US2083767A

US2083767A - Apparatus for mixing concrete

Info

Publication number: US2083767A
Application number: US346570A
Authority: US
Inventors: Porter W Yett
Original assignee: Individual
Current assignee: Individual
Priority date: 1929-03-13
Filing date: 1929-03-13
Publication date: 1937-06-15
Anticipated expiration: 1954-06-15

Description

June 15, 1937. p w 2,083,767

APPARATUS FOR MIXING CONCRETE Filed March 13, 1929 4 Sheets-Sheet 1 WWW June 15, 1937. w YET-r 2,083,767

APPARATUS FOR MIXING CONCRETE Filed March 13, 1929 4 Sheets-Sheet 2 V N) /%//EN7'UR x [WW June 15, 1937. P. w. YETT APPARATUS FOR MIXING CONCRETE F$led March 15, 1929 4 Sheets-Sheet 4 mZON UTZXZZ 7:464

Na E Patented June 15, 1937 UNITED STATES PATENT OFFICE APPARATUS FOR mxme concurs Porter .w. Yett, Portland, Oreg.

Application March 13, 1929, Serial No. 346,570

12 Claims.

This invention relates generally to the art of mixing concrete, and particularly to the mixing of concrete in transit.

The main object of this invention is to provide a special form of mixing apparatus whereby concrete can be thoroughly and uniformly mixed throughout the entire mass of a batch, with the employment of only the minimum amount of water consistent with the production of the highest grade of concrete.

The second object is to produce a mixer whose diameter is small with relation to its length for mounting on a motor truck in which the shape of the mixing cylinder will not interfere with $5 the thorough mixing of the aggregate.

The third object is to produce a concrete mixer in which the materials may be thoroughly mixed in transmit without particular regard as to the manner in which the materials are inserted into the mixer. I

The fourth object is to provide a mixing cylinder'in which the flights are so arranged as to secure a number of reversals in direction of travel with relation to the axis of the cylinder as the cylinder is rotated.

The fifth object is to provide a concrete mixing and transporting machine, having a wide range of speed ratios at which the mixing drum may be driven. I accomplish these results in the manner set forth in the following specification as illustrated in the accompanying drawings, in which:

Figure 1 is a plan view of the truck with the mixer removed. Figure 2 is a side elevation.

Figure 3 is a plan view. Figure 4 is a section taken along the line 4-4 in Figure 2. Figure 5 is a section taken along the line 5-5 in Figure 2. Figure 6 is a section taken along the line 3-5 in Figure 2. Figure 7 is a section taken.

along the line I--1 in Figure 2. Figure 8 is a somewhat distorted development of the interior of the mixer showing the mixing flights. Figure 9 is a longitudinal section through one form of water distributing pipe. Figure 10 is a view 5 through a modified form of water distributing pipe. Figure 11 is a fragmentary side elevation showing an alternative form of water supplying device. Figure 12 is a section taken along the line l2--l2 in Figure '11. Figure 13 is a vertical 50 longitudinal section through the mixing cylinder.

Similar numbers of reference refer to similar parts throughout the several views.

Referring in detail to the drawings, there is shown a truck chassis l5 carrying the usual cab 56 I9 and hydraulic drum hoist I'I mounted on the running gear l8. On the chassis I5 is mounted a mixer frame I9 which is hinged on the brackets 20 which are secured on the chassis l5. 0n the forward ends of the mixer frame I 9 are the downtumed arms 2| to which are attached the cables 22 of the hoist II. On the mixer frame l9 are mounted the circular tracks 23 within which is rotatably mounted a cylindrical mixing drum 24 whose end 25 converges toward the cab l3 and is completely closed by a cap 26; whereas the end 21 converges toward the charging mouth 28 through which materials are inserted by a convenient chute 29, or through which the mixed concrete may be discharged at the point of delivery.

Rotation is imparted to the drum 24 through the gear 30 and its pinion 30-A on the shaft 3| which is driven by a pair of bevel gears 32 from the shaft 33, which is on the hinged axis of the frame l9. Motion is supplied to the shaft 33 by the bevel gears 34 through the shaft 35 which passes through a secondary transmission 36 which is interposed between the usual transmission 31 and the gears 34.

Passing through the axis of the mixing drum 24 is a water supply pipe 38 to which water is supplied from an overhead tank 39 through the piping 49 under the control of a valve 4|. The tank 39 is closed and is capable of withstanding several atmospheres of pressure delivered thereto through the pipe 42 from a reservoir 43.

In the top of the tank 39 is provided a filler cap 44 which preferably includes an air check valve 45 which will permit water to flow from the tank 39 after the supply of air from the reservoir 43 is exhausted. In other words, it prevents the water in the tank 39 from being trapped therein after the air pressure in the tank falls below that of the surrounding atmosphere.

It is preferable to subdivide the tank 39, one side of which forms an auxiliary or flushing tank used in washing out the mixer after the materials are discharged therefrom.

It is desirable to support the water pipe 38 by means of a spider 46 and to so reduce its diameter and space the holes 41 therein, as well as limit their dimension, that there will be a uniform distribution of water along the entire length of the mixer to prevent lumping. In actual practice the pipe 38 is either formed of a number of reducing sections (as shown in Figure 9) or as a tapering pipe 38A having holes 4IA (as shown in Figure 10).

Turning now to the interior of the drum 24 (as shown in Figure 8) as a development which,

for the purpose of clarifying the explanation, is somewhat distorted and shown as a true cylinder rather than one having its ends converging, as is actually the case.

It will be noted that the charging end 2T is provided with a plurality of' inclined charging flights 48 and one return bucket flight 49, while the end 25 is provided with a plurality of return flights 50 and one return bucket flight 5|. It will be noted that the

flights

48 and 50 slope in opposite directions.

Within the cylindrical portion of the drum 24 and closest the flights 48 are the first mixing flights 52 which slope in the same direction as do the flights 48. Near the flights 50 are the

second mixing flights

53, 54 and 55 which slope in the same direction as do the flights 50. The flight 54 differs from the

flights

53 and 55 only in the distance it extends toward the center of the cylinder. Across the middle of the cylinder are formed the tumbling flights 56 which overlap the flrst and second mixing flights.

The rotation; of the drum 24 is as indicated by the arrow 51 in Figures 4 to 8 inclusive.

Referring, now specifically to Figure 8 there is shown, by means of the dotted lines 58, the various paths which a given quantity of aggregates may "follow during the mixing operation. It will be noted that as they fall upon the charging flights 48 they are carried forward, some of them falling into the bucket flight 49, some on the flights 52 and some on the tumbling flights 56. Those falling on the

flights

48 and 52 are naturally advanced along the cylinder, while those falling upon the tumbling flights 56 may go backwardly or forwardly or be carried to the top of the cylinder, from which point they are dropped to the bottom of the cylinder, or on some intervening flight. Those portions falling upon the

flights

53, 54 or 55 will be carried backwardly to the center of the mixer where they are again picked up by the tumbling flights 56 and thrown downwardly. Those portions falling upon the carry-over flight 59, which slopes oppositely to the return flights 50, will be carried over to the extreme front end 25 of the mixing drum 24, after which they pass around the end and sides of the carry-over flight 59 and then fall upon the flights 50, which start them backwardly toward the center of the mixer.

It will be noted that the

flights

48, 49, 50 and Si extend to the inner surface of the mixer; whereas the

flights

52, 53, 54, 55 and 55 are spaced therefrom, as better shown in Figures 4 to '7.

While it will be possible to secure backward and forward travel of the aggregate within the mixer by the use of flights other than those illustrated, the arrangement employed herein possesses numerous advantages which make the use thereof desirable.

It can be seen by a study of Figures 4 to 8 inclusive that the materials along' the mixer are given not only a thorough mixing with relation to the materials near by, but also with relation to all of the other parts disposed along the length of the mixing cylinder.

It must be understood that in charging these machines it is preferable to provide an inclined runway in which the rear end of the machine will be uppermost, which greatly assists the distribution of the aggregates along the entire length of the cylinder, and of course when the mixer is discharged the cylinder is inclined in the opposite direction by means of the hydraulic hoist H, as is well understood. In the draw ng t p si on of the cylinder is shown as horizontal, which is the normal operating position, or the position of the cylinder in transit during which time the mixing is taking place.

Now bearing in mind the desirability of thoroughly dry mixing the aggregates, then moistening same with the minimum amount of water consistent with the formation of first class concrete, and the importance of then delivering concrete to the molds as soon as possible after it is moistened, it can readily be appreciated why it is advantageous to mix the concrete in transit. Experience has shown that the best type of mixer for this purpose is a drum of relatively great length and small diameter and conforming somewhat to the chassis of the truck on which it is mounted.

The use of this type of drum causes several problems to arise, flrst the diiflculty of uniformly distributing the batch along the length of the cylinder and then the dimculty of thoroughly dry mixing every particle of material in the'batch with relation to every other particle of material in the batch, and lastly the difllculty of wet mixing the batch without the use of an objectionable amount of water. Should large volumes of water come in contact with the neat cement it would form large lumps instead of a uniform paste, which in existing types of-machines requires additional apparatus to again break up these lumps.

With the old style drum of a large diameter and short length the aggregates could be deposited within the drum in any fashion desired and secure fairly uniform mixing throughout the batch, owing to the fact that it is largely a tumbling operation in which little or no longitudinal travel of the material is necessary with relation to the mixing drum, but with the long small diameter drum it is desirable not only to charge the drum in a fairly uniform manner but that the materials themselves be moved backwardly and forwardly along the drum, as well as tumble in the ordinary fashion, in order that the promotion of ingredients in the batch and the state of saturation thereof be absolutely uniform throughout the entire length of the mixing drum to obtain a creamy mortar without lumps.

Furthermore, should the liquid be added to the mix at one point and reliance placed upon the further mixing action of the drum to distribute the moisture in the mix it would be found that the portion of the mix which is over-saturated will mix with the remainder of the batch with great difliculty and will form in large lumps if the moisture is not uniformly supplied along the length of the cylinder.

For the purpose of insuring this uniform distribution of water and preventing against stoppage of the outlets therefor, there is provided a means for supplying pressure to the water tank, as above described, which will be sufllcient to dislodge any obstructions in the water at the openings 41, after which the water can flow therefrom in asuitable manner by gravity alone.

Turning to Figure 11 it will be seen that there is shown a pump 60 which may be driven by the bevel gears 6| through the shafting 62 which, in turn, is driven from the pinion 30A. Obviously, any other means for providing an additional head for the water supply could be used without departing from the spirit of this invention.

Attention is also drawn to the fact that by the introduction of a secondary transmission 36 which can be used in conjunction with the main transmission, a wide range of speeds can be obtained from which the operator can select the one best adapted for the purpose, at the same time permitting the engine to run at the desired speed for driving the truck in transit.

The outstanding feature, of course, is the drum itself; whose rotation causes its flights to carry the inserted charge first toward the opposite end of the cylinder and then backward toward the front thereof in repeated successions, not in a steady stream but one which is constantly being diverged (as illustrated in Figure 8) for the purpose of securing an absolutely uniform mix along the entire length of the cylinder.

Attention is drawn to my copending application, Serial Number 313,014 covering an apparatus for charging this mixture satisfactorily.

Attempts have been made to supply water to portable mixing machines in transit by gravity 20 from an overhead tank. This, however, did not work out satisfactorily unless the mixer was in a horizontal position when the water was being discharged into the aggregates. If it sloped in one direction or the other the distribution of water would be unequal causing one end of the cylinder to receive too much water and the other end not enough, making it diflicult to fully distribute the moisture, especially on short hauls where the mixing time was limited.

30 I claim:

1. A mixing cylinder having one end of same closed and the other end open for charging purposes, a plurality of charging flights within said cylinder adjacent to said open end adapted to draw materials into said cylinder, a plurality of first mixing flights sloping in the same direction as do said charging flights, a plurality of second mixing flights sloping in the opposite direction to said flrst mixing flights, tumbling flights between said first and second mixing flights, and return flights at the closed end of said cylinder sloping in the direction of said second mixin flights.

2. A cylinder for mixing concrete having a normally horizontal axis, means for inclining said axis away-from the horizontal, said cylinder having an open charging end whose opposite end is closed, a plurality of charging flights mounted within said charging end adapted to move materials toward the closed end of said cylinder, a plurality of return flights at the closed end of said cylinder adapted to move materials toward the charging end there0f,= a plurality of first mixing flights adjacent said charging flights for moving materials in the same direction as do said charging flights, a plurality of second mixing flights adjacent said return flights adapted to move materials toward the charging end of the cylinder, a plurality of tumbling flights parallel to the axis of the cylinder and mounted between said flrst and second mentioned mixing flights, and a carry-over flight extending from the closed end of said cylinder to said tumbling flights whereby a portion of the materials falling from said tumbling flights shall be carried directly to the closed end of said cylinder.

3. A concrete mixing drum consisting of a cylinder whose length is in excess of its diameter having tapering ends formed thereon one of which is open and the other of which is closed, the open end having a plurality of charging flights mounted thereon close to its inner surface, the closed end having a plurality of return flights mounted thereon also close to its inner surface adapted to move materials in the opposite direction to said charging flights, a carry-over flight extending from said closed end to the middle of the cylinder adapted to convey materials toward said closed end, opposed first and second mixing flights within said cylinder, tumbling flights between said first and second mixing flights, bucket flights forming a portion of one of said charging flights and one of said return flights.

4. In a, concrete mixing and transporting machine the combination of an elongated rotatable cylinder having converging ends one of which is open and the other closed, and a plurality of flights mounted within said cylinder adapted to carry materials from the open end to the closed end of said cylinder and back again in repeated succession, the flow of material from one end of the cylinder to the other being interrupted only by partial diversions of the streams of material causing a fractional part to reverse its direction of travel and join a different stream for the purpose of securing a mixture of uniform characteristics throughout the mix consisting of a set of charging flights at the open end of said cylinder including one bucket flight for elevating a portion of the charge, a set of mixing flights having the same general direction as do said charging flights, a second set of mixing flights having a reverse direction of slope than do said first mentioned mixing flights, a tumbling flight standing substantially parallel to the axis of the cylinder, and return flights opposed to said charging fl ghts and disposed at the closed end of said cylinder.

5. In combination with a motor truck having a drivers cab, a tiltable frame mounted on the truck, a concrete mixer on the tiltable frame, a water tank and piping therefrom to the mixer and a pump interposed in the piping all carried on said tiltable frame, transmission for operating the mixer from the truck power, and a shaft operated by the operation of the mixer arranged for operating said pump.

6. A transit concrete mixer comprising an auto truck, a voluble mixing shell mounted thereon, means to rotate the shell. from the truck's power plant, and means actuated by said power plant means for supplying water to said shell.

7. A transit concrete mixer comprising an auto truck, a voluble mixing shell mounted thereon, means to rotate the shell from the trucks power plant, and water supply means for said shell including a, pump adapted to be driven by said power plant.

8. A concrete mixer, means whereby the mixer may be mounted on a motor truck for operation by the power thereof, piping for supplying water to the mixer, a pump arranged for forcing water through said piping, and means for operating the pump by the power of the truck.

9. In combination with a motor truck, a tiltable frame thereon, a concrete mixer mounted on the frame, power transmission arranged for operating the mixer from the power of the truck, a water tank carried by the truck, and a water pump for forcing water from the tank to the mixer, said pump carried on the tiltable frame and arranged for operation from the power of the truck.

10. In combination with a motor truck having a drivers cab, a tiltable frame mounted on the truck, a concrete mixer on the tiltable frame, a water tank and piping therefrom to the mixer d a, pump interposed in the piping all carried on said tiltable frame, and transmission for operating the mixer and the pu p from the Power of the truck controllable from the driver's cab.

11. In a revolvable cylindrical concrete mixer drum provided with a relatively short cone at one end through which material to be mixed is received and discharged, a plurality of blades se-' drum provided with a relatively short cone at one end through which material to be mixed is received and discharged, the length of the cylindrical portion of the drum being substantially greater than the diameter, a plurality of blades secured to the inner wall of the drum arranged at opposite angles of inclination for screwing the material back and forth and from end to end in the cylindrical portion of the drum as the same is revolved, and blades in the cone portion of the drum inclined to screw the material one way only upon one way revolution of the drum.

PORTER W. YE'I'I'.