US3126605A

US3126605A - Mold for casting a concrete step unit

Info

Publication number: US3126605A
Authority: US
Publication date: 1964-03-31
Anticipated expiration: 1981-03-31

Description

March 31, 1964 R V A D H S U 0 L BY MAHONEY, MIL ER 8- RAMBO BY W ATTORN E Y8 March 31, 1964 L. H. DAVIS MOLD FOR CASTING A CONCRETE STEP UNIT 4 Sheets-Sheet 2 Filed Nov. 10, 1961 mmvrox.

LOUIS H. DAVIS BY MAHONEY, MILLER 8 RAMBO ATTORNEYS March 31, 1964 H. DAVIS 3,126,605

MOLD FOR CASTING A CONCRETE STEP UNIT Filed Nov. 10, 1961 v 4 SheetsSheet 3 2 22 a I50 I50 l3b\i: l3b

sir z 2 I30 24 @{E/ /5 F I I I l I I I l I l I I I I I A INVENTOR. LOUIS H. DAVIS E" E MAfi NEY MILLER 8 RAMBO J. E3 BY wmk ATTORNEYS March 31 1964 H. DAVIS MOLD FOR CASTING A CONCRETE STEP UNIT Filed Nov. 10, 1961- 4 Sheets-Sheet 4 INVENTOR. LOUIS H. DAVIS MAHONEY, MILLER 8x RAMBO BY @m ATTORNEYS United States Patent 3,126,605 MOLD FOR CASTING A CONCRETE STEP UNIT Louis H. Davis, Columbus, Ohio, assignor t0 Concrete Steps, Inc, (folnmhus, (thio, a corporation of Ohio Filed Nov. 10, 1%1, Ser. No. 151,505 1 Claim. (til. 25-118) This invention relates to a mold for casting a concrete step unit. It has to do, more specifically, with a mold for casting a concrete step unit of the hollow, one-piece type and usually embodying a plurality of steps and sometimes a landing.

In recent years, hollow, one-piece step units have come into considerable favor since they can be produced more economically at a shop or factory as compared to concrete step units cast in position on the job site. Another reason for these step units coming into favor is their light weight due to the hollow construction as compared to the massive solid construction of step units cast in place at the job site.

Although many types of molds for concrete step units have been provided in the past, the present invention provides a mold structure having many advantages over the prior art. The structure of the present invention makes it possible to cast the step units upright, that is, in the position the unit will occupy when the unit is installed at the job site. Also, since the step unit is cast upright, the tread surfaces of the steps or landing thereof are exposed and before the material sets, the tread surfaces can be finished by troweling or brushing to the desired texture. Also, due to the nature of the mold of this invention, the step risers can be angled inwardly to provide more toe-room adjacent the next lower tread and, still, the cast unit can be removed readily from the mold. Another important feature of the mold of this invention is that it is so designed and constructed that dividers or baffles may be inserted at various positions in the mold cavity and be held firmly in place to produce a step unit of different total height or rise having different numbers of steps, with or without a landing, and with or without a closed back. The closed back is important when there is no solid wall for the unit to be placed against but is not needed if there is such a wall against which the unit may be installed.

In the accompanying drawings the preferred form of this invention is illustrated and in these drawings:

FIGURE 1 is a perspective view, partly broken away, of a step unit made in the mold of this invention;

FIGURE 1A is a perspective view of the mold of this invention with certain parts removed therefrom for clarity;

FIGURE 2 is a plan view of the mold structure of this invention;

FIGURE 3 is a vertical longitudinal sectional view taken along line 3- 3 of FIGURE 2;

FIGURE 4 is a vertical transverse sectional view taken along line 44 of FIGURE *3;

FIGURE 5 is a vertical transverse sectional View taken along line 55 of FIGURE 3;

FIGURE 6 is an enlarged detail in section taken along line 6-6 of FIGURE 5;

FIGURE 7 is a perspective view showing the positioning of a mold cavity divider around the core of the mold to provide a partial cavity for producing a step unit with a different number of steps than the hole mold cavity will produce; and

FIGURE 8 is a perspective view, partly broken away, of the mold with the core positioned therein and illustrating the use of a baflle unit to modify the mold cavity so as to prevent the formation of a back wall on the step unit.

With reference to the drawings, there is illustrated in FIGURE 1 a concrete step unit 11 of a type which can be produced with the mold of this invention. The unit comprises the back wall '12, a pair of laterally spaced, parallel side Walls 13 at right angles to the wall 12, a top landing 14 at right angles to the

upright walls

12 and 13, and a series of steps comprising the tread surfaces 15 at different levels and adjacent inwardly angled or undercut riser surfaces 16. The mold unit of this invention can be used to produce the step unit of FIGURE 1 or many variations thereof, such as the landing only, a unit with a lesser number of steps than those shown, or a unit which does not have the back wall 12. It will be apparent that the step unit is an integral cast hollow unit and has a completely open lower end.

The mold structure of this invention is illustrated in FIGURE 1A and FIGURES 2 to 8, inclusive. As shown in these figures, it comprises a flat base plate 20 of substantial area which serves as a support for all the mold and core parts and also as the bottom of the mold cavity. Located centrally on the base plate 20 is the core unit 21. This core unit has the upstanding rear wall surface 12a, the laterally spaced, parallel side wall surfaces 13a, the top wall surface 14a, the step tread surfaces 15a, and the riser surfaces 16a which are to form the corresponding inner surfaces of the step unit 11 shown in FIG- URE 1. .These various surfaces are preferably formed by metal plates welded together and to the base plate 20, as illustrated best in FIGURE 3. The base plate 20 we tends outwardly substantially beyond the lower edge of the core 21 resting thereon. It will also be noted from FIGURE 3 that all upstanding surfaces or walls of the core are provided with an upward and inward draft to make possible removal or stripping of the cast step unit from the core 21.

Surrounding the core 21 and in spaced relationship thereto are the outer mold walls which, in cooperation with the core 21, form the upwardly opening mold cavity 22. The outer mold walls include the upstanding rear wall 12b and the upstanding laterally spaced, parallel side walls 13b. The

walls

12b and 13b are preferably formed of flat plates reinforced with angle irons 23 as shown. The upstanding side Walls 13b are joined at their rear edges to the upstanding rear wall 12b at right angles by means of removable bolt units 24 shown best in FIGURES 4 to 6. These bolt units pass through aligning openings in the flat plate of the rear wall 12b where it overlaps the angle irons 23 at the rear edges of the side walls 16b. The U-shaped structure formed by the removably connected

walls

12b and 13b is located on the base plate 20 by means of locating and clamping bolts 25 which extend through aligned openings formed in the base plate 20 and the lowermost angle irons 23 of the side walls 13b.

The forward edge of each of the side walls 13b is stepped to provide horizontal tread plate receiving flanged edges 15b and vertical or upstanding riser plate receiving flanged edges 16b, these edges being provided with boltreceiving openings 26. It will be noted that the edges 16b are angled inwardly and downwardly. The

edges

15b and 16b are so formed and located that they are outwardly of the associated

corresponding core surfaces

15a and 16a. The

corresponding edges

15a and 16a on opposed side walls 13b are in alignment so as to properly receive the tread-forming plates 15c and the riser plates 16c. It will be noted from FIGURE 3 that the plates 16c angle outwardly toward their upper edges in a direction opposite to the inward angle of the riser-forming surfaces 16a on the core 21. The

plates

15c and 16c are removably attached to the corresponding tread and riser flanges by means of more of the removable bolts 24. The plates may be provided with reinforcing channels 27 secured to the outer surfaces thereof, as shown best in FIGURE 3.

In the use of this mold structure, assuming the outer walls of the mold have been removed and the core 21 is centered on and supported by the base plate 20, the outer walls of the sections 1212 and 13b are positioned on the base plate and are located thereon by means of the lecating bolts 25. At that time, also, the rear edges of the side walls 13b are secured to the outer edges of the rear wall 12b by means of removable bolts 24. Then the tread plates 15c and riser plates 160 are secured in position by means of removable bolts 24. This completes the mold cavity 22 which now has its rear wall-forming portion formed by the cooperating core surface 12a and wall 12b, and its side wall forming portions formed by the coop erating core surfaces 13a and side walls 13b. The forward stepped portion of the mold cavity is provided by the tread and

riser core surfaces

15a and 16a, respectively, cooperating with the removable tread and

riser plates

15c and 16c, respectively. Above the top wall surface 14a of the core, the mold cavity is open to receive a fluid or semi-fluid cementitious mix to be poured and set in the mold cavity. The entire mold structure can be vibrated to settle the cementitious mix in all portions of the mold cavity or suitable tamping or agitating tools may be employed.

Before the concrete sets or hardens completely, the riser plates 150 may be removed from the supporting walls 1312. Then the exposed wet surfaces of the concrete may be finished by means of troweling or brushing to provide the desired texture thereon, such as a non-skid surface. Similarly, the upper exposed surface of the landing portion of the steps may be worked.

To completely remove the integral cast step unit after the concrete sufiiciently sets, the riser plates 16c must be removed. Also, the

walls

12b and 13b are disconnected to permit them to be pulled away from the cast unit and the nuts of the bolts at the lower edges thereof may be removed to permit lifting of the walls from the base plate 20. Then the step unit 11 may be lifted upwardly off the core 21. If desired, instead of using a full base plate 20, an outwardly extending base skirt or flange may be welded around the lower edge of the core unit 21.

In some cases, it may be desirable to use the mold structure described to form a lesser number of steps. For this purpose, the arrangement shown in FIGURE 7 may be provided. This arrangement includes a baifie or divider frame which is of rectangular form and which will extend around the core 21 at a selected level depending on the height of the step unit to be produced. The rectangular frame 30 is preferably made of angle iron and preferably rests at its forward side on the associated tread surface 15a of the core 21. The angle iron is so turned that the outer vertical flange rests on the tread surface 15a and is of sufficient height to block the cavity space between that surface and the lower edge of the adjacent riser plate 16c. The horizontal flange of the angle will extend between the associated riser plate 16c and riser surface 16a as well as between the

core surfaces

12a, 13a and the

corresponding walls

12b and 13b, to block the mold cavity at this level. The divider frame 30 will fit snugly around the core 21 at its inner edges and engage the associated

outer mold walls

12b and 13b at its outer edges. It will be positioned at the desired level in the mold cavity 22 by the legs 31. By selecting a suitable size rectangular frame and legs of suitable lengths, the mold unit shown may be modified to form the landing slab alone or the landing slab with one, two, or three associated steps. It will be apparent that with the frame 30 positioned as shown in FIGURE 7, the cavity of the mold will be divided into two separate molding chambers with the area above the divider frame 30 forming a mold cavity for casting a one step landing slab unit, and the area below the frame defining a mold cavity for a two step only unit. In using the present mold structure to simultaneously cast 'two separate step units, it is merely necessary to remove the tread plate 15c immediately below the divider frame .30, in order that concrete may be poured into the lower part of the mold cavity to form the desired two-step unit in the cavity portion below the level of the frame 30 and .ahead of the forward legs 31.

With the mold arrangement previously described, the cast step unit 11 will have the back wall or panel 12. However, if this back wall is not needed, the mold structure may be modified as shown in FIGURE 8. For this purpose an inverted U-shaped divider or baflle frame 35 is provided and this frame is positioned in the mold cavity with its side and upper surfaces flush with the corresponding surfaces of the core 21. It may be bolted to the core :in this position. The front surface of this frame 35 will be angled inwardly to snugly engage the rear angled surface of the core 21 and the rear surface of this frame will be vertical and will engage the inner vertical surface of the back wall 12b of the mold. Thus, when this frame is in position in the rear portion of the mold cavity, the concrete material cannot run inwardly beyond the side and upper surfaces of the core to form the back wall or panel of the step unit. The step unit thus produced will be ex- .actly the same as that shown in FIGURE 1 but will have :10 rear wall or panel corresponding to the wall 12.

It will be apparent that this invention provides for a simple rugged mold combination in which the step unit can be cast in an upright position with undercut or inwardly angled riser surfaces. The mold structure is of such a nature that the tread surface can be exposed readily before it completely hardens in order that it can be worked to provide the proper surface texture thereon. The mold can be readily assembled for casting and disassembled for stripping. Furthermore, dividers or bafiles may readily be inserted in or removed from the mold cavity to provide variations of the mold cavity to vary the resulting casting produced therein.

Various other advantages will be apparent.

Having thus described this invention, what is claimed is:

A mold for casting a concrete step unit comprising an inner core including upstanding back and side walls, a substantially horizontally disposed rectangular top wall and a plurality of relatively adjoining tread and riserforming surfaces stepped downwardly from one end of said top wall, the tread-forming surfaces of said core being substantially horizontally disposed and being separated from one another by an adjoining, relatively upstanding riser-forming surface, each of the riser-forming surfaces of said core being arranged in obtuse angular relation to the tread-forming surfaces of said core; a generally rectangular, horizontally disposed bottom wall member carried by and extending laterally outwardly beyond the lower marginal edges of said core; a pair of opposed, relatively parallel, upstanding outer side wall members carried by said bottom wall member in outwardly spaced relation to the side walls of said core; an upstanding outer back wall member detachably connected with said outer side wall members and extending upwardly from said bottom wall member in outwardly spaced relation to the back wall of said core, said outer side wall members and said outer back wall member having upper edge portions extending a distance above the top wall of said core and said outer side wall members being formed with forward stepped edges disposed generally forwardly and above the riser and tread-forming surfaces of said core; a plurality of outer tread plates detachably secured to and extending between the stepped edges of said outer side wall members and disposed in upwardly spaced parallel relation to the tread-forming surfaces of said core; a plurality of outer riser plates detachably secured to and extending between said outer side wall members and disposed in forwardly spaced, acutely angular relation to the riser-forming surfaces of said core, said outer side wall members, said outer back wall member, said bottom wall member and said outer tread and riser plates defining with said core an integral step and platform molding cavity having a substantially enclosed, downwardly stepped tread and riser section opening adjacent the top wall of said core only; and a generally rectangular, horizontally disposed cavity-dividing frame removably positioned in said molding cavity in encircling relation to said core and at a position substantially below the level of the top wall of said core, said frame closing said molding cavity at a horizontal level substantially above said bottom wall member.

References Cited in the file of this patent UNITED STATES PATENTS Peterson June 19, 1934 Furst June 6, 1950 Cato Jan. 9, 1951 Dartez et a1 Apr. 12, 1955 McLaughlin Oct. 28, 1958 Hart Jan. 20, 1959 Varn'ando Apr. 7, 1959 Henderson Dec. 15, 1959