US3532072A

US3532072A - Spray coating apparatus

Info

Publication number: US3532072A
Application number: US587333A
Authority: US
Inventors: Johannes Kiwiet
Original assignee: Inland Steel Co
Current assignee: Inland Steel Co
Priority date: 1966-10-17
Filing date: 1966-10-17
Publication date: 1970-10-06
Anticipated expiration: 1987-10-06

Description

' Elite States atent Inventor Johannes Kiwiet Riverside, Illinois Appl. No 587,333

Filed Oct. 17, 1966 Patented Oct. 6, 1970 Assignee Inland Steel Company Chicago, Illinois a corporation of Delaware SPRAY COATING APPARATUS 11 Claims, 10 Drawing Figs.

U.S.Cl 118/301,

1 18/322 Int. Cl 1305c 5/00 Field of Search H 1 18/30],

[56] References Cited UNITED STATES PATENTS 2,559i351 7/1951 Drake et all 118/301X 2,700,929 2/1955 Williams 118/301 X 2,867,551 1/1959 Kozak l18/301X 2,874,676 2/1959 Fournier 118/301 Primary Examiner-John P. McIntosh Attorney-Wolfe, Hubbard, Leydig, Voit and Osann ABSTRACT: Apparatus for masking articles having the shape ofa cylindrical shell. Means are provided for raising the article from a conveyor and rotating it within a surrounding masking member. The mask is rotatable and movable transversely to the article and serves to mask areas of the article from spray guns placed adjacent the exterior of the article.

Patented Oct. 6, 1970 Sheet L of 7 m s/vroe. mam/1w mm r,

Patented Oct. 6, 1970 i 3,532,072

Sheet 5 of? f nvmwme.

Mme/vim,

Patented Oct. 6, 1970 3,532,072

Sheet 7 of 7 men/roe. flw/ww KIM/7;

SPRAY COATING APPARATUS The present invention relates generally to spray coating apparatus, and more particularly, to an improved spray coating system for coating portions of external surfaces of workpieces such, merely by way of example, as a cylindrical shell which may comprise the sidewall of a container or the like. In its principal aspects, the invention is concerned with improved spray coating apparatus characterized by their ability to rapidly coat select portions of a workpiece surface with a material such as paint, lacquer, rust inhibitor, or other material in a liquid or semi-liquid state, yet wherein the coating is applied uniformly within sharp and well defined limits even where the surface being coated includes irregularities, contours, projections, curls, and the like.

In various industries, such, for example, as the container manufacturing industry, efforts have been made to apply uniform coatings to the surfaces of workpieces, e.g., the cylindrical sidewall of a container, yet wherein the coating can be applied on a mass production basis. Interior and exterior surfaces of container sidewalls are conventionally coated separately, often utilizing different coating materials. Rapid handling of shells for coating is troublesome and difficult and some areas present even greater problems in coating such as, for example, about the curl formed on the upper edge of a container sidewall. Multi-material coating, striping and the like have also heretofore presented additional difficulties in handling and were not readily susceptible to rapid mass production operations. While there is disclosed and claimed in my copending application Ser. No. 492,682 filed October 4, I965, and assigned to the assignee of the present invention, centrifugal spray coating methods and apparatus for uniformly coating the internal surface of a cylindrical shell, prior to the present invention, there has not been a completely satisfactory solution to the problem of applying coatings to select portions of the external surface of the workpiece within sharp and well defined limits.

Accordingly, it is a general aim of the present invention to provide an improved spray coating system characterized by its ability to rapidly apply a coating of spray material to select portions of the external surfaceof the workpiece to be coated. While not so limited in its application, the invention will find especially advantageous use in applying a uniform coating about a curl formed on an edge of a cylindrical shell, such, merely by way of example, as the cylindrical sidewall of a 55 gallon shipping drum of the type commonly made from sheet steel or other suitable material.

In accordance with another of the important aspects of the present invention, it is an object to provide improved apparatus for spray coating portions of the external surface of a cylindrical shell characterized by their versatility and which readily permit effective use thereof in multi-material coating,

striping and the like, yet wherein the coatings are applied in rapid, continuous operations. In this connection, it is an object to provide a reliable external work surface coating system particularly suitable for mass production operations.

Yet another aspect of the present invention is to provide an improved spray coating apparatus for externally coating portions of external surfaces of cylindrical workpieces wherein the spray material may be applied within distinct, preselected, limits about the workpiece surface yet wherein no special preparation of workpiece is required and such coating can be applied to workpieces in a continuous manner. In this connection it is an object of the present invention to provide a spray coating apparatus of the foregoing type characterized by its ability to apply different materials or color coatings to portions of a workpiece surface simultaneously or in a successive manner.

Other objects and advantages of the invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings, in which:

FIG. I is a fragmentary, and partially diagrammatic, elevation view of an exemplary material spray system for applying coatings to external portions of a cylindrical shell, such system embodying the features of the present invention;

FIG. 2 is a top plan view of the exemplary spray coating apparatus shown in FIG. 1;

FIG. 3 is an enlarged fragmentary elevation view, partly in section, of a spray coating apparatus used in conjunction with the spray system of the present invention, here illustrating the device in readiness for receiving a cylindrical shell;

FIG. 4 is a fragmentary elevation view partly in section of a portion of the apparatus shown in FIG. 3, here depicting the shell held in position by the apparatus in readiness for the coating operation;

FIG. 5 is an enlarged fragmentary cross-sectional view taken substantially along the line 55 in FIG. 3, here depicting the rotatable clamping arrangement for holding the workpiece during the coating operation;

FIG. 6 is an enlarged, cross-sectional view taken substantially along the line 6-6 in FIG. 4;

FIG. 7 is an enlarged fragmentary cross-sectional view taken with a portion of the upper mask cut away for purposes of depicting the interior along the line 7-7 in FIG. 4;

FIG. 8 is an enlarged fragmentary section of the exemplary apparatus of FIG. 1, depicting the spraying of a curl on the upper edge of a cylindrical shell, and illustrating the upper and lower masks for limiting the application of the coating within desired limits;

FIG. 9 is an enlarged fragmentary view in section taken with a portion of the upper mask cut away for purposes of depicting the interior along the line 9-9 in FIG. 1, here illustrating the scraper arrangement for removing excess spray material from the upper mask; and

FIG. 10 is a fragmentary front end view, similar to FIG. 4, here depicting a slightly modified spray coating apparatus also embodying the features of the present invention.

While the invention is susceptible of various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.

Referring now to the drawings, there is diagrammatically illustrated in FIG. I an exemplary spray coating system generally indicated at 20, which is particularly suitable for coating select portions of the external surface of

cylindrical shells

21, 22 on a mass production basis and in accordance with the present invention. While the particular type of workpiece to be coated is not critical to the present invention, it will be appreciated as the ensuing description proceeds, that the exemplary spray coating system 20 shown in FIG. 1 will find particularly advantageous, but by no means exclusive, use in coating portions of the external surface of a cylindrical shell .such as the sidewalls of conventional 55 gallon shipping containers which can be made of sheet metal or any other suitable natural or synthetic sheet material.

As here illustrated,

cylindrical shells

21, 22 are fed to the spray coating station, generally indicated at 24 in seriatim order, by means of a conveyor belt 26 or the like. The particular means for driving the conveyor belt are not critical to the present invention, and may take any of a wide variety of conventional forms well known to those skilled in the art. It should suffice to say that the drive system for the conveyor belt is such that control means are provided for automatically moving the belt to transfer shells from work station to work station, and for intermittently stopping the belt as successive shells reach a work station so as to permit performance of an operational cycle. In the present instance, in order to insure that the

shells

21, 22 are properly aligned with work station 24, for example, the belt is provided with a plurality of positioning lugs 28 which serve to accurately position the shells at predetermined points on the conveyor belt 26.

For the purpose of axially moving the cylindrical shell 21 into the illustrative spray coating station 24, there is provided a pair of oppositely facing C-shaped brackets 30 which are respectively disposed on either side of the conveyor belt 26. Each of the C-shaped brackets 30 includes a pair of upright posts 32 having annular flanges 34 formed adjacent the upper ends thereof, such flanges normally being disposed at the level of or slightly below the level of the upper surface of the belt 26. The arrangement is such that when the belt 26 is stopped with a cylindrical shell accurately positioned beneath the coating station 24, the lower peripheral edge 36 of the shell is disposed immediately above the two pairs of flanges 34. As shown in FIG. 1, the brackets 30 are coupled to a roller follower member 38 the latter raising and lowering shell 21 under the guidance ofa disc cam 40. The disc cam 40 is fixed to a generally horizontally extending drive shaft 42, driven by motor 44 through roller chain and sprocket drive 46.

The exemplary spray apparatus 20, as shown in FIG. 1, is supported above

shells

21, 22 carried by belt 26 on a generally rectangular framework 50 including spaced horizontally extending members 51 and spaced vertically extending columns 52.

For the purpose of distributing liquid or semi-liquid spray material on the surface of the workpiece to be coated, the exemplary apparatus 20 includes spray nozzles 54, 55 adjustably mounted respectively to horizontally extending support shafts 56, 57 which are in turn connected to vertically extending sup port shafts S8, 59 (FIG. 2) through

slide clamps

60, 61. The

vertical support shafts

58, 59 are connected to a slide clamp 64 fixed to a cross member 51, outboard of the apparatus. The arrangement is such that the spray material, which is normally maintained in a supply reservoir (not shown) is delivered under pressure by means of one or more pumps (not shown), through spray nozzles 54, 55, the latter here being completely adjustably supported in the work station 24.

In order to confine both air-borne particles of spray material emanating from the spray nozzles and drippings from excess spray material carried away from the apparatus, there is provided a rectangular enclosure 66 surrounding the work station. Exhaust vents 68 disposed at the top of the enclosure 66 are connected to a suitable exhaust fan and filter system (not shown) to remove the air-borne spray particles and fumes from within the enclosure. A drain 69 at the bottom of the enclosure 66 received drippings and settled particles of spray material which may be returned to the material source, or discarded, as desired.

In accordance with the present invention, provision is made for receiving the workpiece in the work station 24, rotatably supporting the workpiece within the work station enclosure and rotating the workpiece at a preselected position relative to the path of spray material projected outwardly from the spray nozzles so as to apply a coating to a selected portion of the work surface. To this end, a powerhead, generally indicated at 70 (FIGS. 1 and 3), extends vertically along the center of the work station 24 supported by a pair of cross members 72 of frame 50.

As best shown by reference to FIG. 3, the powerhead 70 includes a stationary outer sleeve 74 bolted to frame members 72 through collar members 76. Disposed within the stationary sleeve 74 and supported with a suitable thrust bearing 78 is a rotatable sleeve member 80 which is rotatably driven by a belt and pulley arrangement 82 through motor drive mechanism 83 (FIG. 1). Centrally supported within the rotatable sleeve 80 is an axially shiftable and rotatably supported shaft 86.

In keeping with the invention, the powerhead 70 includes provision for positively clamping the workpiece for rotation with rotatable sleeve 80. As best shown by reference to FIGS. 3, 4, and 5, conjointly, a plurality of expanding shoes, generally indicated at 84, extend radially outward from a spider member 86, the latter being secured to a flanged hub member threadably connected to rotatable sleeve 80 as indicated at 90 (FIGS. 3 and 4). As here shown, (FIG. the clamping shoes 84 are generally T-shaped and have a pair of spaced axially extending bores 88 which receive pins 89 extending radially outward from the spider member 86.

For the purpose of normally urging the clamping shoes 84 radially inward towards their non-expanded position, compression springs 92 or the like surrounding the outer ends of pins 89 are carried in an enlarged cavity portion of bores 88 so that the springs are confined between a shoulder portion 94 on clamping shoes 84 and retaining members 96 secured to the ends of pins 89. Thus, the springs 92 tend to normally bias the clamping shoes 84 radially inward and, when expanded, the clamping shoes are cammed radially outward against the biasing effect of the springs 92.

For the purpose of properly positioning a shell 21 about the clamping shoes 84, there are provided a plurality of stop fingers 98 (FIGS. 3 and 5) pivotally mounted at the ends of arms 100 on spider member 86. As viewed in FIG. 3, the shell is raised until its upper peripheral edge engages abutment shoul ders 100 on stop fingers 98. For the purpose of retracting the stop fingers after the workpiece has been properly positioned, guide pins 101 projecting horizontally from the stop fingers ride in generally L-shaped camming slots 102 formed in plates 104.

In carrying out the present invention, provision is made for camming the clamping shoes 84 radially outward and retracting the stop fingers 98 after the workpiece has been moved into a proper position with respect thereto. To accomplish this, a support plate 106 (FIGS. 3, 4, and 6), mounted below spider member 84 and secured to central shaft 86 of powerhead 70 through suitable support member 107, carries a plurality of upstanding camming members 108 which serve to define outwardly facing cam surfaces 109. The camming members 108 extend through slots 110 provided in clamping shoes 84 and to facilitate relative movement between camming members 108 and clamping shoes 84 for camming the latter radially outward, rollers 112 mounted on the shoes 84 engage the outwardly facing cam surfaces 109 of camming members 108. Suitable adjusting screws 116 (FIG. 6) are provided to regulate the position of the camming members thereby enabling alignment of the expansion of each of the expanding shoes 84.

Plate members 104 which include the guide slot 102 that receives guide pins 101 of stop fingers 98 are also secured to support plate 106. Thus, when the support plate 106 together with the central shaft 86 is shifted downwardly, the cam surfaces 109 of members 108 and rollers 112 on clamping shoes 84 coact to cam the clamping shoes 84 radially outward and at the same time guide pins 101 of stop fingers 98 ride in slots 106 thereby retracting the stop fingers 98 radially inward, as shown in FIG. 4.

Secured to the underside of support plate 106 is a generally frustoconical shaped guide plate 113, the generally inwardly tapering sidewalls of which help to guide the shell 21 over the clamping portion of the powerhead 70.

In order to rotatably drive the support plate 106 and its associated central shaft 86 together with spider 86 and rotatable sleeve 80, there is provided a vertically oriented drive pin 120 secured to support plate 106 and passing through a suitable opening provided in spider 86. The drive pin 120 also insures that camming members 108 are not torque transmitting members.

In keeping with the invention, provision is made for lowering the support plate 106 thereby expanding the clamping shoes and retracting the stop fingers 98 synchronized with the elevating of the workpiece into work station 24, as previously described.

In the exemplary form of the invention, the upper end of the central shaft 86 is threadably received in an annular carrier member 124 (as best shown in FIG. 3). The carrier member 124 is provided with an annular recess 125 which receives a pair of rollers 126 secured to spaced arms 127 of a yoke member 128. The opposite end of the yoke member 128 includes a roller follower 130 which rides on a disc cam 132, the latter being fixed to a horizontally extending shaft 134 supported at the top ofthe apparatus (FIGS. 1 and 2).

In order to drive shaft 134, there is provided, as best viewed in FIG. 1, a generally vertically extending shaft 136 which interconnects the workpiece lifting drive shaft 42 to shaft 134 through

bevel gear couplings

137, 138.

In accordance with another of the important aspects of the present invention, provision is made for restricting the amount of surface sprayed so that only a preselected portion of the workpiece is coated within well defined limits. In order to achieve this result, as best shown by reference to FIGS. 1, 3, 4, and 8, conjointly, upper and

lower masks

140, 142, respectively, are provided to permit spray material from nozzles 54, 55 to be applied to the surface of the workpiece between the masks and prevent application of spray material to other portions of the workpiece.

The upper mask 140 which is of generally dish-shaped construction surrounds the powerhead 70 and an arrangement is made so that the upper mask 140 is rotatably driven and axially shifted together with support plate 106.

Referring to FIGS. 3, 4, and 8, conjointly, the upper mask 140 is secured to the top of an annular flange 143 formed on sleeve member 144 surrounding powerhead 70, while an annular guard member 146 is secured to the lower end of flange 143. Camming plates 104 are secured to the underside of guard member 146 by welding or the like so that guard member 146, sleeve 144 and the upper mask 140 are all positively connected to the support member 106 through camming plates 104.

For the purpose of shielding the internal surface of the workpiece and the lower members of the powerhead from accumulated overflow and dripping of spray material, particularly from the upper mask 140, the guard member 146 is provided with upstanding annular projections or baffles 150 which serve to confine the excess spray material on the top surface of the guard member. A screen 152 carried on the top surface of the guard member provides additional aid in confin ing excess accumulated material on the top surface of the guard member.

In order to prevent a large build-up of spray material on the upper mask a scraper arrangement is provided (best illustrated in FIG. 9) which is adjustably supported on a pin 156 protruding from collar 158 surrounding sleeve member 144. The collar is stationarily secured to the enclosure 66 through anchor bolt 160. The scraper, generally indicated at 162, comprises a generally U-shaped support plate 164 pivotally mounted to a support bracket 165, the latter including a clamp 166 which receives pin 156 of collar 158. The slotted portion 168 of support plate 164 receives an outward end portion of the mask 140 and upper and

lower scraper members

170, 171, respectively, mounted on the support plate 164 are spring biased against the upper, lower, and end surfaces of the mask 140 by springs 172.

In order to direct spray material removed from the mask scraper 162 there is provided a trough-like drip tray 176 bolted to the underside of support plate 164 and having a downwardly inclined portion 177 which allows the material to flow away from the work area.

In accordance with yet another of the important features of the present invention, provision is made for shifting the lower mask from its initial concentrically disposed surrounding relationship with respect to the workpiece, when receiving the same, to a position in relatively close proximity to the workpiece external surface in the vicinity of the spray nozzles so that a well defined limit of spray coverage can be accom plished. To this end, referring to FIGS. 1, 3, and 4, conjointly, the lower mask 142 is carried by a horizontally shiftable slide member 180, the latter being slideably mounted to frame 50. A relatively large diameter opening 181 is provided in the slide member 180 to allow the workpiece to pass into the work station 24, surrounded by enclosure 66, which is secured to slide member 180.

As best shown by reference to FIGS. 3 and 4, it will be observed that the mask 142 includes a main support ring 184 having a generally frustoconical-shaped, upstanding sleeve 185 about its inner peripheral edge 184a and a generally frustoconical-shaped depending sleeve member 186 about its outer peripheral edge 18412. The mask 142 is concentrically supported with respect to the opening in slide member so that a cylindrical workpiece, brought into the workstation passes through both the opening 181 ofslide member 180 and the central opening 187 of mask 142 to position the workpiece about the powerhead 70.

In order to shift the lower mask 142 from its initial concentrically disposed position with respect to the workpiece, as shown in FIG. 3, to a position wherein the upper peripheral edge of sleeve member is in relatively close proximity to the workpiece external surface in the vicinity of the spray nozzle, as shown in FIG. 4, provision is made for moving the slide member 180 coupled with the workpiece elevating and powerhead descent and expansion apparatus. To this end, referring to FIGS. 1 and 2, a horizontally extending link 190 journaled at one end to slide member 180 is coupled to vertically extending link 192 through toggle linkage 193. The upper end of link 192 is connected to a cantilever 194. Secured to the cantilever 194 is a follower member 195 which engages a cam disc 196, the latter being secured to drive shaft 134.

Cam discs

40, 132, and 196 are profiled and so arranged that rotation of their

respective drive shafts

42, 134, in sequence, raises the workpiece into work station 24, lowers powerhead 70 to clamp the workpiece thereto and shifts the slide member 180 carrying the lower mask 142 to the right, as viewed in FIG. 1. Continued rotation of shaft 42 reverses the sequence of operation, first shifting the slide member 180 and mask 142 to a centered position with respect to the workpiece, raising the powerhead to release the clamping members and lowering of the workpiece back on to the conveyor 26.

In accordance with yet another aspect of the present invention, provision is made for rotating the mast 142 with respect to the workpiece and at a sufficient angular velocity to centrifugally carry accumulated spray material away from the inner peripheral edge of the mask. To accomplish this, referring to FIGS. 1, 3, and 4, conjointly, main support ring 184 of mask 142 is bolted or otherwise secured to a circular rack member 198 through removable bolts 200 or the like.

For the purpose of driving the circular rack 198, there is provided a pinion 202 fixed to shaft 204 which is rotatably journaled in slide member 180. A pulley 206 fixed to the lower end of shaft 204 beneath slide member 180 receives a belt 208 rotatably driven by pulley 209 of mask drive" motor 210, the latter being mounted on slide member 180. In order to support the mask 142 for rotation with respect to the slide member 180 and the workpiece, a plurality of spool members 212 are rotatably journaled to slide member 180 and located about the periphery of circular rack 198 to supportingly receive the same, yet permitting relative rotation between the circular rack and the spools.

In the preferred form of the invention, the mask 142 is shifted so that a gap of approximately Va inch is maintained between the workpiece and the inner peripheral edge of the mask in the vicinity of thespray nozzles to insure proper separation between the area to which the coating is being applied and the remaining surface area of the workpiece. Also, advantageous results are obtained when the mask 142 is rotated at approximately 100 r.p.m., to centrifugally carry excess spray material away from the inner peripheral edge of the' mask. While those skilled in the art will appreciate that the present invention is not limited to any particular gap dimension or speed of mask rotation, they are presented, merely by way of example, and may vary, dependent upon the spray material utilized, the configuration of the workpiece being coated and the type of spray nozzles used.

Having in mind the foregoing structural details, a brief description of a typical spray coating operation will serve to facilitate an understanding of the present invention. To this end, reference is first made to FIG. 1 wherein the apparatus is shown with shell 21 positioned along belt 26 beneath the spray device 20. At the start of the cycle, shell 21 is raised off of the conveyor belt and moved upwardly until the upper peripheral edge 36a of the shell engages stop fingers 98 on powerhead 70, as illustrated in phantom in FIG. 1. After the shell has been brought into position in work station 24, the powerhead is lowered to urge the clamping shoes 84 radially outward thereby clamping the shell to the powerhead for rotation therewith and bringing mask 140 into position above the central opening of the shell. After this occurs, the mask 142 is shifted to the right (FIGS. 4, 7, and 8) thereby assuming the position wherein the inner peripheral edge of the mask 142 is in close proximity to the shell adjacent the left hand edge of the latter as viewed in FIGS. 4, 7, and 8 to define a lower limit of spray coverage. When the mask 142 is in position, both the powerhead supporting the shell and the mask 142 are rotated through their

respective drive motors

83, 210 and subsequently spray material is delivered to nozzles 54, 55 for distribution onto the surface of the shell between the limits defined by masks 140, 142 (FIG. 8).

In the illustrative embodiment shown in FIG. 8, the apparatus has been shown as used for application of a coating to a curl formed at the upper peripheral edge of the shell 21. Consequently, the arrangement is such that material emanating from spray nozzle 54, to the extent that it is not blocked by mask 140, covers approximately the upper half of the curl while material emanating from spray nozzle 55 covers the lower portion of the curl.

After the shell portion being covered has been completely rotated past the spray nozzles, a preselected number of times, the latter are de-activated and rotation of both the powerhead 70 and the mask 142 is ceased. The mask 142 is then shifted back to its concentrically disposed position about the shell (FIG. 3) and the powerhead is raised, thereby retracting the clamping shoes to their inward position to release the shell. The shell 21 is then returned to the conveyor belt and the cycle repeats itself for shell 22 and each subsequent shell positioned along the conveyor belt.

Turning now to FIG. 10, there is shown a slightly modified spray coating apparatus 208 which is quite similar in construction and operation to that shown in FIG. 1. However, in the exemplary apparatus shown in FIG. 10, the construction is such that multi-color coating or striping can be accomplished with a different material or color coating also being uniformly applied within sharp and well-defined limits on the exterior surface of the shell. In this instance, the apparatus includes a powerhead 70B, masks 140B, 1428, slide member 180B and enclosure 66B, all similar to those shown in FIG. 1.

In carrying out this form of the invention, provision is made for applying a band of differing material or different colored material intermediate the upper and lower peripheral edges of shells in a rapid and continuous manner. To this end, a second rotatable and transversely shiftable mask 242 is carried by slide member 180B in an axially spaced relation with respect to mask 1428. For the purpose of distributing spray material on the surface of the workpiece intermediate the masks a spray nozzle 246 is provided projecting horizontally into the enclosure 668 between the masks 142B, 242.

In the present exemplary form of the invention, the mask 242 includes a circular rack member 248 and an annular material guard member 250 removably secured to the rack by bolts 252. The guard member 250 which may be of unitary construction, includes a generally horizontally extending portion 250A and a generally upstanding frustoconical shaped portion 2508, the latter portion being in surrounding relationship to a shell supported on the powerhead 70B.

In order to confine material drippings and excess material moving outwardly along the surface of mask 242 due to centrifugal action, there are provided a plurality of projections or baffles 254 on the top surface of the horizontal portion 250A.

For the purpose of receiving any material overflow from the top surface of the mask horizontal portion 250A, an annular trough 256 surrounds the outer peripheral edge of the guard member 250 and is located slightly below the guard member so that material flowing over the extreme outer baffle member 254 will fall into the trough 256. A suitable drain 258 is provided in the trough which may, if desired, be connected to the source ofmaterial for reuse thereof.

In order to support the mask 250 on slide member 1808 and to rotate the mask 250 in a manner substantially similar to that used in conjunction with mask 142B, shaft 204B which carries pinion 202B for driving mask 1428 and shafts 260 which carry support spools 2128 are extended in length and also carry, respectively, a drive pinion 262 and spools 264 for driving and supporting rack 248 of mask 242. Pinion shaft 2043 is rotatably journaled in slide member 1808 with the lower end portion of the shaft extending below the slide member connected to pulley 206B driven by belt 208B in a manner similar to that described with respect to FIG. 1.

For the purpose of defining an upper limit of spray coverage from nozzle 246 and to prevent spray material from being applied to the undersurface portions of the mask 1428, there is provided an annular shield 266 secured to the rack 1988 of mask 142B.

It will, of course, be understood to those skilled in the art that certain ofthe features and advantages of the present form of the invention may be utilized in a more simplified arrangement for coating a portion of the cylindrical shell surface. Where such usage is desired, and, for example, a curl is not to be coated, but the band or stripe is to be applied, then mask 1408 and the upper portion of mask 1423 could be omitted and the apparatus may merely be provided with at least mask 250 and shield portion 266 of mask 1428, without departing from the present invention. In addition, a plurality of pairs of masks could be carried on slide member 180B with spray nozzles located between respective pairs of masks for applying alternate bands of different color material or the like and the masks can be adjustably mounted to vary the spacing therebetween to enable the application of coatings having varied widths to the shell surface.

It will be apparent from the foregoing that there has herein been disclosed and described in detail novel spray coating systems employing apparatus which, although characterized by their simplicity and reliability, serve to insure rapid and continuous application of a coating to select portions of a workpiece within well defined limits. Not only does the novel arrangement of a powerhead and rotating masks contribute to such coating ability, but, moreover, there has herein been disclosed novel apparatus for applying spray particles to portions of a workpiece surface whereby the coating is applied uniformly within sharp and well defined limits even where the surface being coated includes irregularities, contours, projections and the like, yet wherein such coating can be applied in a continuous, mass production manner.

Iclaim:

1. Apparatus for externally coating a select surface portion of a cylindrical shell, comprising, in combination, a frame, means defining a work station carried by said frame, at least one material spray nozzle disposed in said work station, a powerhead adapted to support said shell for rotation in the work station adjacent said nozzle, means including a mask concentric with and surrounding the shell for defining a limit to said surface portion to be coated, means for shifting said mask transversely with respect to the surface so that the inner peripheral edge of the mask in the vicinity of the nozzle is in close proximity to the surface and means for rotating said mask while applying spray material to said surface portion from the nozzle.

2. Apparatus as claimed in claim 1 including a second mask concentric with the shell for defining another limit to said surface portion to be coated, and said second mask and said other mask being spaced from one another on opposite sides of unblocked spray material projected to said surface portion.

3. Apparatus as claimed in claim 2 wherein said second mask is connected to said powerhead for rotation therewith and said second spray limit is adjacent an end peripheral edge of said shell.

4. Apparatus as claimed in claim 2 wherein said second mask surrounds the shell and includes means for coupling said second mask to said other mask for simultaneously shifting both of said masks transversely with respect to the shell sur face and for rotating said masks while applying material to said surface portion from the nozzle.

5. Apparatus as claimed in claim 1 wherein said powerhead includes a plurality of radially expanding clamping shoes and means for camming said shoes radially outward to engage the internal surface of said shell so that said shell is positively clamped to the powerhead for rotation therewith.

6. Apparatus as claimed in claim 5 wherein said powerhead includes a rotatable outer member and an axially shiftable, rotatable inner member, means for axially shifting said rotatable inner member toward said shell, and means associated with said axially shiftable member for actuating said clamping shoe camming means when the member is shifted towards said shell.

7. Apparatus as claimed in claim 5 wherein said powerhead includes a plurality of stop fingers pivotally mounted about the periphery of said powerhead for engagement with a shell to position said shell about the powerhead and means for retract ing said stop fingers when said shoes are cammed radially outward to clamp said shell to the powerhead.

8. Apparatus for externally coating a select surface portion of a cylindrical shell, comprising, in combination, a frame, means defining a work station carried by said frame, at least one material spray nozzle disposed in said work station, means for supporting said shell for rotation in the work station adjacent said nozzle, means including a mask surrounding the shell for defining an axial limit to said surface portion to be coated, means for rotating said mask and means for relatively shifting said mask transversely with respect to the surface so that the inner peripheral edge of the mask in the vicinity of the nozzle is in close proximity to the surface.

9. Apparatus as claimed in claim 8 including a second mask surrounding the shell for defining another limit to said surface portion to be coated, said masks being spaced from one another on opposite sides of unblocked material projected to said surface portion.

10. Apparatus as claimed in claim 9 wherein said second mask is connected to said supporting means and said second spray limit is adjacent'the peripheral edge of said shell.

11. A spray coating system for externally coating select sur face portions of cylindrical shells, comprising, in combination, conveying means for transferring said shells to a preselected position along said conveyor in seriatim order, a frame, means defining a work station carried by said frame, at least one material spray nozzle disposed in said work station, a powerhead adapted to support a shell for rotation in the work station adjacent said nozzle, means for axially moving a shell from said position into and out of said work station, means including a mask concentric with and surrounding a shell supported by said powerhead for defining a limit to said surface portion to be coated, means for shifting said mask transversely with respect to the surface so that the inner peripheral edge of the mask in the vicinity of the nozzle is in close proximity to the surface, means for rotating said mask while applying spray material to said surface portion from the nozzle, and means for controlling said apparatus in continuing cycles for each subsequent shell along said conveyor means.