US2989291A - Continuous mixing machine for concrete and similar substances - Google Patents

Description

June 20, 1961 J. w. BEDNER 2,989,291

CONTINUOUS MIXING MACHINE FOR CONCRETE AND SIMILAR SUBSTANCES Fileo. July 14, 1958 2 Sheets-Sheet 1 WHIP." -ii I I I I 19 a l8 5 I l5 l2 i 3|32l2 40 4142 7 I 38 I I f AU 1 26 I I ,J 3

June 20, 1961 J. w. BEDNER 2,989,291

CONTINUOUS MIXING MACHINE FOR CONCRETE AND SIMILAR SUBSTANCES Filed July 14, 1958 2 Sheets-Sheet 2 United States Patent l 2,989,291 CONTINUOUS MIXING MACHINE FOR CON- CRET-E AND SIMILAR SUBSTANCES Julius W. Bedner, 287 Marco Polostraat, Amsterdam, Netherlands Filed July 14, 1958, Ser. No. 748,286 4 Claims. (Cl. 259-474) My invention relates to a continuous mixing machine for concrete and similar substances.

Several machines of this kind have been proposed. Such known machines either do not give a very good mixing and continuity in the mixture obtained, or they need very much time for the mixing, so that for given dimensions the capacity is quite small.

Thus most mixing-machines for concrete and similar substances operate batchwise and not continuously. This gives the possibility to mix as long as necessary, but has the disadvantages of batch discharge, special means for discharging, such as the tilting of the mixing-drum, and a small capacity by the need to interrupt or decrease the intensity of the mixing for discharging the mixture.

My invention aims at removing such disadvantages and giving an improved continuous mixing-machine for concrete and similar substances which gives, with a high capacity for a given size, an intimate and continuous mixture.

My invention will now be described with reference to the annexed drawings, from which the several features of a machine according to my invention will become clear.

In said drawings: I

FIGURE 1 represents a vertical longitudinal section, in part elevational view, of a mixing-machine according to the invention in a preferred embodiment.

FIGURE 2 represents a vertical end view of the masiderably greater radial dimension than that of the stationary drum 6. The drum 12 is substantially cylindrical and has two rims 13 welded thereto for supporting the. drum and an outer toothing 14 for driving the drum. This drum has a conical part 15 at the left end, engaging from the outside on the space 10 at the drum 6 and there. is a conical part 16 on this drum 12 at the right end, serving as a flaring discharge end for the drum 12. At the left end of the cylindrical part of the drum 12 there is a: rim 17 with a corrugated outer shape as given only for part of the periphery in a dotted line in the upper part of FIGURE 2. This rim 17 engages a roller 18 and thus through a linkage 19 entrains during rotation of the drum a vibration or shaking of the grid, not shown, arranged between the hopper 3 and the fall pipe 7.

On the frame 1 there is an electric motor 20 driving a? V-belt pulley 21, said pulley driving through V-belts a pulley 22 of greater diameter. 'The pulley 22 is arranged on a shaft 23, supported in suitable brackets upon the frame and which, at about the middle of the length of the drum 12, is provided with a cog wheel or pinion 24 engaging the toothing 14 of the drum 12 for rotating this drum. The shaft 23 is arranged to the right of the verti-. cal center plane of the drum as seen in FIGURE 2. Both to the right and to the left of this vertical center plane a number of supporting brackets 25 are arranged with supporting rollers on axles supported for rotation in said brackets, as appears from the drawings andas. is quite obvious as such. The left bracket 25 as seen in FIGURE 1 to the side where the shaft 23 is arranged supports this shaft and the corresponding supporting roller is arranged chine according to FIGURE 1, as seen from the right in FIGURE 1.

Referring to the drawings the mixing-machine is arranged upon a frame 1, provided with wheels 2. A hopper 3 serves for supplying the substances to be mixed.

Around this hopper there is a water trough 4 and this trough is, together with the hopper, supported in a supportingstructure 5, fixed to the frame 1. Belowthe hopper 3 there is arranged a stationary drum 6 with a horizontal axis and the substances to be mixed enter this drum from the hopper 3 through a fall-pipe 7, opening at its lower end into this drum. The stationary drum 6 is closed at the left end as seen in FIGURE 1 and is open at the right end. The fall-pipe 7 opens into this drum in the proximity of the left end. In the upper end of the fall-pipe 7 a closing flap could be arranged, and above this flap a grid; said flap and grid may be of usual structure and are not shown in the drawings. There are provided means for shaking or vibrating the grid in order to prevent clogging and bridge building of the substances to be mixed. The parts necessary for this purpose will in part be described below. They are not shown entirely in the drawing as they have nothing to do with the invention and could also be omitted.

The upper end of a water-supply-pipe 8 opens into the water trough 4, which upper end is closable by means of a closing member 9. The water-pipe 8 at its lower end opens into an annular space 10 around the right end of the drum 6. This space 10 is open at the right end. The flap (not shown) in the upper end of the fall-pipe 7 could be coupled by means of a linkage 11 to the actuating means for the water closing member 9, so that the supply of substances to be mixed is coupled in a desired manner to the supply of water to supply both water and substances at the same time in desired mutual quantities.

The right end of the stationary drum 6 opens into the left end of a rotatable drum 12. This drum has a conon said shaft 23.

The shaft 23 has, at the front end of the frame, a; sprocket wheel 24, driving a sprocket wheel 25 through a chain, arranged upon a shaft 26, supported in a bearing: 27, arranged on a supporting structure 28. The shaft 26 extends into the stationary drum 6 and is there providedwith a traverse 29, on which parallel shafts 30 are se cured in equal distances from the center-line of this drum to both sides of the shaft 26. These shafts 30 extend in parallel tothe centerline of the drum 6 towards and into i the left part of the rotating drum 12 as seen in FIGURE 1 and are, at this end, secured to a traverse 31. To this traverse 31 two parallel shafts 32 are secured, situated in the same plane as the shafts 30, but at a greater dis-: tance from the center-line of the drums band 12. These shafts 32 extend to the discharge end of the drum 12 and: are, at this end, secured to a traverse 33. The traverses 29 and 31 have the shape of a double crank web. The traverse 31 is shown in FIGURE 2 by means of a dotted; line. The traverse 33 has a circular shape as appears from FIGURE 2 and is provided with a conical flaring part 34. An axle 35, supported rotatably in a bearing 36 of a supporting structure 37 on the frame, is secured to the traverse 33. The entire mixing means, formed by the parts 25, 26 and 29-34, is thus supported at both ends in the bearings 27 and 36 upon the frame independently of the drums 6 and 12.

These mixing means are provided on the shafts 30 with flat stirring arms 38, secured to these, shafts with their transverse direction inclined so that they tend to move the substances to be mixed towards the discharge end of the drum 12. Moreover these stirring arms 38 are, as appears from FIGURE 2, inclined with respect to a plane A through the two shafts 30 in their longitudinal direction. This inclination is preferably such, as is shown in FIGURE 2, that the angle between the longi: tudinal axis B of each of said. arms and said plane through the shafts 30 differs from 9t)? in such a manner that the stirring arms move from the horizontal position of said plane through the shafts first to a more fiat or horizontal position, which will be clear from the direction of rotation of these parts as given by an arrow in FIGURE 2. In other words, each of said stirring arms is disposed on its respective shaft with its longitudinal axis arranged at an acute angle to said plane, the forward edge of said stirring arm relative to the direction of ro-' tation of said mixing means leading said plane by an acute angle 0.

The stirring arms 38 are displaced with respect to one another on the shafts 30, so that said arms on one shaft 30 are provided between the arms on the other shaft 30, as seen in FIGURE 1 and as measured in the direction of the center line of the drum 6. These arms 38 are asymmetrically disposed on shafts 30 in such manner that the portions thereof which extend toward the center are longer than are those portions which extend radially outwardly. Moreover a helical blade 39 is fixed to the shafts 30 and leaves an axially central cylindrical space between the shafts 30 entirely free, said blade having only a small radial dimension. This blade is so inclined that it is adapted to move the substances to be mixed towards the discharge end.

Stirring arms 40 are provided on the shafts 32, inclined in the same directions as the stirring arms 38, but having about the same length in both directions from the shafts 32, said arms 40 leaving a greater distance between them and the inner wall of the drum 12 than is the space left between the arms 38 and the inner wall of the stationary drum 6. A helical blade 41 of about the same shape and inclination as the blade 39 in the drum 6 is provided in this part and this blade constitutes the elongation of the blade 39. As shown, the helical blade 41 and stirring arms 40, secured to shafts 32, are arranged intermediate the center line of the drum 12 and the periphery of the latter.

Thin metal strips 42 are provided in the drum 12 and fixed thereto, said strips making a small angle to the longitudinal direction of the drum so that they tend to move the substances to be mixed towards the discharge end of said drum. Moreover these strips are inclined with respect to the radial direction as seen in FIGURE 2, so that in the part of the drum 12 which at a given moment moves upwardly, they constitute with the inner wall of the drum a kind of trough for adequately lifting the substances to be mixed.

In the operation of the plant the substances to be mixed are delivered to the hopper 3 by metering devices not shown, which could be of known and usual construction. They deliver the substances to be mixed to the hopper 3 in the correct mutual quantities. For concrete there will be three metering devices, for sand, gravel and cement respectively. These devices could operate batchwise although the mixing takes place continuously. Said substances fall from the hopper 3 into the stationary drum 6, a possible flap (not shown) in the upper part of fall-pipe 7 being opened, so that said substances somewhat uniformly pass this flap under the influence of the grid and of the fact that the fiap could only be opened partially, thus giving a restricted opening. The easiest way to attain this is to have the flap urged towards the closed position by a counterweight or spring structure and to have it open under the weight, upon it, of the substances to be mixed, thus also opening the water-flap 9 by said weight through the linkage 11. Thus water from the trough 4 flows through the pipe 8 to the space 10 and from there enters the drum 12. The substances to be mixed are already partially mixed in the drum 6 by the stirring means moving therein and they are moved to the right as seen in FIGURE 1 by the co-operation of the stirring arms 38 and of the helical blade 39. Thereafter the partially mixed substances pass into drum 12 and are lifted therein by the metal strips 42, fall from these strips after they have reached a certain elevation and so fall into the center of the space in the drum 12, the mixing means engaging these falling substances by the stirring arms 40 and the helical blade 41. The mixture therewith falls substantially through the free central space between the shafts 32, but is influenced during this fall by these parts. It will be clear from FIGURE 2 that the falling mixture is, in the upper part of its falling path, beaten and thrown to the left as seen in FIGURE 2 by the stirring arms 40 and, in the lower part of this falling path, the falling material is thrown to the right by said arms. Thus the mixture is mixed by alternatively moving it to the left and to the right and at any time a quantity of the mixture is lifted by the strips 42 again and again and dropped thereby allowing it to be acted upon by the mixing means.

It will be clear that it is possible to constitute the stirring arms in a different manner and to combine them with their shafts to corrugated members instead of shafts with flat separate arms welded thereto.

What I claim is:

1. A continuous mixing machine for concrete and similar substances, including in combination a rotatable mixing drum having a substantially horizontal axis, and rotatable mixing means within said drum, the center of rotation of said mixing means being substantially in the center line of the drum, said drum being provided with lifting means fixed to its inner surface, for lifting substances to be mixed, means for rotating the drum in one direction and means for rotating the mixing means in the opposite direction, characterized in that the mixing means comprises at least two spaced substantially parallel stirring mixer members extending substantially parallel to the axis of rotation of the drum and arranged on different sides of said drum axis the mixing means leaving a substantial unobstructed free space in the zone of the center line of the drum, said stirring mixing members being arranged intermediate the center line of saiddrurn and the periphery thereof, each of said stirring mixing members comprising a shaft extending substantially parallel to the axis of rotation of said drum, and a plurality of longitudinally spaced stirring arms secured to said shaft, each of said stirring arms being disposed with its longitudinal axis arranged at an acute angle to a plane which passes through said shaft and the center line of said drum, the forward edge of said stirring arm relative to the direction of rotation of said mixing means leading said plane by said acute angle.

2. A continuous mixing machine as defined in claim 1, further characterized in that the stirring arms of one shaft are otfset from the stirring arms of the other shaft.

3. A continuous mixing machine as defined in claim 1, further characterized in that said mixing means includes a helical blade of small radial extension fixed to and surrounding said stirring mixer members, said blade being so inclined as to provide forward thrust to substances undergoing mixing.

4. A continuous mixing machine as defined in claim I, in which said lifting means comprises a plurality of helically disposed strips substantially coextensive in length with the length of the drum and inclined in planes perpendicular to the drum axis, for lifting substances to be mixed in the peripheral direction during the rotation.

References Cited in the file of this patent UNITED STATES PATENTS 221,364 Ruger et al. Nov. 4, 1879 409,560 Carey et a1. Aug. 20, 1889 869,522 Scheifiier Oct. 29, 1907 1,858,796 Wilcoxson May 17, 1932 1,861,416 Iaeger May 31, 1932 2,080,508 Sackett May 18, 1937 2,700,533 Miller Jan. 25, 1955

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