US 3207466 A
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Description (OCR text may contain errors)
Sept. 21, 1965 R. F. VANCE 3,207,466
CONCRETE BLOCK MOLD Filed Aug. 6, 1962 INVENTOR.
fiober/ 51 6006 Robe/7 J Pa/Cb United States Patent 3,207,466 CONCRETE BLOCK MOLD Robert F. Vance, 2144 E. 26th Place, Tulsa, Okla. Filed Aug. 6, 1962, Ser. No. 215,184 2 Claims. (Cl. 249-85) The present invention relates to concrete block molds, more particularly of the type designed to produce a concrete block in two sections interconnected by tie rods.
The usual type of concrete block is a rectangular block that is an integral hardened mass of concrete having a plurality of apertures extending vertically therethrough. These apertures save material and make the block lighter in weight and also provide dead air spaces in walls built from such blocks. To some degree, these apertures assure that less moisture will be absorbed through the walls built from the blocks; however, the integrally formed and transversely extending webs that space apart these apertures are no more water resistant than the rest of the material of the block. As a result, water can seep from the outer face of the blocks through these webs to the inner face and make the interior of the building damp.
It has been proposed to form concrete blocks in two sections and to interconnect the two sections by means of a plurality of tie bars extending between the two sections and bridging the gap between the sections, the tie bars being embedded at their ends in the concrete of the sections. Devices of this type as heretofore proposed, however, have suffered from a number of disadvantages. They have not provided good thermal insulation and they have been subject to considerable damage during temperature changes due to the difference in the coeflicients of expansion of the tie bars and the blocks. Also, the blocks made according to these earlier concepts have been fragile and subject to damage during handling.
Although a number of attempts have been made to overcome these and other difficulties and disadvantages in this art, non, as far as is known, has been completely successful when practiced industrially on a commercial scale.
Accordingly, it is an object of the present invention to provide concrete block molds adapted to produce concrete blocks of improved strength, water resistance, durability and insulating properties.
Another object of the present invention is the provision of concrete block molds that will be relatively simple and inexpensive to manufacture and easy to use for the rapid production of concrete blocks, and which will be rugged and durable themselves in addition to producing rugged and durable concrete blocks.
Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawing, in which:
FIGURE 1 is an exploded perspective view, with parts broken away, of a concrete block mold according to the present invention;
FIGURE 2 is a transverse cross-sectional view of a mold of the invention showing in broken lines the removal of one of the stripper cores;
FIGURE 3 is a plan view of a mold according to the invention, indicating the manner of disassembly of the mold box;
FIGURE 4 is a view similar to FIGURE 2 but showing a completed block in the mold and the stripper cores being withdrawn; and
FIGURE 5 is a perspective view with parts broken away of a finished concrete block produced in a mold of the present invention.
Referring now to the drawing in greater detail, there is shown an open-topped mold box 1 adapted to rest on the usual moldboard 2. Mold box 1 is in the form of two separable sections as shown in FIGURE 3, each section including a side wall 3 and an end wall 5 of mold box 1. End walls 5 are recessed as at 7 to receive in vertically sliding relationship a pair of opposed stripper cores 9 that meet along the midplane of the mold box in inner walls 11 that are horizontal and coplanar. The side walls of stripper cores 9 include side wall sections 13 that are vertical, that is, that are perpendicular to inner walls 11 and that extend from inner walls 11 a substantial distance away from inner walls 11 and terminate in outwardly inclined side wall portions 15 that diverge from each other. Divergent side wall portions 15 are discontinuous at end walls 5 and do not extend into the recesses 7 but instead abut against the portions of end walls 5 adjacent recesses 7, thereby to maintain the vertical slidability of stripper cores 9 in recesses 7.
Each inner wall 11 has a plurality of semicylindrical recesses 16 therein that extend transverse to the length of inner wall 11 and its associated stripper core 9. The axes of these semicylindrical recesses lie in the plane of inner wall 11. Recesses 16 in the opposed stripper cores are opposed to each other. Thus, when stripper cores 9 are assembled in mold box 1 with their inner walls 11 contacting each other, the recesses 16 will be in registry and will form complete cylindrical recesses whose axes are parallel to each other and coplanar with inner walls 11.
A tie bar in the form of a spool 17 is disposed in each recess 16. Each spool 17 has a cylindrical central portion 19 of reduced diameter, which fits snugly in the cylindrical recess provided by a pair of opposed recesses 16. Central portions 19 are hollow except for a central internal plug 21. Central portions 19 terminate endwise outwardly in enlarged annular shoulders 23 which are perpendicular to the axis of spool 17 and which terminate radially outwardly in cylindrical peripheral surfaces 25. Each spool 17 is provided with hollow, open-ended enlarged ends 27; and these enlarged open ends are bounded by conical surfaces 29 that begin at the axially outer ends of cylindrical peripheral surfaces 25 and extend axially outward to the ends of the spool. Surfaces 25 and 29 are also provided with ribs 31 generally parallel to the elements of the cone of surface 29.
Spools 17 are made of plastic. By plastic is means polyacrylic resins such as polymethylmethacrylate, amino resins such as melamine, epoxide resins, phenolic resins such as phenolformaldehyde resins, polyamide resins, i.e. nylon, cellulosic resins as cellulose nitrate or acetate, natural or synthetic rubber, such as hard rubber, silicone resins, styrene resins such as polystyrene, and vinyl resins. Practically all of these plastics are plastics consisting essentially of organic substances of high molecular weight. Practically all of them are also synthetic resins. The spools of the present invention are thus characterized in that they are waterproof, have low coelficients of thermal expansion and thermal conductivity, are inert or highly resistant to oxidation, and have a limited resiliency to the extent that they do not shatter upon handling of the blocks.
To use the mold box of the present invention, the device is assembled as seen in FIGURES 1, 2 and 3 and a quantity of fluent concrete 33 is introduced into the mold cavity and agitated as by a multiplicity of moving mechanical fingers until it fills the whole cavity almost completely. Notice that the concrete starts into but does not fully enter the hollow portions of reduced central portion 19 of spool 17, as shown in FIGURE 4. After the concrete has hardened, the stripper cores 9 are removed as shown in FIGURE 4 and a finished block is' left as in FIGURE 5. The finished block is characterized by a pair of sections 35 of concrete, spaced apart and held in unitary assembly by a plurality of spools 17 extending between and interconnecting the sections 35 in a permanent assembly. Thanks to the configuration of stripper cores 9, each section 35 is characterized by a vertical central surface 37 that extends full length of the inside of each section 35, the two vertical central surfaces 37 of the opposed sections 35 confronting each other and being parallel to each other and spaced apart a distance equal to the length of reduced central portion 19. Each central surface 37 terminates edgewise vertically in a side surface 39. The corresponding side surfaces 39 of each section 35 are spaced apart from each other by the gap that is bridged by spools 17 and diverge from each other. By contrast, the opposed inner surfaces of sections 35 adjacent spools 17, that is, central surfaces 37, do not diverge from each other.
A number of advantages flow from the mold construction just described and its manner of use. The provision that central portions 19 of spool 17 be of reduced diameter assures that spools 17 will have a limited resiliency under shock and will not be rigid as they would be if they were of greater diameter. The hollow construction of these central portions 19 contributes to this result and also assures that the cross-sectional area of central portions 19 will be reduced, thereby to reduce the heat flow from the outer section 35 to the inner section 35, with resultant increase in the insulating properties of the block. The plug 21 that prevents the spools from being hollow from end to end has an extent axially of the tie bar substantially less than the axial extent of the associated recesses 16 and does not appreciably increase the heat conductivity of the spools or their rigidity, but does serve to block the inner passageway of the spools so that moisture cannot flow from the outer section 35 through the spool to the inner section 35 of the block. Also, the provision of central part 21 assures that there will be a dead air space on either side of it so that concrete will not tend entirely to fill up the hollow portions of the spools, as seen in FIGURE 4. With the concrete thus spaced from plug 21, both the flexibility and the heat-insulating properties of the spools are improved, for the formation of concrete pipes on either side of and in contact with plug 21 is thereby prevented. Also, if plug 21 were missing, concrete could fill the cavity of the spool entirely and provide a convenient passageway for moisture and hea The provision of annular shoulders 23 in contact with perpendicular side walls 13 of stripper cores 9 also serves an important function. Shoulders 23 and their associated cylindrical peripheral surfaces 25 assure that the margins of the opening into the block at surface 37 will be of substantially greater diameter than the diameter of reduced central portion 19 of spool 17. This means that the concrete which defines those margins of the openings will be substantially stronger than if the openings were of a diameter equal to the diameter of central portion 19. These margins are further strengthened by the realtionship that surfaces 37 are vertical and parallel to each other. If the surfaces were inclined as are surfaces 39, then the margins of the concrete about the spools would be much thinner and more sharply angulated, as will be clear from an inspection of FIGURE 4. As will also be clear from an inspection of FIGURE 4, the fact that peripheral surfaces 25 are cylindrical rather than conical as are surfaces 29 further contributes to the strength of the margins of the concrete by avoiding sharply angled margins. Thus, the margins of the concrete about the spool are renedered quite massive and strong by the combination of a large diameter for peripheral surface 25, a cylindrical contour for surface 25, and a vertical disposition for surfaces 37. Each of these feaures contributes significantly to the strength of the block adjacent the spools; and together, these features provide a block which is desirably rugged and durable even when being roughly handled.
Ribs 31 keep spools 17 from being figures of revolution about the axis of the spool, and thus prevent twisting or rotation of the spools relative to either section 35 of the block. The enlargement of end 27 of the spools prevents the spools from pulling out of the block; while the Waterproof nature of the material of the spools prevents them from transmitting water. The inertness of the material of the spools prevents oxidation and failure of the spools in contact with the material of the blocks when the blocks are saturated with water. Finally, the low coefiicient of thermal expansion of the material of the spools roughly matches the low coeflicient of thermal expansion of the concrete and thus prevents damage to the blocks from differential thermal expansion; while the low coefficient of 'heat transfer of the material of the spool makes the spools good insulators between the block sections.
From a consideration of the foregoing description, it will be obvious that all of theinitially recited objects of the present invention have been achieved.
Although the present invention has been described and illustrated in connection with a preferred embodiment, it is to be understood that modifications and varia- .tions may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.
What is claimed is:
1.'A mold for concrete blocks, comprising a mold box containing a pair, of stripper cores having opposed recesses in their opposed surfaces, and a tie rod disposed in each pair of opposed recesses and extending endwise beyond the stripper cores a substantial distance in both directions, the tie rods having enlarged radially extending integral shoulders that abut flat against the outer sides of the stripper cores, the shoulders having peripheral surfaces that extend outwardly away from and normal to the outer sides of the stripper cores for substantial distances, said outwardly extending peripheral surfaces terminating away from the stripper cores in surfaces that extend radially outwardly from said peripheral surfaces at the ends of the tie rods.
2. A mold as claimed in claim 1, said radially outwardly extending surfaces having portions of substantial area lying on a cone.
References Cited by the Examiner UNITED STATES PATENTS WILLIAM J. STEPHENSON, Primary Examiner. MICHAEL V. BRINDISI, Examiner.