US1941726A

US1941726A - Cement gun nozzle

Info

Publication number: US1941726A
Application number: US417950A
Authority: US
Inventors: John T Vawter
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-01-02
Filing date: 1930-01-02
Publication date: 1934-01-02
Anticipated expiration: 1951-01-02

Description

Jan. 2, 1934. J. T. v w 1,941,726

CEMENT GUN NOZZLE Filed Jan. 2, 1930 Patented Jan. 2, 1934 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to cement gun nozzles and deals with the deposition of particles of a hydrated concrete mixture upon a surface by the usual air pressure means. The phenomenon of rebound is well known to the cement gun industry as a gradation or a series of degrees of rebound ranging between necessity at one end and a wholly unnecessary waste of material at the opposite end. 'In cases where extreme density of deposition is the chief aim, the rebound is accepted as the means by which the energy of the compressed air is transmitted to the surface to be condensed. But in cases where the density required is comparable to average hand work, rebound becomes an expensive nuisance both with respect to loss of time and material. This invention, therefore, broadly speaking, deals with the control of the amount and kind of rebound which occurs when a cementitious mixture is deposited by means of cement gun equipment.

In considering rebound, it is appreciated that two factors are involved. The first factor relates to the nature of the surface on which the deposit is made to take place, and the second deals with the ballistic properties of the particles of con- 4 veyed material. The characteristics of the depositing surface bear only an indirect relation to the problem involved in this invention and, consequently, will not be discussed since the present invention is more concerned with rebound due to causes more intimately connected with the momentum of air used in the transporting of the material and with the incident impact of the particles of material upon the depositing surface.

Rebound, in the sense as used in this invention, is intended to include the particles deflected from a depositing surface by the force of incident velocity and also those particles swept from the surface by the blast of released air which is shot directly against the surface with the material particles. This latter phenomenon may be termed air erosion and is one of the problems sought to be benefited by this invention.

Another aspect of this invention deals with the ballistics of the particles involved.

As to the ballistics of the'particles of material, it is well understood that the incident velocity of the projected particles is derived from air propulsion. However, as soon as the air has conveyed each particle to the nozzle and has imparted a projecting velocity to the particles, the work of the air is finished and it then becomes a hindrance instead of a benefit in the further work of depositing. The ideal arrangement would be a nozzle wherein a complete separation of air from the particles was effected prior to the particles leaving the nozzle. Under this arrangement, the particles would proceed on their own path of projectionand would travel the remaining distance from the orifice of the nozzle to the surface of deposition under their own momentum. A nozzle designed upon this principle is fully described in my copending application, Se-' rial No. 417,648, filed Dec. 31, 1929, and operates upon the principle of a tromb shaped nozzle whereby the air is deflected from the sand at substantially right angles to the flow of the sand as it leaves the nozzle orifice. It is thus obvious that by separating the air from the material, the disadvantage of sweeping particles, already deposited,v from the depositing surface would be avoided. However, there remains another method of reducing'rebound and the sweeping action of the air or what I term air erosion and that is by reducing the velocity of the air before it leaves the nozzle orifice. Means for this purpose is to be considered as one of the prime objects sought in this invention.

For the purpose of reducing air erosion, this invention contemplates a partial absorption of the air velocity at a point prior to the departure of the particles from the nozzle orifice. The principle involved in this invention is based upon the theory that the compressed air which is forcing the particles along the path of travel will have performed all of its useful work as soon as the nozzle orifice is reached and that unless it is deflected or its energy absorbed,'it will continue to travel to the depositing surface and will impart its remaining energy to removing particles from the surface. In addition to removing particles it will set up eddy currents or counter currents in direct opposition to the depositing of material. In order to obviate this condition, I have devised a nozzle whereby the excess velocity of the air within the nozzle is applied to drawing outside air into the nozzle in a manner to partially absorb the unexpended energy remaining in the air. By this method the energy still remaining in the live air after it has delivered the particles to the nozzle orifice, is partially absorbed by setting into motion a volume of static air surrounding the exterior of the nozzle. The direct result is a decrease in the velocity of the sand and air column before leaving the nozzle orifice. This in turn reduces rebound of particles by decreasing the incident velocity and also tends to decrease air erosion by debilitating the air. A nozzle having the foregoing characteristics will be appreciated as accomplishing the major purposes of this invention, namely, to decrease the rebound of particles by reducing the incident velocity thereof and to decrease air erosion of deposited particles by reducing the air velocity before it leaves the nozzle.

An added advantage resides in this arrangement for this reason. It is assumed that the density of deposited product depends largely upon the nozzle pressure. This assumption is based upon practice, and also'upon the factthat'yarious city and country specifications for Gunite stipulate a minimum nozzle pressure in order to insure a certain density of product. Therefore, by reason of work performed in the nozzle .proyided by this invention, it is clear that a considerable resistance is oiiered to the passage of .air therethrough and that, consequently, such a nozzle will maintain a comparatively high nozzle pressure which conforms to the above requirements in practice.

it .is apparent that :a-com'binati'onof the principle of the "present invention may be :made with the principle or :another of inventions disclosed :and claimed in any .copending application, Serial No. $17,647, illed Dec. 30, 1929. .In the said "copending application, the velocity of the partiroles is meduced by mechanical :obstructing means. Evidently, :a combination of the two principles, to wit: the present invention, and the foregoing :copending :imren'tion, would :produce .a nozzle particularly -su'itable ior depositing cement in quarters where rair eros'icn llS objectionable and where high density of :product is :not required.

In my said :copending application, Serial No. 4117,6228, filed 33cc. 31, 1929, I have disclosed :a nozzle involving the ltromb ssh-aped nozzle. "Zilhis arrangement, in :conibinati'on with the principles of the mresent invention, produces a nozzle tha't greatly reduces *the "velocity of the released air obstruction .in the path of the projected :sand

zpa'rtioles to decrease the velocity of :-said :pa-rtioles; :and

Big. f irshows :an'o'ther combination :of principles :in which the prino'iple of this iinvention is inconporated with "a second principle :of deflecting ithe excess :air ifrom the path of the projected particles.

in the drawing herewith, I have :more or less diagrammatically iillustrated lmy invention sand haveishown arnozzle diatta'ched to .-a waterlring 2B which in tunn iszmounted :upomaconventionall material conveying Fhose In all the iforms :n'f nozzles embodied .in ithis invention, there is in- :curporatedan air massage orra series of air pas- :sages designated :at 11. .The passages i121 :Will'be ;appreciatedzaszproviding:communication'fromthe sexterior :of ithe nozzle it'o the interior of rsaid mozzle.

ln fthe pperation :of the nozzle embodying the principle oi iaJbsorbing the excess velocity of the air transporting medium before it leaves the nozzle orifice, which form is illustrated in Fig. 1, the sand particles are conveyed through the hose C and are hydrated in passing through the water ring B whereupon they pass outwardly in a sand and air column in the direction of the arrow 12. As the particles propelled by the air continue to pass outwardly through the nozzle A; the air pasages .11 beginto operate and serve to communicate the zone of :staticair surrounding the exterior of the nozzle with the interior of the nozzle. This arrangement is recognized as providing an aspirating means of drawing outer .air through the passages 11 into the interior of the nozzle A by means of the excess energy of the 29.211 which has transported the material to this point and has no further usefulness. It is readily understood that by thus setting up a mov ment to a volume of external air, a large percentage of the energy of the live air within the muzzle is :absorbed. Ellhis .pnimziple of mar- .tielly oalbsorhing the nelocity or :live air within the nozzle after :it :has performed .its usefulness :by rcans'mg :it to :mone la 'Mclume rof idead air, 113 to be considered ;as the heels .of my invention, and operates to materially :rednce the viability :of the :sand and :celumn, 1am consequence -:of which .is to decrease the speed dihe apantiole before :being projected. lBy thus rdeomasing the ,speed of the marfiicles and the welocity (of the :air, "the rebound of particles due rto velocity and erosion pf ipariiicles mine to 'air is reduced. A nezzlerol this typeropenateszsezt- .isfactorily 'to deposit ;a large alolume of ipradnct having :an average :clensity. The :chief :benefit of such a :nozzle is the reduction :of zrehonnd clue to incident yelocity and impact an dihe -;.pz=vrtioles and :a lessening of :air erosion.

,In Fig. .1 have aemlmdied -irltce gpninciples not the present iinvention the :of an- .other of .:my inventions disclosed :in ssaiid moncnd- Ling application, ZSmiial .llo. AeIFLGA'Z. it :will foe noted in Fig. .3 ithat the :same mozzle 11A zis iutilizefl zin iconsunction with a nonventional water ming Brandzthe usual imaterial conveying hoseiC. Ellhe same zair massages care provided and ithe we- ;locity ef :the .excess air is absorbed in the :same manner. embodied :an :o'bstnucting cilement 7D arranged :in

:the path .of thesand particles. .pnsposenf this arrangement is its cause a. disturbance .-amongst the particles and thereby appreciably decrease the velocity :of the particles zthemselves. 'I hisarrangementobviously increases the rhenefits sought 1130 .be :efiected :by this invention, mamely, :the niinimizingipf rebound of :by ade- -creasing the velocity 2 hereof :and ithe reduction of 'air erosion :by absorbing a :certain amount .01 excess .air velocity. A nozzle :of this ichamcter ri-s However, in this :arrangement, .=I lnave is particularly adapted ttoreduee air erosiomand a J todeposit a large volume of rmaterial wherezdensity-of produc't is not of-.prime2importance.

Fig. 4 illustrates the principle :of the present invention in combination with it-he :prinoiple of another of :my inventions. in the illustration ing the velocity of excess air is identical with the :method disclosed :in the present iil'lXIBlilliDIl.

In combination with this arrangement, zhave illustrated a second arrangement comprising an adaptation of :a trom'b designated :15 which is In combination with rthe mile :15,

its

arranged to deflect air separated fromthe column of sand and air by expansion through passages 16. This principle of deflecting air from the sand column has been fully described and claimed in my copending application, Serial No. 417,648, filed Dec. 31, 1929.

In combining the principle of this invention with the principle of the above mentioned invention, an intermediate member 1'7 is incorporated between the tromb 15 and a tromb 15' and is shaped in a manner to define one side of the passages 11 and 16; This type of nozzle may be said to meet the general requirements of the elimination of air erosion and the reduction of particle speed. A nozzle of this character will find general usefulness in almost all kinds of work.

In the drawings shown, it is to be understood that the principles involved are more or less diagrammatically shown and that this invention is intended to include all forms of nozzles which embody the principles disclosed in the drawing and the specification.

I claim as my invention:

1. In a nozzle for use with cement gun equipment: means for reducing the speed of the particles projected therethrough, said means including passages in said nozzle arranged to communicate the flowing air within the nozzle with exterior air surrounding the nozzle; and a particle obstructing element arranged within the orifice of the nozzle. 1

2. A nozzle of the character described comprising: a casing adapted to be mounted upon a material conveying conduit, said casing embodying an expanding nozzle having passages communicating the interior of said nozzle with the exterior air surrounding said nozzle; and a particle obstructing element arranged in the orifice of said nozzle.

3. A nozzle of the character described comprising: a casing adapted to be mounted on the discharge end of a material conveying conduit, said casing forming an expanding nozzle having its inlet end spaced apart from the end of the conduit to form an air inlet passage therebetween, and a particle obstructing element centrally disposed in said nozzle.

JOHN T. VAWTER.