US3461840A - Curtain coating apparatus for applying coating materials - Google Patents

Description

Aug. 19, 1969 J. a. TURNER 0 CURTAIN COATING APPARQTUS FOR APHJYING COATING MATERIALS Filed April 4; 9 2 h9'2. $"599i.

I In We 7: to 7 JONATHAN B. TURNER J. B. TURNER CURTAIN COATING APPARATUS FOR APPLYING COATING MATERIALS Filed April 4., 1966 2 Sheets-$hee 2 I'd/kn tar JONATHAN B. T'URMER United States Pateiat "ice US. Cl. 118-314 3 Claims ABSTRACT OF THE DISCLOSURE An apparatus for coating articles which comprises a plurality of nozzles for forming one or more unbroken curtains of coating material and means for grasping an article and projecting it through the curtain or curtains onto a receiving means.

The present invention relates to a method and apparatus for applying paint or other coating materials. More specifically, the invention relates to a method and apparatus particularly adapted to the application of a coating to the top and side surfaces of various types of molding including picture frame sections and the like.

While various types of automatic spray apparatus are known in the art, there has not heretofore been developed a wholly satisfactory method and apparatus for the spray coating of elongated molding strips such as picture frame sections or the like which often have rather varied and intricate profiles. In order to assure that all areas to be coated are in fact reached by the spray, particularly where the molding element has a relatively complex profile, it has been common to use a fine atomized spray which tends to cover all exposed areas, such as the top and side surfaces of a molding element which is lying on a work surface beneath the spray. However, such systems, while they are effective in covering all areas to be coated, have several disadvantages, since they utilize unduly large quantities of coating material, and they also require rather elaborate exhausting equipment and makeup air equipment to handle the fine spray or mist which tends to fill the entire area where the coating operation is being carried out.

The present invention relates to an improved method and apparatus for applying such coatings by creating one or more non-atomized substantially continuous curtains of coating material and by feeding the molding elements to be coated through such curtains at a predetermined high rate of speed. One or more nozzle members are utilized to produce such curtains of coating material, and while it may be said that the nozzles spray the coating material on the molding elements, it should be understood that the term spray is used herein in a broad sense, since in fact I provide for a substantially continuous relatively low impact non-atomized curtain of coating material which impinges on a molding strip passed therethrough at a relatively high speed and deposits a coating thereon of unusually high quality.

It is therefore a general object of the present invention to provide an improved method and apparatus for the coating of elongated molding elements and the like so as to eliminate the foregoing disadvantages of the methods heretofore known and produce an improved coating which can be applied at relatively small cost and in a minimum of time.

A more specific object of the invention is to provide a method and apparatus including one or more nozzle members for the coating of elongated molding elements and the like which method and apparatus utilize a nonatomized uniformly distributed curtain of coating ma- 3,461,840 Patented Aug. 19, 1969 terial so as to minimize waste of such material and eliminate the need for elaborate exhausting equipment, while at the same time providing all of the advantages of atomized spray systems with respect to ability for coating intricate profiles and the like or predetermined selected portions of the top and side surfaces thereof.

The foregoing and other objects and advantages of the invention will be apparent from the following description thereof.

Now, in order to acquaint those skilled in the art with the manner of making and using my invention, I shall describe, in conjunction with the accompanying drawings, the best mode contemplated by me of carrying out the invention.

In the drawings:

FIGURE 1 is a side elevational view, partly broken away, showing coating apparatus constructed in accordance with the present invention;

FIGURE 2 is an end elevational view of the coating apparatus of FIGURE 1;

FIGURE 3 is a top plan view of the apparatus of FIG- URE 1 further showing fluid conduit means and pressure regulating apparatus which comprises a part of the coating machine of FIGURES 1 and 2;

FIGURE 4 is a schematic elevational view illustrating an arrangement where a plurality of nozzles are utilized to coat the top and side surfaces of an elongated molding strip in accordance with the present invention;

FIGURE 5 is a perspective view of a fan deflection type spray nozzle which may be used in conjunction with the apparatus of FIGURES 1-3 in accordance with the invention;

FIGURE 6 is a side elevational view of the nozzle of FIGURE 5; and

FIGURE 7 is a schematic elevational view illustrating the manner in which a molding strip to be coated is moved past a spray nozzle along a path sufiiciently close to the nozzle as to pass through a substantially solid curtain of coating material emitted from the nozzle.

Referring now to the drawings, FIGURES 1-3 show a coating machine 20 including a carriage 22 having an upper feed table 24, upright supporting legs 26, a bsae 28, and a plurality of casters 30 on which the carriage is mounted so as to facilitate movement of the machine 20 to any desired location. A pair of side plates 32 are sup ported from the upright legs 26 at each longitudinal side edge of the feed table 24, and in the embodiment being described three shafts 34, 36 and 38 extend horizontally between the side plates 32 and beneath the feed table 24. The three shafts 34, 36 and 38 are parallel to one another and spaced along the length of the feed table 24, and each shaft has its ends supported in bearings (not shown) carried by the oppositely disposed side plates 32.

A variable speed drive motor 40 is supported on a frame member 42 and includes a motor pulley 44 which drives a second pulley 46 through an endless drive belt 48. The driven pulley 46 is 'aflixed to a shaft 50 which in turn dirves an endless chain 52 by means of a sprocket 53 (see FIGURE 2). The endless chain 52 is wrapped over drive sprockets 54, 56 and 58 (see FIGURE 1) mounted on the ends of the shafts 34, 36 and 38 respectively, and a pair of guide sprockets 60 and 62 serve to maintain the drive chain in proper wrapped relation on the several drive sprockets.

The shaft 34 has a friction drive roller 64 fixedly mounted thereon intermediate the ends of the shaft for rotation therewith. The diameter of the roller 64 is such that it projects upwardly through an opening in the feed table 24 to provide for frictional driving engagement between the roller and a molding strip or the like disposed at the top of the feed table. In a similar fashion, a friction drive roller 66 is fixedly carried on the shaft 36 intermediate the ends thereof, and a friction drive roller 63 is similarly mounted on the shaft 38. Each of the friction drive rollers 64, 66 and 68 is positioned approximately midway between the ends of the respective shaft on which it is mounted, and each such roller projects slightly above the top surface of the feed table 24 so as to be capable of frictional driving engagement with the underside of a molding strip M disposed above the table, as shown for example in FIGURE 2.

A pair of bearing supports 70a and 70b are mounted at the top of the feed table 24, and each supports a bearing 72 in a vertically adjustable manner. A horizontal shaft 74 has one end supported in each of the bearings 72 so that the shaft is freely rotatable. The bearing supports 70a and 70b are provided with threaded vertically movable adjusting rods 76a and 76b respectively which are manually rotatable to adjust the height of the bearings 72 and thereby adjust the height of the rotatable shaft 74. A guide roller 73 is fixedly mounted on the shaft 74 approximately midway between the ends of the shaft for rotation therewith, and as best shown in FIGURE 2 the roller 78 is adjustably spaced above the top surface of the feed table 24 in spaced relation to the drive roller 64.

In a similar manner, a second pair of bearing supports 80a and 8011 support bearings 82 which carry the ends of a horizontal shaft 84. A guide roller 86 is carried on the shaft 84 midway between the ends thereof, and threaded adjusting rods 88a and 881) may be manually rotated to adjust the height of the rotatable shaft 84 and thereby adjust the spacing between the guide roller 86 and the top of the feed table 24. In the embodiment being described, a third pair of bearing supports 90a and 9% support bearings 92 which rotatably carry the ends of a horizontal shaft 94. A guide roller 96 is carried on the shaft 94 midway between ends thereof, and threaded adjusting rods 98a and 08b serve to adjust the spacing between the guide roller 96 and the top of the feed table 24.

The three guide rollers 78, 86 and 96 are disposed immediately above the three friction drive rollers 64, 66 and 68 respectively so as to cooperate with the latter in feeding a molding strip through the coating apparatus. In addition, a pair of side guide rails 100 and 102 are mounted in spaced parallel relation at the top of the feed table 24 so as to guide a molding strip which is being fed through the apparatus, and preferably at least one of the side rails is laterally adjustable to accommodate various sizes of molding elements. The side rails 100 and 102. may be made of nylon or have nylon bearing pads or the like on the inside thereof in order to provide smooth non-friction surfaces for engagement with a molding strip moving therealong.

A pair of upright rods 104 and 106 are provided at the spray end of the machine 20 at one side thereof, and in the embodiment being described one such rod 104 has a horizontal nozzle support rod 108 attached at its upper end so as to extend inwardly over the guide path defined by the side rails 100 and 102. A coating supply hose 110 (see FIGURE 3) extends from a pressure regulator unit 112 to the horizontal support rod 108 where it is held by a suitable clamp 114 which permits adjustment of the hose along the length of the rod. At the end of the hose 110 there is provided a nozzle 116 for producing a nonatomized spray or curtain of paint or other coating material.

A supply container 118 including a pump (not shown) is provided for holding a supply of the coating material, and a supply hose 120 is connected from an outlet fitting 122 at the container to a by-pass strainer unit 123 and then to an inlet fitting 124 provided at one end of a header 126. The pressure regulator unit 112 is connected with the header 126, and FIGURE 3 shows three additional pressure regulators 128, 130, and 132, so that when desired as many as four different nozzles may be supported over the feed path so as to direct a curtain of coating material at molding strips or the like which are fed through the apparatus. A large catch pan 134 is disposed underneath the spray or coating area for collecting any paint which is not deposited on the molding strips passing through the coating area. A return hose 136 has one end connected at the bottom of the catch pan 134, and its other end, which includes a filter 137 (see FIGURE 2), feeds into the supply container 118 so as to recirculate all unused paint for further use.

The coating material is pumped under pressure from the supply container 118 through the conduit to the bypass strainer unit 123. The unit 123 includes a pair of filters or strainers 138 and 140 arranged in parallel, and these strainers can be alternately opened to the line 120 so that when one strainer requires service or replacement it can be disconnected from the line and the other strainer put into use, without need for shutting down the entire machine. The supply of coating material passes through one of the strainers 138 and 140 and is then supplied to the header inlet 124 to which the four fluid pressure regulators 112, 128, 130 and 132 are connected. The embodiment being described is adapted to have up to four nozzles, such as the nozzle 116, positioned at the coating area and directed at a molding strip being fed through the machine as such molding passes over the catch pan 134. Each such nozzle is supplied with coating material from a conduit, such as the hose 110, which extends from one of the pressure regulators 112, 128, 130 and 132 to a corresponding nozzle, and thus the pressure at each nozzle is individually controlled. Any excess coating material which is pumped from the supply container 118 and not conducted through the nozzles will pass through a return hose 142 (see FIGURE 3) connected at the rear end of the header 126 and will be conducted directly back to the supply container. A surge tank 144 is provided at the rear end of the header 126 where the return hose 142 connects thereto.

FIGURES 5 and 6 show the fan deflection type nozzle 116 which is Well suited for use with the present invention. The nozzle 116 includes a body portion 148 having a longitudinal fluid passage 150 from which the paint or other coating material is emitted. The nozzle 116 is further provided with a head portion 152 which includes an inclined deflection surface 154 spaced from and opposite the end of the fluid passage 15.0 and at an inclination to the longitudinal axis of the latter. Consequently, as the coating material leaves the passage 150 it impinges against the inclined deflection surface 154 and is formed into a very thin fan-shaped spray as indicated generally in FIGURES 4 and 7. As the angle a defined between the longitudinal nozzle axis and the deflection surface 154 is increased, the width or included angle of the fanshaped spray pattern will be increased, while reduction of the angle a will reduce the width or included angle of the spray pattern.

A fan-deflection type nozzle such as the nozzle 116 has been used extensively heretofore as a water nozzle to produce a spray of water. However, within a limited distance from the nozzle, the spray will comprise a nonatomized curtain, and in accordance with the present invention such a nozzle is utilized to apply paint or other coating material to a molding strip which is passed sufficiently close to the nozzle as to be conducted through the non-atomized curtain portion of the spray produced by the nozzle. In other words, the molding strip to be coated is moved at a relatively high speed past the nozzle along a path sufiiciently close to the nozzle that the nonatomized curtain of coating material impinges on the molding before the spray has had a chance to break up into atomized particles. While other types of nozzles may be utilized in conjunction with the method and apparatus of the present invention, it is important that the nozzle used be of a type which will produce a substantially continuous non-atomized curtain of coating material at least for a limited range, and that the molding being coated be disposed within such range.

It is also important to note in connection with FIG- URE 4 that a plurality of nozzles may be located at the coating or spray area over the catch pan 134 and aimed at a molding strip M or the like moving along the feed path defined by the side rails 100 and 102 and over the pan 134. Thus, FIGURE 4 shows three fan deflection type nozzles 156, 158 and 160 which are located in different positions and all directed at a molding strip M which is being moved longitudinally through the three spray curtains. FIGURE 7 illustrates the manner in which one of the single fan deflection type nozzles will produce a very thin fan-shaped spray which remains a substantially solid curtain of coating material within a distance L from the nozzle, beyond which the spray tends to break up into atomized particles, and there is shown a molding strip M which in accordance with the present invention is passed through the curtain of coating material at a distance from the nozzle which is less than the distance L.

In operation, a strip of molding M is positioned lengthwise on the top of the feed table 24 and one end of the molding is fed between the side rails 100 and 102 into the nip defined between the first friction drive roller 64 and the first guide roller 78, whereupon the molding strip will be advanced through the apparatus by the roller 64 and the additional friction drive rollers 66 and 68, while being held down by the three upper guide rollers 78, 86 and 96. In this manner, the molding strip M is conveyed rapidly over the catch pan 134 and through the curtain or non-atomized portion of the spray produced by the nozzle 116 and is delivered to a take-away conveyor 162 (see FIGURE 1) which moves transversely to the direction of feed through the coating apparatus 20 and which conveys the coated molding strip M to a dryer 164.

Where the molding strip M is relatively simple in configuration and the entire top and side surfaces are to be coated, it may be suflicient to employ only a single nozzle such as illustrated in FIGURES 1-3. On the other hand, in some instances where the profile of the molding strip is more complex, or where it is desired to coat only certain selected portions of the top and side surfaces of the molding, it will :be necessary to utilize a plurality of spray nozzles directed at the molding from different angles, as shown by way of example in FIGURE 4. It is an important advantage of the present invention that any desired number of nozzles may be utilized and may be positioned and aimed from different angles as may be necessary to coat all or selected portions of the top and side surfaces of molding strips having varied and intricate profiles, and yet the disadvantages of conventional atomizing spray systems are eliminated.

In particular, the spray curtains utilized in accordance with the present invention are substantially continuous non-atomized sprays, preferably of low impact, and all coating material not deposited on the molding is collected in the catch pan 134 and recirculated. Waste of coating material is thus at a minimum, and no exhaust-equipment or make-up air equipment is necessary. The speed at which the molding strips M are fed through the apparatus by the friction drive rollers 64, 66 and 68 is in the range of 400 to 750 feet per minute. The pressure at each nozzle is preferably maintained between and 25 psi. in order to achieve the desired substantially continous non-atomized curtain of coating material. The total system pressure produced at the header 126 by the fluid pump (not shown) is adjustable up to approximately 125 psi. in the particular embodiment being described, in order that ample pressure may be supplied at each of the four nozzles where it is desired that all such nozzles be utilized, it being understood that the pressure at each nozzle is individually controlled by a corresponding one of the pressure regulators 112, 128, 130 and 132. The nozzle pressures and the speed at which the molding strips M are fed through the coating area are all significant factors in the method described herein in order to achieve the important advantages of the present invention.

The foregoing method and apparatus are extremely useful in applying paint and other coating materials to the top and side surfaces of molding strips. The molding may be of any length, width and thickness, and the profile may be plain or may be ornamented with deep or shallow ornamentation. The spray area may contain one or a plurality of nozzles, preferably fan deflection type nozzles, aimed so as to coat the entire top and side surfaces of the molding strips or only selected portions thereof. Due to the non-atomized substantially solid curtain of coating material which is provided, and the relatively high speed of 400 to 750 feet per minute at which the molding passes through the spray area, there results a smooth, even coat of predetermined thickness and hiding power, without any of the common defects such as sag, run or orangepeel. Elaborate exhausting equipment and make-up air equipment is not required, and clean-up of the apparatus is rapid and inexpensive. The coating machine 20 is readily portable, and changeover from one color to another is accomplished by simply moving one coating machine out of the production line and moving another machine into the line. Moreover, I have found that coatings of paint or the like applied by the foregoing method and apparatus are superior in flatness and drying capabilities, and because of the high speed at which the machine operates, and the fact that the paint is directed only to those specific areas where it is required, coatings can be applied at less expense than with the methods and apparatus heretofore known.

I claim:

1. A curtain coating apparatus comprising means to form an unbroken curtain of coating material in a coating zone, means upstream of said coating zone to feed individual strip form articles into and through said coating zone along a predetermined path and means downstream of said coating zone to receive said articles; said feeding means comprising a plurality of pairs of cooperating rolls arranged along said path one roll of each of said pairs being placed below said path, the other being placed above said path, said rolls having horizontal axes, said rolls above said path being vertically adjustable so that each of said pairs of rolls can grasp an article to propel it along said path, and drive means connected to each of said rolls below said path for driving said rolls at a speed suifcient to project an article through said coating zone and onto said receiving means..

2; The apparatus of claim 1 wherein the receiving means comprises an endless belt conveyor means positioned to be driven in a direction transverse to said path.

3. The apparatus of claim 1 wherein said means to form an unbroken curtain of coating material comprises a plurality of nozzle means disposed at an angle to each other and directed at the feed path of said individual strip form articles.

References Cited UNITED STATES PATENTS 2,982,245 5/ 1961 Curler et al 11869 3,067,060 12/ 1962 Glaus. 3,220,379 11/1965 Wallis. 3,303,816 2/1967 Lauring.

FOREIGN PATENTS 727,567 2/ 1966 Canada.

RALPH S. KENDALL, Primary Examiner I. H. NEWSOME, Assistant Examiner US. Cl. X.R.

Images