US1297081A - Method of and apparatus for mixing concrete. - Google Patents

Description

H. P. BROWN.

METHD 0F AND APPRATUS FOR MIXING CONCRETE. Plxcfmon FILED umu. 1914.

3 SHEETS-SHEET l.

A TTURNEY H. P. BROWN.

METHOD 0F AND APPARATUS FOR AMIXING CONCRETE APucATloN FILED DEc.24. |914. 1,297,081; Patented Mar. 11,1919.

EI//Qo l N.

YL u? H. P. BROWN.

musgo 0F AND APMM/Tus Fon MIXING CONCRETE.

Patented APPLICATION FILED BEC.24. 1914.

Mar. 11, 1919.

{ETS-SHEET 3- WITNESSES l/WENTR 'Ano/mfr UNITED sTATEs PATENT oEEIoE.'v

HAROLD P. BROWN, NEW'YOBK, N. Y.

To all whom it mag/concern:

Be it known that I, .HAROLD P. BROWN, a citizen of the'United States, residing in the borough of Manhattan of the city of New York, in the county of New York, in the State of NewYork, have inventedl certain new and useful Improvements in Methods of and Apparatus forMixing Concrete. of which the following is a specification, reference being had to the accompanying drawings, which form a part hereof.

This invention relates to the method of and apparatus for-mixing and placing concrete or similar cementitious material and is concerned particularly with the conveying and placing of mixed cementitious material containing sand, stone and cement. It is 'comparatively easy to place grout which is substantially of the consistency of cream but it is very diilicult to pla'ce concrete, which, in its wet state, is a plastic solidandcon tains segregated rock material. It has been proposed to mix the dry constituents of cementitious materials first and then convey them through a suitable conduit, as by means of a blast of compressed air, toward the point of discharge, and hydrate the mixture at the instant of discharge. way it has been sought to minimize the dangers of clogging. By the present invention,

" it has been sought to overcome all of the diiliculties, expense and disadvantages incident to former methods and apparatus and provide a new and improved method of and apparatus for mixing` concrete thoroughly and then granulating the mass by means of a fluid blast and conveying it through a conduit to an improved nozzle through which it is discharged in placing. AIn using the word fluid I wish 4to have it understood in its broadest sense to include any suitable flowing medium, particularly gas,

vapor, air and steam. The invention seeks particularly to insure a uniform mixture of the cementitious materials before they are delivered to the conveyer and to subject them to the action of preferably an elastic gaseous element, for example steam, which may or may not serve as the impelling force, and which has the peculiar property of accelerating hydration of the 'mixed mass to just the-proper degree, and,

after the mass has been placed and pressure released, of accelerating drying and crystalization. thereby insuring a strong, dense deposit after a comparatively short period of In this METHOD OF AND APPARATUS FOR. MIXING CONCRETE.

Patented Mar. 11,1919.

i 4Application led December 24, 1914. Serial No. 878,850.

time for setting. The invention has for a further object the provision of an improved mixer whereby the materials are thoroughly agitated and brought into uniform and intimate association throughout'the batch, the

mixing devices being of such a character as to scrape the elements thereof continuously 'and prevent the setting of concrete at any point within the mixer and, at the same time, to convey the material toward the point of discharge. Still another feature of the invention resides in the provision of an improved nozzle for applying the concrete, -this nozzle being susceptible of ready .manual manipulation for thel purpose of dislodging such material as tends to clog therein. Other objects will appear hereinafteras the description proceeds, reference now being had to the accompanying drawings for a detailed description of ,a preferred embodiment of the ,invention In the drawings- Figure 1 is a view partly in side elevation and partly in vertical section of a complete portable apparatus embodying the invention, the conveying conduit and the nozzle therefor being omitted.`

Fig. 2 is a view in end elevation of the apparatus shown in Fig. 1.

Fig. 3 is a fragmentary view in transverse vertical section taken through the mixer drum shown in. Fig. 1.

Fig. 4 is a fragmentary view on a' somewhat larger scale taken on the plane indicated by the line 4--4 of Fig. l and looking inthe direction rof the arrows.

Fig. 5 is a fragmentary view in perspective showing the mixing blades mounted on their supporting shaft and carrying the improved auxiliary agitating and scraping devices. v

Fig. 6 is a detail view in perspective and on a somewhat larger scale, of the mixing blades.

.Fig 7 is a fragmentary view in vertical section taken through the discharge head of the mixing drum and showing particularly the valve for controlling the passage of material from the drum into the conveyer.

Fig. 8 is a view in side elevatior and purely conventional, of a' complete plant for practising the .improve method.

As shown in Fig. 1,4 the improved mixing apparatus comprises generally,- a stationary drum a. in which are disposed 0peratively mixing blades b secured on a shaft e to which rotative movement is imparted through a gear d keyed on one end thereof and in mesh with a driving pinion e driven by a suitable motor f which is provided With the usual controlling and reversing devices. rl`he elements referred to may conveniently be mounted on a portable carriage frame g, the wheels g thereof, being preferably so proportioned with respect to each other as to support the drum in an inclined position to facilitate the discharge of the mixed material therefrom, as Will appear hereinafter.

rl`he present invention seeks to provide for a more uniform mixing of the cementitious materials and to provide an apparatus which shall be efficient in operation and entirely suitable for the successful practice of the improved method of mixing;` and placing concrete. To this end, the drum (1 the mixing blades b and many of the associated parts possess novel characteristics. T he constituentsV of the concrete may be fed into the drum a from a hopper a', indicated in dotted lines in Fig. 1, and conveniently supported on a hollow dome a? With Which it communicates through an opening a formed in the dome and controlled by a suitable flap valve a* Which may be held in closed position against the action of gravity by means of a rod a5, the free end of Which is 'Within convenient reach of the operator.

The material passes through. the dome a2 and an opening as formed in the Wall of the drum a, into the drum, Where it is engaged and mixed uniformly and thoroughly by the rotating mixing blades Z) and their auxiliary mixing devices, as will appear later, and conveyed steadily toward a suitable discharge opening a7 formed in the remote lhead es of the drum. Under some conditions of use it may be desirable to introduce the material into the drum through a filling opening a formed in the same head a8 of the drum as the discharge opening a?. rl`he filling opening a may be controlled conveniently by a suitable gate valve (do.

The devices by which the mixing is effected after the material is introduced into the drum, Will new be considered; rlhe rota-V shaft c may 'be slipped ed from the shaft v ery readily. To insure a gast-ight and grittig'ht union between the shaft o' and the rerees/,esi

to Fig. i, one such source of fluid pressure is indicated at Z as a Water or oil pump, although it is evident that compressed air or steam at a pressure equal to or greater than the maximum pressure in the drum, may be substituted. ln this ligure is shown a pressure grease cup m .by Which the glands are lubricated.

The agitating or mixing elements include the .series of blades b formed generally of l -shaped outline and provided with notches Z1 in .theiredges whereby the adjacent blades 1are iiiterlocked when assembled on the shaft c in the manner 'shown in Fig. 5, and the use of bolts or other securing means is obviated except for bolts n Which are passed through the end blades of the series and are engaged with the support-ing shaft c to retain all of the intermediate blades in place. Where the blades Aare L-shaped, the supporting shaft is made square and the blade elements are alternately placed 18()o apart around the axis of the shaft. The end blades 7) are provided with a supplemental blade b2 which is preferably secured in placeby means of the loc-king bolt fn, and' is arranged to bisect the obtuse angle formed' by the other twoblade elements of the paddle to which it is applied. `While the agitatingr system described Would be effective in mixing the material in the area through which the blades sweep, it is evident that there is'a space between the paddles and the Walls of the drum in which the concrete undisturbed and would tend to set. in order to insure the uniform mixing of the v material throuehout and revent the setting thereof, auxiliary mixing elements ii ne form of chains 723 are secured to the elements b, a very effective disposition ofthe chains being illustrated in Fig. 5. ln this gure it appears that three independent chains pass from the end paddles and are secured to the next blade element of the series which is disposed at substantially 90 from the blade element to which the chain is attached. ln this Way, the chains extend in a substantially spiral direction from one end of the drum to the other and exert a lateral pressure on the material which tends to force Ait from one end of the drum toward the other. 1n practice, it has been found best to pass the chains through the blades elements adjacent their outer edges and to hold the chains against longitudinal movement by means of split links b4 secured to the blade elements and engaging links of the chains at the points Where they pass through the blade' elements, respectively.

To eachl of the chains between adjacent 'in the longitudinally extending chains b5,-

is such that during the operation of the mixer, the chains or .springs engage the walls ofthe drum and continually dislodge the material therefrom so as to insure a uniform and thorough 'admixture When the speed of rotation of the blades b is below what might be termed the critical speed, the chains and springs will fall away from the walls of the drum, under the influence of gravity, as` they are carried up the side of the walls and will scrape the surfaces of the blades. If, however, the speed of rotation exceeds this rate, the springs and chains will be maintained in engagement with the side walls at all times, under the action of centrifugal foA 1e. Under either condition, it will be evid nt that these auxiliary elements are actii ly employed in doing useful work, whether it be in -:;raping the blades of the paddles or in removing the material from the walls o-f the drum ther than that, the spirally disposed chains 62 exert a constant lateral pressure o-n the material tending to force the same toward the discharge end of the drum. It should be noted here that if the material is introduced into the drum a through'the opening` a, the direction of rotation of the paddles need only be changed from time to time in order to convey the materialfrom one end of the drum to the other. It is also important that the slack in the auxiliary cleaning and feeding-elements should not be so great as to permit them tobecome jammed between the wall of the druin aI and the ends of the blades b. Equivalent elements such as rods, may be employed to carry on the auxiliary scraping and mixing operations Ywhich are effected by the chains and springs' ply pipe qa), are discharged. In Fig. 8 isI shown a complete plant for carrying on the mixing including a source of steam such as a boiler g4, a superheater g5 through which the steam may be by-passed by proper manipulation of the valve Q6, and a separator or drain Q7. Extending through the casing Q is a sleeve 1' of somewhat greater diameter than the diameter of the discharge opening ar,7 and in which is mounted slidably a piston valve, indicated generally at s, the stem of which-s is threaded into a closure block r for the sleeve 7 and has fastened .on its free end a hand wheel s2 to facilitate manual manipulation of the valve .8. The closure block 1" may be maintained in position by means of a U-bolt r2 which is secured in the outer end of the sleeve r and abuts against a shouldered portion r3 of the block r. The piston s proper, is preferably built up with a yielding gasket 83 and a metallic cover lplate s4 Iwhich is adapted to fit snugly within the discharge opening a7 and have its inner face fiush with the inner wall o f the head aB of the drum a, thereby obviating the danger of a deposit of concrete or of interference with the mixing elements'. The gasket 83, when the valve is'in closed position-may rest against the outer wall of the head a8, around the periphery of the opening a", and thereby effect a gas-tight closure of the said opening.

When the material has been thoroughly mixed, the hand wheel s2. may be rotated to move the Valve s axially in the sleeve r and open the discharge port a7, thus Permitting the material to bev forced'out through this opening under the influence of the spirallyl disposed chains b? and this movement is assisted in the preferred structure, by surface pressure applied to the mixture b-y a gaseous element introduced into the upper part of the drum a, as through a valve controlled conduit communicating with the filling dome a2. This gaseous element, it should be remarked, preferably is one which possesses all of the peculiar properties which are to be pointed, out later with respect to the' conveying medium. The discharge material falls in a free stream or mass, through an opening r4 cut in the lower portion vof the sleeve 1" and registering with the discharge duct g2, this opening being extended around .I

the circumference of the sleeve for an appreciable distance so as to insure effective coperation of the gas or vapor with the. mixed material. The action of the fluid element on the mass of'concrete as it is discharged from the mixer may Well be termed an atomizing or more properly va granulating action, in that the blast of fluid picks up the concrete and exerts a continual stress thereon tending to withdraw the material from the mixer drum-IL and thoroughly subdivide the mass. As the concrete is picked up by the iiuid blast at the opening r4 in the sleeve r it is carried on in its granulated state through the discharge duct g2 and into the conveying conduit u tothe applying nozzle o from Which it is directed to the desired place of deposit. From this description it will be evident that the mixed materials are carried `from the mixer to the'point of deposit in the presence of (when steam is emof such characteristics as to affect the finely divided particles of mixed materialy in such manner as to maintain them in propercondition during the conveying and accelerate drying and crystallization -after placing. Steam, which is always available on engineering jobs requiring concrete Work, is probably the most inexpensive element and, when applied in the manner taught by this invention, has been `found to impart to concrete all of the properties which are recognized as being desirable;

WV hen the desired quantity of concrete has been discharged in the manner described, the valve in pipe t may be moved to closed position and the supply of Huid under pressure may be. shut off in the conduit g3. The pressure in the mixer drum a Will then fall to that of atmospheric pressure and the flap valve a4 may be permitted to open under the influence of gravity for the introduction of a fresh charge of materials.

The improved nozzle is indicated by the i reference character/v and includes manually operable clamping devices o by Which the nozzle may be formed on the conveying pipe u' which is of yielding material, this being accompanied by a compression of the hose u at the end of the nozzle and a restriction of its area so that the inely divided particles of material Will pass through this constricted portion and be shot out of thenozzle to the point of application with great force. rThe application of the material in this Wayis especially desirable as the particles serve totamp the material previously applied andV thereby form a dense mass. lt has been found that the presence of an elastic gaseous element during the conveying of the material, after the latter has been uniformly and thoroughly mixed serves to a marked degree to prevent clogging 4throughout the length of the conveyor.

However, there may be a slight tendency for the concrete to clog in the hose at the point Where the hose 'u is compressed and provision is therefore made, inthe form of the'clamping devices fv, for the ready opening of the nozzle o to the full diameter of the hose and the release of the lodged materials atthe end of the hose. After the particles have been dislodged, the nozzle may be very readily recompressed lby proper manipulation of the lever.

While the preferred form of the apparatus for practising the improved method ployed) an elastic gaseous element which is maenner has been described in some detail, it is to be understood that the invention is not to be limited to the precise construction shown but may be Varied by the substitution of such equivalent elements as suggest themselves to those skilled in the art. Further, the improved method set forth in the appended claims may be practised in any apparatus capable of carrying out the method Without departing from the scope of such claims.

The coil springs l? are preferably extended so that they yieldingly press against the heads of the drum and thus keep such heads clean.

bWhere it is not necessary to move the 'conveying conduit u, it may be made of ordinary pipe. Where it is convenient to have a iiexible conduit or portion of conduit, it

is preferably composed of flexible hose Whose interior surface is a very pure rubber or similar yielding substance.

lt is found that the highly abrasive mixture does not readily attack such surfaces. ln fact the rubberseems to acquire a slimy coating Which acts as a lubricant. ln these iiexible conduits, if in sections, it is desirable to so extend the yielding interior surfaces into the couplings that no portion of the hard parts of such couplings is exposedl to abrasion.

lt is'to be noted that upon closing the valve p, all concrete in the'sleeve s is forced ba'clrinto the mixer so that none remains to set and clog the discharge apparatus.

l claim as my invention l. Mixing the constituents of a cementitious mixture including Water, applying independent pressure to said constituents While being mixed, discharging the mixed material in mass, granulating the discharged mass by means of a fluid blast inde endent,

of. said mixing pressure' and impelllng the material in such granulated condition from the mass.

Q. Mixing under steam -pressure the constituents of a cementitious mixture including Water, discharging the mixed material in mass, granulating the discharged mass by means of a fluid blast and impelling the material in such granulated condition away from the mass.

8. Mixing under superheated steam pressure the"constituents of a cementitious mixtureincluding Water, discharging the mixed material inmass, granulating the discharged the material in such granulated condition away from the mass.

5. Mixing under .heat and pressure the constituents of a cementitious mixture including water, discharging the mixed material. in mass, granulating the discharged mass by means of a fluid blast and impelling the material in such granulated condition away from the mass.

6. The method of mixing and placing concrete etc., which consists in mixing the materiais in a plastic condition in the presence of steam and feeding the plastic ingredients to a separate blast of steam to be caught up and carried on by the blast. 7. Apparatus for mixing and conveyin concrete including a mixer drum provided with inlet and outlet openings, agitating means for the plastic conglomerate disposed operatively in the drum, said means comprising a rotatable shaft, a series of mixing' blades mounted thereon and auxiliary agitating devices carriedA loosely by the blades and adapted to sweepv through the material in the zone without the area of the blades, whereby the material is uniformly and thoroughly mixed, a chamber through which the concrete passes from the outlet opening, a valve to control the outlet opening, means to introduce a blast of an elastic gaseous element into the chamber to atomize the plastic ingredients, and a conduit through which the'concrete is carried on by the gaseous elementto the place of deposit.

. 8. Apparatus. for mixing and conveying concrete including a mixer drum provided with inlet and -outlet openings, agitating means for the plastic conglomerate disposed operatively in the drum, said means comprising a rotatable shaft, a series of mixing blades mounted thereon and auxiliary agitating devices carried loosely byl the blades and adapted to sweep through the material in the zone without the area of the blades, whereby the material is uniformly and' thoroughly mixed, a chamber through which the concrete passes from the .outlet opening, a valve to control the outlet opening, means to introduce a blast of an elastic gaseous element into the chamber to atomize the plastic ingredients, a conduit through which the concrete is carried on bythe gaseous element to the place of deposit, and means for choking the said conduit to increase the effective force of the blast. t 9. Apparatus for mixing and conveyin concrete including a mixer drum provided with inlet and outlet openings, agitating means for the plastic conglomerate disposed operatively in the drum, a chamber through which the material is passed from the outlet openings, means to introduce a blast of an elastic gaseous element into said chamber to atomize the .plastic ingredients, a conduit having an interior of yielding material through which the plastic concrete is carried i on by the gaseous element, -and means for choking the said conduit and allowing it to expand at pleasure for increasing the effec# tive force of the blast and' for clearing the conduit.

10. A. mixer for cementitious materials including a mixer drum, a rotatable shaft, Va

lseries of mixing blades mounted thereon,

chains secured to said blades and extendin spirally of the drum, separate chains secure to the first named chains and extending longitudinally of4 the drum, and coil springs carried by the second named chains, all of said chains being slack and adapted to sweep through the zone without the area of the blades and scrape the walls of the drum and the blades.

11. In a concrete mixer, agitating apparatus comprising-a rotary'shaft, a'series of mutually interlocking mixin blades provided with segmental angularubs for causing them to rotate with the shaft and means for. holding the said blades in their interlocked position.

12. In a concrete mixer, agitating devices comprising an angular shaft, a series of mixing blades mounted thereon and each provided with an angular bearing surface to cooperate with the angular shaft and with means for interlocking the proximate blade elements, and means to secure the end blade elements of the series to the shaft to maintain the entire series in interlocked position.

13. In a concrete mixer, agitating devicesv pomprising a square shaft, a series of L- shaped blade elements mounted thereon and each provided with notches in its edges to interlock the adjacent blade elements, and

to be closed by an axially moving piston and a piston for closing the port, said piston in closing adapted to move beyond said port and to drive all contents before it into the path of the mixing devices. 16. A concrete mixer including a coritainer ,provided withv an inlet and an outlet opening, having a discharge port and a closure therefor, said closure being adapted to drive the contents of the discharge port before it into the path of the mixing devices.

17. A mixing chamber for receiving the ico constituents @i e Cementitious mixture including Wefe means for mixing the seid ingedieis in said chambel', means for epplyiiig independent pressure to said constituents while being mixed., means for dis Chai-ging the mixed materiel in mass, and

' means foi applying e Huid blast te the saii This specification signed and witnessed this 7th day ofiecember A, D., 1914:.

I HAROLD P BROWN..

Signed in the presence 0f- JAMEs COMERY, ANTHONY EHeMPseN.

Images