US2967669A

US2967669A - Centrifugal spraying device

Info

Publication number: US2967669A
Application number: US719357A
Authority: US
Inventors: Edward O Norris
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-03-05
Filing date: 1958-03-05
Publication date: 1961-01-10
Anticipated expiration: 1978-01-10

Description

Jan. 10, 1961 E. o. NORRIS CENTRIFUGAL SPRAYING DEVICE Filed March 5, 1958 2 Sheets-Sheet 2 /,v vewron? EflIV/IEO 0. rva/ee/s ATTOQNFY United States Patent CENTRIFUGAL SPRAYING DEVICE Edward 0. Norris, Roseville Road, Westport, Conn.

Filed Mar. 5, 1958, Ser. No. 719,357

1 Claim. (Cl. 239-219) The present invention relates to centrifugal spraying devices for coating, painting and the like and constitutes an improvement over the general type of spraying devices described in US. Patent No. 2,550,714.

One object of the present invention is to provide a new and improved centrifugal spraying device.

A more specific object is to provide a new and improved centrifugal spraying device for producing a fanshaped finely-divided spray gradually varying in density across its width from a comparatively heavy side to a lighter but still dense side to effect a more uniform or an improved distribution of the spray material over the object sprayed.

In accordance with certain features of the invention, a distributor or atomizing disc and an intercepting or collecting case open at its outer end and defining an annular collecting channel or trough are power-driven and are mounted to rotate about non-parallel axes, while spraying or coating material is continuously fed to the device. The atomizing distributor is designed to project an annular spray from its periphery by centrifugal action and is positioned with its plane of rotation disposed at an acute angle to the plane of rotation of the collecting case and intersecting the opening at the outer end of the case. The periphery of the atomizing distributor is located in close proximity to the inner peripheral wall of the collecting channel of the case and has an angular part of its periphery in shielded and intercepted position in relation to the case, whereby the sectorial part of the annular spray projected centrifugally from said shielded part of the distributor is intercepted by said case and collected by centrifugal action in its annular collecting channel, while the other unshielded part of the periphery of the distributor is free to escape through the opening of the case in flabellated form towards the object to be coated or sprayed. The shielded peripheral portion of the distributor dips into the liquid or other spray material in the collecting channel of the case and as the distributor continuously rotates, this peripheral portion of the distributor emerges from shielded position in relation to the case and then immerges into shielded position, causing the spray material picked up by said peripheral portion to be discharged from the case as a fan-shaped spray. The discharged spray by this action varies in density across its width, being heavy at the side or edge of the spray where the distributor emerges from the shielded position in relation to the case and tapering to a lighter density at the side or edge where the distributor immerges into shielded position. A spray having such density tapering characteristics has great advantage, for example, when a round can or shell cover is being sprayed while rotating on a conveyor spindle. In this case, this heavy edge of the spray is directed towards the rim of the cover, where there is the greater amount of area to be covered, and the lighter edge toward the center which has the least area, thereby attaining a more uniform distribution of the spray material over the cover.

If all of the spraying or coating material discharged from the unshielded peripheral portion of the distributor was that which had been picked up by the distributor from the collecting channel of the case, then the side of the spray discharged from the immerging region of the distributor might be too light in density to effect full proper coverage of the region of the object receiving this lighter side of the spray.

As an important feature of the present invention, in order to avoid the adverse conditions described above, feed of fresh spraying material is continuously directed to the distributor in a manner to discharge from its unshielded peripheral portion a spray of uniform density across its width. This spray of uniform density is combined with the spray of varying density produced from the spray material picked up by the distributor from the collecting channel of the case, to form a single composite fan-shaped spray which is heavy on one side of the emerging point of the distributor and which gradually diminishes in density across its width to the other side of the spray, but to an extent to afford at the latter side of the spray, material of substantial density. As a result of this density pattern, a more uniform distribution and better coverage is assured and a more generally satisfactory operation is attained.

Due to the power-drive connections to the case and to the distributor, there is a more positive differential between the peripheral speed of the case and that of the distributor. This positive difference in speed results in a more definite stirring of the material in the collecting channel of the case, thereby assuring under all operating conditions elimination of centrifugal sedimentation of the pigment or any other of the heavier ingredients in the coating or spraying material gathered in this collecting channel.

The centrifugal device of the present invention can be operated in connection with an electrostatic field or charge to improve performance.

Various other objects, features and advantages of the invention are apparent from the following description and from the accompanying drawings, in which Fig. 1 is a longitudinal axial section through one form of centrifugal spraying device embodying the present invention;

Fig. 2 is a longitudinal axial section through another form of centrifugal spraying device embodying the present invention; and

Fig. 3 is a longitudinal axial section through still another form of centrifugal spraying device embodying the present invention.

Referring to Fig. 1 of the drawings, the centrifugal spraying device is shown mounted in a fixed tubular housing 10, which is preferably made of non-conducting material, such as a phenolic or other plastic material, to permit in conjunction with other non-conducting elements of the device to be described, the effective use of an electrostatic field, as will be described hereinafter more fully and which carries axially thereof a shaft 11 mounted for rotation in an upper ball bearing 12 and in a lower needle bearing 13. The shaft 11 which may be made of steel is held in the housing 10 by the ball bearing 12 against axial movement and at its lower end, is bored to receive the end of a drive shaft 14, preferably made of non-conducting material such as nylon.

Secured to the upper end of the shaft 11 is a centrifugal distributor or atomizing disc 15. For mounting this atomizing distributor onto the shaft 11, there is provided a hub 16, preferably of non-conducting material positioned on the upper end of the shaft, and axially located thereon by a replaceable spacer collar 17 embracing said shaft and seated on an annular shoulder 18 formed on said shaft. This spacer collar 17 can be replaced by a collar of different length to vary the axial position of the distributor on the shaft 11, and thereby to vary the axial position of the distributor in relation to the collecting case 30 to be described.

Seated on the hub 16 is the centrifugal distributor 15 and clamped against this distributor is a removable sealing ring 20 of non-conducting material terminating in an axial cap nut 21 threaded on the upper end of the shaft 11, and pressing the distributor against the hub and the hub against the spacer collar 17.

The distributor 15 is in the general form of a flat circular disc terminating peripherally in a depending flaring annular rim or lip 22, so that the distributor is in the form of a shallow inverted dish. Fresh spraying or coating material is continuously fed to the distributor 15 beyond the periphery of the hub 16 in the manner to be described, and is guided and centrifugally carried to the peripheral rim 22 of the distributor where it is propelled as an annular atomized spray by centrifugal force. For spreading and guiding the spray material fed to the distributor along the underside of the distributor towards its peripheral rim 22, there is secured to the underside of the distributor a spreader ring 24 concentric with the shaft 11 and the distributor and having a series of notches 25 along its upper end defining a series of ports annularly arranged and separated by lands 26, to which the distributor is connected by studs 27a. This spreader ring 24 has an internal conical wall surface 27 concentric with the shaft 11 and flaring towards the distributor 15 for guiding and conducting the spray material centrifugally towards the ports 25. This spray material after passing through the ports 25 is distributed as a film along the underside of the distributor 15 and is forced by centrifugal action outwardly towards the peripheral rim 22 of the distributor 15 where it is ejected as an annular spray.

A rotary intercepting and collecting case 30 is supported for driven action from the shaft 11 about an axis tilted in relation to said shaft and to the axis of rotation of the distributor 15. To that end, a tubular bracket 31 is threaded at its lower end to the upper end of the housing 10 and locks the outer race of the ball bearing 12. At its upper end, this tubular bracket 31 supports a double race ball bearing unit 32 in tilted axial position in relation to the axis of the shaft 11. A hub 33 mounted on this ball bearing unit 32 has a sleeve34 on the inside of this unit terminating at its lower end in a flange 35 abutting the lower race of this unit and a web 36 threaded onto its upper end and having a labyrinthic running seal 39 with the bracket 31. A tubular feed member 37 presents an inner conical wall surface 38 tapering downward towards the axis of the ball bearing unit 32 to cause any liquid deposited on said surface to rise centrifugally towards its upper end and is threaded to the hub web 36. A series of notches 40 on the periphery of the hub web 36 defines ports for the passage of the spray feed upward towards the distributor 15.

The intercepting and collecting case 30 seats on an annular flange 42 extending outwardly from the tubular teed member 37 and is secured to said flange by studs 43. This case 30 is dished and terminates in a rim 44 tapering upwardly towards an opening 45 in the outer end of the case and defining an annular channel, or trough 46 in which the spray material projected from the distributor 15 and intercepted by said case is collected.

For feeding fresh spray material to the distributor 15, there is provided a feed collar 47 embracing the upper section of the housing 10 and threaded to the outside of the lower end of the bracket 31. This collar 47 is locked to the housing 10 by means of a set screw 48 and carries a material feed nozzle 49 removably retained on said collar by means of a set screw 50 and connected to a conduit 51 leading to a source of fresh spray material (not shown). The nozzle 49 extends into the tubular feed member 37.

The shaft 11 drives the distributor 15 and at the same time drives the collecting case 30. Because the axis of rotation of the collecting case 30 is tilted in relation to the axis of rotation of the distributor 15, special means must be provided for driving the collecting case from the shaft 11. For that purpose, there is provided a bearing bushing 53 embracing the shaft 11 and rigidly secured thereto by means of a pin 54. This bushing 53 in connection with a snap ring 55 at its lower end and a shoulder 56 at its upper end retains the inner race of the bearing 12 and at this upper end rigidly retains the lower end of a spring 57, embracing the shaft 11 and bearing at its upper end against and connected to a metal friction ring 58 having a facing ring 59 of leather or similar friction material located in a recess 60 in the lower end of the hub sleeve 34. This friction ring 59 is resiliently pressed by the spring 57 against an axially facing driven face of the hub sleeve 34. As a result ofthe flexible drive spring assembly described, the collecting case 30 is driven from the shaft 11 about an axis tilted in relation to the axis of said shaft.

The fresh feed of spray' material delivered to the atomizing distributor 15 through the feed nozzle 49 is discharged centrifugally as an annular spray from around the entire rim 22 of the distributor. The plane of rotation of the distributor 15 is disposed at an acute angle to the plane of rotation of the collecting case 30 and said distributor is located along the shaft 11 in relation to the case so that the plane of this annular spray projected from the distributor rim 22 intersects the opening 45 of the case. As a result of this arrangement an angular section 63 of the distributor rim 22 extends into the case 30 in position to be shielded by said case, so that the sectorial part of the annular spray projected from said shielded rim section is intercepted by said case and centrifugally collected in the collecting channel 46 of the case as a liquid layer, while the other angular section 64 of the distributor rim is in exposed unshielded position in relation to said case to permit the sectorial part of the annular spray projected from said exposed rim section to escape and discharge freely through the opening 45 of the case as a fan-shaped spray. The angle of this discharged fan-shaped spray depends upon the angular relation between the axis of the case 30 and that of the distributor 15 and the axial position of the distributor on the shaft 11, this axial position being adjusted by the selection of a spacing collar 17 of the proper length. The case 36 may normally intercept 200 to 280 of the annular spray of 360.

Although the distributor 15 and the collecting case 30 rotate at substantially the same angular velocity, they have different peripheral speeds due to the differences in their diameters. The peripheral rim section 63 of the distributor 15 interceptively shielded by the case 30 extends into the liquid layer collected in the channel 46 of the case and this action serves two functions. This peripheral rim section 63 of the distributor 15 as it passes through the liquid layer in the collecting channel 46 stirs up the material in the channel, and thereby prevents centrifugal sedimentation of the solids, as for example, the pigment in this material, this stirring action being more positively assured due to the power drive to both the case 30 and the distributor 15. At the same time, the peripheral rim section 63 of the distributor 15 dipping into the liquid layer in the collecting channel 46 picks up the spray material and ejects it centrifugally from the distributor lip 22 as a spray through the case opening 45 as said rim section emerges from interceptively shielded position in relation to the case 30.

For electrostatically assisting the spray discharged from the distributor 15 through the case opening :5, an electrostatic field is created between the distributor and the article to be sprayed. For that purpose, housing 10, atomizing distributor 15, collecting case 30, hub 16, sealing ring 20. spreader ring 24, tubular bracket 31, hub web 36, tubular feed member 37,.feed collar 47, and

possibly the feed nozzle 49 are made of non-conducting material such as nylon and/ or phenolic resin. Other components of the spray device may be made of con ducting material, such as the shaft 11,

bearings

12, 13, 32, spacer collar 17, hub sleeve 34 and spring drive assembly '53, 57. The high voltage lead from a power pack (not shown) is connected to the device by a metal screw 67 having a contact with the outer race of the needle bearing 13. This screw 67 conducts the charge to the steel shaft 11 which is carried to the atomizing peripheral rim 22 of the distributor by means of a thin coating 68 of conductive material, such as graphite, applied tothe underside of the distributor from the shaft 11 to the outer edge of the rim.

In the operation of the device described the distributor 15 and the case 30 are driven at a speed which may be in the order of 3450 rpm. The peripheral rim section 63 of the atomizing distributor 15 extending into the case 30 and dipping into the liquid layer in the collecting channel 46 carries some of the liquid out of shielded position and into exposed or unshielded position. As a result, the

liquid picked up by the distributor lip 22 from the liquid.

layer in the collecting channel 46 is discharged centrifugaL ly as a fan-shaped finely divided spray from the unshielded rim section 64 of the distributor 15 and through the case opening 45 towards the article to be coated. This discharged spray resulting solely from the liquid gathered by the distributor rim 22 from the collecting channel 46 of the case 30 has a side edge of heavy density at the region where the distributor rim emerges from shielded position, and this density gradually diminishes across the width and at the other side edge of the spray at the region where the distributor rim irnmerges into shielded position, the density is light. The density of the spray at this latter side edge may be too light to afford proper full coverage thereby of the article to be coated.

The continuous feed of fresh spraying material to the distributor 15 remedies this situation. The feed for this purpose, delivered through the feed nozzle 49 into the rotating tubular feed member 37 is forced centrifugally through the ports 40 and into the spreader ring 24 where it is annularly spread by centrifugal action along the internal conical surface 27 of said spreader ring and outwardly along the underside of the distributor 15, and forced through the ports 25 towards the rim 22 where the liquid is centrifugally discharged as an annular finelydivided spray of uniform density around 360. The angular portion of the spray projected from the shielded section 63 of the distributor rim 22 is intercepted by the case 30 and collected in the collecting channel 46 of the case, while the portion of the annular spray projected from the unshielded section 64 of the distributor rim is discharged through the case opening 45 as a fan-shaped spray having uniform density throughout its full width. This fan-shaped spray combined with the fan-shaped spray of density varying gradually across its width results in a single fan-shaped spray having a side edge of heavy density and diminishing gradually in density thereacross to the other side edge where the density is lighter but still substantial enough to afford proper coverage of the region of the article coated by said lighter edge.

Fig. 2 shows a modified construction in which the atomizing distributor 15a is similar to the distributor 15 in the construction of Fig. 1, except that distributor 15a has two adjoining and depending annular rims or lips 22a and 22b and the conductive coating 68a such as graphite extends over the lower surface of the distributor and over the surfaces of these rims to conduct the electric current to both rims for the creation of the electrostatic field from said rim. The discharge edges of the two rims 22a and 22b are at different axial positions along the axis of extending below the edge of the outer rim 22a and serving to spray the fresh material supplied to the distributor 15a 7 through the feed nozzle 49, while the outer rim 22a will discharge the material collected by said outer rim from the liquid layer intercepted by the case 30 and gathered in the collecting channel 46 of said case. Although the two sprays are discharged from the two separate rims 22a and 22b, they are close together sufliciently to merge into a single spray.

The double rim feature of Fig. 2 not only serves to discharge the two sprays from two different edges of the distributor 15a but serves to increase considerably the peripheral atomizing area of the rotor and thereby serves to increase the efliciency of the device.

Fig. 3 shows a modified construction in which the rim or lip 22c of the distributor 15c turns upwardly or outwardly from the device. In this modified construction, the distributor comprises a web 70, and the spreader ring 240 has integral therewith a substantially radial annular flange 71 constituting an extension of said web and terminating in the upwardly turned and upwardly flaring lip 220. This spreader ring 240 is secured to the web 70 by means of studs 27c and has notches 25c serving as ports to permit passage of the liquid therethrough by centrifugal action.

The construction of Fig. 3 serves to minimize electrostatic field interference between the atomizing distributor 15c and the charged spraying material in the collecting channel 46 of the case 30 and to reduce the tendency for the spray to deposit on and respray from the lip or rim of the case.

While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not to be limited thereto, but is to be construed broadly and restricted solely by the scope of the appended claims.

What is claimed is:

A rotary spray device comprising a rotary distributor disk, means feeding sprayable material to said disk at a point remote from the periphery thereof, means rotat ing said disk at a rate to cause said material to flow radially outwardly along the surface thereof and to be discharged from the periphery of said disk as a uniform spray due to the action of centrifugal force, a collecting case mounted to rotate in a plane inclined to the plane of said disk, said case having a peripheral wall forming an internal annular channel and being positioned to intercept the spray discharged from a predetermined portion of the periphery of said disk, means rotating said case at a rate substantially the same as that of said distributor to cause the intercepted spray to form a layer held centrifugally in said channel, said disk being mounted with its peripheral edge dipping into said channel adjacent said wall to thereby pick up additional spray material from said channel and to discharge the same peripherally as a spray combined with the first mentioned spray.

References Cited in the file of this patent UNITED STATES PATENTS