US 2516684 A
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Description (OCR text may contain errors)
July 25, 1950 R. M. DOULL ETAL 2,516,584
- PNEUMATIC CEMENT-APPLYING APPARATUS Filed De. 11, 1947 INVENTORS ROBERT.M.DOULL MAjKO RADONICH ATTORNEYS water iing.
Patented July 25, 1950 cause stars-s PNEUMATIC, pEME'Nir-APPLYING APPARATUS Robert M. Doull and Marko Radonich, Montreal, Quebec, Canada Application December 11, 11947, ISerialNo. 791,064
2 Claims. 1
This invention relates to pneumatic cementapplying apparatus in which compressed air is utilized to shoot a hydrated mixture of sand and cement aggregate through a nozzle onto the surface to be covered. In the conventional apgparatus of this type the aggregate is supplied to the nozzle through a flexible hose and the total amount of water required for hydration is introduced through a water ring located at or near the point where the aggregate enters the nozzle. In U. S. Patent 2,392,408, granted Jan, ,8, 1946, there is described an improved pneumatic cement-applying apparatus wherein improved hydration of the aggregate and other advantages are obtained by the provision of a rear water ring through which part of the total amount of water required for hydration is added to the aggregate at a point located an appreciable distance in advance of the point where the aggregate enters the nozzle, the balance of the required amount of water being added through a front water ring located at or near the point of entry of the aggregate into the nozzle. In "this apparatus the front and rear Water rings are iconnected to separate branches of a water sup- ';ply pipe. jI hese branches are equipped with 'v ailves which-are adjusted by 'the op'era'tor to pre- ;determine the proportion of the required amount of wateradded to the aggregate at each ring.
,The best results are obtained when the valves .are accurately adjusted so that approximately one-third of the total amount of water required for hydration is-added at the rear'water'ring and the balance added to the aggregate at the front Efiicient operation of the apparatus described in said prior patent requires accurate proportioning of the relative amounts of water supplied to the aggregate through the front and rear water rings and experience has shown that the adjustments necessary to accomplish this cannot "safely be left to the judgment or guesswork of the operator. Difierent aggregates re quire difierent amounts of water for eflicient hydration and it takes considerable time for a skilled operator adjustments necessary to ensure for different conditions of operation, the required accurate proportionate distribution of the water between the front and the rear water rings. Because of this it sometimes happens that the potential efilciency of operation of the apparatus described in our prior patent is not realized in practice owusing the apparatus described invour prior patent to acquire the skill and judgment necessary to bperate the .water supply valves to provide the ing to incorrect setting of the water supply valves.
Another undesirable feature of the apparatus disclosedin said prior patent is the existence of a differential pressure between the front and rear water rings which adversely aiiects the accurate .proportioning'of the water between the two rings and also tends to reduce the pressure on the rear ring with-resulting plugging of the orifice of this ring and subsequent' losspf time and faulty operation.
With the foregoing in mind one object of the present invention is to provide an improved pneumatic cement-applying apparatus in which the proportionate distribution of water between the front and rear water rings is automatically taken [care of in a foolproof manner;
Another object of the invention isfto provide an improved pneumatic cement-applying apparatus in which provision is made for maintaining identical water pressure conditions on each of the front and rear water rings.
.Qther objeotsfadva'ntages and'characteristic iteature's of the invention will bejrnore readily understood Ifrornthe following description of the accdmpanying drawings illustrating what We now conceive to be the preferred embodiment of our invention. p
In these drawings: i
The single figure is a longitudinal sectional view of a pneumatic cement-applying apparatus embodying our invention. V
Referring more particularly to the drawing, 5 designates -a-nozzle through which. :the hydrated sand and cement aggregate is prejected onto the surface to :beooVQItBd. The rear endoi the nozzle is screwed into :the internally threadedtront end I of a'ringwshaped nozzle couplings. A rubber liners arranged ini'nozzlea andis'provided, at-itsrearend, with an outwardly directed sealing flange it clamped between the rear end of "the-nozzle and the front 'side:ofan annular flange l extending inwardly from an intermediate poi";- tion of coupling 8. 1 The rear end portion 12 of coupling ll is "in- ,t'ernallythreaded andscrewed onto-the front end of'a metal tube is. The rear and of tube 13' is screwed into the internally threaded iront end portion M of a ring-esha'ped'hosegcoupling -'l5"having an internally threaded rear end p'ortion it in which the delivery end of a flexible hose I? is secured by an externally threaded fitting l8. Coupling i5 is machined to make a running fit on tube l3 to permit convenient removal of coupling l5 and other interior parts of the complete asseiribly hereinafter described. Coupling ii is locked in place by locknut la.
Couplings 8 and I5 serve, in conjunction with tube 13, to provide the outer and end walls of a water jacket whose inner wall is formed by an inner tube 2! and front and rear water rings 22 and 23. i
The front water ring 22 is machined to provide a front spigot portion 24 of reduced diameter which is a press fit in a recess 25 provided in the rear side of coupling flange H. The rear portion of water ring 22 is similarly machined to provide a rear spigot portion 26 which is a press fit in the front end of tube 21. The rear water ring 23 is similarly machined to provide a spigot portion 21 which is a press fit in the rear end of tube 2i and a second spigot portion 28 which is a press flt in a recess 29 provided in an annular flange 30 projecting inwardly from an intermediate portion of the hose coupling ring IS.
A tubular rubber liner 3| is cemented to the inside of tube 2! so that it extends the full distance between the front and rear water rings 22 and 23. The inner circumferential surfaces of front and rear water rings 22 and 23 are flush with the inner circumferential surface of liner 3! and form therewith a smooth tubular passage 32 through which the sand and cement aggregate is forced from the delivery end of the hose 1! to and through the nozzle 5.
Front water ring 22 is pierced by holes 33 through which water is delivered from water jacket 20 to the sand and cement aggregate at approximately the point where the aggregate enters nozzle 5. Rear water ring 23 is provided with similar holes 34 through which water is delivered from the water jacket to the sand and cement aggregate at points located an appreciable distance in advance of the point of entry of the aggregate into nozzle 5.
The number and/or size of the holes 33 and 34 provided in the front and rear water rings 22 and 23 is predetermined so that the water is metered to give the correct proportionate distribution between the two water rings. The arrangement and/or size of the holes in the two rings is preferably predetermined so that approximately onethird of the total amount of water required for hydration is delivered through the holes 34 of rear water ring 23 and the balance through the holes 33 of front water ring 22.
The provision of the common water jacket 20 through which the water is delivered to both water rings ensures the maintenance of identical water pressure conditions at each ring and is an important factor in maintaining accurate relative proportioning of the amount of water supplied to the aggregate through said rings.
The holes 33 and 34 of water rings 22 and23 are preferably inclined, as shown, so that the water flowing through these holes is directed in the direction of flow of the aggregate through the water rings.
Water under pressure may be supplied to water jacket 20 in any suitable manner. In the present instance we have shown a water supply hose 36 having its delivery end screwed into a water inlet opening 31 provided in the nozzle coupling 8 at the rear side of flange H.
Another advantage of the present invention is that it provides a self-contained hydration unit which is lighter in weight than the equivalent arrangement described in our prior patent and which is composed of parts which are accurately machined to ensure tight joints in the assembled relation thereof and which can be assembled and disassembled with great ease and rapidity.
Having thus described the nature of our invention and a preferred embodiment thereof, it will be understood that various modifications may be resorted to within the scope and spirit of the invention as defined by the appended claims.
1. In pneumatic cement applying apparatus of the character described, a hydration unit comprising front and rear centrally apertured end members each having internally threaded front and rear end portions and an inwardly directed intermediate annular flange, an outer tube having its front and rear ends screwed, respectively, into the internally threaded rear end of the front end member and the internally threaded front end of the rear end member, said tube formin with said end members, the outer and end walls of a water jacket, separately formed front and rear water rings butted, respectively, against the rear side of the flange of the front end member and the front side of the flange of the rear end member so that said rings form end portions of the inner wall of the water jacket, an inner tube connecting said water rings and forming an imperforate intermediate portion of the inner wall of the water jacket, said rings being pierced by openings extending from the outer to the inner circumference thereof and providing water passages through which water is discharged from the water jacket into the space surrounded by said rings, means for supplying water under pressure to said water jacket, an aggregate supply conduit screwed into the internally threaded rear end of said rear end member and a nozzle screwed into internally threaded front end of said front end member.
2. Pneumatic cement applying apparatus as set forth in claim 1, in which the water rings are provided with end portions of reduced external diameter fitted in the ends'of said inner tube and opposite end portions of reduced external diameter fitted in recesses provided in the flanges of said end members and in which the inner portion of the inner tube lying between said water rings is covered by a resilient non-metallic tubular liner having its inner annular surface flush with the inner annular surfaces of said water rings.
RQBERT M. DOULL.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS