US2495379A - Concrete mixer - Google Patents

Description

D. o. MCINTOSH CONCRETE MIXER Jan. 24, 1950 Filed March 26, 1946 2 Sheets-Sheet l DAVID O. McINTOSH Jan. 24, 1950 w WAWWMAWMM Patented Jan. 24, 1950 UNITED" STATES PATENT OFFICE CONCRETE lVHXER David 0. McIntosh, Nashville, Tenn., assignor of one-half to Charles W. Akers, Nashville, Tenn.

Application March 26, 1946, Serial No. 657,096

4 Claims.

' action of the material being mixed. For instance,

in the case of concrete mixers, it is rather common practice to provide replaceable liners to the side and end walls of the drum or other container in which the concrete is mixed whereby as the liners become unduly abraded and worn, new liners can be substituted. As is also well known, practically all concrete mixers have means in the interior of the drum or other container for facilitating mixing of the concrete, these means taking the form of paddles, blades or similar members which are mounted either on a rotatable shaft extending through the container or on the wall or liners of the container. Rotation of these members by the shaft or by the container effects a cascading or mixing action on the part of the concrete within the mixing container, depending upon the particular type of the apparatus and in almost every instance, these mixing members whether they be paddles, blades, buckets or the like, are detachably mounted in order to readily permit their replacement when they become excessively worn by the abrasive action of the concrete. The present invention, therefore, is to prolong the life of these structural parts that are subjected to the abrasive action of the material being mixed and, particularly in the case of concrete mixers, to minividual recesses be of small area, compared to the and harden. It is also preferred that the inditotal area of the surface of a structural part to be protected, so that if the protective material in one recess should be fractured and dislocated during the mixing operation, such dislocation will be limited to a comparatively small area. It will also be understood that when any portion of the protective layer is fractured and becomes detached, the surface thus exposed will again become coated by additional material accumulating and hardening thereon.

' ularly pointed out in the appended claims.

mize the wear imposed on the walls of the mixing chamber and on thesurfaces of the mixing members whereby the use of the so-called liners and replacement of mixing members may be dispensed with or their life of usefulness prolonged so as to materially reduce the frequency with which they have to be replaced.

More particularly, the invention consists in protecting the desired surfaces of the structural parts of the mixer with a protective layer of the material being mixed, it being understood that the invention is limited in the sense that the material being mixed is of such a nature, as in the case of concrete, that it will set or harden to form a wear resistant covering on the surface to be protected. Specifically, the invention contemplates the provision of retaining recesses in the surfaces to be protected, these recesses preferably being formed by ribs on said surfaces which subdivide, so to speak, each surface to be protected into a multiplicity of recesses in which the con r r o e ma eri l, will be retained In the accompanying drawings in which a concrete mixing apparatus has been adopted for purposes of illustration Figure 1 is a top plan view of the drum of a concrete mixing machine, showing the interior of the drum and the mixer blades;

Fig. 2 is a fragmentary plan View of a mixer blade or paddle having a surface embodying the present invention;

Fig. 3 is a sectional view on the line 3-3 of Fig. 2;

Fig. 4 is an edge view of the structure shown in Fig. 2;

Fig. 5 is a view similar to Fig. 2 illustrating a modified form of the invention; and

Fig. 6 is a similar View illustrating a still further modification of the invention.

Referring to Figure l, the particular type of mixer here used for purposes of illustration consists essentially of a drum [0 of substantially semi-cylindrical cross-sectional shape and mixer blades H removably mounted on a shaft l2 disposed axially of the drum and adapted to be rotated by suitable driving connections constituted in part by gears l3, M, with the latter mounted on a drive shaft [5 on which the drive pulley I6 is also mounted. However, it will be understood that the mechanisms for revolving the mixer blades H and actuating drum ID for discharging the contents of the latter form no part" of mixers on the present day market.

In mixers of the type illustratedthe inner surface of the drum or container In is provided with removable liners, the end walls being shown in the present instance as being provided with said surfaces so that the latter are well protected.

This accumulation of concrete is efiected by forming retaining recesses in or on the surfaces to be protected. Preferably, the recesses are formed by ridges or ribs welded on said surfaces although the molding of the ribs, where the liners or blades, orsimilar members, are cast, is also contemplated.

For instance, as shown in Figs. 2 and 3, the surface to be protected may be provided with a multiplicity of retaining recesses [9 by marginal ribs and intersecting ribs 2 l, 22 formed thereon, the ribs 2i, 22 being disposed parallel to the marginal ribs 2!} or, if desired the intersecting ribs may be disposed diagonally of the marginal ribs as indicated at 2| 22 in Fig. 5. Again, as shown in Fig. 6, the recesses may be formed by a number of annular ribs 23 arranged in any desired pattern and bounded by the marginal ribs 29. In Fig. 4 the edge of a blade or paddle is shown provided with marginal ribs 2% and transverse ribs 2 l forming the retaining recesses IQ. For purposes of simplifying the drawings, only fragments of a blade or paddle have been illustrated in detail in Figs. 2 to 6 but it will be understood that all surfaces which it is deemed desirable to protect, for instance the liners of the side and end walls of the drum or other container will be likewise provided with retaining recesses l9. It will also be further understood that in those types of mixers wherein the liners are not provided on the wall surfaces of the drum or other container, the ribbing or recessing will be formed directly on the surfaces to be protected.

In some instances it may not be necessary to provide intersecting ribs or to have the recesses closed entirely around their edges. Referring to Fig. 2, the surface to be protected may be subjected to abrasion only by a flowing movement on it, say, in the direction of arrow A, as where the concrete moves in contact with the surface from one edge to the opposite edge of the blade or other mixer member or surface. In such cases, the surfaces will be provided only with the ribs 2| formed transversely of the direction of flow of the concrete, the intersecting ribs 22 being omitted so that the individual recesses may extend the length of the surface. Thus the ribs disposed transversely of the flow of concrete will serve as dams and cause the concrete to accumulate on the surface. However, intersecting or annular ribs are preferred as such arrangement results in the surface to be protected being subdivided into a multiplicity of small recesses or areas which are advantageous in that rupture of concrete hardened in any one recess will not affect concrete 5 which has hardened in the other recesses on a given surface. For instance, in the case of mixing concrete, if a particularly hard piece of aggregate is caught between the drum or liner wall and a blade and breaks olf or gouges out hardened con crete in one of the recesses on the drum or liner wall, the concrete in the other or adjacent wall recesses will not be affected and the wall surface will be exposed only in the one recess out of which the concrete has been broken. For this reason,

the preferred construction consists in making the ribs approximately three-sixteenths of an inch in width and so arranging them that the individual recesses have a surface area of approximately one or two square inches. It will be appreciated that the layer of hardened concrete need not be of any appreciable depth so far as concerns its function of preventing abrasion of the metal surfaces of the drum or liners and blades. However, it should be of sufficient thickness to prevent its being too readily cracked or broken during the mixing operation. In actual practice, ribs or recesses of one-eighth inch depth have been found to serve the purpose entirely satisfactorily. As previously pointed out, in the event portions of the hardened concrete facings formed on the surfaces to be protected are broken out during the mixing operation, the areas thus exposed will quickly accumulate more concrete which will harden and reestablish the protective facing.

While the members which facilitate the mixing action in the machine illustrated in the present instance are properly termed blades, it will be appreciated that the invention is equally applicable to mixing members of other types as well as to containers differing in design from the open top drum illustrated herein.

What is claimed is:

l. A machine for mixing abrasive material such as concrete comprising a container having an inner wall over which the concrete flows as it is mixed, spaced ribs arranged on the inner walls of said container extending transversely of the direction of flow of concrete on said walls in a manner to obstruct such flow for accumulating and retaining a protective layer of concrete, the surface of said walls between said ribs constituting the major portion of the surface area of said walls and members movable in the interior of the container for facilitating mixing of the concrete.

2. A concrete mixer comprising a container in which the concrete is mixed, mixing members movable within said container and over the surfaces of which the concrete flows to facilitate mixing of the concrete, and spaced ribs on said mixer member surfaces, said ribs being disposed transversely of the direction of flow of concrete on said surfaces in a manner to obstruct such flow, the surfaces of said mixing members between said ribs constituting a major portion of the surface area of said mixing members whereby a protective layer of concrete is accumulated and retained on said surfaces between said ribs.

3. A concrete mixer comprising a container in which the concrete is mixed, mixing members movable within said container and over the surfaces of which the concrete flows to facilitate mixing of the concrete, upstanding ribs on the surfaces of said members arranged transversely of the direction of flow of concrete on said surfaces in a manner to obstruct such flow and forming depressions in said surfaces between said ribs, the aggregate area of the depressions between the ribs on each member constituting the major portion of said surface of said member whereby a protective layer of concrete will be formed in the depressions of each member.

4. A concrete mixer comprising a container in which the concrete is mixed, a plurality of spaced ribs on the inner surface of said container arranged transversely of the direction of flow of concrete on said surface to obstruct such flow and forming between said ribs a multiplicity of 5 recesses constituting the major portion of said REFERENCES CITED ribbed surface, mixing members movable within the container for facilitating mixing of the contg g i rtiferences are of record m the crete, and a plurality of spaced ribs on the sur- 8 n face of each mixing member arranged transverse- 5 UNITED STATES PATENTS 1y of the direction of flow of concrete on said sur- Number Name Date face and. forming between said ribs a multiplicity 1 390 251 schoppner Sept 6 1921 of recesses constituting the major portion of the 1848095 Bartlett 1932 ribbed Surf-ace each mixing member- 1:9531733 Vollrath 111111 Apr: 3: 1934 DAVID O. McINTOSI-I. 10

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