US3822855A - Casting mold with steam-heated water jacket - Google Patents

Abstract

A process and moulds are described for moulding large slablike building elements from pre-heated concrete in which the moulds are heated by controlled injection of steam into voluminous water-filled cavities in the moulds regulated to keep the mould temperature at or near the desired concrete hardening temperature.

Description

Hummelshoj f I I A. [111 0 3,822,855 1451" July 9,1974

[22], Filed:

[ CASTING MOLD WITH STEAM-HEATED WATER JACKET [75] Inventor: Gustav Erik Hununelshoj,

Bagsvaerd, Denmark [73] Assignee: Thomas Schmidt A/S, Bagvaerd,

Denmark Mar. 3, 1972 21 Appl. 190.; 231,473

[30] Foreign Application Priority Data Mar. 15, 1971 Denmark 1222/71 [52] U.S. Cl .L 249/79, 249/81, 249/120,

249/161 [51] Int. Cl 822d 27/04 [58] Field of Search 249/79, 81, 78, 111; 425/170; 165/108, 169

[56] References Cited UNITED STATES PATENTS 2 ,2 39, 1 9 5 4/1941 Henderson 249/79 2,602,210 7/1952 Rumble 249/79 2,632,088 3/1953 Meyrick et-al 249/78 X- 2,63 7,l98 5/1953 Spangler 425/170 X 3,124,627 3/1964 Hood 3,251,405 5/1966 'Hallstriim 3,441,243 4/1969 Walz..-.

Saunders 249/79 X Primary Examiner -Robert D. Bladwin Assistant Examine'rJohn McQuade [57] ABSTRACT A process and moulds are described for moulding large slablike building elements from pre-he'ated concrete in which the moulds are heated by controlled injection of steam into voluminous water-filled cavities in the moulds regulated to keep the mould temperature at or near the desired concrete hardening temperature.

5 Claims, Driawing Figures PATENTED JUL 9'974 $22,855

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PATENTEDJUL 91m $8355 SHEET 3 0F 4 It is known that the hardening of cast concrete bodies, such as concrete elements for building purposes, can be promoted by the concrete being poured in a warm state, e.g., by heating the materials during processing in the concrete mixer. This method possesses advantages over other known methods for heathardening in which the concrete bodies are heated in the moulds after pouring.

Similar conditions prevail in casting other hardening masses, but since the invention is of greatest interest in concrete casting, and particularly in production of concrete elements, it will in the following be described in connection herewith, without any intention of limiting the scope of application and usefulness of the invention.

If any advantages are to be gained by the use of preheated concrete it is, however, necessary that the poured concrete shall not immediately loose its heat to the relatively cold metal mass of the mould. A large concrete element mould has a metal mass which is at least equal to the mass of the poured concrete, and as the specific heat of steel is about 0.11 kilocalories/C/kg, while the concrete has a specific heat of about 0.24 kilocalories/C/kg, varying slightly according to its composition, a concrete mass poured at e.g. 60 may in a short time be cooled to about 40C by a mould with an initial temperature of about As the rate of hardening is doubled or halved every time the temperature of the concrete is increased or reduced by 10C resp., it will be obvious that the hardening effect in the said case will be reduced to one fourth, which means that the hardening time will be multiplied by four. It is also important that the heat of the concrete mass is well preserved during the hardening process, both its initial heat content and the heat developed during the hardening process, without any risk of local overheatings. With a view to this, it is known to equip the moulds with cavities into which steam is blown directly and condenses on the surfaces which define the mould and form the pouring cavity of the assembled mould, but as the steam must necessarily have a temperature of l001l0C, the mould surfaces will be heated to too high temperatures, which may lead to local damage to the concrete element during the hardening process due to heat stresses and due to the fact that adjacent to the hot mould surfaces steam bubbles are formed, which mar the surface of the elements.

All these difficulties are overcome by the apparatus according to the invention for steam-heating casting moulds for hardening masses, particularly concrete. The invention is characterized in that the steam is introduced into water-filled cavities in the casting moulds.

By this means, the possibility is obtained of a rapid and effective heating of the moulds to the desired temperature without risk of overheating, the transmission of heat from the steam supplied to the mould occurring very quickly and effectively by the condensation of the steam in the water-filled cavities which ensures that the steam will not get into direct contact with the surfaces of the mould; moreover, the content of warm water in the cavities provided for that purpose in the moulds represents a considerable heat reserve, the specific heat of the water being about nine times the specific heat of the metal mass of the mould and four times the specific heat of the concrete,.so that the latent heat of the water can compensate for the loss of heat which will occur to the surroundings when the mould is left after the pouring, from the surface of the concrete as well as from the surface of the mould, whether the environment is the manufacturing shed itself or a hardening chamber in which, by other means, a relatively high temperature is produced and maintained.

The introduction of steam into the water-filled cavities may according to an embodiment of the invention commence prior to the pouring, so that the relevant mould parts have in advance been brought up to or close to the desired hardening temperature. In this manner cooling of the concrete on pouring into the moulds with adesired hardening temperature is avoided, and at the same time a shortening of the time necessary for the total casting process is obtained, the preliminary heating of the moulds taking place so quickly and simply that it can be performed simultaneously with the other preparatory operations, such as cleaning and oiling and possibly assembling of mould parts into a mould ready for pouring.

As mentioned above, the invention also comprises a casting mould for use in performing the method, characterized by cavities for holding water and by means for blowing steam into this water.

These means may according to the invention. consist of an injector which is adapted to set up a circulation of the water in the said cavities by the injection of steam. By this means is achieved, firstly, a rapid and effective mixing and condensation of the steam into the water and, secondly, a rapid distribution of the supplied heat over the whole of the mass of water at disposal, which results in a quick and uniform thorough heating of the mould.

The condensate formed constitutes an addition to the mass of water present in the water-filled cavities of the mould, and, consequently, the mould is according to the invention provided with one or more overflow means through which excess water may flow off. For practical reasons, such overflow means should be closedas long as steam supply does not take place, and they are therefore advantageously according to the invention designed in the form of outwardly opening automatic valves.

Moreover, the mould according to the invention may advantageously be provided with one or more temperature measuring points, e.g. thermometer pockets, at points where the temperature of the water represents the temperature of the cast body during the hardening process. By this means it becomes possible to watch the course of the hardening process by keeping an eye on the temperature at the selected points.

The invention is illustrated in the drawing in which FIG. 1 diagrammatically shows a section through a mould, suited for carrying out the method, in section on line I-I in FIG. 2,

FIG. 2 shows a section on line II--II in FIG. 1,

FIG. 3 shows another embodiment of a mould according to the invention in section on line III-III in FIG. 4, and

FIG. 4 shows the same as is shown in FIG. 3 on line IVIV in FIG. 3.

The mould shown in FIGS. l and 2 is intended for producing large plate-shaped building elements of concrete by a number of such moulds 5 being assembled into a battery in which the interstices between the moulds constitute pouring cavities and must be supposed to have boundaries along the bottom and on the sides, such as separately fitted side pieces and end mould parts, not shown, e.g., in the form of U-shaped frames accommodated in the interstices between the individual moulds 5.

In the example shown it is assumed that the moulds rest on wheeled bogies 6 and are displaceable thereon along a wheel track which may serve as transport or production line.

Each mould consists of a substantially rectangular plate with face plates 3 which delimit the pouring cavities, into which concrete 1 has been shown poured in FIG. 2. This illustration is purely disgrammatical, the concrete bodies produced being normally cast around a reinforcement, and it is possible to give the bodies any desired profile by correspondingly profiling the plates 3.

The mould delimiting plates 3 are stayed in relation to each other by means of sections 4 of steel, and between them, water jackets 2 are provided in the form of closed cavities which during the operation are filled with water.

Prior to or during the pouring of concrete the water in the water jackets 2 is heated by steam being blown in through connection nipples 7 and adjoined injectors 8 adapted to impart, by the steam injection, a powerful circulation to the water in the water jackets, as indicated by arrows in FIG. 1. As explained above, this results in a very rapid and uniform heating of the mass of water present and thereby of the mould, so that, when the concrete is being poured, the mould already has the temperature at which it is desired that the hardening should take place.

In the embodiment shown in FIGS. 1 and 2 it is obvious that the battery constituted by the moulds will during the hardening process have a comparatively small free surface for emitting heat to the surroundings The heat emission will substantially occur along the outer edges of the moulds, and consequently, the water jackets are chiefly placed there. The hardening process proper is exothermic, but not sufficiently so to keep step with the emission of heat which would take place to the surroundings, but which is now compensated for by the heat contained in the water masses, which heat may be supplemented also during the hardening process by additional steam injection; thus, the concrete can easily during the entire hardening period be kept at a desired hardening temperature which may e.g., be over 60C.

In order to avoid an excess pressure in the water jackets the latter are provided with an overflow means 9, through which excess water deriving from the condensation of the supplied steam can drain off freely.

To control the course of the hardening process there is, in the vicinity of the comers of the mould, provided thermometer pockets 11 into which thermometers can be inserted for watching the temperature of the water. This will represent the momentary temperature of the concrete and may therefore be accepted as a measure of the temperature at which the hardening process takes place, and thus as a measure of the time which elapses before the hardening has proceeded sufficiently far.

FIGS. 3 and 4 show in an 'analoguous manner a mould constructed with a view to producing large, plate-shaped concrete elements by pouring in a horizontal position, the individual parts having the same reference numerals as in the embodiment just described. The upper plate 3 serves, as it is shown in FIG. 3, as mould plate and must be supposed to be supple- I mented with edge moulds which may be designed as simple rails, but may also be made as water boxes with.

a view to steam heating by steam being blown into the mass of water present in the boxes.

When the moulds are transported, e.g. suspended in yokes from a crane, difficulties may arise due to movements of the water in the cavities. To counteract this, the moulds may, as indicated in FIG. 4, be equipped with suitable baffle plates 13 in the form of steel plates provided with perforations or other apertures which subdue the passage of the water without impeding temperatureand pressure-balancing flows between the individual mould sections.

It will be understood that the advantages, gained by the method and the casting moulds according to the invention, as regards accellerating the hardening process and avoiding damage to the cast concrete bodies will also obtain although to a lower degree even if the concrete is poured at a lower temperature than the optimum hardening temperature or possibly without having been preheated in the concrete mixer.

I claim:

1. A mould for casting objects from hardening masses such as concrete or the like comprising:

at least one mould member having a mould surface defining at least a portion of a mould cavity into which said hardening mass is placed and a back surface backing said mould surface,

means within said mould member defining at least one water cavity contacting at least a portion of said back surface and adapted to be substantially entirely filled with water, and

steam injection means communicating with said water cavity and terminating in at least one steam injector so oriented with respect to said water cavity as to establish a circulation of water within said water cavity when steam is passed therethrough and to prevent the steam from impinging directly upon said back surface, and to maintain the desired water temperature within said water cavity.

2. A mould as set forth in claim 1 wherein at least one of said water cavities is positioned adjacent to that point of said mould surface from which the disipation of heat during hardening of said mass is the greatest.

3. A mould as set forth in claim 2 wherein said one of said water cavities is positioned adjacent to the outer peripherial portion of said mould surface.

4. A mould as set forth in claim 1 further comprising automatic overflow means communicating with said water cavity for releasing excess water from said water cavity.

5. A mould as set forth in claim 4 wherein said automatic overflow means comprises at least one outwardly opening automatic valve.

Claims (5)

1. A mould for casting objects from hardening masses such as concrete or the like comprising: at least one mould member having a mould surface defining at least a portion of a mould cavity into which said hardening mass is placed and a back surface backing said mould surface, means within said mould member defining at least one water cavity contacting at least a portion of said back surface and adapted to be substantially entirely filled with water, and steam injection means communicating with said water cavity and terminating in at least one steam injector so oriented with respect to said water cavity as to establish a circulation of water within said water cavity when steam is passed therethrough and to prevent the steam from impinging directly upon said back surface, and to maintain the desired water temperature within said water cavity.

2. A mould as set forth in claim 1 wherein at least one of said water cavities is positioned adjacent to that point of said mould surface from which the disipation of heat during hardening of said mass is the greatest.

3. A mould as set forth in claim 2 wherein said one of said water cavities is positioned adjacent to the outer peripherial portion of said mould surface.

4. A mould as set forth in claim 1 further comprising automatic overflow means communicating with said water cavity for releasing excess water from said water cavity.

5. A mould as set forth in claim 4 wherein said automatic overflow means comprises at least one outwardly opening automatic valve.

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