US2986338A - Spray coating applicator - Google Patents

Description

y 1961 R. D. FOSTER 2,986,338

SPRAY comma APPLICATOR Filed Aug. 5, 1959 oO0000000OOOOOOOGOODOOOOOOOOOOQ 0 /0 5 Q R. D. FOJfer /9 E ;4 INVENTOR.

r BY 2 /2 2/ ATTO/P/VA'K United States Patent( 2,986,338 SPRAY COATING APPLICATOR Filed Aug. 3, 1959, Ser. No. 831,224

, V 1 Claim. (Cl. 239-222) This invention relates to an improved rotary spinner head' for uniform application of a protective coating on the internal surface of a cylindrical object such as a length of pipe preparatory tojits installation as part of a fluid conveying pipe line system. v

In addition to exterior corrosion resistant coverings on pipe lines buried in the ground, it is desirable to place a thin smooth coating film on the interior pipe surface both as a protective coating and to reduce flow friction. Conveniently; internalcoating is done in advance of joining adjacent ends of long p ipe sections and the practice heretofore has been to mount an air operated paintspray gun on a long beam by which the gun and attached air and paint hoses are run from end to end through the pipe. Forbetter control and the deposit of a thoroughly mixed paint coating in thin and. uniform film form over an internal surface without waste, it is here proposed to atomize and throw the'paint as an almost imperceptible mist without a pressure air propellant and by centrifugal force from a hollow spinner.

An object of the invention is to provide a hollow rotary spinner having internal co-operating formations by which liquid paint delivered at the hub first is distributed uniformly in all radial directions and then gains momentum by sweeping from center over an outwardly and backwardly flaring surface of a rotating baffle skirt until flung off the free end of the baffle and impacted forcibly against a forwardly and outwardly flaring spinner surface for a further thinning spread and mixing travel in reverse axial but continued outward direction until discharged in broken up or foglike form from the spinner.

A further object of the invention is to provide a spinner rim with a paint collecting chamber having convergent sides and from which a multiplicity of circularly spaced jet passages lead from a common plane and each on a center line divergently related to the center lines of the next adjacent passages for a discharge of atomized paint particles in fan pattern throughout a wide range outwardly from the spinner head.

Other objects and advantages will become apparent during the course of the following specification having reference to the accompanying drawing wherein Fig. 1 is a side elevation of the improved spinner head and its drive mounting; Fig. 2 is an enlarged vertical sectional view of the hollow spinner head; Fig. 3 is an enlarged elevational view of the spinner rim periphery showing the grouping of jet outlets; and Fig. 4 is a detail section of a fragment of the spinner rim on a still larger scale illustrating the divergent relation of several jet passages.

Referring to the drawing, the hollow spinner head has its hub 1 keyed or otherwise securely fastened on one end of a tubular shaft 2 to be rotated by suitable means, as, for example, a belt pulley 3, at a high spinning rate. Merely by way of example, a rate of seven thousand r.p.m. would be suitable for a spinner head of approximately eight inches in outside diameter and three thousand six hundred r.p.m. would be suitable for use with a spinner head of approximately sixteen inches in diam- Patented. May so, tee;

eter. In effect, the limit of speed for the spinner'may considered as that which the particular unit canwithstand without breakage from centrifugal force. Length offlthe drive shaft may be as long as the axial dimension of the pipe vor other article ,to be internally coated-by relative movement longitudinally between the pipe and the spinner head. Conveniently, the shaft} is rotatably mounted in suitable bearings 4 which, if desired, can be mounted on atraveling carriage for co-operation with a stationarily mounted pipe to be internally coated,

Housed within the tubular drive shaft'Z and projected throughout its length is a nonrotatable" paint deliverycon duit or pipe 5 joined at its rear end, as by a flexible hose 6, with a suitable source of paint supply to be delivered at a low flow pressure andat-a rate substantially that to be discharged by the spinner without appreciable pile up orjr'e'tention of paint withinthe hollow spinner head. An, antifriction bearing 7 is interposed between ,the nonrotat-f able paint supply pipe 5 and the rearend of the'r'otatable' shaft 2. A similar antifriction bearing 8 is interposed between the huh I and the forward end of the paint de livery pipe 5, which latter terminates in a nozzle-9 having.

a fl'ow passage coaxial with the axis of the spinnerhead' and its drive shaft 2.

Th'e' spinner head is a hollow body provided by an annular flange'or wall'10 integral with thehub 1 and with an axially extending peripheral rim 11 to which is detachabl-y securedby screws 12 a front wall or cover plate 13 forwardly spaced from the flange wall 10. Pilotedin'a central opening in the cover plate 13 is the hub portion of a'rearwardly extended and cup-shapeddistributor: 14 secured to the'plate by screws 15 in outwardly nested overlapping relation to the nozzle 9. Rising from the base of the cup-shaped member 14 and on the longitudinal center line thereof is a rearwardly tapered boss or cone 16 terminating in slight clearance relation to the nozzle 9. The peak or point of this boss 16 is carefully I machined and positioned by the cover plate 13 so as to be in true axial alignment with the axis of the delivery passage in the nozzle 9 and the rotational axis of the spinner head. Accordingly, the oncoming paint column projected from the nozzle will be pierced at its exact center by the pointed tip of the tapered boss 16. The symmetrical sides of the boss recede forward on a curved line so that paint discharged axially from the nozzle 9 will be evenly distributed circularly around the tapered boss 16 in all radial directions.

With the spinning of the head during paint delivery,

the paint will spread in an ever increasing circle radially outwardly and sweep outwardly and rearwardly on the backwardly flaring internal bafile surface of the skirt wall 17 of the cup-shaped member 14. The thickness of the circular paint stream will thin out as it flows over the outwardly enlarging baflle surface area and is propelled outwardly under centrifugal force imparted from the spinner head. The free end of the skirt 17 ends in axially spaced relation with the annular flange 10 and against which the paint impacts as it emerges from the free end of the skirt 17. The impact may tend to break up the liquid paint toward particle form to bounce from one to the other of the hollow chamber front and rear walls 13 and 10. The interior face of the back wall or annular flange 10 is flared outwardly and forwardly, preferably in two steps, the first of which, as at 18, is at a greater inclination than that of the second portion 19. Both inclined surfaces are convergently related to the front wall 13 whereby the axial width of the hollow spinner head decreases as its diameter increases. Peripherally, the forwardly flaring portion 19 merges into a more sharply inclined wall surface 20 of relatively short radial dimension and for co-operation with a mating and convergently related opposing side wall a circular paint collecting chamber at the rim.

For good manufacture design, the convergent walls 20 and 21 merge into a curvature of-small radius adjacent their, point of intersection; Extending outwardly through the wall of the rim 11 and radiating from adjacent such point of intersection, are a series of circularly spaced drilled passages or holes 22. Each leads from the interior of the hollow head near a common transverse plane and on a center line which intersects approximately the point of intersection of theconvergent sides 20 and 21. In a practical embodiment and for a spinner head of approximately sixteen inches in diameter, there will be provided a total of two hundred holes equally circularly spaced apart butdrilled successively at angles to one another and arranged in four rows. As best seen in Fig. 4, the center lines of the holes in the four rows respectively diverge outwardly from the common plane of the inner ends of all holes so that their outer ends, in groups, will be spaced apart in the spinner axial direction. Therefore, the outlets of the holes of any one group will be offset from those of the other groups in a pattern substantially as shown in Fig. 3. It will be seen that each hole in the axial direction of the spinner is divergently related to its neighboring hole and the outlets of the several holes are circularly equally spaced apart and provide a symmetrical arrangement for discharging atomized paint through a relatively wide angle with a high degree of equality of distribution toward the surface to be coated.

What isclaimed is:

A rotary hollow head for receiving on the rotational axis thereof a stream of liquid paint and through centrifugal force on the liquid causing the same to be evenly spread circularly and outwardly to the rim of the head and to be projected therefrom in mist form, said head 21 in the rim ll for defining having a peripheral rim and front and rear walls secured to and axially spaced apart by said rim to define a chamber, a hollow drive hub supporting the rear wall, a liquid paint feed pipe housed in the hub and terminated in an axially directed discharge nozzle, a centrally disposed and rearwardly pointed spreader boss carried by the front wall in axial alignment with said nozzle and provided radially outwardly thereof with a rearwardly and outwardly flared annular bafiie wall terminating in closely spaced relation with the interior surface of said rear wall for transferring the distributed liquid thereto, said interior surface of the rear wall extending forwardly and outwardly toward said rim and said rim having outwardly converging sides to provide an internal liquid receiving trough and having a plurality of circularly spaced apart jet passages each projecting through the rim on a straight center line which substantially intersects the point of side wall convergenceand each passage communicating at its inner end with the narrowest part of the trough and in a plane common to the inner ends of all jet passages and transverse to the axis of the rotary head, each jet passage having its center line projected divergently outwardly in relation to the center line of next adjoining jet passages.

References Cited in the file of this patent UNITED STATES PATENTS 1,736,799 Planert Nov. 26, 1929 2,503,722 Gothard Apr. 11, 1950 2,645,525 Nyrop July 14, 1953 FOREIGN PATENTS 73,724 Austria Sept. 10, 1917 500,907 Italy Nov. 22, 1954 506,003 Germany Aug. 28, 1930

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