US2170936A - Method and apparatus for making artificial stone - Google Patents

Description

C. F. BARON Aug. 29, 1939.

METHOD AND APPARATUS FOR MAKING ARTIFICIAL STONE 1936 2 Sheets-Sheet 1 Filed Nov. 18

INVENTOR Carol 1 75421) TTOQE EY C. F. BARON Aug. 29, 1939.

METHOD AND APPARATUS FOR MAKING ARTIFICIAL STONE Filed Nov.

, 1936 2 Sheets-Sheet 2 INVENTOR- Ccuoljffia 7 0/1 ATTORN Patented Aug. 29 1939 UNITED STATES PATENT OFFICE ivmrnon APPARATUS FOR MAKING ARTIFICIAL STONE g 11 Claims.

This invention relates broadly to the art of making molded concrete blocks, such as are commonly used in the erection of buildings, and it deals with the methods, as well as with the apparatus, employed in the manufacture of such blocks.

One object of the invention is: to provide an improved method for manufacturing concrete blocks, which method renders it unnecessary to touch the block from the time the concrete is poured into the block-mold, to the time when the blocks are set and cured, and ready for the builders use.

Another object of the invention is: to provide a simple and efiicient apparatus in/on which the blocks are formed or cast in molds and. may there remain during further treatment and until finished, and then be removed individually, one after another, and stored in close and compact formation. Referring to the apparatus specifically, so as to permit the manufacture and removal of the finished blocks along the lines indicated above, the invention provides a. plurality of ad- ,iaoent concrete-receiving molds or receptacles separated from each other by comparatively thin partitions which may be readily primarily assembled to form such receptacles, and which can be readily withdrawn or disassembled to release the finished blocks, for removal.

Inasmuch as my improved method of making the blocks, and the apparatus for doing so, are very closely allied with each other, and their relationship as to the position of the blocks on/in the apparatus remains the same throughout the entire process, the following description of the invention will explain the entire process, step by step, commencing with the primary building-up of the apparatus to prepare it for receiving the concrete mixture in the block-molds, and following the successive steps required to produce the finished blocks, without, in the least, changing their positions in/on the apparatus during that period, and finishing with the final taking down of the built-up mold parts to liberate the finished blocks for removal and storage.

Referring to the drawings:

Figure .l is a perspective View or the apparatus, the uppermost portion being partly broken-away 50 to disclose the molds filled with concrete mix-.

ture.

Fig. 2 represents a side view of the apparatus, with the hood raised.

Fig. 3 is a cross section, on line 3-3 of Fig. 2,

55 the hood being down in operative position,

Fig. 4 is a longitudinal section, without the hood.

Fig. 5 is a plan view of the apparatus, with the molds in place, and corresponding to Fig. 4.

Fig. 6 illustrates one step in building-up the 5 molds on the table.

Fig. 7 shows, in perspective view, one end of the frame which forms a part of and supports the hood fabric to form the curing chamber of the apparatus. 10

Fig. 8 illustrates a modification of the endclosing plate of the molds to be used for forming full-length end-blocks, such as shown in Fig. 9.

Fig. 9 shows a full length end-block. 15

Fig. 10 shows a half-length end-block.

Fig. 11 is another modification of the endclosing plate, this species being adapted for making jamb-blocks, a full-length block being alsov shown in this figure. 20

Fig. 12 represents a half-length jamb-block, also produceable with the use of the end-plate shown in Fig. 11. Rows of any of the types of the blocks just described may be cast at the same time with the regular wall blocks. 7 25 Fig. 13 represents a number of block-courses, sectionally, as they are built-up in horizontal for floors, or in vertical layers for Walls.

Fig. 14 shows, in perspective view, the manner in which staggered or overlapping superposed 30 courses of blocks are laid, each course here having one end-block, one regular block, and one jamb-block to provide for a window or a door casing.

Fig. 15 is a perspective view of a regular block 35 provided with a. special facing applicable to the block while in process of manufacture.

In the manufacture of concrete blocks, it has been, and still is, common practice to cast a large number of such blocks at the same time on a table adapted to be transported immediately, after the molds are filled with the desired concrete mixture, from this filling station to another location where the freshly-poured casts are subjected to special treatments, and thus permit another table with a new. set of molds to be placed under the chute bringing the fluid concrete from the mixer. Ordinarily, each table is placed on, or forms a part of,.a car which must needs be strong enough to carry the weight and yet be easily movable for travel, as for instance on rails which, however, in accordance with my present invention, need not necessarily extend into any building or chamber to bring the molds into locations for further treatment. In other words: the car may now be entirely in the open, because such enclosures, as are required to confine the molds for treatment, may, in one aspect of my present invention, be applied directly to the car itself, in contradistinction to the usual manner of running the car into one or more buildings or chambers built permanently and especially for that purpose.

The car, such as at present preferred, comprises a pair of longitudinally-extending base-channel bars 26 supported by track wheels 2| in any convenient manner. Extending laterally across the channels 20 and supported thereby are a series of smaller channeled beams 22 carrying the table plate 23 on which the block-molds are removably built up into definite positions relative to each other, as follows:

The formation of the molds must, as a matter of course, conform to the type of block to be made, the prefer-ably regular type being shown in Fig. 6. This block B is substantially a rectangular parallelepiped having a centrally cored transverse hollow channel a extending through it and at each end a semi-cylindrical groove b so that, when a series of blocks are placed endto-end, each pair of adjoining grooves b will also form a cylindrical transverse passage similar to the channel a. Likewise, when a series of blocks are placed fiatwise and in overlapping or regularly-staggered courses, the channels a of one course and the end-grooves b of the adjacent course will be in alignment vertically or horizontally, as the case may be, and form passages for ventilation or conduits for wires, pipes, etc. as may be desired when outfitting a building. Of course, it will be understood, that, when erecting a building, the adjoining blocks are to be united by a suitable cement binder.

According to the present invention, the molds for the regular blocks are built-up into composite formation by assembling a number of plates, of which there are used three specific kinds, viz: partition-plates 25 extending across the table, spacer plates 26 placed longitudinally of the table and between the partitions 25 to form rectangular boxes or molds, and end-plates 21 which also extend across the table and are firmly but removably secured to the table-top, (preferable by withdrawable bolts or pins) and which, when so attached, will hold the entire assemblage firmly together, and against shifting on the table.

Considering first the end-platesZl, (see Figs. 1 to 4) they are formed of sheet metal and have their opposite ends attached, preferably by spotwelding, to angular reinforcing or stiffening strips 28, each having at its lower end a perforated ear 28a to receive a lock pin 29 for securing that end of-the plate 2'! to the vertical leg of an L-shaped guide rail 39, two of such rails being provided and fixed to the table-top near the side margins thereof, respectively, and so distanced from each other that the ears 28a will closely contact the inner faces of the rails 30. Each strip 28 has also an upper ear 28b to which is secured the upper end of a brace SI whose lower end is'detachably held against the outer side of the rail 30 by alock pin 32, both pins 29 and 32 preferably having eye-ends to facilitate their withdrawal, when required. Inasmuch as the end-plates 28 and their attaching devices'are duplicates, and the extreme le'ngth of the endplates 28, as well as ofthe partition-plates 25 is the same throughout the guide rails 30 are parallel and therefore hold those plate edges in proper alignmentlongitudinally of the table; it

being understood, of course, that the plates are disposed at right angles across the table and relative to the rails, see Fig. 4.

Considering next the partition-plates 25, these are similar in size and shape to the end-plates, excepting their end strips 28a which are here bent into U-form and do not have any holding ears. Attention is called to the fact that the spaces between the inner edges of the two opposite strips of each plate must be exactly the same to provide for properly placing the partition-plates so as to leave uniform block spaces between them. Also, that the distance from each inner end-strip edge to the outer face of the strip-bend must be uniform, to insure parallelism of the guide bars withthe inner strip-edges to provide for proper location of spacers 26.

The spacers 26 are merely plain thin sheet metal plates (see Fig. 6) all of which are exactly of the same size, so as to be interchangeable ad lib., and which are interposed between the opposite faces of the several partitions and also their cooperative end-plates. As it is important that these spacers 26 must be equally distanced from each, across the table, so that the widths of the molds for the cast blocks will all be the same, means are provided on the partitions and on the working faces of the end-plates, for accomplishing that result, and, in accordance with my present invention I make use of a row of cores C required to produce the grooves 17 in the ends of the cast blocks B. In Figs. 1 and 4 it will be seen that the table is here adapted to handle six longitudinal rows of blocks, each row consisting of seven blocks, making a total of forty-two blocks for each setting. Therefore, six sets of groovecores are required on each of the two opposite contact faces of each partition, and, in order to produce the partitions as light in weight as possible, I preferably form all the cores C from thin sheet metal intosemicylindrical shape provided with top and bottom attaching tabs 0 which latter may be spot-welded on the working faces of the several plates. The length of each groovecore is equal to the width of the block to be made, and the spaces between each adjacent pair of cores on the plate are equal to the thickness of the spacers which fit snugly between them and abut the working faces of the partitions. In other words: when a pair of cooperative spacers are properly engaging the partitions between which they are located, there will be formed a rectangular mold, whose end walls respectively have the cores necessary to produce the end-grooves, b, b of the block B. Also, inasmuch as the spacerends contact firmly against the faces of the partitions, and the spaces which the plate-ends enter between the cores are equal to the thickness of the spacer-plates, it follows that, even if the cores C are, per se, open at both ends, yet there can be no leakage of concrete mixture into the cores because the side face of the spacer-plates seal them.

In Figs. 1 and 4, the partition-and-core combination has been clearly illustrated, attention being now called to the fact that the upper and lower edges of the core-tabs do not extend to the upper and lower faces of the block, so that the full contour of the block-cast may be preserved. On the other hand, the thickness of the tabs will naturally leave a slight depression equal to their thickness in each end-face of the block, and for that reason I preferably feather the tabedges, to reduce and taper this depression in the manner shown. The same construction applies to the cores C attached to the end-plates 21, only one set however being required for each end-plate.

When building-up the molds, one end-plate 21 being fixed in position, the first set of six spacers may be entered into the spaces between the cores C of the end-plates, whereupon the first partitionplate 28 is slid along between the rails 30 until the still free edges of the spacers are entered into the spaces between the cores on. the partition and there contact the face of the partition. The same operation is performed with the second set of six spacers being entered between the cores C on the obverse face of the first partition, and the second partition is properly located. It is evident that, if the end-plate 21 is disposed at right angles relative to the guide rails Sii, the partition-plates will also be thus disposed, due to the fact, that the spacers are all interchangeable and of exactly the same size. After the last set of spacers has been placed, the final endplate is brought into engagement with the still free spacer-edges and then locked by the insertion of the lock pins 29 and 32, thus providing, in the exemplary apparatus shown in the drawings, a series of forty-two adjacent and interconnected molds, any pair of which are separated from each other across the table by only one member, viz.; one spacer-plate 26; and longitu:- dinally of the table by a single partition-plate 25, features which are helpful and economical when screeding the concrete mixture in the molds, by a lute or similar device.

Referring again to the block B of Fig. 6, each of the molds assembled as above described, takes care of a rectangular concrete-block as far as its general dimensions and the end-grooves, b, b are concerned. It, therefore, remains only to provide in the molds means for forming in each block the interiorly-central conduit or channel a, so that, when the finished blocks are laid in overlapping courses when erecting a building, the conduit or of one layer or course will line-up with another conduit formed by the combined semi-cylindrical grooves b, b of any pair of adjoining blocks. For that reason, each spacerplate 26 has a central aperture 26a of a diameter equal to that established by the combination of the grooves b, b of the pairs of adjoining blocks, all the apertures 26a of the spacers therefore becoming aligned and adapted to receive a single core structure, such as 35, shown in Fig. 6 andpreferably formed of a cylindrically-curled strip of sheet metal whose outside diameter is substantially equal to that of the apertures 26a, and whose length is sufficient to have its ends project (see Fig. 4) slightly beyond the outer faces of last spacers for each transverse row of blocks on the table. The cores 35 are then pushed through the aligned spacer-apertures Zita, in which theyfit closely, and their projecting ends are then expanded, preferably by tapered plugs 35, so as to have a tight fit in the apertures of the outermost spacers of each particular row, and thus seal the molds against leakage. The insertion and endexpansion of the cores 35 constitute the final step building-up the forty-two molds-of the apparatus, and they are now ready to receive such concrete mixture as may be commensurate with the requirements, directly from a mixer (not shown). If required by the nature of'the concrete mixture, the table 23 may be equipped with a vibrator V (see Fig. 1) to agitate the mixture as it settles in the molds, and to thereby densify the cast, even before the curing operation is begun. I

In recapitulation be it stated that the abovedescribed manner of building-up the molds from pluralities of partition-plates 25, spacers 26 and end-plates 21 respectively, is a simple process which, although possibly requiring slightly more time in its accomplishment, when compared with the time required for assembling a set of individually-separable molds, possesses the advantage that the entire mold outfit is light in weight, costs less in producing the necessarily large number of parts, eliminates waste of mixture due to screeding the casts when the molds are filled, and also permits rapid removal of the finished blocks, without any liability of damaging the finished block faces or corners by having them stick to the sides of preformed box-type molds as used heretofore.

When all the molds arefilled from the mixer, the car may be rolled out from under the mixer or filling station to another nearby location where the casts are to be dehydrated and cured, a process which was heretofore generally carried out in an enclosed building or room where the casts were kept for a sufficient period, usually from one week to ten days, to permit the mixture to set or harden to a small extent before any actual heat was applied, during which setting period the casts were protected from the direct rays of the sun and from drying winds, by covers of canvas, burlap, or sand.

In my improved method, I do not employ any coverings of any kind during the setting period, but allow the casts to harden or set naturally for a period of about one to two hours, according to atmospheric conditions, a short period if temperature is warm, and a longer period if the temperature is cold. The central cores 35 are then released by the removal of the plugs 36, and withdrawn, leaving the central channels a open and unobstructed from end-to-end, and ready for steam-curing, which latter is accomplished under a hood normally suspended in raised position and adapted to be lowered to entirely enclose the table top and the filled molds supported thereon.

In conformity with my present invention, this hood and the steam-supplying elements are combined into a single unit comprising a series of bows H which are centrally spaced at the top on a tie-plate H and whose opposite side ends H are substantially vertically parallel and are attached to nozzles N projecting toward each other from .a pair of steam- supply pipes 37, 38 which extend in parallelism with, and are supported along, the sides of the mold-carrying table 23, respectively. The nozzles N of each pipe are so spaced longitudinally thereof that, when the pipes are placed into their positions on the table, their respective nozzles will be in alignment with and facing the outer openings of the central channels a. At one or both ends of the car, the steam pipes 3'! and 38 are rigidly connected preferably by pipes and fittings such as shown in Fig. 7, each of the connector branch pipes Ma, 38a being provided with a valve 39, whereby the passage of superheated steam at about 250 F., supplied through a flexible steam-house 66, may be regulated, as weather and temperature conditions may dictate to produce the best results. From the foregoing it will be understood that the steam pipes and their associated bows and nozzles form a strong unitary frame which may be covered with canvas H over the top and ends, and whose side aprons h hang over and are adapted to entirely enclose the sides of the molds on the table, and thus form a closed hood adapted to be raised or lowered over the molds by a suitable tackle or crane (not shown) attachable to the hood at eye bolts, as shown. Inasmuch as it is necessary that the hood be properly located on the table so as to bring all the nozzles N into alignment with the cores a of the blocks, respectively, there are secured to the table top 23 a series of brackets or stands 4| whose upper ends are bifurcated, as at Ma, to receive and support the side steam pipes 31, 38 at their required altitude above the table-top, and also to act as side gages or stops to be contacted by the T-fittings such as 31b, 38b of the pipes 31, 38 respectively, to locate the nozzles properly lengthwise of the table.

As shown, the top of the hood is crowned and located closely over the tops of the molds, a feature which maintains the emanating gases warmer and close to the product and also tends toward economy by the conservation of steam, the condensation of which will naturally accumulate on the underside of the canvas-covering and run off toward the side aprons of the hood and to the table-top where it will undergo more or less of revaporization, according to the temperature of the table .as produced by live steam issuing from the nozzles into the hood, and particularly into the open ends of the cored channels a, of each transverse row of block-casts. The steamjets are therefore projected toward each other, bringing their initial heat into direct contact with the bare interiors or channels of the hollowed block-casts and thereby hastening the curing of the latter in a very substantial manner, from the inside of the cast toward the outside thereof. Furthermore, inasmuch as the several spacer-plates are made of metal, they will also become hot, by virtue of the live steam coming into direct contact with the edges of the plate perforations 26a, and thus assist in dehydrating the casts, especially at the side faces thereof, during the curing operation, the latter taking only from four to eight hours, depending upon the particular concrete-mixture and the latent heat of the vapor.

At the expiration of that period, the steamvalves are closed, and the hood is raised. The steam-cured casts and the molds are then to be exposed for gradually cooling-off and consequent contraction and resultant densification or hardening, this process requiring from one to two days, depending upon the atmospheric conditions. Upon the conclusion of this curing period the molds .and blocks are taken apart, piece by piece, and stacked, the blocks being then completely finished and ready for immediate use.

When taking-down or disassembling the molds, one or both of end-plates 21 are liberated by the withdrawal of the securing- pins 29, 32 and removed from the table. The outer ends of the first row of spacer-plates 26 will therefore be freed and may be pulled out to clear the sides of the blocks, without any liability of breaking or otherwise damaging either the corners or faces of the blocks, the blocks being thereupon removed from the table as fast as the spacer-plates 26 are taken out, that is to say: very speedily, as compared with the time required to slide finished cast blocks out of either unitary or individually-assembled molds, with their accompanying danger of damaging the cast blocks and thus causing waste of product.

The blocks which are to be cast on my improved apparatus can, of course, be any of the various types used in the erecting of buildings, all the blocks matching cross-sectionally but differing at their ends to meet different purposes, as illustrated in Fig. 14. In Fig. 9 there is shown a full-length terminal or end-block E such as may be used for floors or partitions at their junctions with walls, etc., in which case the semicylindrical groove 11 is dispensed with at one end, the block then having a full face end I). The end-plate 21 against which those blocks are cast, should therefore not have any cores 0; so that other means have to be provided for properly spacing the end-edges of the last row of spacerplates where they abut against the inner face of the end-plate. In the preferred form thereof shown, these means consist in forming the spacers 45 so as to have tabs 45a (see Fig. 8) projecting beyond the edge of the plates and adapted to enter slots 46 provided for them in the end-plate 41 at proper distances between them. In Fig. 10 there is shown a half-length end-block Ea, having a plain end-face b, without any end-groove, just like the full-length block E of Fig. 9. By referring to Fig. 14 the utility of the half-length blocks Ea will be apparent, the lower layer or course L consisting of a full-length end-block E, a regular block B, and a half-length jambblock J a, the latter being shown, per se, in Fig. 12, and having its end notched out at 7' to receive the jamb or casing of a door or window. The next i and superposed layer or course I. consists here of a half-length end-block Ea, a regular block B, and a full-length jamb-block J, so that the vertical joints between the adjacent blocks of one course will be in staggered relation to the joint lines between the adjacent blocks of the next course. The next superposed layer or course L will, of course, be like the course L the courses alternating as they are successively built-up, as is common practice.

From the foregoing description the necessity of providing half-length jamb-blocks Ja, will be evident, because the casing-receiving notches a of the superposed courses must be in vertical alignment, and match. By referring to Fig. 11 it will be noted that the notches :i are formed in the blocks, J, Ja by substituting, on the inner face of the end-plate 21, cores Co of rectangular form, for the semi-cylindrical cores C used in the casting of the regular blocks B, it being understood that the cores Ca are spaced to closely receive the edges of the several spacer-plates 26 of that row.

It is obvious that, while my invention has been fully explained by the drawings and the description pertaining thereto, the showings are only of exemplary nature, especially in regard to the shapes and sizes of the blocks and the cores necessary to produce them; furthermore that cop ings, caps, sills and other building-elements can be economically manufactured by my improved method, with equal facility.

As to carrying out my improved method of manufacturing the blocks by the use of the apparatus described, a brief and concise rsum of the successive steps and the pertinent manipulation of the apparatus to carry out those steps, may be in order to clarify the entire situation, from the time of building-up the molds to the time where the finished blocks are removed, ready for use, as follows:

1. Build-up the molds, by assembling the end plates 21, partitions 25 and spacers 26, and securing the end-plates 21 to the table rails 30 by using the pins 29, 32. r

2. Place the long center-cores 35 into their positions by passing them through the apertures 26 of the spacers and so as to slightly project beyond the faces of the outermost spacers of each row, and drive-in the plugs 36, to make tight joints and prevent leakage of the fluid-mixture of concrete toward the outside of the outermost molds.

3. Fill the molds, from the mixer chute, and screed their tops.

4. Clear the car from the mixer chute and bring it under the raised hood, (which constitutes the curing station) to protect the molds from direct sun or rain.

5. Let the concrete set, while in the open, for a period of one to two hours, viz: a short period, if the atmosphere is warm, a longer period, if cold.

6. Remove the core plugs 36, and pull out the center-cores 35.

7. Drop the hood, to completely enclose the molds.

8. Open both steam-valves, to steam-cure the casts in the molds from four to eight hours, by injecting the steam into the central core-channels of the casts, bringing hot vapor into direct contact with the now bare inside of the cast, and curing the latter from the inside, outwardly.

9. Shut-off the steam and raise the hood, letting the molds stand as they are, for one to two days.

10. Take off the end-plates, upon withdrawal of the pins 29, 32.

11. Take the mold-plates and cast blocks apart, piece by piece, and store them away for immediate or future use.

Considering the method involved, the total time actually used from the time that the molds have been filled and screeded, need not exceed three days, maximum which is a considerable saving over the period of from ten days to two weeks required heretofore.

Concerning the apparatus used, the molds can be quickly assembled and locked to and on the table in predetermined positions, without bolts, screws, clamps, or tools. The hood is individual to any car, and can be quickly placed into correct position to line-up all the steam-nozzles with the core-channels of the casts, without requiring adjustments of any kind, either horizontally or vertically. The steam-supply can be handily regulated in accordance with the prevailing condition of the atmosphere, and can be readily dis connected when not needed, either from the hood itself, or by raising the hood from the table. When dismantling the table, the mold-parts of each of the three types used (being exactly alike in shape and light in weight) can be easily stacked or stored in compact form.

It is sometimes desirable to make blocks which are coated at their upper faces with a layer of hard veneer, to produce certain color efiects, and also a hard wearing surface, especially when the blocks are to be used for flooring. Such a block is illustrated in Fig. 15, where the block B has a top-facing F which may consist primarily of a plastic compound adapted to be spread over the exposed tops of the uncured concrete in the molds, the concrete in that instance being screeded with a lute of variable depth to leave room for the veneering compound which then is screeded level with the tops of the molds and is cured at the same time with the concrete cast. In another instance ornamented or enameled tiles may be applied to the tops of the cured concrete casts, a cement being then used for intimately binding the concrete block and its veneer together, all while the casts are still in the molds.

It is obvious, of course, that variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

I claim:

1. A method of casting interiorly-channelled concrete blocks which comprises projecting jets of steam simultaneously into the opposite open ends of the bare interior channel of each block and against the exterior of the same to cure the block from the inside as well as the outside, and maintaining the warm steam in close proximity to and in contact with the surfaces thereof to maintain the product and gases emanating therefrom at a uniform heat.

2. A method of casting and curing concrete blocks in a molding device comprising a plurality of molds having removable cores, the steps of pouring the concrete to fill the molds and screeding the same, initially setting the blocks, removing the core from the molds, enclosing the molds with a means disposed in close proximity to the outer surface thereof, and simultaneously projecting low pressure steam into the channels formed in the concrete blocks by the removal of the cores and to the outer surface of the blocks so as to cure the blocks from the inside as well as from the outside, the steam being maintained in intimate engagement with the product by the enclosing means whereby the product and gases emanating therefrom are maintained at a uniform heat.

3. In a method of casting and curing concrete blocks in a molding device having removable cores therein and a curing hood thereon, the steps of pouring the concrete to fill the molds and screeding the same, producing an initial set in the blocks, removing the cores from the mold, lowering the hood into position over the mold in close proximity to the product, and. forcing low pressure steam through the channelsformed in the blocks by the removal of the cores and also to the outer surface of the same to simultaneously cure the blocks from the inside as well as from the outside, the steam being maintained in close proximity with the product causing a uniform heat to be-maintained on the product.

4. An apparatus for casting concrete blocks, comprising a table, a series of adjacent molds arranged in longitudinal as well as in transverse rows and secured thereon, a hood movable to expose and completely enclose the table-top and said molds, and steam-supply pipes supporting said hood and having nozzles extending into the interior thereof.

5. An apparatus for casting concrete blocks, comprising a table, a series of adjacent molds arranged in longitudinal as well as in transverse rows and secured thereon, a hood movable to expose and completely enclose the table-top and said molds, steam-supply pipes supporting said hood and having nozzles extending into the interior thereof, and devices secured to the tabletop for positioning said steam pipes on the table to bring said steam-nozzles into predetermined positions relative to said molds, and simultaneously position said hood over said molds.

6. An apparatus for casting concrete blocks, comprising a table, a series of adjacent molds arranged in longitudinal as well as in transverse rows and secured thereon, a hood vertically movable'to expose and completely enclose the tabletop and said molds, and steam-supply pipes supporting said hood at the outer sides thereof and having nozzles extending through the sides of said hood into the interior thereof.

7. An apparatus for casting centrally-channeled concrete blocks, comprising a table, a series of adjacent molds arranged in longitudinal as well as in transverse rows and secured thereon, a hood movable to expose and completely enclose the table-top and said molds and steam-supply pipes supporting said hood and having nozzles extending into the interior thereof and adapted to project steam-jets into said channels formed in the blocks in the molds, respectively, at the opposite open ends thereof.

8. An apparatus for casting centrally-channelled blocks comprising a table; a series of adjacent molds arranged in longitudinal as well as transverse rows and secured thereon; a hood movable to expose and completely enclose the table and said molds; and a steam supply pipe supported on said hood and having nozzles extending into the interior thereof and adapted to simultaneously project steam jets into the open ends of said channels formed in the blocks in the mold and to the free exterior surfaces of said blocks to thereby cure the concrete from the inside as Well as from the outside.

9. An apparatus for casting centrally-channelled blocks comprising a table; a series of adjacent molds arranged in longitudinal as Well as transverse rows and secured thereon; a hood movable to expose and completely enclose the table and said molds; and a steam supply pipe having nozzles extending into the interior of the hood to simultaneously project steam jets into the open ends of said channels formed in the blocks in the mold and to the free exterior surfaces of said blocks to thereby cure the concrete from the inside as Well as from the outside.

10. A method of casting and curing concrete blocks in a molding device comprising a plurality of molds having removable cores, the steps of molding the blocks and initially setting the same; baring the interior of the block by removing the cores from the molded blocks; and projecting low pressure steam into the interior of the blocks and into engagement with the outer surface thereof to cure the blocks While they are still in the molds.

11. A method of casting and curing concrete blocks in a molding device comprising a plurality of molds having removable cores, the steps of molding the blocks; forming channels extending through the molded blocks by removing the cores; simultaneously projecting low pressure steam into the open ends of each channel and into engagement with the bare interior of the blocks; and maintaining the steam in intimate engagement with the outer surface of the blocks to cause a uniform heat to be maintained thereon and the product cured simultaneously from the inside and outside While in the molds.

CAROL F. BARON.

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