Method and apparatus for producing hollow bodies of hardenable material and products produced therewith

Abstract

 Method and machine for producing hollow monolithic bodies of hardenable material and thereby light bodies, such bodies being hollow bodies produced by centrifugation in a mold (l) which follows at least simultaneously two tracks of which one is a rotation about the axis (6) of the mold (l), while the other is a rotation of the mold (l) along an endless track (defined by axis 24), whereby uniformly hollow structured bodies are achieved, where the material resistance coefficient increases progressively from the periphery towards inside. For the building field, these hollow bodies (2) may be made of concrete and therefore are made of the same material of which light structural members can be formed, which use as a substituent of gravel in the concrete, such hollow members.

Description

Technical Field of the Invention:

[0001] The present invention reiates to a method for producing hollow monolithic, preferably closed bodies of hardenable material, as well as it refers to a machine for producing such bodies and as a consequence, the present invention likewise relates to products which may be produced using such hollow bodies.

Background Art:

[0002] During the last fifty years, the art of building has very substantially progressed, particularly in the field of reinforced concrete. With a view of increasing the speed of building on the one hand and to reduce the weight of large structures on the other hand, many different building members, such as prefabricated blocks, slabs and the like, have been conceived, as well as means which enable to reduce the weight per volume unit, of the concrete members. Later developments enabled also to apply these disclosures for reducing weight, to the manufacture of prefabricated blocks and slabs.

[0003] Within the field of lightening concrete structures, an extra light type of concrete has been created some twenty years ago and which is produced by adding to the basic mixture of powdered cement, sand and water, other products which generate cells in the concrete during the setting thereof. These cells where produced by foams, which were added to the mixture of cement, sand and water, so that during the setting of the slurry, such foams disappeared and a cellular concrete was achieved. Such a cellular concrete has a low compressive resistance and shows the additional drawback that the cells which are produced are not of uniform size, so that the resulting slabs could only be used where no loads had to be born.

[0004] In order to improve such a situation, additional products have been conceived, such as small hollow bodies made of plastic material, particularly of polystirene and polyurethane, which are added to the slurry instead of foam, to produce a light concrete. This last system has the drawback that during the generation of the slurry in the concrete mixer, one could not assure that these plastic hollow bodies, also called fillers, would maintain their original shape, due to the high wear to which they were subject during the mixing with the sand, the cement powder and the water in the mixer. An additional drawback of these fillers is that their own resistive features, their co­eficient of expansion to heat, etc. are different to those of the remaining materials which integrate the concrete mixture.

Disclosure of Invention:

[0005] Bearing in mind the foregoing, it has been conceived that an ideal result would be achieved, if light concrete could be produced, where the filler members are made of the same mixture as the one of the concrete, whereby the different behaviors as far as expansion, resistance, etc., is concerned, would be removed, at the same time as a better interrelationship or adherence would be achieved amongst the different materials. To achieve such a result, it was necessary to conceive a special method which enables to produce hollow monolithic bodies of such a material.

[0006] Once such a method and pertinent machine had been conceived, it became evident that the just mentioned hollow bodies could also be produced for different purposes, such as floating buoys. Such buoys may be built of concrete, since upon producing the hollow monolithic bodies by means of the method herein proposed, it is possible to achieve a product which is water-tight, due to the fact that the internal portion of the hollow body consists of a extremely compact wall member and thereby becomes water-tight.

[0007] Upon further developing the invention, it was realized that the proposed method could also be used with other starting materials, such as polymerizable plastics for producing hollow closed seamless bodies, curable rubber for producing resilient products, such as balls and the like, hot chocolate for producing eggs and other seamless figures. What is important, is that the starting material is flowable and hardenable.

[0008] For the purpose of the present invention, the expression "hardenable material" should be interpreted as including any kind of starting material or mass which may be supplied in a flowable state and which is converted within a suitable mold into a solid hollow, seamless, preferably closed product, to which end the centrifugal force is used. Accordingly, the expression "hardenable" is generic for generating the hardening by setting, polymerization, curing, solidification and the like.

[0009] The method of the present invention for forming hollow monolithic, preferably closed bodies of hardenable material comprises the steps of loading a flowable and hardenable mass into at least one hollow mold which circumscribes, by means of an internal wall member, a closed space with a central zone, said closed space forming a first volume, the volume of the loaded mass being smaller than said first volume, closing said mold, rotating said mold about its own central zone at the same time as moving said hollow mold at least along one endless path, that assures that each point of the internal wall member which circumscribes said closed space is subject - during a period of the time which is required to move once along the endless path - to the maximum centrifugal force effect, generated by the movement of said hollow mold, continuing said simultaneous path and rotation of the mold during the time necessary until said mass becomes hardened throught its entire thickness, to define a self-supporting body with a hollow interior, stopping the movement of the mold, opening said mold and discharging the thus formed hollow body.

[0010] As to the basic concept of the machine for producing hollow monolithic bodies of hardenable material, the latter comprises at least one hollow mold body loadable with a starting material, the internal wall member of said mold body defines a closed space, said mold body being rotatably mounted about a first rotary axis which enables to rotate said mold body about itself, said mold body being rotatably mounted on a supporting member, in turn rotatably supported on a second rotary shaft, defining a second rotary axis forming an angle, different of l80° with said first rotary axis, the orientation of said rotary axes being such, that all the zones of the internal wall member are successively subject to the maximum effect of the centrifugal force, generatable by the movement of said hollow mold body and its supporting member.

[0011] The products which may be produced with these hollow bodies may not only be spheres, balls, buoys, hollow eggs and the like, but such hollow bodies upon being made for instance of concrete may form part of a concrete slab or of a reinforced concrete slab, in order to reduce the weight thereof. For this purpose, such hollow bodies (for instance in the shape of spheres) made of concrete, may be arranged in a predetermined arrangement in a form. These spheres may be in contact with each other to define a first type of array or they may be distributed in spaced apart rows, where the spheres of each roll are in contact with each other. In the first case the resulting slab will be extremely light and yet being formed of a single type of material, i.e. concrete. Such a slab will preferably be used as a non-load bearing partition. On the other hand in the second case, the spacing between rows of spheres or balls, forms the necessary space to locate therein iron rods or to simply assure that between rows of balls, concrete girders are formed either made of concrete or reinforced concrete, whereby high load resisting slabs are achieved.

[0012] Since the size of the hollow balls may be any, within normal limits, small size hollow balls having a high resistance may be produced, to be loaded in concrete mixers, instead of gravel and thus producing a special mixture, for generating light concrete bodies made of a single material.

[0013] When in the method hereinabove defined a starting material, such as a slurry made of powdered cement, granular material and water, is used, such granular material may for instance be sand. Due to the centrifugal force generated during the manufacturing steps of the hollow spherical members, and as the setting progresses, the size of the granular material not yet set, decreases prior to successively setting, whereby a body member is achieved which from outside towards inside, is increasingly water-tight.

[0014] The method hereinbefore defined may use, as has already been stated, as starting material a mass consisting of powdered cement, granular material and water, said mass being capable of setting as time goes by to define a self-supporting monolithic body. To this end a mold is rotated and moved a long an endless path, during a time sufficient to generate a hollow, preferably closed, body, the outer layer of which is integrated by the granular material having substantially the same granulometry as the one the granular material had, when supplied, while the successive layers of the body towards the inside of the body and with regard to its total thickness, have decreasing size granules, to thus generate an internal face of the hollow body which is substantially smooth and liquid-proof, to which end the mold is rotated and moved during the time necessary for progressively decreasing, due to the frictional effect which is generated, the size of the granular material not yet set with the pertinent portion of the concrete slurry in the setting process, and timing the setting speed in relationship to the time the mold moves through its path, to thereby produce a hollow body, the resistance of the material and the liquid-proof feature of which progressively increase from its outer face towards its inner face.

Brief Description Of The Drawings:

[0015] In order to facilitate the comprehension of the present invention, the latter will now be described in relationship to several embodiments which are forwarded by way of example and which are explained in relationship to the accompanying drawings, wherein:

Figure l is a plan view of a first embodiment of a machine for producing hollow monolithic, closed bodies of hardenable material, in accordance with the present invention.

Figure 2 is a longitudinal section of a hollow mold body, in open position, to be loaded.

Figure 3 is a schematic perspective view of a more sophisticated, second embodiment of a machine for producing hollow bodies, in accordance with the present invention.

Figure 4 is an outside view of a sphere, partially shown in section, produced according to the method of the present invention.

Figure 5 is a side elevation of a buoy for navigation, produced by the method according to the present invention.

Figure 6 is a longitudinal section of a portion of a form and which shows the way how a light concrete slab may be produced, using hollow monolithic bodies manufactured according to the method of the present invention.

Figure 7 is a longitudinal section of a portion of a form which shows the way how to produce a concrete slab which is lightened, but which in turn includes girders made of the same concrete.

Figure 8 is a sectional view of a reinforced concrete slab, using an arrangement similar to the one shown in Figure 7.

[0016] In the several Figures the same reference numerals identify equal or corresponding members.

Detailed Account of Examples of the Invention:

[0017] The hollow monolithic bodies of hardenable material may be manufactured both in the machine shown in Figure l, as well as in the machine shown in Figure 3. To this end both machines use a plurality of mold bodies l, which in this particular showing are spheres, although, as will be understood further on, they may have other shapes.

[0018] These mold bodies l are to produce hollow spheres 2 (see Fig. 4). Reference will now be made to Fig. 2, where further details of the mold body l illustrated in open position, are shown. This mold body l comprises, in this embodiment, two unequal halves, of which the lower half 3, also called lower semi-sphere, is larger and has a pair of coaxial projecting shafts 4, 5, defining a first rotary axis 6, passing through the central zone of the mold body l. The upper half or upper semi-sphere 7 is hinged to the lower half 3 by a hinge 8. The mouth 9 of the lower half 3 has on its outer face a closure pin l0, provided with a resilient blocking member ll. A latch member l2′ is hinged onto the outer face 7′ of the upper half 7. Upon the latter being fit onto the mouth 9 of the lower half 3, thereby closing the hollow mold body l, the latch member l2′ is fit onto closure pin l0, thereby maintaining mold body l closed. The mouth 9 has an inside step l2 on which a resilient gasket l3 is fit and which cooperates with a recessed neck l4 defining the mouth l5 of the upper half 7. It will thus be understood, that when the hollow mold body l is closed, obviously after having loaded the material to be molded, a hermetic chamber is formed, which may be opened to discharge the hollow sphere 2, once the hardening process of the starting material has been concluded.

[0019] It will be evident to those skilled in the art, that the inside shape of the mold body l and even the outside shape may be different to the one shown, to achieve members of other shapes, being those bodies of revolution or not. For example, in Fig. 5 a shape of a buoy l6 has been shown. Other shapes which may be required in the building art, where filler bodies are to be produced, may have a plurality of projecting or anchoring arms, not shown, to which end it would become necessary that the walls of the mold body l be made thicker, in order to enable to have certain recesses therein to define such anchoring arms.

[0020] By mere way of illustration in Fig. 5, a tower l7 is shown on the top of the buoy l6. Said tower l7 may for instance be a light signal emitting tower for navigation.

[0021] Returning now to Fig. l, in order to explain the machine, as well as the method for producing the hollow monolithic bodies in accordance with the present invention, it may be seen that in said machine two mold bodies l have been shown in a generic manner and each one is journaled by means of projecting shafts 4, 5 in a cage l8, which may have a larger length than the one shown, to house a larger number of mold bodies l therein. This cage or supporting member l8 comprises a pair of parallel arms l9, 20, spaced apart by a pair cross members 2l, 22. A cage driving shaft 23 emerges from the central portion of the cross member 2l and defines a second rotary axis 24. Conveniently, the lower cross member 22 is provided with a supporting shaft 25 which is coaxial with the second rotary axis 24. Both shafts 23, 25 are journaled in pertinent bearings 25, 27, respectively, whereby the cage l8 is rotatably supported and capable of rotating about the second rotary axis 24, as will be later seen. In this embodiment, the rotary axes 6 and 24 form an angle of 90° amongst themselves, which is ideal when hollow spherical members should be produced. In case hollow body members of other shapes are desired, it may be advisable that the rotary axes 6, 24 form an angle different from 90°, so that the possibility is foreseen that any angle may be formed between these two axes 6, 24, with the exception of an angle of l80°.

[0022] The cage driving shaft 23 carries on its free end a frusto-conical pinion 28, which meshes with a rotary ring gear 29 carried by a driving shaft 30, forming part of an electric motor 3l. It will already be understood, that upon the driving shaft 30 rotating the ring gear 29, the movement is transmitted to the cage l8, which will rotate about the second rotary axis 24.

[0023] The cage driving shaft 23 passes through a stationary plate or ring gear member 32, which to this end has a central bore 33. Merely as illustrative, a stationary frame 34 has been shown which supports the stationary ring gear member 32. The latter meshes with a frusto-conical gear 35 mounted on a shaft 36 carried by the arm 20. Shaft 36 carries a first gear 37, meshing with a second gear 38, carried on the free end of the projecting shaft 5, defining thus a gear train or transmission means. Each projecting shaft 4 passes through arm l9 and carries at its free end a third gear 39, which third gears 39 are intermeshed for example through a chain 40. In case there are more than two mold bodies l in a cage l8, obviously such a chain 40 will mesh along all the third gears 39.

[0024] Conveniently, in order to increase production, the electric motor 3l and more particularly the rotary ring gear 29 may simultaneously drive a plurality of cages of the tyoe pf cage l8 and in this connection and by way of example several frusto-conical pinions 28′ mounted on pertinent cage driving shafts 23′, are shown.

[0025] As to the operation of the machine shown in Fig. l, once each of the mold bodies has been conveniently loaded with a hardenable mass, which may for instance consist of one part of powdered cement, three parts of sand and one part of water and obviously the volume of such a mass must be smaller than the volume defined by each of the mold bodies l and upon these mold bodies l being closed, the electric motor 3l is started, which upon rotating the rotary ring gear 29, will rotate the cage l8 about the second rotary axis 24. Simultaneously, the frusto-conical gear 35 starts to rotate along the stationary plate or ring gear member 32 and thereby rotates shaft 36 which transmits the movement to the gear train 37, 38 and thereby rotates the mold bodies l about the pertinent first rotary axis 6. The arrangement is such, that the number of revolutions of each mold body l be larger than the number of revolutions of the cage l8, per unit of time.

[0026] Upon there being more than one mold body l, the transmission system consisting of the third gears 39 and chain 40, assures that all the mold bodies l of the cage l8 will simultaneously rotate. Thus, each mold body l moves with the cage l8 along an endless circular path at the same time as each mold body l rotates about its own first rotarty axis 6.

[0027] Thus, a centrifugal force is generated, the maximum effect of which moves along the internal walls 4l′, 4l˝ (see Fig. 2) which define the inner space of the mold body l and thereby assures that the flowable mass is uniformly distributed over the internal walls 4l′, 4l˝. As time goes by, the setting of the concrete slurry starts, whereby a first portion of the mass with granules or sand members 42 (see Fig. 4) having the original size starts to set, since these sand granules are located by the centrifugal force onto the inner walls 4l′, 4l˝ almost immediately after the movement has started. The remaining portion of the slurry continues its movement tending to adhere to the sand granules 42 of original size, but while they rotate, they are subject to a friction effect amongst themselves, so that the successive layers of granules 43, 44 decrease in size until reaching towards the end of the setting process, producing the inside face 45 of the sphere by means of a powder of sand, identified by reference numeral 46. This generates therefore a completely smooth inner face 45 and the latter is liquid-tight. In other words, the porosity of the mass of which the sphere 2 consists, decreases from the outer face 47 of the hollow sphere 2 towards the inner face 45. Once the shaping of the sphere 2 is concluded, the machine is stopped, the mold l or each one of the molds l are opened and the spheres 2 discharged.

[0028] Depending on the material of which the lower and upper halves 3, 7 are made, it may be advisable, prior to loading them with the cement slurry, to sheath the internal walls 4l′, 4l˝ with a separating agent, to avoid that the sphere l sticks to the internal walls 4l′, 4l˝.

[0029] When concrete spheres of small diameter are to be produced, it may become convenient to add to the concrete slurry substances which accelerate the setting. In this event, it is advisable that the machine is not merely a machine which rotates the mold bodies l only in two octogonal planes, but in three octogonal planes, to speed up the generation of the maximum, moving,centrifugal force in a very distributed way. Thus a slurry of high setting speed may be used to achieve a high yield of manufacture.

[0030] Basically, such a machine is similar to the machine already described and therefore, for the some type of members, the same reference numerals have been used. In fact, the mold bodies are identified by reference numeral l and again only two of such bodies have been shown, arranged in a cage l8 having the arms l9, 20 and the cross members 2l, 22. The upper cross member 22 is provided with a cage driving shaft 23, which passes through the stationary plate or ring gear member 32. This ring gear member 32 meshes with a frusto-conical gear 35 which transmits the movement to the gear train 37, 38. On the other hand, the mold bodies l are interrelated through the third gears 39 and the chain 40. The difference of this machine shown in Fig. 3, with regard to the one shown in Fig. l, consists in that the electric motor 57 is directly mounted on the cage driving shaft 23 and its casing 58 supports, by means of support members 59, the stationary plate or ring gear member 32 on the one hand, while the top cap 58′ of the casing 58 is provided with a bushing 60, in which a bearing shaft 6l is mounted which does not have to rotate and which at its free end rotatably supports a cross shaft 52, which in turn is retained in its position through a pair of support members 63.

[0031] Actually, the bearing shaft 6l is a hollow shaft through which a driving shaft (not shown) which is driven by the same rotor (not shown) of the electric motor 57, which drives the cage driving shaft 23. The top end of the driving shaft housed in the bearing shaft 6l, has driving means such as a pair of frusto-conical meshing gears (not shown), driving the cross shaft 62 and thereby the gears 64, 65 become driving gears.

[0032] It will thus be understood, that on the one hand the cage driving shaft 23 performs the same role both in the machine of Fig. l as well as in the machine of Fig. 3, but on the other hand the driving gears 64, 65 assure in turn that the entire assembly rotates along the inner circular track defined by the inside teeth 67 of a stationary ring gear 66. Ring gear 66 is mounted on a base member 68. In order to assure that the machine will be balanced, likewise the lower cross member 2l is provided with a bushing 69, in which a bearing shaft 70 is housed and which by means of a cross shaft 7l supports freely rotating gears 72, 73.

[0033] The stationary ring gear 66 is made of electricity conducting metal and divided into two ring members 66′, 66˝ through a central isolating ring member 74. Base member 68 is provided with a pair of electricity conducting, isolated conductors 75, 76 which forward electric current respectively to the ring member 66′ and 66˝, which transmit the power through gears 64 and 65 to the electric motor 57.

[0034] As to the operation of this machine, the electric motor 57 receives power through the conductors 75, 76 and will rotate on the one hand the cage driving shaft 23 and on the other hand likewise the assembly along the endless track defined by the inside teeth 67. However, the number of revolutions per unit of time of the cage l8 about its rotating axis 24 (see Fig. l) is larger than the number of revolutions which the assembly performs along the stationary ring gear 66.

Industrial Exploitation:

[0035] Tests have shown that these spheres l are capable of floating during extremely long periods, not to say indefinitely, in any type of liquid. Thus, if the molds are sufficiently large, buoys l6 may be produced of the type shown in Fig. 5.

[0036] It is also to be pointed out that the larger the thickness of the spheres or similar members is, the larger will be the resistance of the internal portion thereof. Bearing in mind this principle, it is possible to produce small diameter hollow spheres of the type of 30 mm diameter, to use them as a substituent for gravel, that is to say to add them in a concrete mixer to constitute a mix of water, cement powder and such spheres and pouring the resulting mass into a form. On the other hand, upon manufacturing these spheres of larger size, for instance a diameter of l00 mm, light and/or highly resistant slabs may be manufactured in pertinent forms.

[0037] In this connection reference is now made to Fig.6, wherein a form 48 is schematically shown, where in first instance a first concrete mass 49 is being produced, but prior to reaching to a total setting, a layer of spheres 2 is located thereon in a manner that they are in mutual contact to thereafter pour onto this assembly, preferably in first instance a powdered cement layer and finally a cement slurry up to totally filling the form 48. The resulting slab is a light slab and characterizes by the fact that, as described in the introductory portion of this specification, the constituents consisting of the sphere 2, the concrete mass 49 and the remaining mass are all of the same material and accordingly the resulting end product, i.e. the slab, will have a uniform behavior.

[0038] In the example shown in Fig. 7, a form 50 is shown in which basically the same process as described in relationship to Fig. 6 is followed with the only difference that the spheres 2 are arranged in spaced apart rows, so that the concrete 5l becomes located also between the rows of spheres 2 thus forming girders and thereby a resistant slab is produced.

[0039] In Fig. 8 a slab 56, of the type produced in form 50 is shown (see Fig. 7), but the difference resides in that previously iron rods 52 were located in the mold 52 between the rows of spheres 2 and above as well as below such spheres 2 the cross rods 53 are arranged, forming thus an array of tension resistant members. The dotted line 54 indicates a theoretical separating line between girders 55. This is merely to show that adjacent rows of spheres 2, define amongst them, girders 58 and thereby a high resistive slab 56 is achieved.

[0040] From the foregoing it is apparent, that upon changing starting material, using for instance a flowable mass of curable rubber and curing such mass in the mold (each mold would have to be provided with pertinent heating means), balls may be manufactured.

[0041] If the starting material is a polymerizable plastic, then it is also possible to produce pertinent products for many different uses, as will be evident to those skilled in the art. Here again each mold may conveniently be provided with pertinent heating means.

[0042] Referring to the possibility of using the invention for producing hollow figures of chocolate and similar eatable products, the heating means in the molds would be used in a reverse sequence, that is to say when filling a hot flowable eatable mass, such as chocolate or a sugar syrup into the mold the heating means will be active to assure a good flowability of the mass into the small interstices the mold may have for a complicated figure and then the heating means are stopped to start the solidification of the mass during the centrifuging.

[0043] It will be understood, that improvements may be introduced in the embodiments described by way of example and modifications may be made in the construction and materials employed, without departing from the scope of the invention as defined in the appendant claims.

Claims

1. A method for producing hollow monolithic, preferably closed, bodies of hardenable material, characterized in comprising the steps of:

a) loading with a flowable, hardenable mass of material, at leat one hollow mold which circumscribes, by means of an internal wall member, a closed space with a central zone, said closed space forming a first volume, the volume of the loaded mass being smaller than said first volume,

b) closing said mold,

c) rotating said mold about its own central zone at the same time as moving said hollow mold at least along one endless path, that assures that each point of the internal wall member which circumscribes said closed space is subject - during a period of the time which is required to move once along the endless path - to the maximum centrifugal force effect generated by the movement of said hollow mold,

d) continuing said simultaneous path and rotation of the mold during the time necessary until said mass becomes hardened throughout its entire thickness, to define a self-supporting body with a hollow interior,

e) stopping the movement of the mold,

f) opening said mold and discharging the thus formed hollow body.

2. A method as claimed in claim l, characterized in that said hollow mold is simultaneously moved along a first and a second circular paths, which are octogonal to each other.

3. A method as claimed in claim 2, characterized in that the number of revolutions which the hollow mold has to perform about its own rotary axis is larger than the number of revolutions which is required by said mold to move along said first endless path, which in turn is larger than the number of revolutions which is required for moving said mold along said second endless path.

4. A method as claimed in claim l, 2 or 3, characterized in that the mass of flowable and hardenable material consists of powdered cement, granular material and water, said mass being capable of setting, as time goes by, to define a self-supporting monolithic body, said mold being rotated and moved therefor, during a time sufficient to generate a hollow, preferably closed body, the outer layer of which is integrated by the granular material having substantially the same granulometry as the one the granular material had, when supplied, while the successive layers of the body, towards the inside of the body and with regard to its total thickness, have decreasing size granules, to thus generate an internal face of the hollow body which is substantially smooth and liquid-proof, to which end the mold is rotated and moved during the time necessary for progressively decreasing, due to the friction effect, the size of the granular material not yet set with the pertinent portion of the cement slurry in the setting process, and timing the setting speed in relationship to the time the mold moves through its path, to thereby produce a hollow body, the resistance of the material and the liquid-proof feature of which progressively increase from its outer face towards its inner face.

5. A method as claimed in claim 4, characterized in that the granular material is sand.

6. A method as claimed in claim l, characterized by simultaneously producing a plurality of hollow bodies in a plurality of molds arranged in a single driving arrangement.

7. A method as claimed in any of claims 4 to 6, characterized in that the hollow monolithic bodies produced, are located in a form for producing a light concrete member, a cement slurry is then poured into said form until filling it and is then allowed to set, to thereafter withdraw the light concrete member formed in the form.

8. A method as claimed in claim 7, characterized in that a first layer of concrete is produced in a form, said form having a larger molding height than the thickness of said first layer, rows of monolithic hollow bodies are arranged on said first layer upon being half-set, where the hollow monolithic bodies which form the rows are in mutual contact amongst themselves, said hollow monolithic bodies are made of the same material than said first layer, and the form is then filled with a settable slurry of the same material of which said first layer and said hollow bodies are made, to thereby produce the light concrete member with hollow monolithic bodies housed in the interior thereof.

9. A method as claimed in claim 8, characterized in that the hollow bodies of adjacent rows are in mutual contact with each other.

l0. A method as claimed in claim 8, characterized in that said rows of hollow bodies are spaced apart from each other.

11. A method as claimed in any of the preceding claims, characterized in that the internal wall member of the hollow mold is sheathed with a separating agent, prior to loading the space of the hollow mold with the flowable and hardenable material.

12. A machine for producing hollow monolithic bodies of hardenable material, characterized in comprising at least one hollow mold body (l), loadable with a starting material, the internal wall member (4l′, 4l˝) of which mold body (l) defines a closed space, said mold body (l) being rotatably mounted about a first rotary axis (6) which enables to rotate said mold body (l) about itself, said first rotary axis (6) forming part of a rotary shaft (4, 5) mounted in a supporting member (l9), in turn rotatably supported on a second rotary shaft (23) defining a second rotary axis (24) forming an angle, different of l80°, with said first rotary axis (6), the orientation of said rotary axes (6, 24) being such, that all the zones of the internal wall member (4l′, 4l˝) are successively subject to the maximum effect of the centrifugal force generatable by the movement of said hollow mold body (l) and its supporting member (l9).

13. A machine as claimed in claim l2, characterized in that the first (6) and second rotary (24) axes form an angle of 90° amongst themselves.

14. A machine as claimed in claim l2 or l3, characterized in that the closed space of the mold body (l) has the shape of a sphere.

15. A machine as claimed in any of claims l2 to l4, characterized in that the mold body (l) consists of two openable semi-spheres (3,7), one (3) of which is provided with a pair of projecting shafts (4,5) which define a coaxial axis forming the first rotary axis (6), the free ends of said projecting shafts (4,5) being rotatably mounted in a pair of parallel arms (l9,20), spaced apart by at least one cross member (2l) defining with said parallel arms (l9,20) a cage (l8) forming said supporting member, a cage driving shaft (23) projecting from the central portion of said cross bar (2l) and defining the second rotary axis (24), said cage driving shaft (23) being connected to a driving motor (3l, 57) capable of rotating said cage (l8) about the second rotary axis (24) and transmission means (32, 35, 36, 37, 38, 5, 4, 39, 40) connected to at least one (5) of said projecting shafts (4,5) of said mold body (l) capable of rotating said mold body (l) about its first rotary axis (6).

16. A machine as claimed in claim l5, characterized in that said parallel arms (l9,20) support a plurality of mold bodies (l) provided with pertinent pairs of projecting shafts (4,5), defining pertinent first rotary axes (6), said projecting shafts (4,5) being drivingly interrelated through said transmission means (4,39,40).

17. A machine as claimed in claim l6, characterized in that one (5) of said projecting shafts (4, 5) of one of the rotary mold bodies (l) is in meshing relationship through a gear train (35, 37, 38) with a stationary ring gear member (32).

18. A machine as claimed in claim l7, characterized in that said driving motor (3l) comprises a rotary ring gear (29), said cage driving shaft (23) defining said second rotary axis (24) supports a pinion (28) which meshes with said rotary ring gear (29).

19. A machine as claimed in claim l7, characterized in that said driving motor (57) furthermore comprises a cross shaft 62, which supports at least one gear (64, 65) driven by the cross shaft (62) and which meshes and moves along the inside teeth (67) of a stationary ring gear (66), which surrounds said driving motor (57) and said cage (l8).

20. Hollow monolithical bodies produced by the method as claimed in any of claims l to 6.

2l. Light concrete members produced by the method as claimed in any of claims 7 to l0.

Drawing