The polymer suspension stream is advantageously ejected ~rom the spray gun at a pressure of 15-150 psi (1-10 atmosphere). A
suspension of particles in the suspension medium is advantageously kept in a storage tank in which the particles are stirred up by Eeeding in nitrogen or other gas. When the stream is to be applied, the appropriate valve is opened to allow the gas to escape with particles suspended therein and carried to the electrostatically charging chamber o~ the spray gun prior to mixing with the chilling gas medium. Various other means may be used to feed polymer particles into the gas stream such as Venturi, screw feed~ blower, pump, etc.
Although large objects of various shapes may be treated by the proces of this invention, it is particularly suitable ~or cylindrical objects, including large rolls 1800 millimeters (70.86 inches) or more in diameter and 2500 millimeters (980~
inches) or more in length. If the object does not have end walls or support at the the two ends o the cylinder or other shape, these may be aEfixed for the purpose of making the cylinder or other object rotatable on its linear axis. A supporting axle may be af~ixed concentric with the linear axis and this axle driven by a motor at a controlled rate o~ rotation, advantageously at about 0~1 to 10 revolutions per minute~ with the axle desirably ; ~ , , .. : ~
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resting on roller bearings.
As previously indicated a hood or other partial cover may be used to shield the object against loss of heat, and also during the spraying operation an e~hausting suction may be applied under this hood to remove the gas carrying the particles as well as the remaining particles still suspended therein. The particles which fall below the object may be collected and reapplied if desiredO
The desired temperature of the object to be treated may be attained by applying a stream of hot air under the hood and against the object as it is rotated. Infrared or other appropriate means of heating may be used if desired. The hood has a slot or open area running the length of the object and parallel to the axis of the object through which the electrostatic spraying is to be eEfected. If desired there may be a sliding or hinged door to cover this open area which spraying is not being effected. ~hile the object may be maintained at a temperature as low as 38C (100 4F), it is advantageously maintained at a temperature of about 150-180C
(302-356F). The hot air or other means of applying heat is shut off during the spraying operation after which the hood is removed and the object is allowed to cool. During the spraying operation the chilled particles have a temperature at least 55~C ~130.5F) preferably at least 165C (329F1 below ~he temperature oE the object.
For a roller or cyllnder one inch in thickness, 1800 mlllimeters (70.86 inches) in outer diameter and 2500 millimeters (98.4 inches) long, it generally takes about 12 hours for the temperature to drop from 150C to 60C~ For the spraying operation, such a roll may be satisfactorily sprayed in about 1/2 .
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hour with three operators applying the spray manually with hand-held spray guns. If desired, a plurality o~ spray guns may be held on a rack which is mo~ed, either manually or mechanically, in a path parallel to the axis oE the ohject, -the rate of such parallel movement being adjusted in accordance with the rate oE
rotation of the object to give complete coverage of the object's sur~ace by the sprayed particles.
A stain appearance on the object's surface indicates in~uEficient impregnation of the crevices and pores with the particiles. ~praying is continued until the stain appearance disappears. In some cases satisfactory results may be obtained with 5 complete revolutionsO Preferably 20 or more revolutions produce the desired results and generally there is no additional advantage in exceeding 120 revolutions.
A felt strip or brush with soft rollers extending down From the hood, at a point beyond the spraying area, to the surface of the object and extending along the length o~ the object effects a wiping operation to brush particles into crevices and pores and also to wipe away particles on the surEace of the object between the crevices and pores. This wiping may be effected continuously after the spraying operation or may be done periodically. It is generally satisfactory to perform this wiping operation at least 4 or 5 or more times.
During the spraying operation the spray gun or guns are advantageously held about 300-500 mm (12-20 inches) from the object being sprayed. It is generally sufficient to effect the spraying during 20-100 revolutions of the object. As indicated above, the spraying is continued or repeated until the stained appearance no longer appears after wiping.
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The speed oE the particles toward the object is determined by the pressure of the suspending gas and the voltage of the electro~tatic field. While it is preferred to feed the particles into the gas prior to or during passage of the gas through the spray gun, it is also contemplated that the particles may be fed into the gas stream aEter the gas emanates from the gun in which case the particles will pick up the electrostatic charge on the way to the object's surfaceO However, it is preerred to apply the electrostatic charge to the particles before chilling the particles and to effect the chilling of the particles by mixing a chilled gas with the suspension of charged particles.
For particles of 4.7 gm or 5 microns in size and a voltage of about 80-100 kilovolts applied between the gun and the object i-t is estimated that the particles have an initial velocity of about 11 meters per second and about 0.09-0.10 meters per second in the vicinity of the workpiece~ Smaller sized particles, e.g., of less than 1 micron are more favorable since the ultimate speed due to -the e]ectrical feed will he higher than for larger particles.
In applying the electrostatic charge it may be advantageous to have a series of electrodes spaced in pairs along the pa~h of the suspended particles with a voltage of approximately 20 kilovolts applied between each pair of electrodes and applied transversely to the direction of flow of the gas.
SPECIFIC EMBODIMENT OF THE INVENTION
The description of the process and apparatus of this invention are Eacili~ated by reerence to the drawings.
Fig. 1 is an elevatlonal front vie~ of a roll mounted in a hood for spraying.
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, ~ . ,, :~6~36~72 Fig. 2 is an elevational end view of the roll and hood of FigO 1.
Fig. 3 is a side elevational view of a spray gun adapted to efEect cooling of a gas stream with suspended particles and to supply electrostatic charge to the particles.
Fig. 4 is a top view of the front portion of spray gun shown in Fig. 2.
Fig~ 5 is a side cross-sectional view of the front portion of the spray gun shown in Figs, 2 and 3 taken at line 5-5 of Fig.
3.
Fig. 6 is an end elevational view of a roll mounted in a hood extending a greater distance around the roll with an opening on one side for exposure to a portable heater and a portable spray unit~
In Fig. 1 roll 1 is supported by axle 2 which in turn rests onbearings 3 which rotate on supporting pins 4 fastened to supporting standard 5 which has legs 7', crossbars 6 and base plates 7. Axle 2 is rotated by a belt or chain 8 which is driven by a motor means (not shown) to give the desired rate of rotation to roll 1. hood 9 is positioned above roll 1 and has exhaust outlet 10. If desired the hood may e~tend down further to embrace a larger portion of roll 1.
Fig. Z is an elevational end view of the apparatus of Fig.
1. Heating means 11 is shown positioned on one side (or in back) of roll 1 with supporting means 11'. The spray gun (not shown in this view) is positioned on the opposite side (or in front) of roll 1. Felt or soft bristles 13 are positioned next to the roll 1 above the spray are and are held by support means 14.
Fig. 3 is a side elevational view of spray gun attachment 19 ,", ~` ,..
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designed to effect cooling of a gas stream aFter applying electrostatic charges to particles suspended in the gas stream.
The cooling nozzle 19 is preferably made of polytetrafluoroethylene (PTFE). Metal ring or band 16 slides over the exterior of a portion oE the spray gun attachment 19 to hold gas entrance duct 20 in position. Cold gas such as nitrogen is fed into the spray gun Erom cooling tank 21 which preferably consists o~ a rigid, expanded polyurethane foam in which a heat exchange coil 22 is positioned in cooling chamber 23. The coil is advantageously made of copper tubing having a diameter of about 10 mm. Cover 24 closes the camber to reduce the admission of heat. The coolant contained in the cooling chamber is advantageously either dry ice (solid carbon dioxide) or liquid nitrogen. When the gas inlet line 25 is opened, gaseous nitrogen, or other preferred gas, flows through cooling coil 22 and the cooled gas (preferably at -70 - -140C) flows through hose connector 26 to gas entrance duct 20 attached to and communicating with the recessed portion 20' running around the circumference of attachment 19 and feeding cold gas through channels 27 into the interior of the chamber 15 of cooling attachment 19.
Pig. 4 is a top view o the cooling attachment 19 and spray gun 18 shown in Fig. 2.
Fig. 5 shows the interior structure of the cooling attachment and spray gun taken at line 5-5 of Fig. 4. Nozzle 19 has a gas duct 20 which is fixed in position and is sealed by means of a metal ring 16. Hose 26 (shown in Fig. 3) feeds chilled gas into gas duct 20. From duct 20 the chilled gas is passed through channels 27 into mixing channel 15 where the ~' '.,`~ :
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electrostatically charge~ partic3.es are cooled down to the desired low temperature, preEerably approximately -120C (-184F) and then sprayed onto the roll or other large object being rotated in ~ront of the spray gun, which object is grounded so as to attract and hold the electrostatically charged particles.
Conical impact plate 29 i5 positioned at the outlet end 30 of mixing channel 15 and can adjust the cloud of powder to the desired size by appropriate positioning of the impact plate 29 bylongitudinal movement o:E rod 31. High voltage preferably in the range of 70-120 kv is developed in generator 32 and transmitted through lines 33 into the interior of the spray gun through switch 34 to high voltage condenser cascade 35 and then through high voltage transformer 36 to electrodes 37. Meanwhile particles of the desired size and type are stored in reservoir 38 maintained in suspended state by gas admitted by line 39 at the bottom of the reservoir from which the gas stream conveys the suspended particles through hose 40 into the spray gun where they are electrostatically charged as they pass between electrodes 37 into mixing channel 28 where the particles are chilled to- the desired low temperature by mixture with the cold gas being admitted through duct 20.
Fig. 6 is an end view of the roll arrangement as shown in Fig. 2 except that the hood extends further around the roll by the addition of hood extension 9'. In place oE the heater arrangement shown in Fig. 2, the heater 11 and heater support 11 are made portable by means of wheels 41 fastened to the heater support 11' by supports 42. The heat source is not shown but may be electrical, eqg~, hotwire, or heat lamps, or hot air fed by flexible ducts leading into heater 11. When the roll is properly .,: .
- '' ' '. ' :~; " ' locatedr the portable spray gun (not shown) is moved into the position vacated by the heater and soEt brush 13 is moved in a position above the spray gun. With the rotatable spray gun positioned in the opposite side of the roll it may be desirable to rotate the roll in the opposite direction from that shown in Fig. 2.
While certain features of this invention have been described in detail with respect to various embodiments thereof, it will of course be apparent that other modifications can be made within the spirit and scope of this invention, and it is not intended to limit the invention to the exact details shown above except insofar as they are defined in the following claims.
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:~2~1~6'72 SUP PLEMENTARY D L SCLOSURE
In accordance with the present invention apparatus for the application and compaction of chilled Einely divided particles into the pores and crevices of the metal surface of a large object comprises the combination of:
(a) a means for supporting and rotating said large object about its linear axis at a controlled rate of rotation;
(b) a heating means for applying heat to said large obiect until the temperature of said metal surface is sufficient to give a desired increase in the size of said pores and crevices fo~
receiving finely divided particles;
(c) a charging means for applying electrostatic charges to finely divided particles while suspended in a gaseous medium;
(d) a second charging means for applying an opposite charge to said large object from that applied on said particles;
(e) a cooling means for chilling said electrostatically charged particles; and (f) a means for spraying said chilled, electrostatically charged, gas-suspended particLes onto the said heated surface of said large object and depositing said particles into the pores and crevices in the metal surface of said large object, said rotatable large object being surrounde.d for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object and being surrounded for a substantial portion of the undèrside~ area of said object by a catch basin adapted to catch particles falling from the surface of said object and also adapted to further shield said object from heat loss; said heating means and said spraying means both being ,, .
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portable and each means being adapted to be moved to a position adjacent to the said obiect and to be moved away from said object after performance of its function following which the other means may be moved into a position adiacent to the said object for performance of its function.
Preferably the said heating means comprises a means for directing a heated gas against the surface of said object and the rotatable large ob-ect may be surrounded for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object. The hood may have an exhaust duct connected thereto through which said heater gas may be exited after eit has flowed over a portion of said large object.
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BACKGROUND OF THE INVENTION
Field of the Invention:
This invention relates to a process and apparatus for applying chilled Einely divided particles to the surFace of a ]arge metal object having crevices or pores therein. More specifically~ it relates to a method for chilling and applying electrostatically charged particles to such an objectO Still more speciEically it relates to a method of rotating and maintaining the large object at the desired raised temperature during the application of the chilled particles. Still more speciically it relates to apparatus for effecting this process.
Description o~ the Prior ~rt:
U.S. Patent No. 3,279,936, issued to Clarence WO Forestek on October 18, 196~, is directed to the treating of metal surfaces having crevices or pores therein with perfluorocarbon polymer particles so as to deposit such particles into the pores. By having the metal at a raised temperature to enlarge the pores and the particles chilled to contract them, the particles are interlocked in the pores when the particles and the metal come to an equilibrium temperature whereby the particles are expanded and the pores contracted.
U.S. Patent ~oO 4,051,275 issued on September 27, 1977 was also granted to Clarence W. Forestek and is directed to applying such chilled particles in a fluid stream carrying finely divided particles applied at a pressure of 30-120 psi to compact previously deposited particles and thereafter depositing additional particles in the space freed by the compaction, said additional particles being a temperature at least 100F below the ~.
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'72 temperature oE khe metal surFace so that these additional particles will also be locked into the fissures upon reaching e~uilibrium temperature.
OBJECTIVES OF TH~ INVENTION
It is an objective of this invention to aid in the deposition of such finely divided particles into crevices and pores in the surface of metal objects, particularly larqe objects, by placing an electrostatic charge on these particles.
It is also an objective oE this invention to place an opposite charge on the object to be impregnated with the particles.
It is also an objective of this invention to apply the electrostatically charged particles in a blast of Eluid medium in which the electrostatically charged particles are directed against the metal surFace and into its crevices and pores.
It is also an objective of this invention whereby the blasting of the electrostatically charged particles effects a compaction of the particles already in the crevices and pores so as ~o increase the free space therein thereby increasing space for additional particles to be deposited therein.
It is also an objective of this invention that the object, particularly large objects, can be rotated on an axis so as to expose the deposited particles to repeated compaction upon repeated revolutions so as to effect additional free space for additional deposition of chilled particlesL
It is also an objective of this invention to design an apparatus for the rotation of large objects while said electrostatically charged chilled particles are blasted thereon.
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;,UMMARY OF THE INVENTION
In accordance with the present invention it has been found that the application of finely divided chilled particles of perfluorocarbon polymer or graphite, molybdenum sulfate, boron nitride or other suitable electrostatically charged particles to the surface of a metal object, particularly large objects, having crevices or pores in said surEace can be Eacilitated and more adequately eEfected by rotating the object on it linear axis and maintaining theobjec~ at a raised temperature while applying chilled finely divided electrostatically charged particles oE
perfluorocarbon, etc., onto thesurface thereof. Advantageously the object is substantially enclosed in a hood or shield which protects heat loss from the object. While the object is maintained at the desired temperature, a stream of the chilled electrostatically charged, finely divided particles suspended in dry air or in an inert gas such as helium, nitrogren, argon~
etc., is directed against the metal surface so as to deposit and impinge such particles into the crevices orpores and to compact particles which had been previously deposited in the crevices or pores.
The electrostatic charge applied to the particles is advantageously in the range of 50-150 kilovolts, preferably about lOOkv. Preferablyr the particles are given a positive charge and the object is given a minus potential. However, while this system is preferred, the revers system of charging may be used.
Any appropriate means may be used for applying this charge, but a particularly advantageous device is described in another application being fi~ed by this inventor on the same date herewith. This device comprises a spray gun, such as used for ,,~, .
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. ::
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?lectrostatically spraying paint which has an interior channel through which is p3ssed the sprayinq medium, in this case the suspension of particles dispersed in dry air or inert gas, is mi~ed with a chilled gas. A cooling medium such as liguid nitrogen or solid carhon dio~ide is maintained in an adjacent vessel so that a chil.ling effect can be imparted to the gaseous suspension medium by introducing a chilled gas, preferably the same as used in the original suspension, into the suspensin oE
electrostatically charged particles during its passage through a passageway of the chilling apparatus. Prior to the chilling of the gaseous suspending medium, electrostatic charges are applied to the particles by passing khe suspension oF particles through an electrical field effected by electrodes positioned in the chamber oE the spray gun. Appropriate electrical charge for the electrodes is maintained by a high voltage transformer and condensersO
The chilled gas introduced into the suspension is desirably maintained at -20C (-4F) to -130C (-~02~), preferably -50C
(-58F) to -120C (-184F). While the method of chilling the suspending gas and the suspended particles may comprise any : suitable means for effecting this chilling condition, a particularly effeckive means is the chilling apparatus shown hereinafter for attachment to the front of a spray gun. This preferred chilling apparatus is considered patentable per se and is claimed in a companion application filed concurrently herewith.
The spray gun may be any one oE a number of commercial spray guns suitable for spraying electrostatically charged particlesO
A particularly suitable spray gun is the one marketed under the ~r . :
:.:' "" ' ~8~7;~
trademark "GEM~" which has a Eour electrode and high voltage generating system including a high voltage transEormer and a high voltage ~et of condensers. The cooling attachment is fitted onto the Eront or spraying end of the spray gun so that as ~he spray of suspended electrostatically charged particles emanate ~rom the spray gun they pa~s through a passageway in the chilling apparatus and out over impact spreading cone.
The polymer suspension stream is advantageously ejected ~rom the spray gun at a pressure of 15-150 psi (1-10 atmosphere). A
suspension of particles in the suspension medium is advantageously kept in a storage tank in which the particles are stirred up by Eeeding in nitrogen or other gas. When the stream is to be applied, the appropriate valve is opened to allow the gas to escape with particles suspended therein and carried to the electrostatically charging chamber o~ the spray gun prior to mixing with the chilling gas medium. Various other means may be used to feed polymer particles into the gas stream such as Venturi, screw feed~ blower, pump, etc.
Although large objects of various shapes may be treated by the proces of this invention, it is particularly suitable ~or cylindrical objects, including large rolls 1800 millimeters (70.86 inches) or more in diameter and 2500 millimeters (980~
inches) or more in length. If the object does not have end walls or support at the the two ends o the cylinder or other shape, these may be aEfixed for the purpose of making the cylinder or other object rotatable on its linear axis. A supporting axle may be af~ixed concentric with the linear axis and this axle driven by a motor at a controlled rate o~ rotation, advantageously at about 0~1 to 10 revolutions per minute~ with the axle desirably ; ~ , , .. : ~
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resting on roller bearings.
As previously indicated a hood or other partial cover may be used to shield the object against loss of heat, and also during the spraying operation an e~hausting suction may be applied under this hood to remove the gas carrying the particles as well as the remaining particles still suspended therein. The particles which fall below the object may be collected and reapplied if desiredO
The desired temperature of the object to be treated may be attained by applying a stream of hot air under the hood and against the object as it is rotated. Infrared or other appropriate means of heating may be used if desired. The hood has a slot or open area running the length of the object and parallel to the axis of the object through which the electrostatic spraying is to be eEfected. If desired there may be a sliding or hinged door to cover this open area which spraying is not being effected. ~hile the object may be maintained at a temperature as low as 38C (100 4F), it is advantageously maintained at a temperature of about 150-180C
(302-356F). The hot air or other means of applying heat is shut off during the spraying operation after which the hood is removed and the object is allowed to cool. During the spraying operation the chilled particles have a temperature at least 55~C ~130.5F) preferably at least 165C (329F1 below ~he temperature oE the object.
For a roller or cyllnder one inch in thickness, 1800 mlllimeters (70.86 inches) in outer diameter and 2500 millimeters (98.4 inches) long, it generally takes about 12 hours for the temperature to drop from 150C to 60C~ For the spraying operation, such a roll may be satisfactorily sprayed in about 1/2 .
~ 7 : ~,, .
- .
~;8~7~
hour with three operators applying the spray manually with hand-held spray guns. If desired, a plurality o~ spray guns may be held on a rack which is mo~ed, either manually or mechanically, in a path parallel to the axis oE the ohject, -the rate of such parallel movement being adjusted in accordance with the rate oE
rotation of the object to give complete coverage of the object's sur~ace by the sprayed particles.
A stain appearance on the object's surface indicates in~uEficient impregnation of the crevices and pores with the particiles. ~praying is continued until the stain appearance disappears. In some cases satisfactory results may be obtained with 5 complete revolutionsO Preferably 20 or more revolutions produce the desired results and generally there is no additional advantage in exceeding 120 revolutions.
A felt strip or brush with soft rollers extending down From the hood, at a point beyond the spraying area, to the surface of the object and extending along the length o~ the object effects a wiping operation to brush particles into crevices and pores and also to wipe away particles on the surEace of the object between the crevices and pores. This wiping may be effected continuously after the spraying operation or may be done periodically. It is generally satisfactory to perform this wiping operation at least 4 or 5 or more times.
During the spraying operation the spray gun or guns are advantageously held about 300-500 mm (12-20 inches) from the object being sprayed. It is generally sufficient to effect the spraying during 20-100 revolutions of the object. As indicated above, the spraying is continued or repeated until the stained appearance no longer appears after wiping.
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, , .
.
The speed oE the particles toward the object is determined by the pressure of the suspending gas and the voltage of the electro~tatic field. While it is preferred to feed the particles into the gas prior to or during passage of the gas through the spray gun, it is also contemplated that the particles may be fed into the gas stream aEter the gas emanates from the gun in which case the particles will pick up the electrostatic charge on the way to the object's surfaceO However, it is preerred to apply the electrostatic charge to the particles before chilling the particles and to effect the chilling of the particles by mixing a chilled gas with the suspension of charged particles.
For particles of 4.7 gm or 5 microns in size and a voltage of about 80-100 kilovolts applied between the gun and the object i-t is estimated that the particles have an initial velocity of about 11 meters per second and about 0.09-0.10 meters per second in the vicinity of the workpiece~ Smaller sized particles, e.g., of less than 1 micron are more favorable since the ultimate speed due to -the e]ectrical feed will he higher than for larger particles.
In applying the electrostatic charge it may be advantageous to have a series of electrodes spaced in pairs along the pa~h of the suspended particles with a voltage of approximately 20 kilovolts applied between each pair of electrodes and applied transversely to the direction of flow of the gas.
SPECIFIC EMBODIMENT OF THE INVENTION
The description of the process and apparatus of this invention are Eacili~ated by reerence to the drawings.
Fig. 1 is an elevatlonal front vie~ of a roll mounted in a hood for spraying.
:
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, ~ . ,, :~6~36~72 Fig. 2 is an elevational end view of the roll and hood of FigO 1.
Fig. 3 is a side elevational view of a spray gun adapted to efEect cooling of a gas stream with suspended particles and to supply electrostatic charge to the particles.
Fig. 4 is a top view of the front portion of spray gun shown in Fig. 2.
Fig~ 5 is a side cross-sectional view of the front portion of the spray gun shown in Figs, 2 and 3 taken at line 5-5 of Fig.
3.
Fig. 6 is an end elevational view of a roll mounted in a hood extending a greater distance around the roll with an opening on one side for exposure to a portable heater and a portable spray unit~
In Fig. 1 roll 1 is supported by axle 2 which in turn rests onbearings 3 which rotate on supporting pins 4 fastened to supporting standard 5 which has legs 7', crossbars 6 and base plates 7. Axle 2 is rotated by a belt or chain 8 which is driven by a motor means (not shown) to give the desired rate of rotation to roll 1. hood 9 is positioned above roll 1 and has exhaust outlet 10. If desired the hood may e~tend down further to embrace a larger portion of roll 1.
Fig. Z is an elevational end view of the apparatus of Fig.
1. Heating means 11 is shown positioned on one side (or in back) of roll 1 with supporting means 11'. The spray gun (not shown in this view) is positioned on the opposite side (or in front) of roll 1. Felt or soft bristles 13 are positioned next to the roll 1 above the spray are and are held by support means 14.
Fig. 3 is a side elevational view of spray gun attachment 19 ,", ~` ,..
- :
7~
designed to effect cooling of a gas stream aFter applying electrostatic charges to particles suspended in the gas stream.
The cooling nozzle 19 is preferably made of polytetrafluoroethylene (PTFE). Metal ring or band 16 slides over the exterior of a portion oE the spray gun attachment 19 to hold gas entrance duct 20 in position. Cold gas such as nitrogen is fed into the spray gun Erom cooling tank 21 which preferably consists o~ a rigid, expanded polyurethane foam in which a heat exchange coil 22 is positioned in cooling chamber 23. The coil is advantageously made of copper tubing having a diameter of about 10 mm. Cover 24 closes the camber to reduce the admission of heat. The coolant contained in the cooling chamber is advantageously either dry ice (solid carbon dioxide) or liquid nitrogen. When the gas inlet line 25 is opened, gaseous nitrogen, or other preferred gas, flows through cooling coil 22 and the cooled gas (preferably at -70 - -140C) flows through hose connector 26 to gas entrance duct 20 attached to and communicating with the recessed portion 20' running around the circumference of attachment 19 and feeding cold gas through channels 27 into the interior of the chamber 15 of cooling attachment 19.
Pig. 4 is a top view o the cooling attachment 19 and spray gun 18 shown in Fig. 2.
Fig. 5 shows the interior structure of the cooling attachment and spray gun taken at line 5-5 of Fig. 4. Nozzle 19 has a gas duct 20 which is fixed in position and is sealed by means of a metal ring 16. Hose 26 (shown in Fig. 3) feeds chilled gas into gas duct 20. From duct 20 the chilled gas is passed through channels 27 into mixing channel 15 where the ~' '.,`~ :
6'~
electrostatically charge~ partic3.es are cooled down to the desired low temperature, preEerably approximately -120C (-184F) and then sprayed onto the roll or other large object being rotated in ~ront of the spray gun, which object is grounded so as to attract and hold the electrostatically charged particles.
Conical impact plate 29 i5 positioned at the outlet end 30 of mixing channel 15 and can adjust the cloud of powder to the desired size by appropriate positioning of the impact plate 29 bylongitudinal movement o:E rod 31. High voltage preferably in the range of 70-120 kv is developed in generator 32 and transmitted through lines 33 into the interior of the spray gun through switch 34 to high voltage condenser cascade 35 and then through high voltage transformer 36 to electrodes 37. Meanwhile particles of the desired size and type are stored in reservoir 38 maintained in suspended state by gas admitted by line 39 at the bottom of the reservoir from which the gas stream conveys the suspended particles through hose 40 into the spray gun where they are electrostatically charged as they pass between electrodes 37 into mixing channel 28 where the particles are chilled to- the desired low temperature by mixture with the cold gas being admitted through duct 20.
Fig. 6 is an end view of the roll arrangement as shown in Fig. 2 except that the hood extends further around the roll by the addition of hood extension 9'. In place oE the heater arrangement shown in Fig. 2, the heater 11 and heater support 11 are made portable by means of wheels 41 fastened to the heater support 11' by supports 42. The heat source is not shown but may be electrical, eqg~, hotwire, or heat lamps, or hot air fed by flexible ducts leading into heater 11. When the roll is properly .,: .
- '' ' '. ' :~; " ' locatedr the portable spray gun (not shown) is moved into the position vacated by the heater and soEt brush 13 is moved in a position above the spray gun. With the rotatable spray gun positioned in the opposite side of the roll it may be desirable to rotate the roll in the opposite direction from that shown in Fig. 2.
While certain features of this invention have been described in detail with respect to various embodiments thereof, it will of course be apparent that other modifications can be made within the spirit and scope of this invention, and it is not intended to limit the invention to the exact details shown above except insofar as they are defined in the following claims.
~' , . ~:
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:~2~1~6'72 SUP PLEMENTARY D L SCLOSURE
In accordance with the present invention apparatus for the application and compaction of chilled Einely divided particles into the pores and crevices of the metal surface of a large object comprises the combination of:
(a) a means for supporting and rotating said large object about its linear axis at a controlled rate of rotation;
(b) a heating means for applying heat to said large obiect until the temperature of said metal surface is sufficient to give a desired increase in the size of said pores and crevices fo~
receiving finely divided particles;
(c) a charging means for applying electrostatic charges to finely divided particles while suspended in a gaseous medium;
(d) a second charging means for applying an opposite charge to said large object from that applied on said particles;
(e) a cooling means for chilling said electrostatically charged particles; and (f) a means for spraying said chilled, electrostatically charged, gas-suspended particLes onto the said heated surface of said large object and depositing said particles into the pores and crevices in the metal surface of said large object, said rotatable large object being surrounde.d for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object and being surrounded for a substantial portion of the undèrside~ area of said object by a catch basin adapted to catch particles falling from the surface of said object and also adapted to further shield said object from heat loss; said heating means and said spraying means both being ,, .
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portable and each means being adapted to be moved to a position adjacent to the said obiect and to be moved away from said object after performance of its function following which the other means may be moved into a position adiacent to the said object for performance of its function.
Preferably the said heating means comprises a means for directing a heated gas against the surface of said object and the rotatable large ob-ect may be surrounded for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object. The hood may have an exhaust duct connected thereto through which said heater gas may be exited after eit has flowed over a portion of said large object.
/S
~2 ,~ , .
.
Claims (10)
1. Apparatus for the application and compaction of chilled finely divided particles into the pores and crevices of the metal surface of a large object comprising the combination of:
(a) a means for supporting and rotating said large object about its linear axis at a controlled rate of rotation;
(b) a heating means for applying heat to said large object until the temperature of said metal surface is sufficient to give a desired increase in the size of said pores and crevices for receiving finely divided particles;
(c) a charging means for applying electrostatic charges to finely divided particles while suspended in a gaseous medium;
(d) a second charging means for applying an opposite charge to said large object from that applied on said particles;
(e) a cooling means for chilling said electrostatically charged particles; and (f) a means for spraying said chilled, electrostatically charged, gas-suspended particles onto the said heated surface of said large object and depositing said particles into the pores and crevices in the metal surface of said large object, said rotatable large object being surrounded for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object and being surrounded for a substantial portion of the underside area of said object by a catch basin adapted to catch particles falling from the surface of said object and also adapted to further shield said object from heat loss;
said heating means and said spraying means both being portable and each means being adapted to be moved to a position adjacent to the said object and to be moved away from said object after performance of its function following which the other means may be moved into the same adjacent position for performance of its function.
(a) a means for supporting and rotating said large object about its linear axis at a controlled rate of rotation;
(b) a heating means for applying heat to said large object until the temperature of said metal surface is sufficient to give a desired increase in the size of said pores and crevices for receiving finely divided particles;
(c) a charging means for applying electrostatic charges to finely divided particles while suspended in a gaseous medium;
(d) a second charging means for applying an opposite charge to said large object from that applied on said particles;
(e) a cooling means for chilling said electrostatically charged particles; and (f) a means for spraying said chilled, electrostatically charged, gas-suspended particles onto the said heated surface of said large object and depositing said particles into the pores and crevices in the metal surface of said large object, said rotatable large object being surrounded for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object and being surrounded for a substantial portion of the underside area of said object by a catch basin adapted to catch particles falling from the surface of said object and also adapted to further shield said object from heat loss;
said heating means and said spraying means both being portable and each means being adapted to be moved to a position adjacent to the said object and to be moved away from said object after performance of its function following which the other means may be moved into the same adjacent position for performance of its function.
2. The apparatus of claim 1, in which the said heating means comprises a means for directing a heated gas against the surface of said object.
3. The apparatus of claim 2, in which said rotatable large object is surrounded for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object.
4. The apparatus of claim 3, in which said hood has an exhaust duct connected thereto through which said heater gas may be exited after it has flowed over a portion of said large object.
5. The apparatus of claim 1, in which said rotatable large object is surrounded for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
6. Apparatus for the application and compaction of chilled finely divided particles into the pores and crevices of the metal surface of a large object comprising the combination of:
(a) a means for supporting and rotating said large object about its linear axis at a controlled rate of rotation;
(b) a heating means for applying heat to said large object until the temperature of said metal surface is sufficient to give a desired increase in the size of said pores and crevices for receiving finely divided particles;
(c) a charging means for applying electrostatic charges to finely divided particles while suspended in a gaseous medium;
(d) a second charging means for applying an opposite charge to said large object from that applied on said particles;
(e) a cooling means for chilling said electrostatically charged particles; and (f) a means for spraying said chilled, electrostatically charged, gas-suspended particles onto the said heated surface of said large object and depositing said particles into the pores and crevices in the metal surface of said large object, said rotatable large object being surrounded for a substantial portion of the upper area of said object being hood adapted to reduce heat loss from said object and being surrounded for a substantial portion of the underside area of said object by a catch basin adapted to catch particles falling from the surface of said object and also adapted to further shield said object from heat loss; said heating means and said spraying means both being portable and each means being adapted to be moved to a position adjacent to the said object and to be moved away from said object after performance of its function following which the other means may be moved into a position adjacent to the said object for performance of its function.
(a) a means for supporting and rotating said large object about its linear axis at a controlled rate of rotation;
(b) a heating means for applying heat to said large object until the temperature of said metal surface is sufficient to give a desired increase in the size of said pores and crevices for receiving finely divided particles;
(c) a charging means for applying electrostatic charges to finely divided particles while suspended in a gaseous medium;
(d) a second charging means for applying an opposite charge to said large object from that applied on said particles;
(e) a cooling means for chilling said electrostatically charged particles; and (f) a means for spraying said chilled, electrostatically charged, gas-suspended particles onto the said heated surface of said large object and depositing said particles into the pores and crevices in the metal surface of said large object, said rotatable large object being surrounded for a substantial portion of the upper area of said object being hood adapted to reduce heat loss from said object and being surrounded for a substantial portion of the underside area of said object by a catch basin adapted to catch particles falling from the surface of said object and also adapted to further shield said object from heat loss; said heating means and said spraying means both being portable and each means being adapted to be moved to a position adjacent to the said object and to be moved away from said object after performance of its function following which the other means may be moved into a position adjacent to the said object for performance of its function.
7. The apparatus of claim 2, in which the said heating means comprises a means for directing a heated gas against the surface of said object.
8. The apparatus of claim 3, in which said rotatable large object surrounded for a substantial portion of the upper area of said object by a hood adapted to reduce heat loss from said object.
9. The apparatus of claim 4, in which said hood has an exhaust duct connected thereto through which said heater gas may be exited after it has flowed over a portion of said large object.
10. The apparatus of claim 2, in which said rotatable large object is surrounded for a substantial portion of the upper area if said object by a hood adapted to reduce heat loss from said object.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA510001A CA1268672C (en) | 1986-01-23 | 1986-05-26 | Process and apparatus for applying chilled electrostatically charged particles to the surface of a large metal article |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US82180286A | 1986-01-23 | 1986-01-23 | |
| US821,802 | 1986-01-23 | ||
| CA510001A CA1268672C (en) | 1986-01-23 | 1986-05-26 | Process and apparatus for applying chilled electrostatically charged particles to the surface of a large metal article |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA1268672A true CA1268672A (en) | 1990-05-08 |
| CA1268672C CA1268672C (en) | 1990-05-08 |
Family
ID=25234348
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA510001A Expired CA1268672C (en) | 1986-01-23 | 1986-05-26 | Process and apparatus for applying chilled electrostatically charged particles to the surface of a large metal article |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0237668B1 (en) |
| JP (1) | JPH0685896B2 (en) |
| CA (1) | CA1268672C (en) |
| DE (1) | DE3671847D1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4691865A (en) * | 1986-01-23 | 1987-09-08 | Interlock Corporation | Device for chilling stream of gas-suspended particles |
| DE10101372A1 (en) | 2001-01-13 | 2002-08-01 | Itw Oberflaechentechnik Gmbh | Spraying method and spraying device for coating liquid |
| DE10101369A1 (en) | 2001-01-13 | 2002-07-18 | Itw Oberflaechentechnik Gmbh | Spraying method and spraying device for coating liquid |
| JP2002235958A (en) * | 2001-02-09 | 2002-08-23 | Mitsubishi Heavy Ind Ltd | Air conditioner and its control method |
| US8502157B2 (en) * | 2011-09-09 | 2013-08-06 | General Electric Company | Boron containing coating for neutron detection |
| ITFI20120205A1 (en) * | 2012-10-10 | 2014-04-11 | Eurosider Sas Di Milli Ottavio & C | METHOD AND APPARATUS FOR ELECTROSTATIC PAINTING |
| AU2014248872A1 (en) * | 2013-03-11 | 2015-10-08 | Carlisle Fluid Technologies, Inc. | System and method of producing a coating with an electrostatic spray |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3279936A (en) * | 1964-11-27 | 1966-10-18 | Forestek Plating & Mfg Co | Treating surfaces with perfluorocarbon polymers |
| US4051275A (en) * | 1974-06-21 | 1977-09-27 | Forestek Clarence W | Embedding and compacting particles in porous surfaces |
-
1986
- 1986-05-26 CA CA510001A patent/CA1268672C/en not_active Expired
- 1986-06-16 EP EP86304595A patent/EP0237668B1/en not_active Expired - Lifetime
- 1986-06-16 DE DE8686304595T patent/DE3671847D1/en not_active Expired - Fee Related
- 1986-09-09 JP JP61210832A patent/JPH0685896B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0237668A1 (en) | 1987-09-23 |
| CA1268672C (en) | 1990-05-08 |
| EP0237668B1 (en) | 1990-06-13 |
| JPS62171762A (en) | 1987-07-28 |
| DE3671847D1 (en) | 1990-07-19 |
| JPH0685896B2 (en) | 1994-11-02 |
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