US2809073A - Self cleaning strainer for spray nozzle or the like - Google Patents

Description

Oct 1957 E. H. WAHLERT 2,809,073 I SELF CLEANING STRAINER FDR SPRAY NOZZLE OR THE LIKE Filed April 30. 1956 47 FIG 2 429 45 5/ III I 55 I 54 I I 55 I .55 52 4 40 42 g Q 3 l3 I 2 INVENTOR.

2,809,073 Patented Oct. 8, 1957 ELF CLEANING STRAINER FOR SPRAY NOZZLE OR THE LIKE Ernst H. Wahlert, Normandy, Mo., assignor to Granite City Steel Company, Granite City, 111., a corporation of Delaware This invention relates generally to nozzle cleaning and more particularly to a self cleaning strainer for a spray nozzle or the like.

The principal object of the present invention is to provide a self cleaning strainer for a spray nozzle whereby solid particles carried by the liquid to be sprayed will not obstruct the fluid passage through the nozzle and reduce the efficiency of the nozzle.

A more specific object is to provide a self cleaning strainer adapted to prevent salts found in hard water, rust or other foreign solid particles from accumulating in a spray nozzle and obstructing the flow of water therethrough.

Another object is to provide a flexible strainer and a mounting therefor which will allow flexing of the strainer to break up and control the size of solid particles carried by a fluid medium into a spray nozzle, the strainer being simple and economical to manufacture and service but highly eflicient in operation.

These and other objects and advantages will become apparent hereinafter.

Briefly, the invention comprises a coil spring strainer disposed in the path of the flow of fluid for a spray nozzle and having one end in circumscribing relationship with the spray nozzle intake opening. The invention also comprises mounting means which will allow strainer movement or vibration in response to fluid flow conditions to the nozzle intake for preventing the accumulation of solid particles at the strainer and for reducing the size of solids for easy passage through the spray nozzle.

The invention also consists in the parts and in the arrangements and combinations of parts hereinafter described and claimed. In the accompanying drawing which forms a part of this specification and wherein like numerals refer to like parts wherever they occur:

Fig. 1 is a fragmentary elevational view of a spraying system in which self cleaning strainers embodying the present invention are employed,

Fig. 2 is a cross sectional view showing the details of a typical spray nozzle and associated strainer, the view being taken substantially along line 22 of Fig. 1,

Fig. 3 is a fragmentary cross sectional view taken substantially along line 33 of Fig. 2, and

Fig. 4 is a fragmentary end elevational view of the spray nozzle.

Referring to Fig. 1 of the drawings, it will be seen that spray nozzles are connected in spaced relation to a longitudinal header pipe 11 through which a fluid medium, such as water, is conducted under pressure to each of the nozzles 10. It is to be understood that the header 11 and nozzles 10 shown in Fig. 1 may comprise only a portion of a high pressure hydraulic system. A presently contemplated use for such a high pressure hydraulic system is for descaling or removing the scaly oxide coating formed on the surface of steel being worked in a hot strip rolling mill. Each of the nozzles 10 is provided with a wedge shaped orifice 12 forming an outlet opening for the fluid so that a high velocity, knife-like fan-shaped spray is produced. The nozzles 10 are spaced apart a predetermined distance and the orifices 12 are properly aligned so that the fluid ejected therefrom will produce a uniform pattern of contact or overlap across the width of the steel surface to be descaled. Accordingly, the scale on the surface of the steel is cleanly and uniformly removed by the force of the fluid impringing thereagainst. As will become apparent hereinafter, the fluid is forced through the header 11 under relatively high pressure from the supply pump P so that a high velocity spray will be produced by the nozzles 10.

Inasmuch as each of the nozzles 10 is connected to the header 11 in an identical manner, only one will now be described in detail. Referring particularly to Fig. 2, the longitudinal header pipe 11 has a bore 13 adapted to conduct fluid from a source, such as pump P, to each of the nozzles 10 connected thereto. Diametrally opposed transverse bores 14 and 15 are formed through the wall of the header 11, the nozzle 10 being positioned in the lower bore 14 and the upper bore 15 being adapted to receive means 16 for releasably securing a strainer 17 in position to filter solid particles from the fluid passing to the nozzle 10.

A collar 18 is secured in the lower bore 14 of the header 11 by welding or the like as at 19, the collar 18 having an inner end portion 20 within the lower bore 14 and an outer end portion 21 extending outwardly therefrom. The outer end 21 of the collar 18 is bored to provide a threaded opening 22 for securing the body of nozzle 10 to the header 11. The inner end 20 of the collar is provided with a smooth counterbore 23, and an annular shoulder or wall 24 is formed between the threaded opening 22 and the counterbore 23.

The nozzle 10 includes a body member 25 having a threaded inner male end 26 adapted to be engaged in the threaded opening 22 of the collar 18 and a threaded outer male end 27 to which a cap 28 is connected. A hexagonal head 29 is formed on the body 25 intermediate the ends 26 and 27 so that a suitable tool (not shown) may be applied thereto for attaching the nozzle 10 to the header 11 or for removing it therefrom. The inner end 26 of body 25 is provided with a threaded bore 30 in which the threaded end 31 of a sleeve 32 is secured, the bore 33 of the sleeve forming the inlet opening or mouth for the nozzle 10. An opening 34 is formed through the body 25 of the nozzle between the inner and outer ends 26 and 27, the wall of the opening 34 being conterminous with the wall of the bore 33 of the sleeve 32 at the inner end 26 and converging downwardly or tapering to form an elongated throat or opening at the outer end 27. The nozzle 10 also includes a tip 35 in which the orifice 12 is formed, the tip 35 having a beveled peripheral side wall 36 adapted to be contacted by a complementary side wall 37 of the cap 28. Accordingly, the tip 35 is held in position on the outer end 27 of the nozzle body 25 with the orifice 12 in communication with the throat of the opening 34, the walls of the orifice 12 diverging therefrom.

It is now apparent that the fluid passage through the nozzle 10 includes the bore 33 of the sleeve, the opening 34 through the body 25 and the orifice 12 of the tip 35. The side walls of these openings are conterminous to reduce fiow resistance and prevent the accumulation or depositing of solid particles in the nozzle 10. It is also apparent that the size of the opening 34 is restricted at the outer end 27 of the body 25, and is formed into an elongated shape to register with the inner end of the wedge-shaped orifice 12 whereby fluid pressures will be increased and a fan-shaped spray formed by the nozzle 10.

When the inner end 26 of the nozzle 10 is secured to the collar 18, the sleeve 32 extends through the bore 14 and into the header 11 in spaced concentric relationship with the counterbore 23 of the collar 18 so that an annular opening 38 is formed therebetween. The shoulder 24 of the collar defines the end or bottom of the opening 38, and forms an abutment surface for the lower end 39 of the strainer 17.

The strainer 17 comprises a helical coil spring 40 adapted to form a cylindrical column having a bore 41 extending transversely of the bore 13 of the header 11 between the bores 14 and 15. When the spring 40 is relaxed or not under strain, the adjacent coils thereof are spaced apart a predetermined distance to form a continuous helical opening 42 through the column so that its bore 41 will be in communication with the bore 13 of the header 11. The size of the opening 42 or the distance between the adjacent coils is smaller than the narrowest dimension of the fluid passage of the nozzle 16 so that large solid particles will not pass into the nozzle and obstruct the flow of fluid therethrough, as will be described more fully hereinafter.

A collar 44 having a threaded bore 45 is secured in the upper transverse bore 15 by welding or the like, shown at 46. The means 16 for positioning the strainer 17 in the header 11 includes a plug member 47 having a threaded portion 48 for releasably securing it in the bore 45 of the collar 44. The outer end of the plug member 47 is provided with a hexagonal head 49 for engagement by a suitable tool (not shown) so that the plug member 47 may be easily attached to or removed from the collar 44. The inner end of the plug member 47 has a cylindrical stud or stem 50 secured thereto in position to extend some distance into the bore 13 of the header 11, the stud 50 being reduced in diameter relative to the plug member 47 to form an annular shoulder or wall 51 therebetween. The stud 50 extends into the bore 13 of the header 11 and has a free end 52, which is fluted by forming spaced axial grooves 53 about the periphery of the stud 50, Fig. 3. When the plug member 47 is secured to the collar 44, an annular opening 54 is formed between the stud 50 and the wall of the bore 45. The shoulder 51 defines the end of the opening 54 and forms an abutment surface for the upper end 55 of the spring 40.

As shown in Fig. 2, the openings 38 and 54 are diametrally opposed and the ends of the spring 40 are positioned therein with the sleeve 32 and stud 50 forming cores for retaining the ends 39 and 55 of the spring in position for operation. However, the length of the spring 46 between its ends 39 and 55 is shorter than the distance between the shoulders or abutments 24 and 51, respectively, whereby axial movement of the spring 40 is permitted.

The threaded connection between the plug member 47 and the bore 45 of the collar 44 is initially pressure tight, but is subject to wear. Therefore, the plug member 47 is periodically tightened into the collar 44 whereby the annular shoulder 51 is moved toward the annular shoulder 24 of the collar 18. However, the distance between the ends 39 and 55 of the spring is less than the minimum distance between the shoulders 24 and 51 so that axial movement of the spring 40 is assured even after the plug 47 has been tightened and loosened many times, thus causing the abutment 51 to be moved closer to the abutment 24 than initially.

When the nozzle 10, means 16 and strainer 17 are assembled with the header 11, the spring 40 extends transversely of the bore 13 of the header 11 and has its lower and upper ends 39 and 55 in circumscribing relationship with the sleeve 32 and stud 50. The annular clearance between the bore 41 of the spring 40 and the outside diameter of the sleeve 32 and stud 50 is less than the narrowest dimension of the fluid passage through the nozzle throat 12, or substantially the same size as the opening 42 between the coils of the spring 40. Therefore, the fluid forced through the header 11 can pass from the bore 13 to the fluid passages of the nozzles 10 through the openings 42 between the coils of the springs 40 and around the ends of the springs, but no large particles in the fluid can pass into the nozzles, as will be described.

In a high pressure hydraulic spray system for descaling the surface of red hot steel, the dimensional sizes of the orifice 12 of the spray nozzle 10 are necessarily small in order to limit the amount of fluid used per unit of time, to develop a certain spray shape pattern, to uniformly cover the work surface of the steel and to develop the maximum impingement force of the fluid on the steel surface. This limited flow of fluid also minimizes the loss of heat by transference from the steel to the fiuid a very important factor. An actually tested rectangular orifice 12 has outlet opening dimensions of x /2, the inlet opening dimensions being substantially x Accordingly, the maximum opening 42 through the strainer 17 cannot exceed the minimum dimension through the orifice 12, and theopening 42 should be slightly smaller. Otherwise solid particles passing through the strainer opening 42 would lodge in the orifice 12 and obstruct the operation of the nozzle 10 whereby loss of surface quality of the steel would result until the nozzle 10 could be removed and cleaned, which would result in loss of production time.

It is presently contemplated that water be used as a fluid medium. Water normally carries a small percent of magnesium and calcium carbonate or like salts in solid suspension, together with other elements such as iron which cements these salts together in solid form. The compressive strength of such cemented solid particles is relatively weak, and the particles can be broken down into small sizes by crushing. This is also the case with iron oxide ordinarily formed on interior surfaces of water piping systems (not shown), which iron oxide is dislodged at times from pipe walls in laminated form and is carried by the water into the header pipe 11. Therefore, it is apparent that the strainer 17 must be provided to limit the size of the particles carried to the nozzles by the fluid so that the particles will easily pass through the fluid passages of the nozzles 10 and will not be deposited therein. It is also important that such particles are prevented from depositing and building up on the strainer 17 or else the opening 42 will soon be closed. As previously described, this opening 42 is smaller than the narrowest dimension of the fluid passage through the nozzle 10 so that any solid particles passing through the opening 42 will easily pass through the nozzle. In addition, the spring strainer breaks up or crushes the larger particles so that they can be carried off through the nozzles and do not accumulate on the spring 40 and fill the opening 42. This self cleaning action of the strainer will now be described.

When the hydraulic system, including the pump P, header 11 and nozzles 10, is in operation, the strainer 17 has a complex vibratory action which includes three principal components-reciprocation, rotation and lateral deflection. It has already been seen that limited axial movement of the spring 40 between the shoulders 24 and 51 is permitted so that a rapid axial reciprocation of the spring 40 may occur from the pulsation of the fluid thereagainst. This reciprocating motion causes the coils of the spring 40 to be vibrated and alternately compressed when it strikes against each shoulder 24 and 51, whereby solid particles too large to pass through the opening 42 will not be permitted to deposit on the coils and bridge over the opening 42. Solid particles too large to pass through the openings, but small enough to wedge between the coils, are crushed by the working action between the adjacent coils of the spring 40 so that they are broken up and can be carried off through the nozzles 10.

Inasmuch as each end 39 and 55 of the spring 40 circumscribes a stern and is not secured in fixed relation therewith, free rotational movement of the spring 40 is permitted, whereby a continuous change of the entrance surface side of the strainer 17 to the direction of flow of fluid in the header 11 is provided.

The force of the fluid against the spring 40 causes a certain degree of lateral deflection of the spring in the longitudinal direction or" the fluid flow in the header 11. This deflection causes compression of the entrance or upstream side of the coils and expansion on the opposite side of the spring, whereby a sizing action results that is simi ar to the compressing action of the coils due to reciprocable movement of the spring 40. The distance between adjacent coils on the downstream side of the spring is increased during the lateral deflection and crushed or loose particles are permitted to pass through the opening 42.

Although these three components of motion of the spring are apparent separately, in actual operation a complex vibratory motion takes place in which all three components are present. The oscillation of the spring is dependent upon the complex fluid flow conditions or patterns developed in the header 11 by the resistance of the component parts to the fluid flow through the header, together with the resiliency of the spring. Obviously, the strainer is positive acting to filter and size solid particles carried by the fluid so that the passages of the nozzles lfl will not become obstructed. This is imperative in the present use of the strainer inasmuch as removal of even one nozzle for cleaning would cause time loss in the operation of the hot roll mill or uneven results in descaling the steel.

it is apparent that the strainer 17 can be quickly removed, inspected and replaced in the header 11 without effecting the nozzle setting. This is accomplished by removing the plug member 47 and withdrawing the spring through the bore 45 of the collar 44. Previous nozzle devices for descaling applications have been diificult to remove and then realign.

It is to be understood that the foregoing description and accompanying drawings have been given only by way of illustration and example, and that changes and modifications in the present device and in the uses and installation thereof, which will be readily apparent to all skilled in the art, are contemplated as within the scope and spirit of the present invention, which is limited only by the claims which follow.

What I claim is:

1. In combination, a header pipe having a bore for conducting fluid, a nozzle secured to said header pipe and having a fluid passage in communication with said bore, support means projecting into said bore opposite to said fluid passage, and a coil spring strainer extending across said bore and having unattached ends one of which is positioned in circumscribing relation with the fluid passage of said nozzle and the other end being freely movably positioned on said support means, whereby said strainer is adapted to move axially and rotationally relative to said support means and fluid passage and to flex laterally intermediate its ends to crush solid particles in the fluid to a size that will pass through said nozzle and to prevent the accumulation of solid particles on said strainer.

2. In combination, a header pipe having a longitudinal bore and diametrally opposed transverse bores, said header pipe being adapted to conduct fluid through the longitudinal bore; a nozzle secured in one of said transverse bores of said header pipe, said nozzle having a fluid passage including an inlet adapted to receive fluid from said header pipe and an outlet through which the fluid is ejected from the nozzle; a helical coil spring strainer extending transversely of said longitudinal bore between said transverse bores, one end of said spring strainer circumscribing the inlet to said fluid passage; and plug means disposed in the other of said transverse bores and including a stud circumscribed by the other end of said spring strainer; said spring stainer being supported on said stud and said nozzle inlet to move axially, rotationally and laterally in a substantially constant vibratory action responsive to complex fluid flow patterns in the header pipe to reduce solid particles in the fluid too large to pass through the fluid passage of said nozzle.

3. In combination, a header pipe having a longitudinal bore and diametrally opposed transverse bores, said header pipe being adapted to conduct fluid through said longitudinal bore; a nozzle secured in one of said transverse bores and having a fluid passage including an inlet adapted to receive fluid from said header pipe and an outlet through which the fluid is ejected from said nozzle; a helical coil spring strainer extending transversely of said longitudinal bore between said transverse bores, one end of said strainer circumscribing the inlet to said fluid passage; and plug means disposed in the other of said transverse bores and including a stud circumscribed by the other end of said strainer; said strainer being supported on said stud and nozzle inlet to move axially, rotationally and laterally in a substantially constant vibratory action to reduce solid particles in the fluid too large to pass through the fluid passage of said nozzle, the vibratory action of said strainer being eflected by complex fluid flow patterns caused by the resistance of said plug means and strainer to the flow of fluid through said header pipe.

References Cited in the file of this patent UNITED STATES PATENTS 1,246,355 Thomas Nov. 13, 1917 2,197,971 Elze et al. Apr. 23, 1940 2,281,499 Herzbrun et a1. Apr. 28, 1942 2,296,715 Komar Sept. 22, 1942 2,429,417 MaGill Oct. 21, 1947 FOREIGN PATENTS 919,340 France Nov. 25, 1946

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