US3553797A - Apparatus for casting structural units for building construction - Google Patents

Abstract

AN APPARATUS FOR CASTING A PLURALITY OF STRUCTURAL UNITS SUCH AS WALL PANELS OF PREDETERMINED CROSS-SECTIONAL SHAPE COMPRISING, A PAIR OF SPACED TRACKS, A DIE MEMBER CONFORMING TO SAID PREDETERMINED CROSS-SECTIONAL SHAPE ALONG ITS BOTTOM SURFACE, MEANS MOUNTING THE DIE MEMBER FOR MOVEMENT ALONG THE TRACKS, MEANS CONVEYING THE DIE ALONG THE TRACKS, AND MEANS AT THE FORWARD END OF THE DIE FOR EXTRUDING CONCRETE THERETHROUGH AND BENEATH THE MOVING DIE MEMBER UNDER PRESSURE. THE TOP SURFACE OF EACH PREVIOUSLY CAST UNIT SERVES AS A MOLD FOR THE BOTTOM SURFACE OF A SUBSEQUENTLY CAST UNIT.

Description

Jan. 12, 1971 R. J. HORTON 3,553,797

I APPARATUS FOR CASTING STRUCTURAL UNITS FOR I BUILDING CONSTRUCTION Filed Feb. 14, 1968 2 Sheets-$heet 1 INVENTOR ROBERT JACKSON HORTON ATTORNEYS Jan. 12, 1971 R. HORTON 3,553,797

APPARATUS FOR C ING STRUCTURAL UNITS FOR BUILDING CONSTRUCTION Filed Feb. 14, 1968 2 Sheets-Sheet 2 FIGS P1 7 INVENT OR ROBERT JACKSON HORTON ATTORNEYS United States Patent APPARATUS FOR CASTING STRUCTURAL UNITS FOR BUILDING CONSTRUCTION Robert J. Horton, 3192 Palomares Ave., Lafayette, Calif. 94549 Filed Feb. 14, 1968, Ser. No. 705,339 Int. Cl. B28b 15/00 US. Cl. 25-2 2 Claims ABSTRACT OF THE DISCLOSURE An apparatus for casting a plurality of structural units such as wall panels of predetermined crosssectional shape comprising, a pair of spaced tracks, a die member conforming to said predetermined cross-sectional shape along its bottom surface, means mounting the die member for movement along the tracks, means conveying the die along the tracks, and means at the forward end of the die for extruding concrete therethrough and beneath the moving die member under pressure. The top surface of each previously cast unit serves as a mold for the bottom surface of a subsequently cast unit.

The present invention relates to an apparatus for casting concrete structural units useful in building construction.

Precast concrete structural units have been used in walls, floors, roofs and lateral declgingin building construction. Frequently, the units contain re-inforcing bars and sometimes these are prestressed. One of the difficulties with such building units has been their limited size, since such structural units are normally produced at a plant and then are transported to the construction site. Though the structural units may be produced in any desired size at the plant, as a practical matter, transportation consid erations make the manufacture of larger structural units impractical. State highway laws prevent the transporting by truck of structural units of a length and width above certain limits. Even when transported by rail, freight hauling equipment frequently limits the size of structural units which may be transported. It therefore is impossible in certain construction projects to use prefabricated structural units because of their limited size.

Also, such prefabricated units frequently, because of their shape, occupy a considerable amount of space while being transported, thus adding to the cost of transportation of such units.

An object of the present invention is the provision of an apparatus for producing structural units of unlimited size which can be produced on the construction site thus avoiding the size restrictions placed on structural units which are normally transported along the public highways or by rail.

Another object of the present invention is the production of structural units at a lower cost by eliminating the need for transporting prefabricated structural units and requiring only the transportation of raw materials to the construction site at a considerably cheaper rate.

With these and other objects in view, the invention comprises an apparatus for carrying out these objects as will be hereinafter more fully described and illustrated in the accompanying drawings which disclose the preferred embodiments of the invention. It will be understood that though the apparatus is demonstrated as being useful for casting concrete, the apparatus is equally useful for easting other plastic materials used as gypsum.

In the accompanying drawings:

FIG. 1 is a plan view of the apparatus of the present invention;

3,553,797 Patented Jan. 12, 1971 FIG. 2 is a side view partially cut away showing the apparatus of FIG. 1 in operation;

FIG. 3 is a schematic diagram showing the mechanical system for transmitting power to drive the apparatus of FIG. 1;

FIG. 4 is a detailed view of the stacking bar located in the hopper of the apparatus;

FIG. 5 is a sectional view taken along the line V-V of FIG. 1;

FIG. 6 shows in greater detail the hold-down arrangement of FIG. 5;

FIG. 7 shows in cross-section the separation of continuously laid adjacent panels; and

FIG. 8 shows various examples of cross-sectional configurations of panels which may be produced by the process and apparatus of the present invention.

Similar reference characters indicate corresponding parts throughout the several views in the drawings.

Referring to the drawings in detail, and particularly FIGS. 1 and 2, the apparatus consists primarily of a power unit 1 to the underside of which is adjustably secured a die 2. Hydraulic ram-s 23 extend between the power unit and die to permit adjustment of the level of the die as will be explained later. At the front of the die and extending upwardly adjacent the front of the power unit is a hopper 3 for receiving and retaining a reservoir of wet concrete. The power unit 1 includes a set of four wheels 4 designed for use on the rails 15. All of the wheels are power driven by conventional means which may include a gasoline engine or an electric motor 5 which through a chain drive 24 drives shaft 6 and axles 7 transmitting power to the wheels to move the apparatus along the rails 15.

The die 2 has a shape determined by a desired shape of the cast structural unit. A generally trough-like die is shown in use with the apparatus though different structural shapes will require substitution of differently shaped dies which may be easily substituted on the hydraulic rams 23 at the bottom of the power unit.

A supply of concrete mix 8 is. maintained in the hopper 3 by any conventional means, an example of which is shown in FIG. '1 wherein the feed hopper 9, conveyor 10 and chute 11 are secured to the side of the power unit. The conveyor is powered by a separate motor 12, the speed of which may be regulated to maintain the proper level of concrete in the hopper 3'. The feed hopper 9 may be filled directly from a truck carrying ready-mix concrete which may be driven alongside the feed hopper.

Adjacent the bottom end of the hopper 3 is a stacking bar 13 which is shown in detail in FIG. 4. The stacking bar should conform to the general shape of the die in order that it may be located adjacent to the leading edge of the die. This requires that the stacking bar be replaced whenever the die is changed so that the stacking. bar will conform to the die. The stacking bar is reciprocally driven at a generally low velocity by motor 14 which is sealed and located at the center of the hopper. An appropriate rate of oscillation for the stacking bar is about 900 oscillations per minute, though this will vary depending on the rate of travel of the apparatus and'the viscosity and type of concrete mix being laid.

Optionally, finishing tools 25 may be secured to the rear end of the die and may be driven by a suitable power take-off arrangement from the power unit 1. Finishing tools designed to trim off excess concrete at the edges to develop the desired texture on the surface of the concrete panel may be used. An example of an appropriate finishing tool is a rotating brush which creates a fine grain finish on the concrete surface.

The power unit 1 and its wheels 4- are supported on a set of parallel rails 15. The rails are preferably angular as shown in FIG. 6. Initially, the rails are mounted on stationary supports (not shown) but after one or two superimposed structural units or panels have been laid, the rails are secured by bolts 16 to both sides of one or more previously laid structural units. With the laying of one or two additional structural units, it becomes each time necessary to raise the rails a corresponding amount and to bolt them again in the raised position. The rails serve not only to support the power unit and die, but also serve as the side surfaces for retaining and shaping a newly poured structural unit. The rails may be of any desired length depending upon the length of the structural units being poured, and/ or the number of individual structural units which are poured consecutively in end to end relationship at the same level. Thus, the rails may conveniently range between 100 feet and one to two thousand feet.

The rails serve a further function in holding down the power unit and die in order that substantial pressure may be applied to the freshly poured concrete during the shaping and finishig process. Adjacent to and parallel with the front and rear axles 7 of the power unit, are hold-down yo-kes 17. Attached to the end of each yoke and extending downwardly is a hold-down rod 18. The end of which is threaded adjacent the yoke in order that a bolt 19 may be secured thereto. Secured to the lower end of each hold-down rod 18 is a hold-down roller which is designed to roll along the bottom edge of rail 15 as the power unit moves. This necessitates that the lower portion of the rail be angled in order that the hold-down rollers are clear of any obstruction. By tightening bolt 19, the Wheels 4 are pressed against the top surface of rail 15 and are prevented from being dislocated irrespective of the amount of pressure applied by the die to the surface of the freshly poured concrete. Up to 20,000 pounds per square inch of pressure may be applied to the concrete with the arrangement.

The method for producing the structural units and the operation of the above apparatus will now be described. The above-described casting apparatus is transported to the construction site. Appropriately spaced stakes are driven into the ground in two parallel rows and the rails 15 are attached thereto such that the surfaces of the rails opposite each other are appropriately aligned a predetermined distance apart equal to the width of the structural unit to be produced. A shallow trench is then excavated between the rails and the power unit 1 is mounted on the rails and secured thereto by the hold-down arrangement shown in FIG. 6. The die 2 of predetermined configuration is secured to the underside of the power unit after which the hydraulic rams 23 are adjusted such that the die surface is spaced only a small distance above the bottom of the trench. Operation of conveyor 10 is begun and concrete mix is poured into feed hopper 9 which is thereby conveyed through chute 11 into the hopper 3. Motor 14 is started causing stacking bar 13 to oscillate and, simultaneously, the casting machine begins its movement forward along the rails whereby a thin layer of concrete is extruded into the trench from hopper 3 to line the trench. The upper surface of the thin concrete lining due to action of die 2 conforms to the shape of the desired structural unit to be produced. Once the initial lining has been laid and has been permitted to set, production of the individual structural units. may be initiated.

The power unit is returned to the starting end of the lined trough. A release coating is applied to the surface of the "concrete lining to prevent adhesion between the lining and the structural units. Reinforcing rods 21 if desired in the structural units are laid in appropriate positions raised from the surface of the trough lining. In the event that more than one structural unit is to be produced, plywood separation panels 22 are placed transversely in predetermined spaced relationship in the trough. The height of the separation panel is slightly less than the desired thickness of the structural units so that the concrete may be poured continuously, but the set concrete may easily be broken to form the individual structural units or panels.

Production of the first layer of structural units is then initiated by repeating essentially the same procedure as was carried out in laying the trough lining. The die elevation is adjusted by rams 23 such that the space between the die surface and the surface of the trough lining is equivalent to the predetermined thickness of the panel. As the power unit moves forward, a 3 to 5 foot head of concrete mix 8 is maintained in the hopper 3. Concrete mix may be continually poured into feed hopper 9 from a truck which is slowly driven parallel and adjacent to the course followed by the power unit.

The stacking bar moving at about 900 oscillations per minute serves to compress the extruded concrete mix below the die as it is moving forward at the rate of between 2 and 10 feet per minute. With a die eight feet in length, the freshly poured concrete is retained under the die 2 for from three-quarters to four minutes. The stacking bar compresses the concrete with suflicien': force that the die will maintain the pressure on the freshly-extruded concrete at up to 20,000 pounds per square inch. Because of the pressure being applied by the oscillating stacking bar, some of the concrete will be forced forward in advance of the hopper 3. As the die moves forward, the optional finishing tools attached to the rear end of the die serve to give the top surface of the freshly laid concrete the desired texture.

Upon reaching the end of the rails 15 the die 2 is raised by the hydraulic rams 23 and the power unit is returned to the opposite starting end of the rails. Before the next layer of structural units may be poured, sufficient time must elapse for the previous layer to set. However, it will be appreciated that if the tracks are of sufficient length, the time required for the power unit to complete a single run from one end to the other will be nearly sufficient for the initial end of the layer to have set so that little time will be lost while the apparatus remains idle between runs.

Before each successive layer of structural units may be poured, the preparatory steps including the placing of reinforcing rods 21 and the separation panels 22 as well as the coating of the surface of the previously laid concrete with a releasing agent to prevent adherence between adjacent layers must be taken. In addition, the track 15 may have to be raised and bolted to a previously laid layer or layers of concrete.

The preceding steps involved in laying each layer of concrete to form a series of structural units is repeated resulting in the layers being stacked one upon the other. Up to 25 layers may be stacked conveniently.

As indicated earlier, the panels may be of most any shape. But, in any event, they must be of appropriate shape and thickness such that they may be stacked one upon the other, the immediate prior layer serving as the mold for the lower surface of the subsequent layer. Examples of appropriate configurations for the panel are shown in FIG. 8.

Upon completion of the casting operation, the desired number of panels having been cast, the apparatus including tracks is removed leaving only the stack. Conventional lifting equipment, such as cranes, serve to lift consecutively each panel from the top of the stack and without further handling, it may be placed at the appropriate position for the building under construction. Where multiple panels have been poured end to end, the free end of the panel is first lifted from the stack such that the opposite end, which is partially separated from the adjacent panel by the upstanding plywood separator 22 will break away from the adjacent panel immediately above the plywood panel forming a clean break at a predetermined position.

It may readily be seen that by using the described process and apparatus, a plurality of structural units may be produced at the building construction site economically. Once produced, there need be only a single step in handling the product, that being the conveying of the individual panels from the stack to the appropriate location in the building under construction. Transportation problems have been eliminated, particularly where the desired structural units are extremely large. The apparatus itself is not complex and may be easily transported from one construction site to another.

As many embodiments may be made of the inventive concept, and as many modifications may be made in the embodiment shown, it is to be understood that the above description is to be interpreted as merely illustrative and not in a limiting sense.

I claim:

1. Apparatus for casting a plurality of concrete structural units on the ground in the field one on top of the other using a first-cast one of said units as a base form for casting subsequent ones of said units in stacked relationship, comprising: a pair of parallel tracks spaced at a predetermined distance equal to the intended width of each said unit, said tracks serving as side forms for said first-cast one of said units and for each of said subsequent ones of said units; a trough-like die member having a predetermined contour on its underside surface which serves to shape the top surface of each of said units as they are cut one on top of the other; a Wheeled vehic e capable of moving along the top of each said pair of tracks; regulating means securing said die member to the underside of said vehicle for regulating the elevation of said die; means for conveying said wheeled vehicle forwardly along said tracks; plastic extrusion means adjacent the forward end of said die member for extruding plastic material therethrough and beneath said forwardly moving die member under pressure, said plastic extruslon means comprising a hopper having an opening at the bottom thereof adjacent said die member leading edge; means for forcing the plastic material through said opening, said forcing means comprising a stacking bar mounted within the plastic material, said bar having the same predetermined contour along its underside surface as that of said die member predetermined contour and being secured to an inner wall of said hopper so that said stacking bar undersurface is substantially in vertical alignment with said die member underside surface; means for oscillating said stacking bar; hold-down means securing said wheeled vehicle to said tracks during movement therealong, said hold-down means comprising holddown rollers mounted on said wheeled vehicle for passage along the undersides of said tracks, whereby pressure by said die member through said regulating means may be applied to the top surface of the extruded material during formation of said subsequent ones of said units each of uniform and identical cross-section by reason of said die member predetermined contour.

2. The apparatus according to claim 1 wherein said stacking bar oscillating means is capable of oscillating at at least 900 oscillations per minute.

References Cited UNITED STATES PATENTS 1,505,613 8/1924 Weston 25-103X 1,559,014 10/1925 Snyder 25-103X 2,427,044 9/ 1947 Burns 25-10'3UX 2,607,100 8/1952 Urschel 25131SC 2,818,790 1/1958 Canfield et al. 25--118WUX 2,877,530 3/1959 Winn 251M 3,108,518 10/1963 OConner 25-118WUX 3,143,781 8/1964 Kalns 252X 3,177,552 4/1965 Roth et a1. 2532X 3,217,375 11/1965 Kinnard 2541.1 3,292,227 12/1966 Olds 252 J. HOWARD FLINT, In, Primary Examiner US. Cl. X.R.

25--11 32, 103, 118, 131; 249-l3; 264layers dig.

Images