US2762105A - Sectional concrete forms - Google Patents

Description

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United States Patent SECTIONAL CONCRETE FORMS Arthur C. Avril, Wyoming, Ohio, assignor to A and T Development Corporation, St. Bernard, Ohio, a corporation of Ohio Application March 21, 1952, Serial No. 277,830

Claims. (Cl. 25131) This invention relates to the art of erecting poured concrete structures and buildings and is directed particularly to an improved metallic form of sectional construction for molding the walls of the building. The same metallic forms are utilized without change in molding a concrete roof slab upon the building; thus, the number of form units per building and the attendant expense is substantially less than in conventional practice.

The method aspects of erection are disclosed and claimed in the copending application of Arthur C. Avril, Serial No. 85,748, filed April 6, 1949, now abandoned. The present application is directed to the novel features of the form and is a division of the copending application.

The principal object of the invention has been to provide improved sectional forms or molds for utilization in practicing the method, the forms being sectional in the sense that they are adapted to be installed in horizontal courses one upon another, whereby the concrete may be poured into them and tamped in individual courses of controlled depth to provide maximum density, strength and smoothness of finish. Essentially, each sectional form comprises an outside and inside section, the sections being installed in spaced relationship to delineate the wall thickness and configuration.

Another object has been to provide a form structure capable of telescopic length adjustment so that the forms accommodate themselves to variations in the spacing of preset columns which, in practicing the method, constitute the skeleton of the Wall. This feature also adapts the forms, without refabrication or structural change, to variations in the length of the building so that the forms are applicable to practically any concrete wall construction regardless of size.

A further object has been to provide a combined form tie and spacer of simple construction, adapted to clamp the forms against the precast columns on opposite sides whereby the form ties maintain accurately the spacing of the forms and thereby control the wall thickness. In their utility as tie bars, they have the additional function of fastening the horizontal courses of forms securely to one another and thereby facilitate the installation of the forms in a single operation.

Still another object has been to provide a configuration around the marginal edges of the forms which impresses into the wall surface a geometric design which serves to conceal any slight irregularity which otherwise might be apparent along the parting lines of the forms.

The marginal configuration has the added utility of imparting strength and rigidity to the forms without materially increasing their weight or cost.

Described briefly, the erection method in which the forms are used, consists of first installing a foundation or footing and then erecting upon the footing, a series of precast concrete columns spaced from one another to delineate the skeleton of the wall. After the columns are plumbed and braced, with their lower ends grouted in sockets previously formed in the footing, the inner and outer wall forms are installed upon the opposite sides of the columns with the first course of forms resting directly upon the footing. The forms so installed provide a shallow trough into which the wet concrete is poured and tamped, thus bonding the first course to the footing. This procedure is repeated by installing successive courses of forms upon the first course and pouring and tamping each added course before the next is erected.

By this method, the precast columns provide guides which, in conjunction with the forms, delineate the contour and thickness of the walls. The columns become embedded as an integral part of the walls after they are poured. In practicing the method, it is usual to erect a Wall section concurrently in adjacent bays (delineated by the precast columns) by pouring concrete in the forms of one bay while a course of forms is being erected in the adjacent bay. This alternate pouring and form erecting procedure may be followed in one or several parts of the building depending upon its size and the number of men employed on the job so that the building is erected quickly with a minimum waste of manpower.

This method, which is made possible by the present forms, has several advantages over the conventional practice of erecting wooden forms of which the following are considered the most pertinent:

First, by erecting the precast columns and using them as guides for the forms, the time and expense of having skilled craftsmen set Wooden forms is entirely eliminated, making it possible to execute the major portion of the construction work rapidly and accurately with unskilled labor.

Secondly, the procedure of pouringand tamping each courseindividually produces a more uniform mixture of concrete throughout the wall and consequently creates a stronger wall using a given amount of concrete.

Thirdly, individual course pouring and tamping produces-localized agitation and increased pressure in each individual form course. This causes the finer concrete particles to ;be brought intointimate contact with the surface of the forms to provide a smooth architectural finish instead of the naked appearance associated with the usual poured concrete wall.

In general, the present form structure consists of sheet metal panels formed in sections telescopically interfitted to provide the longitudinal adjustment; thus, the forms may be adjusted longitudinally into the spaces intervening between the precast columns to bring the ends of the forms into abutment with the columns accurately and in a simple convenient manner. The spacer or tie bars draw and clamp the inner and outer forms firmly toward each other with their ends engaged against the inner and outer surfaces of adjacent columns.

The spacer bars, which are formed from sheet metal, are arranged to space and align the successive courses of forms accurately in vertical plane with respect to one another. To fasten the spaced forms together, the spacer bars have outer end extensions which are adapted to be clinched over upon marginal flanges formed along the horizontal edges of the forms.

After the concrete has set, the clinched ends are released from the edges of the forms so that the forms can be removed; however, the spacer bars proper remain embedded in the concrete wall. When the forms are removed, the extended ends of the spacer bars may be either broken off flush with the surface of the wall or they may be used to mount metal plaster lath by clinching over the end extensions upon the lath.

The geometric pattern which is impressed in the external wall surface consists of related vertical and horizontal grooves, generally V-shaped in cross section. The horizontal grooves correspond to the horizontal parting lines and the vertical grooves correspond to the vertical ends of the forms which abut the precast columns. Thus, the

vertical grooves are formed along the side edges of the precast columns to conceal any irregularity which may exist between the plane of the form and the outer surface of the column. The configuration of both the exterior and internal wall surfaces presents a smooth textured architectural finish having a pleasing pattern without requiring the additional surface coating customarily applied to poured concrete structures.

As disclosed in the mpending application, the lower courses of forms, after the concrete in them has set permanently, are removed and i installed in leapfrog fashion from the lower upon the upper portions of the wall. In this manner the quantity of forms for a given size building and the attendant expense is reduced to a fraction of the cost of formsfor the'full height of the building.

The costof forms is further reduced by reusing them in pouring the concrete roof slab. When the walls are completely erected, roof beams, similar to the precast columns,

are installed across the walls in position to support the opposite ends of the forms. The wall forms provide a depressed panel in the ceiling which matches the configuration of the inside wall surfaces to provide an attractive appearance.

Further advantages and features of the invention are disclosed in the specification with reference to the drawings in which: 7

Figure 1 is a side elevation of one of the extensible end panels of the interior form assemblies.

Figure 2 is a side elevation similar to Figure 1 of an intermediate form panel adapted to nest with a pair of.

the end panels of Figure 1 to provide an extensible form assembly.

Figure 3 is a side elevation of one of the extensible end panels of the exterior form assembly.

Figure 4 is a side elevation of'an intermediate panel adapted to nest with a pair of the end panels of Figure 3 to form an extensible outside form assembly.

Figure 5 is an end View of the panel illustrated in Figure 1.,

Figure. 6 is an end view of the intermediate panel illustrated in Figure 2. V

Figure 7 is an end view of the fpanel'illustfated' in Figure 3.

Figure 8 is an end view of the panel illustrated in Figure 4.

Figure 9 is an enlarged fragmentary view of a portion of a concrete building wall as viewed from the'gexterior,

' showing the precast columns with several courses of forms installed and showing a portion of the finished exterior wall with the forms removed.

Figure'lO is a view similar to Figure 9 showing the interior forms and a portion of the finished wall pattern. 7

Figure 11 is a longitudinal section view taken along line 1111, Figure 10, illustrating'in greater detail the relationship of the assembled interior and exterior form assemblies.

Figure 12 is an enlarged fragmentary section view taken along line 12-12, Figure 10, showing two courses of forms erected and poured with the third course installed and ready for pouring. V

Figure 13 is a sectional view similar to Figure 12 showing the third 'form poured and showing a vertical reinforcing rod'in place in the wall.

Figure 14 is a view similar to Figure 12 showing the fourth course of forms installedrand ready for pouring.

Figure. 15 is a fragmentary sectional view illustrating a portion of the roof slab, and showing the mode of utilizing the interior wall forms for molding the slab.

Figure 16 is a top plan .view of the building showing the forms installed and thereof slab partially poured as indicated in Figure 15.

Figure 17 is a perspective View showing one of the form ties used in the first course of forms, the he being placed directly upon the footing with its ends clinched over horizontal grooves 24a in the wall surface.

form unit comprises. an exterior assembly indicated gen-.

crally at 16 and-an interior assembly 11. The exterior assembly 10 consists of two end panels 12-12 (Figure 3) and an intermediate panel 13 (Figure 4) which overlies the adjacent inner portions of the end panels to provide the length adjustment. The interior assembly similarly consists of two end panels 14-14- (Figure 1) and an overlying intermediate panel 15 (Figure 2).

The three panels of each form assembly are preferably .forms of sheet steel and upon installation, cooperate with one another to mold theexterior and interior wall surfaces. In order to provide individual form installation and controlled pouring depth, the forms in assembly provide troughs which in the present embodiment are twelve inches deep and sutficiently long to fit between adjacent precast columns. I

As best shown in Figure 11, the interior and exterior form assemblies are installed at opposite sides of the precast columns 16 which are installed in the footing 17 to provide guides for the forms during erection of the wall. By reason of their length adjustment, the opposite ends of the forms assemblies are partially overlapped on opposite sides of the columns in the plane of the wall. Internal 1 stops are formed on the internal surface of the forms successive courses of forms during erection as shown in Figures 12 to 14 and remain embedded in the wall after the forms are'removed. .The forms are shaped to impress in assembly the grooved surface pattern in the exterior wall surface as disclosed. in Figure 9 and the panelled pattern in the interior wall surface as disclosed in Figure 10. V

Each end panel 12 and 14' of'the form assemblies includes right angular flanges 2121 extending outwardly along its. opposite horizontal edges and a similar flange 22 extending vertically along its outer end. This'leaves the end 23 open so that the intermediate panels 13 and 15 (Figure 11) may be fitted telescopically between the horizontal .marginal flanges 21'21. The horizontal flanges 21-21 also provide seats to sustain the courses of forms one uponanother and provide the means engaged by the form ties to secure the courses together. 7

The panels 12 further include horizontal corrugations 24, generally V-shaped in cross section, extending inwardly from the face of the panel in' a direction opposite to the. flanges .21. At the right end of this panel, as

'jacent side of the column.

As shown in Figure 3, the vertical corrugation 25' at the right end of the panel, impresses a vertical V-shaped groove 26a (Figure 9) in the wall surface outlining the columns 16. The horizontal corrugations Z4 impress the As best shown in Figure 7, the'horizontal corrugations 24'form a part of the flanges 21 so that when placed in superposed courses, the channels at the meeting flanges complement of the one another to form the V-shaped grooves in the wall. Thus, the joints at the meeting lines of the forms, which otherwise would form lines in the wall, are concealed by the depressed V-shaped grooves, and slight variations in the plane of the wall which are inconsequential but mar the appearance of it, are not evident. The left end of panel 12, as viewed in Figure 3, also is provided with a corrugation 27 so as to impress in the wall surface a vertical groove delineating the area molded by the intermediate panel 13. i

As shown in Figure 4, intermediate panel 13 is provided with marginal flanges 2828 extending from its outside surface, and includes V-shaped horizontal corrugations 30-30 extending from its inside surface. The horizontal corrugations 30 are adapted to nest in the horizontal corrugations 24 of the end panels 12 so as to form continuous grooves across the wall surface which is molded by the end and intermediate panels in assembly.

The interior form asemblies are substantially the same as the exterior ones except that there is provided a depression to impress in the wall surface a panelled configuration. Each interior assembly consists of a pair of the extensible end panels 1414 and an intermediate panel 15, generally similar to the exterior assemblies as above noted. Referring to Figures 1 and 5, the end panels 14 each include a central depressed portion 31 to stiffen the form and delineate the depressed panel 31a (Figure in the interior wall surface. The horizontal marginal offset portions 32-32 adjoining the flanges 21 from the horizontal ribs 320 in the wall surface between :panels. This construction provides maximum strength,

reduces the volume of concrete used in the construction of the building and provides. an attractive interior surface pattern. As shown in Figure 1, the flange 21 is omitted at the left end of panel 14 so as to permit the intermediate panel to be telescopically interfltted between the horizontal flanges 21-21 with its ends overlying the exterior surface of panel 14, as shown in Figure 11, to permit longitudinal adjustment.

As shown in Figure 11, the space 33 intervening between the ends of theinterior panels 1414, which is covered by the intermediate panel 15, produces a vertical column of concrete between the panels. A similar concrete column is produced in the exterior wall surface at the space 34 intervening between the exterior panels.

'It will be observed that the telescopic relationship of the panels permits the wall sections between the columns to vary in length, this variation being conveniently accommodated by extending or retracting the end panels relative to the intermediate panel.

The forms are clamped in spaced relationship by means of the form ties detailed in Figures 17 to 19. These are placed along the adjoining horizontal flanges with their ends crimped over upon the flanges as hereinafter described.

The spacer or form tie 18 for the bottom course is in the form of a sheet metal angle bar having a vertical flange 35 and a pair of flat extensions 36-36 at opposite ends. These spacers are placed between the footing 17 and first course of forms (Figure 12) with the flange 35 extending upwardly and spanning the inner and outer form assemblies to space them. The spacers are applied in the central portion of the forms as viewed in Figures 9, 10 and 12 so that the end extensions may be clinched over upon the meeting flanges of the end panels and intermediate panels as indicated at 37 (Figure 12) to secure the form panels firmly together and hold them in spaced relationship. Spacers 19 are then placed upon the upper flanges of the asesmblies to secure them together as detailed later.

The spacers or form ties 19 for theupper courses of forms are made from sheet metal stampings providing an upwardly extending spacer flange 38 along one edge and a downwardly extending flange 40 along the opposite edge. 'When placed upon the top of the first course (Figure 12), the upward flange 33 forms a spacer for the next course of forms, and the lower flange 40 extends downwardly to space the upper edge of the bottom course. Spacers 19 are used for all the forms above the bottom course as shown in Figures 12 to 14. It will be noted that spacer 19 is provided with end extensions 4141, each split longitudinally along the line 42 to the aperture 43. This provides a pair of ductile limbs 44-44, one of which is adapted to be bent downwardly and doubled around the flanges of the forms upon which the spacer is placed. The other limb subsequently is bent upwardly and doubled around the flanges of the succeeding set of forms when they are installed. These clinched extensions are indicated at 41a in the drawings.

The tie bars 20, detailed in Figure 19, are in the form of flat sheet metal strips. They are used to tie the end panels of the form assemblies together as shown in Figure 11. These strips are placed between the meeting flanges of the forms and their opposite ends are doubled over upon the flanges to draw the forms toward each other into engagement against the opposite sides of the columns 16. In other words, the tie bars pull the forms together and the spacing is maintained by the column on one end and by the intermediate spacers 18 or 19 on the other end.

During the erection and pouring of the concrete courses, horizontal steel reinforcement rods 45 may be installed along the wall so as to be positioned approximately in a central plane between the forms (Figures 12 to 14). These rods extend through apertures 46 formed in the columns 16. In practice, the rods are made somewhat longer than the space intervening between the columns so that the rods pass through the aperture and overlap each other between the columns, with the overlapped ends wired together if desired.

After several courses of concrete have been poured, vertical steel reinforcement rods 47 are. installed by thrusting them through the soft concrete as shown in Figures 13 and 14. The vertical rods are somewhat longer than the height of the walls so that their upper ends Will extend above the top to be interconnected with the roof slab.

Door and window openings are formed in the wall by installing breach forms at selected points between the spaced Wall forms to mold the necessary openings. A structure for this purpose is disclosed in the copending application of Arthur C. Avril, Serial No. 170,760, entitled Forms for Molding Openings in Concrete Structures, filed on June 28, 1950, to which attention is invited. The breach forms were developed for use with the present wall forms and are sectional in the same manner so that they can be installed piecemeal in successive courses of wall forms. The breach forms are approximately the same width as the spacing between the installed wall forms and their opposite side edges are shaped to fit the internal contour of the forms to prevent leakage of concrete. The breach forms are inserted between the wall forms to delineate the height and width of the required opening and are later removed with the wall forms.

When the wall forms are to be removed, the end extensions of the spacers and tie bars are straightened out so as to disengage the flanges of the forms. It will be observed that the spacers are left embedded in the wall permanently and after removing the forms, these extensions may be broken ofi flush with the wall either with a cutting tool or by bending them back and forth t cause crystallization and breakage.

After the walls are erected, a concrete slab roof may be poured, using the inside form panels 14 as'roof slab forms. If the building is to be more than a single storied structure, a concrete floor, formed in the same manner as the roof, is poured, and the walls of the second story beams or purlins 48 which are somewhat thicker than the'vertical columns 16. These purlins are placed in slots formed in the upper edge of the wall so that the upper surface of the purlins is substantially flush with the top of the wall. After these members are installed, the form panels 14 are mounted between them to support the roof slab, which is poured directly into the forms.

As shown, the forms 14 extend from the inside surface of the walls, with one end supported by vertically ad justable columns or shoring members 50 having stringers 51 to support the forms. The oppositeends of the forms are supported by rails such as wood two by fours 52,

clamped upon opposite sides of the purlins by C-clamps 53. The purlins 48 are spaced apart to receive the forms lengthwise between them and there are provided as many purlins as the dimension of the building requires. The intermediate'rows of forms have both ends supported by the purlins, each purlin being provided with rails 52 for supporting opposite ends of the forms.

To prevent sagging under the weight load of the concrete, the forms are supported intermediately by means of scafloldin'g, generally indicated at 54 and beams 54a. After the scaifold is installed, a rail 55 is installed upon the top of the wall to form a curbing or closure to retain the concrete, which is flowable when poured. The roof slab is reinforced by longitudinal and transverse reinforcement rods and 57 placed upon the forms as shown in Figure 16. After the roof slabhas set thoroughly, the scafiold 54 and shoring members 50 are removed so that the forms may be dropped downwardly and removed. The form contour provides a panelled ceiling which provides maximum strength for the volume of concrete employed and presents an attractive pattern 7 matching the interior walls.

The telescopic forms are constructed to conform to the present day modular construction system, the forms having a minimum length of eight feet according to the prevailing unit of measurement or multiple used in locating I-beams and columns from center to center. Following the system therefore, the precast roof rafters are placed at eight feet centers conforming to the length of the form sections.

In wall construction, the number of form ties is determined by the particular requirements of the job; thus, the spacers may be placed at any desired point along the forms as needed. In the interest of economy, the form ties are formed from light gauge metal, for example, number 16 gauge, thus reducing the crevice between forms *to a minimum to prevent leakage of concrete.

. Maximum lightness of spacers is possible because the pressure is localized in each course of forms and after two or three courses have been poured, .the lower courses have set sufficiently to sustain the courses above without transmitting a cumulative load to the lower ones.

It will be understood that the telescopic relationship of the form panels permits the form assemblies to be adjusted and installed in a simple manner even though the spacing of the columns may be irregular due to the design of the building. This of course lends flexibility and makes it possible to use the standard form units for practically any type of wall construction regardless of length, elevation or thickness. The adaptability of the forms to meet these variable factors naturally effects a saving in costs since the basic form assembly is a standardized production item of low cost construction.

The adaptabilityof the forms is further enhanced by the simplicity of the form ties and convenient random installation. As the successive form assembliesare in- 8 stalled, the form ties, which are concurrentlyinstalled, maintain the intermediate portions of the forms precisely in the same spaced relationship as the end portions which embrace the opposite sides of the precast columns;

As indicated in Figure 12, the intermediate ties are simply placed upon the upper edge of the overlapped panels, then one of the split end extensions is clinched downwardly over the meeting flanges of the intermediate and end panels. Thus, the form ties hold the panels in assembly and also space them accurately 'at opposite sides in a single clinching operation.

After the form is poured and tamped, the next course of forms is installed, then thesecond of the end extensions is clinched over upon the lower flanges of the new course so that the panels of the new course are fastened securely in assembly and in plane with the lower course. This procedure is repeated with the installation of each course and thereby accurately spaces and aligns the form' assemblies with one another by a simple clinching operation which is executed by a pliers or similar hand tool. The ties are left embedded in the finished wall after the concrete sets and if the interior'wall surface is to be plastered, metal plaster lath may be slipped over upon the extended ends of the ties and secured in place by clinching the ends over upon the lath. The ends of the ties project from the exterior wall surface from the apex of the horizontal V-shaped groove and are easily broken off by bending them several times to crystallize the metal.

By virtue of the localized tamping of the individual form coursa made possible by the present invention, the

finer particles of the concrete mix are worked outwardly into intimate contact with the smooth metal surfaces of the forms to produce a fine surface finish which is equivalent or superior to the usualarchitectural finish applied by hand to ordinary poured concrete walls. The fine finish combined with the geometric surface pattern of lines and panels produces a highly attractive architec tural effect comparable only to surfaces which are finished by skilled craftsmen. 7

Having described my invention, I claim:

1. A sectional form structure adapted to extend between adjacent vertical columns in clamping engagement against the opposite sides thereof for molding successive horizontal courses of concrete one upon another to form a wall between adjacent vertical columns, said form structure comprising, respective inner and outer form assemblies each form assembly constituting an elongated to stiffen the same, said flanges providing a seat adapting I said form assemblies to be placed one upon the other in courses, and a series of spacers adapted to be placed transversely across the inner and outer form assemblies, each of said spacers including a pair of flanges extending upwardly and downwardly adapted to extend in endwise abutment against the form assemblies to engage the internal upper and lower edge portions of adjacent courses, said spacers including flat sheet metal extension strips at opposite ends adapted to be interposed between the meeting flanges of the superposed form assemblies and to extend beyond said flanges, said extensions being split longitudinally to form a pair of'limbs,said limbs being doubled over in opposite directions around the flanges to secure the superposed assemblies together in the vertical plane and clamping the flanges of the intermediate and end panels in assembly and in longitudinal adjustment.

2. A spacer for securing together spaced inner and outer concrete forms, said forms having longitudinal flanges extending outwardly along their opposite longi-' tudinal edges and adapted to be placed in successive horizontal courses one upon another with said flanges superposed, said spacer comprising, a flat sheet metal strip having an upwardly extending spacer flange formed along one longitudinal edge and a downwardly extending spacer flange along the opposite longitudinal edge, a fiat extension strip extending outwardly from opposite ends of the strip beyond said flanges and adapted to be placed upon the longitudinal flanges of the forms with the downwardly extending spacer flange disposed transversely across the upper edges of the inner and outer forms, the opposite ends of the spacer flange being in abutment with the internal surface of the inner and outer forms and adapted to hold the same in spaced relationship, the upwardly extending spacer flange being adapted to extend across the lower edges of the next succeeding course of forms, the opposite ends of the spacer flange being in abuunent with the internal surface of the forms to hold the same in spaced relationship, said flat extension strip being split longitudinally to form a pair of ductile limbs at opposite ends of the spacer arranged to be clinched respectively downwardly and upwardly over upon the superposed flanges of the courses of forms to clamp the same in spaced relationship and to secure the superposed courses together.

3. A form structure for erecting a wall by molding horizontal courses of concrete successively upon a footing and upon one another, said form structure comprising, a series of columns rising vertically from the footing and spaced apart from one another, said columns having a thickness equal to the wall thickness and delineating the same, a plurality of courses of inner and outer forms mounted one above the other in vertical planes on opposite sides of adjacent columns and overlapping the columns, the forms having a width less than twice the thickness of the columns, the forms spanning the columns horizontally and providing a mold chamber between the columns with the columns providing end closures of the chamber, each inner and outer form having a horizontal flange along opposite longitudinal edges projecting externally from the mold chamber, the flanges providing seats supporting successive horizontal courses of inner and outer forms one upon another, a series of form ties extending transversely across the inner and outer forms, each form tie having flat sheet metal extension strips at opposite ends interposed between the flanges of the successive courses of forms in the plane thereof and projecting outwardly from said flanges on opposite sides, the sheet metal extension strips providing an interface between the flanges which is sufliciently narrow to prevent the escape of wet concrete from between the forms, the form ties having spaced abutments at opposite ends projecting upwardly and downwardly relative to said flanges and engaging the internal surface of the forms along the interfaces thereof, the spacing of said abutments related to the thickness of the columns and cooperating with the columns to delineate the thickness of the wall, the said sheet metal extension strips of the form ties each comprising a pair of limbs which are doubled over in opposite directions and clinched upon the seated flanges of successive courses of forms, thereby securing the seated flanges to one another and clamping the forms against the said spaced abutments.

4. A form structure for erecting a wall for molding horizontal courses of concrete successively upon a footing and upon one another, said form structure comprising, a series of columns rising vertically from the footing and spaced apart from one another, said columns having a thickness equal to the wall thickness and delineating the same, a plurality of courses of inner and outer forms mounted one above the other in vertical planes on opposite sides of adjacent columns and overlapping the columns, the forms having a width less than twice the thickness of the columns, the forms spanning the columns horizontally and providing a mold chamber between the columns with the columns providing end closures of the chamber, each inner and outer form having a horizon tal flange along opposite longitudinal edges projecting externally from the mold chamber, the flanges providing seats supporting successive horizontal courses of inner and outer forms one upon another, a series of form ties extending transversely across the inner and outer forms, each form tie including flat sheet metal extrusion strips at opposite ends interposed between the seated flanges of the courses of forms, said extensions split longitudinally to form a pair of limbs, said limbs doubled over in opposite directions around the seated flanges and clinched thereon to secure the forms together, the form ties having spaced abutments at opposite ends projecting upwardly and downwardly relative to said flanges and engaging the internal surface of the courses of forms, the spacing of the abutments related to the thickness of the columns and cooperating with the columns to delineate the thickness of the wall.

5. A form structure for erecting a wall by molding horizontal courses of concrete successively upon a footing and upon one another, said form structure comprising, a series of columns rising vertically from the footing and spaced apart from one another, the columns having a thickness equal to the wall thickness and delineating the same, respective horizontal courses of inner and outer forms mounted one above the other in vertical planes on opposite sides of adjacent columns and overlapping the columns, the forms spanning the columns horizontally and providing a mold chamber between the columns with the columns providing the end closures of the chamber, each form having a horizontal flange along opposite longitudinal edges projecting externally from the mold chamber upon opposite sides thereof, the flanges providing seats supporting successive horizontal courses of forms one upon another the forms along one side of the wall having, respective corrugations formed in the opposite longitudinal edges thereof, said corrugations adjoining said flanges, each of said corrugations rising at an angle inwardly from the internal plane of the form adjacent the flange and joining the inner edge of the flange, each corrugation being complementary to the corrugation of the adjoining course of forms, said complementary corrugations in assembly forming a generally V-shaped corrugation having an apex projecting inwardly along said seated flanges, said corrugation impressing a V-shaped groove in the wall along said flanges, and a series of form ties extending transversely across the inner and outer forms, each form tie having flat metal extension strips at opposite ends interposed between the flanges of the successive courses of forms, each form tie having spaced abutments at opposite ends engaging the internal surface of the successive courses of forms along one side of the wall and the apex of said corrugations, along the opposite side, the spacing of the abutments related to the thickness of the columns and cooperating with the columns to delineate the thickness of the wall, the flat metal extension strips of the form ties each comprising a pair of limbs doubled over in opposite directions and clinched upon the seated flanges of the successive courses of forms, securing the flanges together and clamping the inner and outer forms against said abutments.

References Cited in the file of this patent UNITED STATES PATENTS Re. 17,733 Nelson July 15, 1930 645,325 McNamee Mar. 13, 1900 828,031 Kemper Aug. 7, 1906 830,747 Staufer Sept. 11, 1906 1,013,632 Whitthoefft Jan. 2, 1912 1,126,190 Fuehrer Jan. 26, 1915 1,190,977 Bartow July 11, 1916 (Other references on following page) 11 UNITED STATES PATENTS Colt Feb. 27,1917 weiderhold Apr. 2, 1918 Fluor Feb. 8, 1921 Cummings Aug. 25, 1925 Bauschard Nov. 29, 1927 Bierhaalder Dec. 9, 1930 Berton -1- Nov.

12 V Penote July 14, 1931 Heller Mar. 15, 1932 Troiel Oct. 15, 1935 Thorn Nov. 19, 1935 Oldreive ;Ap1'. 24, 1945 14, 1950

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