Nozzle

Abstract

An elongated hollow body formed of an elastomeric material having a bore therethrough. A thread formation of helical configuration is formed in the bore which gradually tapers towards its outlet end. The thread formation comprises a spiral projection and groove separated by a sloping shoulder extending forwardly from the projection of the groove.

Parent Case Text

CROSS-REFERENCE TO A RELATED APPLICATION

This application is a continuation of application Ser. No. 77,880, filed Oct. 5, 1970 entitled Nozzle now abandoned, which application is a continuation-in-part of my earlier application Ser. No. 7747 filed Feb. 2, 1970 on a Nozzle now U.S. Pat. No. 3,692,243.

Description

BACKGROUND OF THE INVENTION

This invention relates to nozzles and, more particularly, to nozzles for mixing and handling cementitious materials.

Various discharge nozzles have been designed in recent year for applying wet cementitious materials to a background surface. Generally, a cementitious material in dry particle form is pneumatically blown into these nozzles wherein it is mixed with water to form a wet cementitious admixture projected through the nozzle outlet to the desired location. One specific use for such cement gun nozzles is in applying a lining of refractory cementitious material to the walls of a high temperature furnace. One problem encountered in the use of these nozzles for applying air-emplaced material is that improper blending of the water with the dry material forms an admixture of undesirable plasticity which fails to adhere properly to the background surface. It has been found that insufficient mixing of the water with the dry materials results in excessive "rebound" whereas excessive wetting of the dry materials causes the mixture to run at the background surface and form a weak, finished structure. Rebound results in wastage of materials and necessitates periodic clean-up of such rebound requiring added labor and equipment shut down, thereby materially increasing costs.

In some nozzle designs, excessive turbulence is generated whereby the finer particles of the granular mix tend to separate from the larger particles resulting in a mix of non-uniform consistency. Also, these fines tend to alternate into elongated filaments and are whipped into a froth-like substance by this excessive turbulence which is collected in a mass at the discharge end of the nozzle, ultimately dropping to the floor or other operator supporting surface rendering the latter sloppy and creating a potential safety hazard.

The invention claimed and disclosed in U.S. Pat. application Ser. No. 7747, filed Feb. 2, 1970, overcomes many of the prior art deficiencies by employing a nozzle having a thread formation of helical configuration formed in the bore of the nozzle to impart a spiral twist or rifling motion to the cementitious ingredients thereby insuring a thorough mix thereof and producing a highly controlled delivery with very little rebound and dust. The present invention constitutes an improvement over U.S. application Ser. No. 7747 by making certain improvements in the bore of the nozzle and in the helical thread formation to produce a more highly efficient nozzle.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an improved nozzle which is even more effective in overcoming the above-noted disadvantages.

It is another object of this invention to provide the foregoing nozzle with an improved internal thread configuration for facilitating the blending of the dry cementitious ingredients with the water while controlling the degree of turbulence generated in the nozzle.

In one aspect thereof, the cement gun nozzle of this invention is characterized by the provision of a nozzle bore having a unique thread configuration of a generally double helical pattern formed in the inner wall surface of the bore. Each of the helices consist of a thread projection and a groove separated by a curved shoulder extending from the projection in a sloping radial outward direction and terminating at the groove to control turbulence imparted to the material conveyed through the nozzle bore.

These and other objects, advantages and characterizing features of the present invention will become clearly apparent from the ensuing detailed description of an illustrative embodiment thereof, taken together with the accompanying drawing wherein like reference characters denote like parts throughout the various views.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a side elevational view of a nozzle of the present invention, shown attached to a liquid injection adaptor:

FIG. 2 is a longitudinal sectional view of the nozzle of FIG. 1;

FIG. 3 is a cross sectional view, on an enlarged scale, taken about on line 3--3 of FIG. 2; and

FIG. 4 is a fragmentary, sectional view, on an enlarged scale, taken about on line 4--4 of FIG. 2.

DETAILED DESCRIPTION OF AN ILLUSTRATED EMBODIMENT

Referring now in detail to the drawings, there is shown in FIG. 1 a nozzle, generally designated 10 and constructed in accordance with this invention, attached to a liquid injection adaptor, generally designated 12. Adaptor 12 comprises a body 15 adapted to be threaded at one end thereof on the inlet end of nozzle 10 and having a bore (not shown) therethrough provided with threads at the other end of adaptor 12 for receiving a suitable hose coupling (not shown) through which dry cementitious material from a suitable source (not shown) is conveyed by air under pressure to adaptor 12 and nozzle 10. A radially extending tapped opening is provided in a boss 13 of adaptor 12 for receiving a suitable conduit connection through which water or some other suitable liquid is introduced into the interior of adaptor 12 and nozzle 10 for admixing with the dry cementitious ingredients. Such general arrangement, being known in the art, requires no further description here.

Nozzle 10 comprises an elongated hollow body 14 (FIG. 2) having a generally cylindrical outline but slightly tapered toward the discharge end. Body 14 is provided with an inlet end 16 and an outlet end 18, the inlet end 16 being externally threaded as at 20 for threaded engagement with adaptor 12 or some other suitable connection means. An annular projection or rib 22 is formed on the outer annular face of nozzle 10 at the inlet end thereof to provide a fluid tight seal seating against the abutting end of adaptor 12. Two pairs of diametrically opposed lugs 24 and 26 are formed on the outer surface of nozzle 10, integral therewith, for facilitating the grasping and handling of nozzle 10.

Nozzle 10 is composed of an elastomeric material, preferably urethane, which is wear and abrasion resistant and sufficiently rigid to accurately guide a stream of material in the desired direction. Nozzle 10 is of a unitary, one-piece construction formed by a suitable molding operation and can be of any convenient size for a given application.

Nozzle 10 is provided with an axial bore, generally designated 28, having a first chamber 30 at the inlet end 16 and defined by a cylindrical wall surface 32, an elongated, intermediate mixing chamber 34, and an outlet chamber 36 defined by a smooth inner wall surface 38 which tapers toward outlet end 18. The intermediate and outlet chambers 34 and 36, respectively, taper from the inner end of chamber 30 to the outer end of outlet chamber 36. This gradual taper tends to choke the cementitious mix as it is conveyed outwardly through nozzle 10 to minimize spreading of such mix and to constrain the projecting stream within the desired path.

A significant feature of this invention is the provision of a specially configurated double helical thread formation, generally designated 40, defining the inner wall surface of mixing chamber 34. Since both helices are identical, it is believed that a detailed description of only one will suffice, it being understood that the helices bear identical reference characters and are spaced 180.degree. apart. As shown in FIGS. 2, 3 and 4, each helix formation comprises a projection 42 and a groove 44 separated by a curved, sloping shoulder 46. The significance of sloping shoulder 46 to provide a gradual, curving transition between projection 42 and groove 44 will appear from the following.

It has been found that the spiral, twisting motion imparted to the admixture of the dry cementitious material, water and air by thread formation 40 effects a cyclonic-like turbulence of these ingredients to efficiently mix the same, resulting in a consistent and thorough mix. The incoming material impinges against the abutment surface defined by the leading face 48 of projection 42 and is guided in groove 44 in a spiraling or rifling motion. While the material is guided in a generally spiral path of movement, it also has an axial component whereby some of the material tends to flow generally axially along the outer surface of projection 42. If groove 44 were to extend completely across the space between adjacent projections 42, a vacuum would be created in the space just rearwardly of the trailing face of projection 42. The suction force of the vacuum, together with the action of centrifugal force would direct the material radially outwardly against the groove tending to create excessive turbulence or agitation causing the fines to be separated from the larger particles to produce a finished cementitious mix of non-uniform consistency. Also, as a result of this excessive turbulence, these fines would be attenuated into elongated filaments and churned or whipped into a frothlike substance. While this frothlike substance constitutes only a negligible portion of the finished mix, it tends to collect at the outlet end of the nozzle and drop off onto the floor or other support surface in close proximity to the operator's feet. This not only pollutes the adjacent working area, but also presents a potential safety hazard to the operator and other personnel in the area.

The provision of shoulder 46 in the nozzle of this invention occupies and eliminates the space forwardly of projection 42 which would otherwise be present in the absence of such shoulder and provides a smooth, curving surface forwardly of projection 42 which merges into groove 44 and upon which the incoming material slides so as to be gradually directed into groove 44, thereby reducing the turbulence to within tolerable limits and eliminating the problems encountered with extreme turbulence. Thus, shoulder 46 is an important feature of this invention in controlling the axial and spiraling flow characteristics imparted to the cementitious mixture.

It has been found that the best results are achieved when the rear edge of shoulder 46 is slightly outwardly offset from the front edge of projection 42. The offset should be very minor, so as not to interfere with the intended function of shoulder 46. The offset provides a spacing shoulder 45 which is inclined forwardly and outwardly at a sharp angle.

A sand hook or undercut 50 is formed at the juncture of groove 44 and leading face 48 of projection 42 for the purpose of trapping a small portion of the granular material therein. This trapped material forms a coating or wear surface protecting at least a portion of the leading face 48 against the abrasive action of the cementitious mix and thereby extending the useful life of the nozzle. It has been found that a 5 degree undercut is satisfactory in providing an adequate cavity for trapping material therein. However, larger or smaller undercuts can be employed as dictated by the size of the nozzle, the force of the air pressure applied, and the type of material forced through the nozzle.

From the foregoing, it is apparent that the objects of the present invention have been fully accomplished. As a result of this invention, an improved gun nozzle is provided for thoroughly mixing dry cementitious materials with water to form a mix of optimum density and consistency. By the provision of a thread formation formed in the inner wall of the nozzle, a spiral twisting or rifling motion is imparted to the admixture as it is forced under pressure through the nozzle, and the thread formation is provided with a shouldered portion providing a gradual sloping transition from the thread projection to the groove to effectively control the turbulence within the nozzle. Also, the nozzle bore is tapered axially to the outlet end thereof for effecting a choking action of the mixture issuing from the nozzle to produce an efficiently controlled delivery with very little rebound.

A preferred embodiment of this invention having been described in detail, it is to be understood that this has been done by way of illustration only.

Claims

I claim:

1. A nozzle for directing cementitious material therethrough comprising: an elongated body of elastomeric material having a bore therethrough, an inlet end and an outlet end, said bore having a mixing chamber intermediate the opposite ends thereof, said mixing chamber being provided with a helical threaded formation on the wall surface defining said mixing chamber, said threaded formation comprising a spiral projection, a spiral groove, and means on the side of said projection toward said outlet end for providing a gradual transistion from said projection to said groove for controlling turbulence within said mixing chamber.

2. A nozzle as set forth in claim 1 wherein said elastomeric material is urethane.

3. A nozzle as set forth in claim 1 wherein said body is of a unitary, one-piece construction.

4. A nozzle as set forth in claim 1 wherein said bore gradually tapers toward said outlet end.

5. A nozzle as set forth in claim 1 wherein said means for controlling turbulence comprises a spiral formation providing a convexly curved transition surface.

6. A nozzle as set forth in claim 1, wherein said mixing chamber is provided with a double helical thread formation each of which comprises a spiral projection, a spiral groove and means on the outlet side of said projection for providing a gradual transition surface from said projection to said groove thereof.

7. A nozzle as set forth in claim 1 wherein said mixing chamber is elongated and said projection has an inner peripheral land surface of substantial axial extent.

8. A nozzle as set forth in claim 1, wherein said mixing chamber is elongated and said threaded formation extends continuously therealong.

9. A nozzle as set forth in claim 8, said nozzle bore having an outlet chamber leading from said mixing chamber to said outlet end, said mixing and outlet chambers tapering toward said outlet end and said outlet chamber having a smooth inner wall surface.

10. A nozzle for directing cementitious material therethrough comprising: an elongated body of elastomeric material having a bore therethrough, an inlet end and an outlet end, said bore having a mixing chamber intermediate the opposite ends thereof, said mixing chamber being provided with a helical threaded formation on the wall surface defining said mixing chamber, said threaded formation comprising a spiral projection, a spiral groove, and means for controlling turbulence within said mixing chamber, wherein said means controlling turbulence comprises a spiral formation disposed between said projection and said groove on the side of said projection toward said outlet end and having a sloping surface extending from said projection to said groove.

11. A nozzle as set forth in claim 10 wherein said mixing chamber is elongated and said threaded formation extends continuously therealong, said mixing chamber being provided with a double helix thread formation each of which comprises a spiral projection and a spiral groove and a spiral formation disposed therebetween on the outlet side of said projection, each of said spiral formations having a sloping surface extending from the associated projection to the associated groove and providing a gradual transition therebetween to controlling turbulence within said mixing chamber.

12. A nozzle as set forth in claim 10, wherein said spiral formation is convexly curved, having its rearward edge slightly outwardly offset from the forward edge of said projection.

13. A nozzle as set forth in claim 12, said offset providing a spacing shoulder which is inclined forwardly and outwardly at a sharp angle.

14. A nozzle for directing cementitious material therethrough comprising: an elongated body of elastomeric material having a bore therethrough, an inlet end and an outlet end, said bore having a mixing chamber intermediate the opposite ends thereof, said mixing chamber being provided with a helical threaded formation on the wall surface defining said mixing chamber, said threaded formation comprising a spiral projection, a spiral groove, and means for controlling turbulence within said mixing chamber, wherein said projection is provided with a leading face on the side thereof toward said inlet end, said leading face being provided with an undercut at the juncture of said face with the inner wall of said bore.

15. A nozzle as set forth in claim 14, wherein said groove extends to said face and said undercut is at the juncture thereof.