CA1041847A - Powder coating of tubing by passing through vibrating coating channel - Google Patents
Powder coating of tubing by passing through vibrating coating channelInfo
- Publication number
- CA1041847A CA1041847A CA206,222A CA206222A CA1041847A CA 1041847 A CA1041847 A CA 1041847A CA 206222 A CA206222 A CA 206222A CA 1041847 A CA1041847 A CA 1041847A
- Authority
- CA
- Canada
- Prior art keywords
- coating
- channel
- article
- tubing
- powder
- 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
-
- 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
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/50—Multilayers
- B05D7/52—Two layers
- B05D7/54—No clear coat specified
- B05D7/546—No clear coat specified each layer being cured, at least partially, separately
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05C19/00—Apparatus specially adapted for applying particulate materials to surfaces
-
- 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
- B05D1/18—Processes for applying liquids or other fluent materials performed by dipping
- B05D1/22—Processes for applying liquids or other fluent materials performed by dipping using fluidised-bed technique
- B05D1/24—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
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/30—Processes for applying liquids or other fluent materials performed by gravity only, i.e. flow coating
-
- 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
- B05D3/0245—Pretreatment, e.g. heating the substrate with induction heating
-
- 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
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
- B05D7/148—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies using epoxy-polyolefin systems in mono- or multilayers
-
- 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
- B05D2401/00—Form of the coating product, e.g. solution, water dispersion, powders or the like
- B05D2401/30—Form of the coating product, e.g. solution, water dispersion, powders or the like the coating being applied in other forms than involving eliminable solvent, diluent or dispersant
- B05D2401/32—Form of the coating product, e.g. solution, water dispersion, powders or the like the coating being applied in other forms than involving eliminable solvent, diluent or dispersant applied as powders
-
- 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
- B05D3/0254—After-treatment
- B05D3/0281—After-treatment with induction heating
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Coating Apparatus (AREA)
- Paints Or Removers (AREA)
- Electrostatic Spraying Apparatus (AREA)
Abstract
ABSTRACT
Tubing is coated with powder by passing the tubing through a vibrated coating channel whilst being supported on a compacted body of the coating powder lying within the channel. Adhesive may be bonded to the tubing before it enters the channel.
Tubing is coated with powder by passing the tubing through a vibrated coating channel whilst being supported on a compacted body of the coating powder lying within the channel. Adhesive may be bonded to the tubing before it enters the channel.
Description
~041847 This invention concerns an apparatus for coating elongate articles.
Although not so restricted, the invention is particularly suitable for use in coating metal tubes or wires.
Fluidized bed techniques have been used to carry out external coat-ing of continuous tubing. However, when fluidized bed techniques are used to coat finite lengths of tubing, problems arise in applying an even coating to the tubing and in physically controlling the tubing in the fluidized bed be-cause of the tendency of the tubing to sag during the coating process. A
first object of the present invention is to prevent sagging of an elongate ar-ticle whilst it is being coated in a fluidized bed.
Further, tubes and wires coated by known processes (e.g. sleeving with extruded plastic tube) suffer from the disadvantage that if they are cut -or flexed, delamination of the coating from the substrate may occur. Accord- ~
ingly, such tubes and wires are usually pre-formed into desired shapes, or -pre-cut to desired lengths, before coating. It is a further object of the pre-sent invention to provide a method of coating an elongate article in such a way that the article can subsequently be bent, croppedJ punched, or drilled, with- ~
out damaging the coating, or the coating delaminating from the article. ~ ~ -According to the present invention there is provided an apparatus 20 for coating an article of indefinite length, the apparatus comprising: means ~ -for heating the article; a pair of convergent plates ~oined together at the -region of their convergence to form a coating channel o~ V-form cross.section;
means for passing the heated article through the heating means and through the V-form coating channel; an inlet and an outlet in the coating channel for the -continuous cycling of coating powder within the coating channel; and means for vibrating the coating channel so as to cause the formation therein of a compact- - :
ed body of coating powder for supporting the article during the coating thereof in the coating channel.
The internal surfaces of the coating channel are preferably of rough-3~ ened or matt finish.
The method of operating the apparatus of the invention to coat anelongate article with powder includes vibrating the coating channel of substanti-_2- ~
1041~47 ally Vee-form cross-section, continuously cycling a coating powder within the channel, a proportion of the powder forming the compacted body in the channel, and passing the article through the channel so as to coat the article with pow-der while supporting the article on the compacted body during its passage through the channel.
The article is preferably coated with adhesive, and the adhesive bond-ed to the article, before the article is passed through the channel.
Thus, the apparatus of the invention is suitable for producing coat-ed elongate articles comprising a substrate, a layer of adhesive bonded to the substrate, and a coating of synthetic resin bonded to the layer of adhesive.
The invention will now be described by way of example with reference to the accompanying drawings in which, Figure 1 is a cross-section through a coating channel according to the invention, Figure 2 is a side view of the coating channel, Figure 3 is a schematic block diagram of a wire coating apparatus, incorporating the coating channel of Figures 1 and 2, for carrying out the method of the invention, . " ' -.' . .. .
' -.
10~18~7 ~igure 4 is a schematic block diagram o~ a tube coating appr.ratus, .corporating the coating channel of Figures 1,and 2, for carrying out the method of the invention, Figure 5 shows a longitudinal crogs-section through a section of wire coated according to the method of the invention, nnd Figure 6 shows a longitudinal cros~-section through a sèction of tube coated according to the method of the invention.
Rererring to ~igures 1 and 2 a powder box 9 is provided -~
with downwardly con~ergent internal side walls 11, 12 to form a coating channel 10 o~ substantially Vee-form cross-section. The po~der box 9 is provided with vibrating means 16 which may be an electromagnetic vibrator operating 3t a frequency of 50 c.p.s. to compact coating material 15 within the coating channel 10. The downwardly convergent side walls 11, 12 of the coating channel 10 are provided with a roughened or matt finish and may ~or example be of wood or grit-blasted metal. This, together with side wQlls 11, 12 o~ the conting channel 10 assists the compacting of the coating material 15 by the vibrating powder box 9. -The powder box 9 is provided with an overhead hopper 19 which continually supplies coating material 15 to the -;
coating channel 10. Opposing chutes 13, 17 are disposed at either end o~ the coating channel 10 to allow continual over~low of coating mat~rial 15. The chutes 13, 17 are -~
ad~u~table to control the rate of overflow o~ coating material 15 and to allow correct overflow rates of coating possesses , -, . .
- 30 materlals-bi¢h / dif~erent rlow characteristics.
10411~47 The o~er~lowing coating material 15 i~ collected by a lower hopper 25 and returned to the overhead hopper 19 by a conveyor system (not shown). The inlet side 18 and chute 17 o~
the powder box 9 are o~ a low-resi~tance or non-conductive material to reduce any heating e~fect due to the proximity o~ a H.T. coil 21 used to heat an article 14 ~uch as wire or tube to be coated immediately prior to entering the box 9.
. horizontal probe 20 made o~ lo~Y-resistance or non-conducting material to reduce the heating e~ect of the coil 21 is tO ~dapted to ~it the rearward end o~ the article 14. The probe 20 i8 mounted on an overhead gantry 26 running on guide track 27 to provide ~orward and rearward movement o~ -the probe 20. i. H.T. shield 22 assist~ in the reduction of heat transmission by the coil 21. ~ roller conveyor (not shovm) supports the article 14 to be coated. Immediately down~tream of the powder box 9 an air jet 23 and suction means 24 are provided ~or the removal or excess coating material ~rom the article. DovJnstream, a ~-~ater quench tank (not shown) i8 provlded ~ith a weir, the water flowing over the weir being controlled by a recirculating pump.
The water tank i~ ted ~ith a belt conveyor boneath the -~ -~ur~ce o~ the v~ter, the article being carried by the belt -- -conveyor as it passes through the quench tank.
In operation a tube 14 is degreased and its fo~ward end clo~ed. The tube 14 i8 tr~n6~erred to a roller conveyor and the horizontal probe 20 fitted to the tubes open rearward end. The tube 14 is adyanced by the probe 20 through the H~T. sheild 22 to the H.T. coil 21 where the tube/is heated.
The heated tube then passes into the coating channel 10 o~
the vibrated po~rder box 9. The tube 14 is supported against ,:
,. , , , , ~, " ,...... ,.. ~, .",. ,, .. "... ... .......
., ,; , ;, . , -, , , , ~ ' . ' , ~ ()4~847 ~agging in a body ofcompacted coating materi.l 15 in the chann~l 10, thereby minimising th~ possibility of pin hol~ng , cxcess coating material 15 spilling ~rom chutes 13, 17 and falling into the lower hopper 25 to be returned by the conveyor ~ystem to the overhead hopper 19. It will be seen ~rom Figure 1 that the powder mass within the coating channel increase~ in density prosressively towards tho bottom. The tube is completely covered by thc coating material but this compacts to a dense bed only at the bottom o~ the trough. Immediately on leaving the po~rder box 9, the air ~et 23 blows against the tube 14 and removes any excess coating material whilst the excess coating material i8 collected by 6uction means 24 and returned via a cyclone system to overhead hopper 19. The tube 14 passes into the water quench tank through the weir system.
Suf~icient distance is allowed between the coating apparatus and the water quench tnnk to a11GW the coating material to sinter through, the di~tance carying according to the size and gauge o~ the tube 14. The tube 14 contacts the belt conveyor beneath the surface o~ the water, at a su~icient distance from the inlet to allow the coating to cool completely. The cooled tube 14 rests on the belt A ' ~ '' conveyor and as the probe 20 reaches the extent o~ its ~ i travel on the overhe~d g~ntry the tube 14 has sufficient -~ -contact with the belt conveyor to continue ~orward movement and release itself ~rom the probe 20. The probe 20 is returned to its ætartlng position by the overhead gantry.
The coateQ tube 14 passes through the water tank to an automatic unlonding ~tation.
~nother embodiment o~ the invention i8 illustrated achematically in ~igure 3, $n 7hich there is sho~m successive , ~ . . . ... .. . .
,, , , , , ",,,, ", ~ " . , , "
104~47 ~tages or a wire coating machine 30 incorporating the coating channel 10 o~ Figure 1. ~ire i8 hauled through the machine continuously nt a con~tant velocity; thus the time a section o~ wire resides in each ~ta8e o~ the machine may be varied by increasing or decreasing the speed o~ the wire through the machine.
Process times and temperature in ench stage of tho machinc may vary according to the 8iZC 0~ the wirc bcing proccssed. Typically, the ~peed o~ the wire mny ~ary between 0.2 and 0.8 metres/second, although these ~igures are not to be taken ns limiting in a~y way.
~ t stage 31, multi-strand wire is ~ed into the coating machine at between 0.2 and 0.8 metres/second. From staBe 31 the wire is fed into a degreasing and cleaning sta8e 32.
~`~ter degreasing and cleaning, the wire is ~ed to stage 33 where it is electrlcally preheated to 300 -380 C
(depending on wire size) for between 122 and 50 seconds. ~-~-~t staBe 34, a p.v.c. adhesive such as Gripsotite 201 is ; - :
electrostatically sprayed onto the heated wire for be ween 1~ and 5 ~econd~ hereupon bonding o~ the p.v.c. to the wire takes place by virtue of th~ heating of the wire.
("Gripsot~te" is the Registered Trade Mark o~ F. Ball and Company Limited).
~rom stage 34 the ndhesive coated wire i8 passed into the vibrated powder coating channel 10 of ~igure 1, where the wire is coated with synthetic resin powder ~or between 1~ and 5 seconds. ~ter being coated with synthetic resin --powder, the wire i8 pas~ed into a coating curing oven 36 where the synthetic resin coating 18 cured ~or bet~een 3~0 and ~4 seconds at 220 - 240C (depending on wire size).
, ,-.,; ,~ ~. , -,,.~.,,,.. , .,.. ,.. ",", ",~" ,"" ~ ", ",, ", , "
,, , ,, .,,-, ,- . . .. . . .. .
~.()4~84~
~ifter curing, the coated wire is quanched ~or between 22~
and 90 seconds in a water bath 37 to 40C. ~inally, the wire is woun~ onto a wire coiling machine 38.
Yet another embodiment o~ the invention is illustrated schematically in Figure 49 in each there is sho~m successive stages of a metal tube coating machine 40 incorporating the coating ch~nnel10 o~ ~igure 1. Process times and temperatures may vnry in this machlne in accordance with the sizes Or the tubes being coated. Tube~ are passed through the machine individually.
The ~irst three stages o~ the machine are arranged to `~
proces~ all tube sizes at a constant speed and handle up to six tubes at a time in order to provide the remaining stages o~ the machine ~ith su~icient quantities o~
aahesive-coated tubes ~or synthetic resin coating.
Tubes are loaded into the machine at stage 41, ~rom whence they are ~ed into the degreasing and cleaning section 42. This is followed by the adhesive spra~ing section 43 where a p.v.c. adhesive such as Gripsotite 201 (Reg. Trade Mar~) is electrostatically sprayed onto the tubing ~or about 5 ~econds. The adhesive coating on the tubing is than covered in an an oven 44 at 250 - 2~5C
~or a period o~ between 3 and ~8 minutes. ~he tubing is 1 -then cooled in a coaing conveyor 45 to not more than about 1 -~
25C above ambient temperature. i.t this stage the tubing i8 cr~mped at its enas in a crimping machine 45a to prevent ! . -powder in a subsaquent stage rrom entering the bore o~ the tube.
~ter ¢irmping, the tube is inductively heated to 300-380 C rOr between 1 ana 6 seconds in sect1on 46, a~ter which ' , the tube is coated with a synthetic resin p~wder in the vibrated pov~der coating channel 10 o~ Figure 1.
î~ter powder coating, the tube i8 w~tar-quenched in a tanX 48 to a temperature not more than about 40C. The tube is finally unloaded in section 49.
Wire 51 coated by tha method of this invention is shown in Figure 5 in longitudinal cross-section. The outer coating o~ synthetic resin 53 is shown bonded to the wire 51 by an adhesive layer 52.
Tubing 61 coated by the method of this invention i8 sho~m in Figure 6 in lon~itudinal cross-section. The outer coating o~ synthetic resin 63 i8 shoYm bonded to the tube 61 by an adhesive layer 62.
IWire or tubing coated according to the invention is characterized in that it may be bent, out or drilled without the external synthetic resin coating delaminating from the wire or tubing.
The adhesive used may be varied to suit individual reguirements, the essential requirements being that it bonds both to the wire or tube and to the external synthetic resin coating. Simllarly, the time and temperature para~eters o~ the metho~ may be varied to suit individual requirements.
~xamples o~ alternative adhesives are, (i) ~or p.v.c., Vyprime ~'151 or ~yprime ~:179 ("Vyprime" is the Regi~tered Trade Mark of Plnstic Coatings Limited), (ii) ~or nylon, Rilprim P.3 ("Rilprim" is the Registered Trade Mark o~
~quibaine-Totel-Org~nico). . - ~:, ~kamples o~ alternative synthetic resins use~ul in the ;~
invention are polyethylene, nglon 1i, nylon ~2, and e.v.a.
- .(ethyl-~ingl acetate copolymer).
_g _
Although not so restricted, the invention is particularly suitable for use in coating metal tubes or wires.
Fluidized bed techniques have been used to carry out external coat-ing of continuous tubing. However, when fluidized bed techniques are used to coat finite lengths of tubing, problems arise in applying an even coating to the tubing and in physically controlling the tubing in the fluidized bed be-cause of the tendency of the tubing to sag during the coating process. A
first object of the present invention is to prevent sagging of an elongate ar-ticle whilst it is being coated in a fluidized bed.
Further, tubes and wires coated by known processes (e.g. sleeving with extruded plastic tube) suffer from the disadvantage that if they are cut -or flexed, delamination of the coating from the substrate may occur. Accord- ~
ingly, such tubes and wires are usually pre-formed into desired shapes, or -pre-cut to desired lengths, before coating. It is a further object of the pre-sent invention to provide a method of coating an elongate article in such a way that the article can subsequently be bent, croppedJ punched, or drilled, with- ~
out damaging the coating, or the coating delaminating from the article. ~ ~ -According to the present invention there is provided an apparatus 20 for coating an article of indefinite length, the apparatus comprising: means ~ -for heating the article; a pair of convergent plates ~oined together at the -region of their convergence to form a coating channel o~ V-form cross.section;
means for passing the heated article through the heating means and through the V-form coating channel; an inlet and an outlet in the coating channel for the -continuous cycling of coating powder within the coating channel; and means for vibrating the coating channel so as to cause the formation therein of a compact- - :
ed body of coating powder for supporting the article during the coating thereof in the coating channel.
The internal surfaces of the coating channel are preferably of rough-3~ ened or matt finish.
The method of operating the apparatus of the invention to coat anelongate article with powder includes vibrating the coating channel of substanti-_2- ~
1041~47 ally Vee-form cross-section, continuously cycling a coating powder within the channel, a proportion of the powder forming the compacted body in the channel, and passing the article through the channel so as to coat the article with pow-der while supporting the article on the compacted body during its passage through the channel.
The article is preferably coated with adhesive, and the adhesive bond-ed to the article, before the article is passed through the channel.
Thus, the apparatus of the invention is suitable for producing coat-ed elongate articles comprising a substrate, a layer of adhesive bonded to the substrate, and a coating of synthetic resin bonded to the layer of adhesive.
The invention will now be described by way of example with reference to the accompanying drawings in which, Figure 1 is a cross-section through a coating channel according to the invention, Figure 2 is a side view of the coating channel, Figure 3 is a schematic block diagram of a wire coating apparatus, incorporating the coating channel of Figures 1 and 2, for carrying out the method of the invention, . " ' -.' . .. .
' -.
10~18~7 ~igure 4 is a schematic block diagram o~ a tube coating appr.ratus, .corporating the coating channel of Figures 1,and 2, for carrying out the method of the invention, Figure 5 shows a longitudinal crogs-section through a section of wire coated according to the method of the invention, nnd Figure 6 shows a longitudinal cros~-section through a sèction of tube coated according to the method of the invention.
Rererring to ~igures 1 and 2 a powder box 9 is provided -~
with downwardly con~ergent internal side walls 11, 12 to form a coating channel 10 o~ substantially Vee-form cross-section. The po~der box 9 is provided with vibrating means 16 which may be an electromagnetic vibrator operating 3t a frequency of 50 c.p.s. to compact coating material 15 within the coating channel 10. The downwardly convergent side walls 11, 12 of the coating channel 10 are provided with a roughened or matt finish and may ~or example be of wood or grit-blasted metal. This, together with side wQlls 11, 12 o~ the conting channel 10 assists the compacting of the coating material 15 by the vibrating powder box 9. -The powder box 9 is provided with an overhead hopper 19 which continually supplies coating material 15 to the -;
coating channel 10. Opposing chutes 13, 17 are disposed at either end o~ the coating channel 10 to allow continual over~low of coating mat~rial 15. The chutes 13, 17 are -~
ad~u~table to control the rate of overflow o~ coating material 15 and to allow correct overflow rates of coating possesses , -, . .
- 30 materlals-bi¢h / dif~erent rlow characteristics.
10411~47 The o~er~lowing coating material 15 i~ collected by a lower hopper 25 and returned to the overhead hopper 19 by a conveyor system (not shown). The inlet side 18 and chute 17 o~
the powder box 9 are o~ a low-resi~tance or non-conductive material to reduce any heating e~fect due to the proximity o~ a H.T. coil 21 used to heat an article 14 ~uch as wire or tube to be coated immediately prior to entering the box 9.
. horizontal probe 20 made o~ lo~Y-resistance or non-conducting material to reduce the heating e~ect of the coil 21 is tO ~dapted to ~it the rearward end o~ the article 14. The probe 20 i8 mounted on an overhead gantry 26 running on guide track 27 to provide ~orward and rearward movement o~ -the probe 20. i. H.T. shield 22 assist~ in the reduction of heat transmission by the coil 21. ~ roller conveyor (not shovm) supports the article 14 to be coated. Immediately down~tream of the powder box 9 an air jet 23 and suction means 24 are provided ~or the removal or excess coating material ~rom the article. DovJnstream, a ~-~ater quench tank (not shown) i8 provlded ~ith a weir, the water flowing over the weir being controlled by a recirculating pump.
The water tank i~ ted ~ith a belt conveyor boneath the -~ -~ur~ce o~ the v~ter, the article being carried by the belt -- -conveyor as it passes through the quench tank.
In operation a tube 14 is degreased and its fo~ward end clo~ed. The tube 14 i8 tr~n6~erred to a roller conveyor and the horizontal probe 20 fitted to the tubes open rearward end. The tube 14 is adyanced by the probe 20 through the H~T. sheild 22 to the H.T. coil 21 where the tube/is heated.
The heated tube then passes into the coating channel 10 o~
the vibrated po~rder box 9. The tube 14 is supported against ,:
,. , , , , ~, " ,...... ,.. ~, .",. ,, .. "... ... .......
., ,; , ;, . , -, , , , ~ ' . ' , ~ ()4~847 ~agging in a body ofcompacted coating materi.l 15 in the chann~l 10, thereby minimising th~ possibility of pin hol~ng , cxcess coating material 15 spilling ~rom chutes 13, 17 and falling into the lower hopper 25 to be returned by the conveyor ~ystem to the overhead hopper 19. It will be seen ~rom Figure 1 that the powder mass within the coating channel increase~ in density prosressively towards tho bottom. The tube is completely covered by thc coating material but this compacts to a dense bed only at the bottom o~ the trough. Immediately on leaving the po~rder box 9, the air ~et 23 blows against the tube 14 and removes any excess coating material whilst the excess coating material i8 collected by 6uction means 24 and returned via a cyclone system to overhead hopper 19. The tube 14 passes into the water quench tank through the weir system.
Suf~icient distance is allowed between the coating apparatus and the water quench tnnk to a11GW the coating material to sinter through, the di~tance carying according to the size and gauge o~ the tube 14. The tube 14 contacts the belt conveyor beneath the surface o~ the water, at a su~icient distance from the inlet to allow the coating to cool completely. The cooled tube 14 rests on the belt A ' ~ '' conveyor and as the probe 20 reaches the extent o~ its ~ i travel on the overhe~d g~ntry the tube 14 has sufficient -~ -contact with the belt conveyor to continue ~orward movement and release itself ~rom the probe 20. The probe 20 is returned to its ætartlng position by the overhead gantry.
The coateQ tube 14 passes through the water tank to an automatic unlonding ~tation.
~nother embodiment o~ the invention i8 illustrated achematically in ~igure 3, $n 7hich there is sho~m successive , ~ . . . ... .. . .
,, , , , , ",,,, ", ~ " . , , "
104~47 ~tages or a wire coating machine 30 incorporating the coating channel 10 o~ Figure 1. ~ire i8 hauled through the machine continuously nt a con~tant velocity; thus the time a section o~ wire resides in each ~ta8e o~ the machine may be varied by increasing or decreasing the speed o~ the wire through the machine.
Process times and temperature in ench stage of tho machinc may vary according to the 8iZC 0~ the wirc bcing proccssed. Typically, the ~peed o~ the wire mny ~ary between 0.2 and 0.8 metres/second, although these ~igures are not to be taken ns limiting in a~y way.
~ t stage 31, multi-strand wire is ~ed into the coating machine at between 0.2 and 0.8 metres/second. From staBe 31 the wire is fed into a degreasing and cleaning sta8e 32.
~`~ter degreasing and cleaning, the wire is ~ed to stage 33 where it is electrlcally preheated to 300 -380 C
(depending on wire size) for between 122 and 50 seconds. ~-~-~t staBe 34, a p.v.c. adhesive such as Gripsotite 201 is ; - :
electrostatically sprayed onto the heated wire for be ween 1~ and 5 ~econd~ hereupon bonding o~ the p.v.c. to the wire takes place by virtue of th~ heating of the wire.
("Gripsot~te" is the Registered Trade Mark o~ F. Ball and Company Limited).
~rom stage 34 the ndhesive coated wire i8 passed into the vibrated powder coating channel 10 of ~igure 1, where the wire is coated with synthetic resin powder ~or between 1~ and 5 seconds. ~ter being coated with synthetic resin --powder, the wire i8 pas~ed into a coating curing oven 36 where the synthetic resin coating 18 cured ~or bet~een 3~0 and ~4 seconds at 220 - 240C (depending on wire size).
, ,-.,; ,~ ~. , -,,.~.,,,.. , .,.. ,.. ",", ",~" ,"" ~ ", ",, ", , "
,, , ,, .,,-, ,- . . .. . . .. .
~.()4~84~
~ifter curing, the coated wire is quanched ~or between 22~
and 90 seconds in a water bath 37 to 40C. ~inally, the wire is woun~ onto a wire coiling machine 38.
Yet another embodiment o~ the invention is illustrated schematically in Figure 49 in each there is sho~m successive stages of a metal tube coating machine 40 incorporating the coating ch~nnel10 o~ ~igure 1. Process times and temperatures may vnry in this machlne in accordance with the sizes Or the tubes being coated. Tube~ are passed through the machine individually.
The ~irst three stages o~ the machine are arranged to `~
proces~ all tube sizes at a constant speed and handle up to six tubes at a time in order to provide the remaining stages o~ the machine ~ith su~icient quantities o~
aahesive-coated tubes ~or synthetic resin coating.
Tubes are loaded into the machine at stage 41, ~rom whence they are ~ed into the degreasing and cleaning section 42. This is followed by the adhesive spra~ing section 43 where a p.v.c. adhesive such as Gripsotite 201 (Reg. Trade Mar~) is electrostatically sprayed onto the tubing ~or about 5 ~econds. The adhesive coating on the tubing is than covered in an an oven 44 at 250 - 2~5C
~or a period o~ between 3 and ~8 minutes. ~he tubing is 1 -then cooled in a coaing conveyor 45 to not more than about 1 -~
25C above ambient temperature. i.t this stage the tubing i8 cr~mped at its enas in a crimping machine 45a to prevent ! . -powder in a subsaquent stage rrom entering the bore o~ the tube.
~ter ¢irmping, the tube is inductively heated to 300-380 C rOr between 1 ana 6 seconds in sect1on 46, a~ter which ' , the tube is coated with a synthetic resin p~wder in the vibrated pov~der coating channel 10 o~ Figure 1.
î~ter powder coating, the tube i8 w~tar-quenched in a tanX 48 to a temperature not more than about 40C. The tube is finally unloaded in section 49.
Wire 51 coated by tha method of this invention is shown in Figure 5 in longitudinal cross-section. The outer coating o~ synthetic resin 53 is shown bonded to the wire 51 by an adhesive layer 52.
Tubing 61 coated by the method of this invention i8 sho~m in Figure 6 in lon~itudinal cross-section. The outer coating o~ synthetic resin 63 i8 shoYm bonded to the tube 61 by an adhesive layer 62.
IWire or tubing coated according to the invention is characterized in that it may be bent, out or drilled without the external synthetic resin coating delaminating from the wire or tubing.
The adhesive used may be varied to suit individual reguirements, the essential requirements being that it bonds both to the wire or tube and to the external synthetic resin coating. Simllarly, the time and temperature para~eters o~ the metho~ may be varied to suit individual requirements.
~xamples o~ alternative adhesives are, (i) ~or p.v.c., Vyprime ~'151 or ~yprime ~:179 ("Vyprime" is the Regi~tered Trade Mark of Plnstic Coatings Limited), (ii) ~or nylon, Rilprim P.3 ("Rilprim" is the Registered Trade Mark o~
~quibaine-Totel-Org~nico). . - ~:, ~kamples o~ alternative synthetic resins use~ul in the ;~
invention are polyethylene, nglon 1i, nylon ~2, and e.v.a.
- .(ethyl-~ingl acetate copolymer).
_g _
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An apparatus for Coating an article of indefinite length, the appara-tus comprising: means for heating the article; a pair of convergent plates joined together at the region of their convergence to form a coating channel of V-form cross-section; means for passing the heated article through the heat-ing means and through the V-form coating channel; an inlet and an outlet in the coating channel for the continuous cycling of coating powder within the coat-ing channel; and means for vibrating the coating channel so as to cause the formation therein of a compacted body of coating powder for supporting the article during the coating thereof in the coating channel.
2. An apparatus as claimed in claim 1 wherein the article is fabricated of metal and the heating means comprises an induction coil.
3. An apparatus as claimed in claim 1 further including means for cool-ing the coated article when the coated article has left the coating channel.
4. An apparatus as claimed in claim 1 comprising means for coating the article with adhesive and means for bonding the adhesive to the article before the article is passed through the V-form channel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB3691673A GB1470662A (en) | 1973-08-03 | 1973-08-03 | Process and apparatus for coating articles |
| GB2276974 | 1974-05-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1041847A true CA1041847A (en) | 1978-11-07 |
Family
ID=26256103
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA206,222A Expired CA1041847A (en) | 1973-08-03 | 1974-08-02 | Powder coating of tubing by passing through vibrating coating channel |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5250046B2 (en) |
| CA (1) | CA1041847A (en) |
| FR (1) | FR2239293A1 (en) |
| IE (1) | IE39654B1 (en) |
| IN (1) | IN142051B (en) |
| SE (1) | SE7409900L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102009015533B9 (en) * | 2009-04-02 | 2011-01-13 | Babcock Borsig Service Gmbh | Method and apparatus for coating metallic pipes or other long components of limited cross section |
-
1974
- 1974-07-26 FR FR7426026A patent/FR2239293A1/en active Granted
- 1974-07-31 SE SE7409900A patent/SE7409900L/xx unknown
- 1974-08-02 JP JP49088968A patent/JPS5250046B2/ja not_active Expired
- 1974-08-02 IE IE1647/74A patent/IE39654B1/en unknown
- 1974-08-02 CA CA206,222A patent/CA1041847A/en not_active Expired
- 1974-08-03 IN IN1748/CAL/74A patent/IN142051B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE2434775B2 (en) | 1977-03-17 |
| FR2239293A1 (en) | 1975-02-28 |
| DE2434775A1 (en) | 1975-02-13 |
| JPS5250046B2 (en) | 1977-12-21 |
| SE7409900L (en) | 1975-02-04 |
| IN142051B (en) | 1977-05-21 |
| IE39654L (en) | 1975-02-03 |
| FR2239293B3 (en) | 1978-05-19 |
| IE39654B1 (en) | 1978-12-06 |
| JPS5045024A (en) | 1975-04-22 |
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