ROTARY SPRAYERS FOR APPLYING UNIFORM COATS

Abstract: The rate of travel of each spray head (27) (27A) of a rotary sprayer along arcuate paths across a conveyor (16) carrying work to be spray-coated is so varied from a maximum adjacent the margins of the conveyor (16) to a minimum centrally thereof that the thickness of the deposited layer is substantially uniform wherever applied. In one embodiment, each spray head (27) has a connection (26) (92) (93) (94) with the outer end of a fixed rotor arm (25). A rod (95) pivotally attached to the connection (26) has a cam follower (99) in engagement with a rotor-encircling cam path (100) and a link (97) pivotally connected to the rotor hub (23) with the cam path (100) operable to effect the swinging of the spray heads (27) to affect their travel rates in the wanted manner. In another embodiment, each spray head (27A) is fixed on a rotor arm (26A) pivotally connected to the rotor hub (23A) and having an angularly disposed arm (105) carrying a cam follower (99A) held in a rotor-encircling cam path (100A) operable to swing the rotor arms (26A) to affect the required variations in the rates of travel of the spray heads (26A). To prevent momentary pressure increases and decreases as spray head valve elements (38) are closed and opened from being causes of uneven sprayed coats, the rotor (20B) has a chamber (110) through which spray material is delivered which is disposed and dimensioned to provide an air cushion.

Description: - i Description Rotary Sprayers For Applying Uniform Coats Technical Field This invention relates to rotary sprayers used in spraying work while carried by conveyors. Examples of such work are hides, parts thereof and pieces of sheet plastic or of other sheet material where lack of uni¬ formity in the thickness of sprayed layers or coats detracts from the appearance of the sprayed work. Background Art One type of rotary sprayer has rotor spaced from a conveyor with its axis normal to the center thereof. Each of a series of spray heads is connected to the rotor by a radial arm of a length such that the spray heads have arcuate paths intersecting the margins of the conveyor. Such a rotary sprayer is illustrated by United States Patent No. 4,151,808 in which it is noted that the radial spacing of the spray heads from the rotor axis should be as great as is practicable in order to make the thickness of the deposited material as nearly uniform as possible wherever applied along the spray path or paths. It will be appreciated that as the radius of the arcuate paths increases, the amount of travel of the spray heads lengthwise of the conveyor decreases on both sides of the center of the conveyor relative its transverse travel . The maximum radial distance between the spray heads and the rotor axis is so limited for practical reasons, both of contruc- tion and space available for sprayer installations, that it has hitherto been necessary to accept a varia¬ tion in the thickness of the deposited layers that results in a departure from ideal quality of the sprayed work and, in addition, a waste of spray material. The rotary sprayer disclosed in United States Patent No. 2,397,482 utilized spray heads that discharged fan- shaped spray and the spray heads were turned by cam means as they followed arcuate paths across the conveyor to maintain the fan-shaped sprays parallel and lengthwise thereof. Disclosure of Invention In accordance with the present invention, a rotary sprayer is of the type having a rotor spaced from the center of a conveyor with its axis normal thereto and provided with a series of spray heads spaced a distance from the axis of the rotor which establishes an arcuate path therefor such that each spray head intersects ' the margins of the conveyor with the operation of each spray head automatically controlled to effect the discharge of spray when and where wanted to spray on work carried by the conveyor. Means are provided to make the thickness of sprayed layers substantially uniform wherever applied by so varying the relation of each spray head to its normal arcuate path that the thickness of the spray mate¬ rial deposited thereby, wherever applied, approaches to a wanted extent that uniformity that would result if that path were straight, in practice by gradually controlling the rate of travel of each spray head for a maximum adja¬ cent the margins of the conveyor to a minimum centrally thereof. In one embodiment of the invention, such variations in rates of spray head travel are effected by connecting each spray head to a rotor arm in a manner enabling its radial spacing from the rotor axis to be effected by means of a cam follower in engagement with a fixed, rotor- encircling cam path. Such variations in radial spacing is preferably accomplished by connecting each spray head to its rotor arm for movement in an arc relative to the outer end thereof and under the control of a rod provided with the cam follower. In another embodiment of the invention, each spray head is fixed on the outer end of a rotor arm pivotally connected to the rotor to swing in a plane parallel to the conveyer and provided with a laterally disposed arm carrying a cam follower in engagement with a rotor encir¬ cling cam path. In order to prevent momentary pressure increases and decreases from being a cause of variations in the volume of sprayed material as the discharge of spray from each spray head is shut off or resumed, the rotor is provided with a chamber through which spray material passes for delivery to the spray head and which is disposed and dimensioned to provide an air cushion. Brief Description of Drawings The details of the invention will be described in connection with the accompanying drawings in which - Fig. 1 is a perspective view of an installation in which a rotary sprayer in accordance with the invention is used to spray hides carried by a conveyor; Fig. 2 is a top plan and partly sectioned view of the housing for the rotor drive; Fig 3 is a section, on an increase in scale, taken approximately along the indicated line 3—3 of Figure 1; Fig. 4 is a section, on a further increase in scale, taken approximately along the indicated line 4— of Figure3; Fig. 5 is a section, on an increase in scale, taken approximately along the indicated line 5—5 of Figure 1; Fig. 6 is a view of a spray head and its connection with the rotor as viewed from the position indicated by the lines 6—6 of Figure 5; Fig. 7 is a section of the rotary air control joint taken approximately along the indicated line 7—7 of Figure 5 showing schematically the control of air thereto; -Δ - Fig. 8 is a schematic view of a spray head; Fig. 9 is a view illustrating the movement of the spray heads relative to their normal arcuate paths. Fig. 10 is a fragmentary and partly sectioned side view of a rotor in accordance with another embodiment of the invention; Fig. 11 is a view taken approximately along the indicated line 11—11 of Figure 10; and Fig. 12 is a fragmentary vertical section of the rotor illustrating the embodiment of the invention in which the volume of discharged spray material is held constant in spite of momentary pressure variations that occur as the valves of spray heads are closed and opened. Best Mode For Carrying Out The Invention As shown in Figure 1, apparatus in accordance with the invention has a vertical stand 15 at one side of a conveyor, generally indicated at 16, and a housing 17 extending, transversely of and a substantial distance above the upper course of the conveyor. The housing 17 supports a rotor, generally indicated at 18 with the rotor axis normal to the center of the conveyor. The rotor 18, as may best be seen in Figure 5, includes a vertical upper shaft 19 having an axial bore 21 extending from end to end thereof, a coaxial bottom unit 20 having an axial bore 22 in its upper end, and an intermediate hub or flange 23 having an axial port 24 placing the bore 21 in communication with the bore 22. The rotor hub 23 includes a series of radial tubular arms 25. A connection in accordance with the invention, generally indicated at 26 and later detailed, supports a spray head, generally indicated at 27 at the outer end of each arm 25. The construction of the rotor sprayer and its functioning may be most readily understood with reference to the construction and wanted operation of the spray heads. For that purpose, reference is made to Figure 8 wherein a spray head 27 is schematically shown as having a chamber 28 having a nozzle or discharge port 29 and a spray fluid inlet port 30 below an air inlet port 31. The stem 32 of a chambere valve element 33 extends downwardly from an upper chamber 34 provided with a port 35 below the head 36 of the stem 32 which is normally urged downwardly by a spring 37 to seat the cham¬ bered valve element 33 to close the discharge port 29 and the fluid inlet port 30 with which a port 38 of the valve element 33 registers when the valve element is raised by admission of air through the port 35 into the upper chamber 34. The valve element 33 has a restricted outlet port 39 in alignment with the discharge port 29. With this construction, each spray hea 27 is normally closed to block the discharge of the spray form ing fluids but is readily opened by an air pulse of wanted dur tion delivered through the port 35. The shaft 19 of the rotor 18 extends through the bottom a top walls of the housing 17 and through a transverse support 4 mounted therein and is rotatably supported by bearing units 41 The shaft 19 is provided with a sprocket 42. An electric moto 43, mounted in the housing 17 is connected to a gear box 44 driving a Reeves pulley 45 which is connected by a belt 46 to pulley 47 fast on a vertical shaft 48. The shaft 48 carries a sprocket 49 connected to the drive shaft sprocket 42 by a chai 50. A conduit 51 from a source, not shown, of air under a wanted pressure is connected by a rotary joint 52 to the upper end of the shaft 19 thus connecting the bore 21 to the conduit 51. The bottom unit 20 of the rotor 18 has, see Figure 5 , a headed section 53 secured to the under- surface of the flange 23 and provided with an upper series of radial ports 54 opening into the bore 22, one port 54 for each spray head port 31 and placed in communication therewith by a conduit 55 and a lower series of radial ports 56 opening into a downwardly opening axial bore 57. There is one port 56 for each spray head 27 and is con¬ nected to the spray fluid inlet port 30 thereof by a con¬ duit 58. The bore 57 is counterbored and threaded to receive the threaded upper end of the upper section 59 of the generally indicated rotary joint 60. A bushed tube 63 extends upwardly through the lower rotary joint section 61 and through the upper section 59. The lower end of the section 61 is counterbored to receive packing 64 against which the threaded end of an end cap 65 of the tube 63 is seated. A conduit 66 from a spray mate¬ rial source, not shown extends through a tubular arm 67 pivotally linked at one end as at 68 to the lower end of the upright 15 with its other end connected to the end cap 65 by a pivot 69 to hold the lower rotary joint section 61 against turning with the rotor 18. From the foregoing, it will be apparent that as the rotor 18 turns, the spray heads 27 have arcuate paths acros the conveyor 16 both upstream and downstream of the rotor axis. In practice, the radial distance the spray heads 27 are spaced from the rotor axis is such that the arcuate spray paths intersectthe margins of the conveyor as far fro said axis as is practicable. It is apparent that spray is to be discharged not only when a spray head is travelling across the conveyor but also that the discharge of spray ma be wanted during only a part of such travel. In addition, it may be desired that spray be discharged only when work i under a spray head or only along one of its spray paths. In order to control the opening of the spray heads 27 when and where the discharge of spray is wanted, the lower end of the shaft 19 is enlarged to provide a shoulder 70 to which a ring 71 of a generally indicated rotary air control joint 72 is secured. The air control joint 72 also includes a control ring 73 separated from the shaft 19 by a bushing 74 and held under pressure against the upper surface of the ring 71 by a concave spring washer 75 by means of a nut 76 threaded on the shaft 19 with a ball bearing unit 77 between the nut and the washer 75. The ring 71 has a series of ports 78 extending verti¬ cally through it, one for each spray head. Each port 78 is placed in communication with the pulse inlet port 33 of the appropriate one of the spray heads 27 by a conduit 79 ex- tending downwardly through holes 80 in the hub 23. In order to control the discharge of spray when and where wanted along either the upstream or downstream arcuate path, air is delivered, see Figures 5 and 7, through ports 81 opening through the undersurface of the ring 73 in a manner such that when a port 78 of the ring 71 comes into a position to receive air there from, a pulse is available to operate the associated spray head with the pulse a duration depending on port dimensions and the rate of rotor rotation. The ring 73 is also provided with relief ports 82. In this connection, it will be noted, see Figures 3 and 5, that the ring 73 has a worm gear 83 attached thereto and that a worm 84 on a shafting 85 within the housing 17 holds the ring 73 from turning except when the shafting is turned by the manually operated, exposed knob 86 by which the rela- tionship of the ring 73 to the conveyor can be adjusted. In the rotary sprayer as disclosed, there are two like conduits 87 by which air is delivered to the ring 73, one for upstream operation and one for downstream spray head operation, each provided with a manually operated valve 88. One such conduit is schematically shown in Figure 7 as in¬ cluding a manifold 89 provided with conduits 90, each con¬ trolled by a valve 91. The valves 91 may be of a manually operated type or they may be controlled as . , disclosed in United States Patent No. 4,151,808 to deliver air to the ring 73 only when work is positioned to receive spray. The rotary spray as thus far described is or may be substantially like that shown and described in the above referred-to patent except for the connections 26 between the rotor 18 and the spray heads 27. Each connection 26, see Figures 4 - 6, includes a member 92 with one end extending into a clevis at the outer end of the associated arm 25 and connected thereto by a pivot 93. A right angular support 94 is attached to the outer end of the member 92 and has a spray head 27 attached to its depending end. The member 92 has a rod 95 connected thereto by a pivot 96 and to one end of an arm 97 by a pivot 98. The arm 97 is pivotally connected to the hub 23. The pivot 98 is also provided with a cam follower 99 in engagement with a cam 100 supported by a bracket 101 on the undersurface of the housing 17 to which bracket the cam 100 is connected as by bolts extending through slots 102 enabling the position of the cam track to be adjusted to ensure its correct position relative to the conveyor 16. The cam is shaped and dimensioned, when properly positioned, to effect the swinging of each member 92 in a horizontal plane to vary the radial distance of each spray head 27 as it crosses the conveyor from a maxi- mum adjacent one margin of the conveyor to a minimum cen¬ trally thereof and then again increase its radial distance until the maximum distance of that spray head is again attained. Each cam follower 99 is held in engagement with the cam 100, during operation of the sprayer, by centrifuga force. In the disclosed embodiment, the conduits 55, 58, and 79 consist of sections interconnected by. couplings 103, one carried by each arm 25. Reference is made to Figure 9 wherein the normal spray path is indicated as it would be were each spray head 27 ha ing a fixed position on an arm 25. Because of the varying radial distance between each spray head and the axis of the rotor 18 effected by the cam controlled connections 26, the resulting spray path is shown as having a constantly decrea ing radial distance from the rotor axis from a maximum adja -■ cent one margin of the conveyor to a minimum centrally there¬ of and a constantly increasing radial distance from the rotor axis until a maximum is reached adjacent the opposite margin of the conveyor. In the embodiment of the invention illustrated by Figures 10 and 11 the housing, rotor and the means delivering air and fluids to the spray heads and the spray heads are or may be identical to that described in connection with Figures 1 - 9 and are not again detailed and like reference numerals dis¬ tinguished by the suffix addition A designate corresponding parts. In this embodiment of the invention, the rotor 18A has the periphery of its hub or flange 23A entrant of clevises at the inner end of arms 103 of the connections 26A and connected thereto by pivots 104. Spray heads 27A are fast on the outer ■ends of the arms 103. The inner end of each am 103 has a member 105 extending laterally thereof substantially at right angles thereto and provided with a cam follower 99A entrant of the cam path 100A attached to the housing 17A. The cam path 100A is so shaped and dimensioned that as a spray head 27A starts across a con¬ veyor it effects the swinging of each arm 103 so that its rate of travel decreases from a maximum adjacent one margin of the conveyor to a minimum centrally thereof at which point, the arm 103 is radial. The cam path then causes each arm to so swing as to effect the gradual acceleration of the travel of its spray head 27A until a maximum rate is attained at the opposite margin of the conveyor. While the path of the spray heads more nearly conforms to that established if their relationship to the rotor axis were fixed, the end result is again that of a substantially uniformity of deposited spray layers on the work. The embodiment of the invention illustrated by Figure 12 is generally similar to that illustrated by Figure 5 and corresponding parts are identified by the appropriate refer¬ ence numerals distinguished by the suffix addition B. The bottom unit 20B includes an upper section 106 in the form of a ring and a lower section 107 having an upwardly open ing chamber 108 placed in communication with the air passage 21B by the bore of the ring section 106. The chamber 108 has radial ports 54B, one for each spray head, not shown, to whic conduits 55B are connected. A rotary joint 60B connects the section 20B to the fixed section 61B. The upper end portion of the section 20B is of increased diameter providing an exposed shoulder 109 and is formed with a lower upwardly opening chamber section 110. A cover or upper section 111 is secured by bolts 112 which exten through the sections 106 and 107 and into the hub or flange 23B. Bolts 113 extend upwardly through the shoulder 109 of th chamber sections 110 and into the upper section 111 to clamp those sections together and incorporate the section 20 B in th rotor 18B. Radial ports 56B adjacent the bottom of the chamber 110, one for each spray head, not shown, have conduits 58B connecte thereto with the space above the ports 56B an air chamber of a capacity such that an air cushion is provided adequate both to absorb the momentary pulses of increased pressure resulting as spray heads are successively closed and thus prevent such pulse from being attended by a momentary increase in the volume of material being sprayed and to function as an attenuator to min mize pressure drops as the valves are opened.

Claims: Clai s 1. Apparatus for spraying work being carried o a con¬ veyor, said apparatus including a rotor spaced from the conveyor with the rotor axis normal relative to the center thereof, means to rotate said rotor, a series of spray heads, a connection between each spray head and said rotor, said connections spacing said heads from the rotor axis a distance such that the spray heads have arcuate paths across the con- veyor upstream and downstream with respect to said rotor axis, means operable to effect the discharge of spray from each head as it travels across the conveyor along at least one of said paths, and means operable to so vary the relation of each spray head to said one path that the thickness of the spray material deposited thereby approaches to a wanted extent that uniformity that would result if said one path were straight. . 2. The apparatus of claim 1 in which the means operable to vary the relation of the spray heads relative to said path includes means operable to move each spray head relative to said one path during the crossing of the conveyor, said last named means including a cam follower carried by each connection, and a fixed cam engaged by each cam follower during said crossing. 3. The apparatus of claim 2 in which the spray head moving means is operative to decrease the rate of travel from a maximum adjacent one margin of the conveyor to a minimum centrally thereof and then increase said rate to a maximum adjacent the other margin of said conveyor. 4. The apparatus of claim 2 in which the spray head moving means is operative to decrease the racial distance of each spray from the axis of said rotor from a maximum adjacent one margin of the conveyor to a minimum centrally thereof and then increase said distance to a maximum adjacent the other margin of said conveyor. 5. The apparatus of claim 2 in which each connection includes a pivot carried by the rotor, a first mem¬ ber of substantial length to which the associated spray head is connected and which is supported by said pivot and the spray head moving means includes a second, relatively short member to which the cam follower is attached and which is connected to and extends laterally of said first member thereby to effect movement of said spray head in response to movement of said second member by said cam path, said cam path shaped and dimensioned to effect the forward swinging of each spray head from a first position into a second position and back into said first position as that spray head crosses the con- veyor, said second position attained centrally of the conveyor. 6. The apparatus of claim 2 in which each connection includes a fixed outwardly disposed support, a mem¬ ber on which a spray head is mounted, means con- necting said member to the outer end of said support and effect predetermined variation in said radial distance, and said cam path so shaped as to actuate the linkage first to decrease said radial distance from a maximum adjacent one margin of the conveyor to a minimum centrally thereof and then increase said distance to said maximum adjacent the other margin of the conveyor. 7. The apparatus of claim 6 in which the linkage in¬ cludes a first link pivotally connected to the rotor and a second link of substantial length pivotally connected to the first link and said member to effect the swinging thereof in a plane to vary the radial distance between said head and the rotor axis„ 8. The apparatus of claim 2 and structure by which said rotor is rotatably supported and the cam path at least partially encircles the rotor and is adjust¬ ably connected to said structure to enable the cam at . ■ i J - 9. The apparatus of claim 1 in which the means oper¬ able to effect the discharge of spray from each spray head includes means to deliver spray mate¬ rial thereto, means to deliver air thereto, a 5 normally closed valve associated with each head in control of said spray material and said air delivery means, and means operable to deliver air to each valve to effect the opening thereof only where wanted during the crossing of the 10 conveyor by said head, and the means delivering air to said heads includes a passageway extending axially upwardly through said rotor and provided with an air chamber, and conduits, one for each spray head and in communication therewith and 15 with said chamber below the upper end thereof providing an air cushion absorbing momentary pressure increases occurring- each time a spray head valve closes and minimizing pressure drops as said valves open. 20 10. The apparatus of claim 9 in which the- rotor includes an upper shaft portion, a coaxial bottom unit and an intermediate hub, said bottom unit includes an upper portion of increased ■ diameter providing a headed section having an 25 exposed bottom shoulder, said headed section including a lower portion of said air chamber and an upper portion thereof detachable con¬ nected thereto and to said hub, and bolts ex¬ tending upwardly through said shoulder inter- 30 connecting said chamber portions, said conduits are connected to said lower portion.

Inventors: BECK ALFRED E, CUSHING RICHARD D
Applicants: CIRCLE MACHINE CO INC
Application year: 1981
Main classification: B05C5
IPC codes: B05B13