US3719168A

US3719168A - System for applying uniform layer of a flowable material to a substrate

Info

Publication number: US3719168A
Application number: US00126456A
Authority: US
Inventors: R Kazee
Original assignee: KADALE EQUIP CO
Current assignee: KADALE EQUIP CO
Priority date: 1971-03-22
Filing date: 1971-03-22
Publication date: 1973-03-06
Anticipated expiration: 1990-03-06

Abstract

A system for dispensing and applying a uniform layer of liquid or flowable material is described. The system includes a distributor unit from which droplets of the material can be propelled by centrifugal force, and means are provided for spinning the distributor unit at relatively high rpms. The distributor unit includes a cylindrical chamber into which flowable material is received for distribution therefrom, and the cylindrical chamber is provided with annular channels associated with spaced rows of openings which penetrate the wall of the cylindrical chamber. The system is especially useful for coating lining compounds or interior surfaces of pipes.

Description

United States Patent Kazee 1 1 March 6, 1973 1 SYSTEM FOR APPLYING UNIFORM 2,520,397 8/1950 Green ..1 18/306 LAYER F A F O MATERIAL 2,986,338 5/1961 Foster ....239/224 x TO A SUBSTRATE Primary ExaminerJohn P. McIntosh Attorney-Cushman, Darby & Cushman [57] ABSTRACT A system for dispensing and applying a uniform layer of liquid or flowable material is described. The system includes a distributor unit from which droplets of the material can be propelled by centrifugal force, and means are provided for spinning the distributor unit at relatively high rpms. The distributor unit includes a cylindrical chamber into which flowable material is received for distribution therefrom, and the cylindrical chamber is provided with annular channels associated with spaced rows of openings which penetrate the wall of the cylindrical chamber. The system is especially useful for coating lining compounds or interior surfaces of pipes.

9 Claims, 3 Drawing Figures PATEHTEUHAR elm- 3719168 U SHEEIEUF 2 Y I INVENTOR /6 I 26 R056? 2B K0255 QRXTTORNEYJ SYSTEM FOR APPLYING UNIFORM LAYER OF A FLOWABLE MATERIAL TO A SUBSTRATE BACKGROUND AND BRIEF DESCRIPTION OF INVENTION The invention relates to a distributor system for applying a uniform layer of flowable material to a substrate surface. More specifically, the invention is concerned with providing for uniform application of lining compounds, such as coal tar-epoxy compositions, onto inner surfaces of pipes, especially concrete pipes. The system provides for an optimization of centrifugal forces in a spinning distributor unit so as to achieve very carefully controlled coating and penetration of a substrate.

It is known in this art to provide for various forms of spraying devices and spinning devices which are capable of injecting or applying a liquid spray to the interior of a pipe or onto another surface. Typically, prior art devices have provided for such things as spray nozzles and spinning distributor heads which receive a supply of liquid for dispensing onto a surface. The various spinning head arrangements which have been tried are very often complex and of such design as to require frequent cleaning and other maintenance, thereby resulting in unwanted shutdown time for the dispensing system. Furthermore, there has been a problem with prior art applicators of producing localized buildup, lumping or sagging of certain lining materials which are typically applied to inner surfaces of concrete pipes. Known distributor systems are shown and described, for example, in U.S. Pat. Nos. 2,185,570; 2,303,088;

3,017,116; 3,034,729; 3,180,312; 3,197,143, and in German Pat. 373,724 and French Pat. 361,840.

The present invention provides for improvements in systems of the type in which a flowable material is carried from a source to a rotating distributor unit for being propelled from the distributor unit onto an inner surface of a pipe or other surface. Rotation of the distributor unit causes the material to be subjected to centrifugal forces which propel droplets of the material through rows of spaced openings provided through a cylindrical wall portion of the distributor unit. Preferably more than one row of openings are provided along the length of the distributor unit so that there is an overlapping of thin coating layers onto a substrate as the spinning distributor unit is moved relative to the substrate. In order to optimize and control the force and velocity to which individual droplets are subjected, annular channel means are formed into the inner wall surface of the distributor unit for channeling a reservoir of the flowable material behind the spaced openings. Typically, the spaced openings are arranged in a plurality of rows positioned axially along the distributor unit, and a corresponding number of annular channel means are formed in association with the rows to provide an annular reservoir behind each row of openings. In addition, all interior surfaces of the distributor unit are smooth so that there is an uninterrupted and easy flow of material across the inner wall of the distributor unit and into each of the annular channels. This provision for a reservoir of flowable material behind each opening not only assists in increasing the velocity of movement of droplets of materials through the openings, but also assures a uniform supply of material for all of the openings of the distributor unit so that a uniform application of material can be achieved.

Means are provided for spinning the distributor unit at a relatively high speed, for example, in the range of 15,000 to 25,000 rpms, and preferably around 20,000

to 23,000 rpms. However, speeds up to 45,000 rpms may be used with more viscous materials to obtain good atomization and continuous film coverage of the material. This represents a substantially higher rate of spinning than has been utilized with many known prior art devices of this type. The relatively high spinning rate and the provision for annular reservoir channels within the distributor unit itself both contribute to better distribution characteristics of droplets of flowable material from the distributor unit. Individual droplets are propelled at relatively high velocities which are subject to careful control, and as a result, very precise and uniform coating (and penetration, where desired) can be achieved in the application of a lining material to the interior of a pipe.

In a preferred embodiment, the system of this invention provides for a conduit means which carries flowable material from a source into a distributor unit which receives and subjects the material to centrifugal forces. The conduit means dumps material directly into the distributor unit without a requirement for deflecting devices or other collateral structures. The distributor unit has a chamber for receiving the material, and the chamber is defined by a cylindrical sleeve means which is closed at one end and which is at least partially open at an opposite end so as to receive a continuous supply of the material from the conduit means. The cylindrical sleeve means has a plurality of rows of spaced openings formed radially therethrough for releasing droplets of the material from the chamber of the distributor unit when the material is subjected to centrifugal forces. Annular channel means are formed into the inner wall surface of the cylindrical sleeve means for channeling a reservoir of the material behind the spaced openings in each of the rows of such openings. The rows of spaced openings are located at the bottoms of their respective channels so that each droplet of material will be subjected to the same head of liquid pressure and will travel through the same wall thickness of the cylindrical sleeve. Means for subjecting the material to centrifugal forces may comprise a motor means, operated by a pneumatic drive, for spinning the distributor unit about its central longitudinal axis. Preferably, spinning is maintained at constant level, between about 20,000 to 45,000 rpms, during application of material to a substrate.

The system of the present invention may be combined with known structures for moving the distributor unit in either a horizontal or vertical path for coating a pipe interior, or other substrate, as it moves along the path. Preferably a greater number of dispensing openings are provided in a trailing row, than in a leading row, of such openings in the distributor unit so that there is an initial wetting of the surface, followed by a heavier layer of the coating material. Typically, the system may be used for applying flowable materials which are useful in lining cured or uncured cement or ceramic pipes, or cast metal pipes, with coal tar solution (with no epoxy resin), epoxy resin compositions, and coal tar-epoxy resin combinations. Very uniform and satisfactory lining layers can be applied withthicknesses controlled in the range of 16 to 40 mils or whatever thickness is desired. Pipes provided with such linings are typically used in sanitary sewer applications.

These and other advantages and features of the present invention will become apparent in the more detailed discussion which follows, and in that discussion reference will be made to the accompanying drawings as briefly described below.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic representation of a distributor system of the type contemplated by this invention as shown in use for coating the interior of a pipe (shown in section);

FIG. 2 is an elevational view, partly in cross section, of a distributor unit construction utilized in the system of the present invention; and

FIG. 3 is a perspective view of a coupling arrangement provided for assembling the distributor unit and motor portion of the system to a relatively long conduit means.

DETAILED DESCRIPTION OF INVENTION Referring to FIG. 1, the system of the present invention is illustrated with reference to an operation for coating the interior of a horizontally disposed pipe 10. The FIG. 1 illustration is schematic and is not intended to illustrate relative sizes and proportions. For example, the diameter of the pipe which is being coated by the system may be much greater than that shown, as compared to the diameter of a spinning distributor unit 12 associated with the system. Also, the system may be utilized in operations wherein the pipe 10 is vertically disposed rather than horizontally disposed as illustrated in FIG. 1.

In operation, the system provides for an airless application of a lining or'coating material to the interior wall surface of a pipe 10. Flowable material is fed to a distributor unit 12 by way of a conduit means 14 communicating with a source of supply for the flowable material. The conduit means 14 introduces the flowable material directly into a chamber defined within the distributor unit 12. From there, the flowable material is propelled outwardly from I the distributor unit 12 through the two rows of openings 16 which are shown in the example of FIG. 1. Motor means (not shown) are provided for spinning the distributor unit 12 about its central longitudinal axis to thereby subject the flowable material to centrifugal forces. As the distributor unit 12 is rotated rapidly about its axis, it is also moved axially along the length of the pipe, or other article, to be coated. Any known carriage and centering means 18 may be provided for allowing a sliding or rolling movement of the distributor unit 12 and its associated structures, through the interior of the pipe. The distributor unit 12 is moved toward the right in the FIG. 1 view during a coating operation. The distributor unit 12 is mounted or carried at the end of a relatively long condu it means 20 which functions as a carrier and support for the spinning distributor unit 12 as it passes through the hollow interior of a pipe.

FIG. 2 illustrates, in enlarged scale, details of the distributor unit 12 and its associated structures. The distributor unit 12 which is shown in FIG. 2 is viewed in a vertical attitude as contrasted with the horizontal attitude of the unit of FIG. 1. Basically, the distributor unit comprises a cylindrical sleeve means having a closed end so as to define a generally cylindrical chamber within the distributor unit for receiving flowable material from the conduit means 14. As shown, the conduit means 14 is provided with a one-way ball valve structure '22, which opens when flowable material is fed from a source of supply, and which closes when feeding is stopped (by control means not shown). A terminal end 24 of the conduit means 14 is positioned within the cylindrical chamber of the distributor unit so as to introduce flowable material directly into the chamber without interruption in its flow. All inner surfaces of the chamber are relatively smooth, and thus, the material can flow about the entire periphery of the chamber without interruption and without the use of deflectors or other guiding devices. In the arrangement shown, flowable material would contact a closed end wall portion 26 of the distributor unit while the unit is being rotated at a relatively high speed. From there, the material would flow radially outwardly to thecylindrical wall portion of the chamber and would collect'in annular channel means 28 formed into the inner cylindrical wall surface of the chamber.

The annular channel means function as reservoirs for holding a continuous supply of flowable material behind a plurality of spaced openings 16 formed through the cylindrical wall of the distributor unit. In addition, the annular channel means provide for a pressure head of flowable material behind each spaced-opening 16 so that the effect of centrifugal forces on the flowable material will be optimized for propelling the material outwardly from the distributor unit. In the preferred arrangement, a single row of spaced openings 16 is associated with a single annular channel means 28 so that each spaced opening 16 can be placed at the bottom of its associated channel. This assures a known and identical pressure head of flowable material behind each spaced opening of a given annular channel, and assures that each droplet of material will travel for the same distance through the thickness of the wall of the cylindrical sleeve portion of the distributor unit.

Any known means may be provided for subjecting the flowable material in the distributor unit 12 to centrifugal forces so as to force the material out of the distributor unit chamber and onto a substrate. In the illustrated embodiment, an air motor means 30 of known construction is utilized for driving the distributor unit 12. This is accomplished by mounting the distributor unit 12 on a drive shaft 32 of the motor means 30 so that the distributor unit 12 will be rotated about its central longitudinal axis. It can be seen that the end 26 of the distributor unit 12 is essentially a closed end structure, but an opening can be provided through its center at 34 for receiving a fastening bolt which secures the distributor unit 12 to the drive shaft 32 of the motor means 30. The motor means 30 is preferably an air motor of known construction, and air is supplied to and returned from the motor means 30 by

coaxial hoses

36 and 38, respectively. It is important to provide for an air return with the hose 38 to prevent contamination of a freshly applied coating by moisture or lubricant that may be carried in the air stream. Also, if the air were allowed to exhaust in the area of the distributor it could fall onto a freshly applied film, causing a multiple film effect with delamination problems. This provides for an integral structure for the distributor unit 12 and its motor means 30 which can be easily connected and disconnected from an air supply system carried within the conduit 20.

FIG. 3 illustrates a coupling assembly which may be utilized for securing the distributor unit 12 and its motor means 30 to the carrier conduit 20. As shown, the carrier conduit is provided with a rigid end structure, in the form of a sleeve, for receiving the cylindrical shape of the motor 30 and for connecting the motor 30 to its air supply system contained within the conduit 20. Once the motor means 30 and its attached distributor unit 12 are in position, a fastening band 40 (see FIG. 2) is secured around the assembled structures to maintain them in position. The conduit 20 may be of a rigid construction throughout its entire length, or it may be flexible wherever desired.

As an example of a typical construction for the distributor unit, the chamber of the unit is formed from two basic subassemblies. A first subassembly having the closed end wall 26 and an opposite open end can be manufactured from aluminum and provided with a central bore 34 for mounting the unit to the drive shaft of a motor means. This subassembly is formed with an outside diameter of approximately 5 inches and with a minimum inside diameter of 4.250 inches. Annular channels 28 are formed to a depth of approximately 3/32 inches outwardly from the minimum inside diameter of the subassembly, and openings 16 are drilled with 1/16 inch diameters. Preferably, the openings 16 are equally spaced apart in their respective rows, and twice as many openings are provided in the trailing row (at the lower end of FIG. 2) as compared with the leading row (the upper row in FIG. 2). For example, 18 equally spaced openings 16 may be provided in the upper row, and 36 equally spaced openings may be provided in the bottom row. This provides for an initial wetting of a pipe interior by the leading row as the distributor unit is moved axially through the pipe; followed by an overlapping coating layer applied by the greater number of openings in the trailing row.

In the example construction, a second subassembly 50 is formed from aluminum for attachment to the open end of the first subassembly. The subassembly 50 functions to partially close the open end of the first subassembly so that a certain amount of overfilling of the annular reservoirs 28 and of the chamber of the distributor unit can be achieved without danger of spilling of flowable material from the unit. Basically, the second subassembly 50 is provided with an annular lip for attachment to the open end of the first subassembly together with a depending sleeve 52 which functions to contain flowable material within the unit while it is spinning. The sleeve portion 52 is of a diameter which permits entry of the conduit 14 into the chamber defined within the distributor unit 12.

The above-described system provides for very excellent control over thickness and uniformity of coating of pipe interiors. Very thin coating can be accomplished with no localized lumping or sagging of the lining.

Although the system of the present invention may be used in applying a variety of liquid and flowable coating materials and paints, it is especially useful for applying coal tar-epoxy coatings of various compositions. Coatings of this type are described, for example, in US. Pat. Nos. 2,765,288; 2,889,305 and 3,976,256. Other compositions of this type provide for certain co-reacting polyamide resins with an aromatic tertiary polyamine catalysLThe coating compositions may be applied to cured or uncured concrete pipe with the system of the present invention, and penetration and uniformity of coating application and attachment are exceptionally good. The system may be utilized manually (by holding the distributor unit at the end of its carrier conduit 20 by hand) or with additional structure for supporting and guiding the unit, as is known in this art. Coatings may be applied to uncured pipe, and the coated product may be subjected to kiln drying for curing of the pipe and setting of the coating.

Having described the basic features and relationships of the invention, it can be appreciated that certain equivalent structures and designs may be substituted for those described herein. Equivalent substitutions of this type are intended to be included in the scope of protection defined in the claims that follow.

What is claimed is:

l. A'system for applying a uniform layer of a flowable material to a substrate comprising the combination of a source of flowable material and a conduit means for carrying the material from the source to a distributor unit which receives said material and sub jects the material to centrifugal forces,

a distributor unit for propelling droplets of spray of said material onto a substrate which is to be coated, said distributor unit having a chamber defined by a cylindrical sleeve means which is closed at one end and which is arranged to receive a continuous supply of said material, said cylindrical sleeve means having a plurality of rows of spaced openings formed radially therethrough and opening into said chamber for releasing droplets of said material from said chamber when the material is subjected to centrifugal forces, and annular channel means formed into the inner wall surface of said cylindrical sleeve means and opening into said chamber for channeling a reservoir of said material behind said spaced openings in each of the rows, with one such channel means being associated with each of said rows of spaced openings, to thereby increase the velocity of movement of droplets of spray from said distributor unit when centrifugal forces are applied to the liquid material being propelled therefrom, and

means for subjecting said material to centrifugal forces for forcing the material out of the chamber and through the spaced openings formed through the cylindrical sleeve means.

2. The system of claim 1 wherein said means for subjecting the material to centrifugal forces comprises a motor means connected to said distributor unit for spinning the distributor unit about the central longitudinal axis of its cylindrical sleeve means.

3. The system of claim 2 wherein said motor means comprises a motor operated by air pressure, said motor means having a drive shaft means connected to the closed end of the cylindrical sleeve means of said distributor unit.

4. The system of claim 2 wherein said motor means is capable of spinning said distributor unit at between about 20,000 rpms and 45,000 rpms.

5. The system of claim 1 wherein said cylindrical sleeve means of said distributor unit is partially closed at its end opposite to said closed end so that said flowable material can occupy space around the entire inner wall surface of said cylindrical sleeve means without spilling out from said partially closed end.

6. The system of claim 1 wherein said distributor unit is carried at the end of a relatively long conduit means which provides for insertion and movement of the distributor unit into and through a hollow pipe structure so that flowable material can be applied to the interior of the hollow pipe structure.

7. The system of claim 6 wherein said relatively long conduit means contains and supports an air delivery system for operating said motor means.

8. The system of claim 1 wherein said distributor unit is assembled from two basic subassemblies comprising a first subassembly in the form of a sleeve having an end which is closed and an opposite end which is open, together with a second subassembly which can be secured to said open end of said first subassembly for partially closing the open end thereof.

9. The system of claim 1 wherein there are two rows of spaced openings in said distributor unit, and wherein there are a greater number of openings in one of said rows than in the other, said greater number of openings being in the row which is in a trailing position as the distributor unit is moved axially relative to a surface being coated.

1' I? t II

Claims

1. A system for applying a uniform layer of a flowable material to a substrate comprising the combination of a source of flowable material and a conduit means for carrying the material from the source to a distributor unit which receives said material and subjects the material to centrifugal forces, a distributor unit for propelling droplets of spray of said material onto a substrate which is to be coated, said distributor unit having a chamber defined by a cylindrical sleeve means which is closed at one end and which is arranged to receive a continuous supply of said material, said cylindrical sleeve means having a plurality of rows of spaced openings formed radially therethrough and opening into said chamber for releasing droplets of said material from said chamber when the material is subjected to centrifugal forces, and annular channel means formed into the inner wall surface of said cylindrical sleeve means and opening into said chamber for channeling a reservoir of said material behind said spaced openings in each of the rows, with one such channel means being associated with each of said rows of spaced openings, to thereby increase the velocity of movement of droplets of spray from said distributor unit when centrifugal forces are applied to the liquid material being propelled therefrom, and means for subjecting said material to centrifugal forces for forcing the material out of the chamber and through the spaced openings formed through the cylindrical sleeve means.