BACKGROUND OF THE INVENTION Prefabricated construction forms an important part of the effort to industrialize building in Israel and the rest of the world. Prefabricated construction is based on the manufacture of pre-cast elements, mainly made of reinforced concrete, poured into a metal mould, removed, and transported to the site.

For this purpose factories have been set up both in Israel and abroad in which pre-cast elements are manufactured, based on the above principle, and supplied to building sites. The above elements may also be manufactured on the building site in order to avoid transportation.

Concrete is a heavy, rigid material and its transportation and handling costs are high. On the other hand, pouring pre-cast elements on the building site requires a logistics infrastructure, which on completion of the work must be transferred to the new site.

Consequently, in every case the choice must be made between ordering elements from a pre-cast production factory, set up for this purpose, and pouring the concrete on the building site itself. The mould is intended for manufacturing the pre-cast element in the site itself, or in the pre-cast factory, depending on the circumstances.

The element itself is a spatial element consisting of an upper slab (ceiling) supported by a frame of 4 horizontal beams (square), which in turn is supported by 4 legs in the corners (pillars).

The horizontal beams frame has steps and projections on their external sides, which are designed to support adjacent elements. The whole forms an integral monolithic unit cast on a single occasion. The said mould is designed to create such an element including all its components, when the element is produced, as previously said, in a single casting inside the mould, and it is also entirely removed from the mould by a single action of the crane.

The progress offered by the invention lies in the fact that no attempt has been made in the past to produce such a spatial pre-cast element-a slab with 4 beams, 4 pillars, steps and projections, all in a single pouring, and with a single removal.

The problems that must be overcome are as follows: 1. Positioning the mould on the area of the site which has no preparation for this.

2. Horizontal leveling of the mould before every pouring.

3. Vibrating the large mould in order to achieve the required concrete density between the reinforcing rods.

4. Removal of the element without damaging it, because of the fact that the concrete contracts during the hardening process, and vacuum areas are created because of the special shape of the element.

5. The option of handling the mould on the site itself, as well as on public roads between the various sites.

6. The option of pouring concrete many times in the same mould without deviating from the dimensions, despite the frequent rocking and movement of the mould.

Description of the invention The mould is a three dimensional spatial structure made of sheet reinforced with metal profiles.

1) The upper part of the mould, the roof of the mould, is made of bent sheet reinforced with profiles, in the form of an inverted bath with inclined sides. It shall be referred to in the following as"the head of the mould".

2) The head of the mould rests on a metal frame, which is a spatial structure made of metal profiles, which form a kind of rectangular box. The structure is reinforced by diagonal metal profiles on all sides which give the box particularly great rigidity. This box is supported off the floor by metal legs with a mechanical or hydraulic horizontal leveling device.

3) 4 boxes made of sheet metal reinforced with profiles are attached vertically downwards at the corners of the head of the mould. Each box is constructed from 4 sheet sides, two of which on the inside of the mould are permanently attached to the head of the mould, and the other two external sides are detachable. These boxes shall be referred to below as the pillars. The pillars are of height of between 2 and 3 m, and of width of up to 60cm. They are open at the top and closed at the bottom. The pillars do not touch the floor.

4) The mould described above may be constructed with 4 pillars only, with 2, or with more than 4. A pair of pillars may be constructed of a specific height, with another pair of a different height, in order to obtain a sloping head of the mould.

5) The mould may be constructed without a skeleton box, in which case the head of the mould will be directly supported by the pillars which will be placed on the floor. Clearly, in this case the mould is less stable.

6) A metal cone may be attached to the lower shelf of the pillar so as to create a conical opening in the bottom of the concrete pillar of the pre-cast element.

An additional shelf may be attached, parallel to and under the lower shelf which closes the bottom of the pillar. The additional shelf is attached to the mould and a mechanical or hydraulic jack may be placed on it.

The jack may be operated so that it presses the bottom of the pre-cast element upwards against the mould and thus helps to extract the pre-cast element from the mould if the extraction crane finds difficulty in extracting the element.

Method of using the mould 1) The crane places the mould on the concrete slabs.

2) The reinforcing rods are placed in the mould in accordance with the plan.

3) The mould is horizontally leveled using its seatings by means of the leveling bolts in the seatings, or hydraulically.

4) The external sides of the pillars and beams are closed and locked.

5) The concrete is poured into the mould.

6) The mould containing the concrete is vibrated using vibrators attached to it.

7) The concrete is left to harden for one day.

8) The external sides of the pillars and ceilings are opened.

9) The element is extracted from the mould using the crane. If necessary, use is made of jacks on the underside of the pillars.

10) The mould is cleaned and smeared with oil in preparation for the next pouring.

Advantages of the invention 1) The mould is extremely strong because of its unique structure, and is designed to be used not only in pre-cast factories but also on field sites, and to maintain its accuracy over many pourings.

2) The mould permits the creation of complex concrete pre-cast elements having a frame of beams under a horizontal surface, with slots for positioning adjacent elements, and supporting pillars, everything done in a single pouring. The element is subsequently extracted in a single crane action.

3) Minimal treatment of the mould is required between pourings. The mould is entirely fixed except for the external sides of the beams and pillars, which are detachable in order to extract the element.

Both opening and closing is easy and rapid.

4) The mould is fitted with its own leveling devices, as well as means for extracting the element from the mould if the crane encounters difficulty in doing so for any reason.

The invention is explained in the following diagrams: Fig. 1: Vertical section of the mould across its width The"inverted bath"-the head of the mould (2) has slightly inclined internal walls (4), and the head of the mould is supported by a rectangular box forming the frame of the mould (1), made of heavy metal profiles which produce frames which are reinforced by diagonal metal profiles.

The pillars (boxes) (3) are placed vertically under the head of the mould, do not touch the floor, and are ready to accept the concrete poured into them.

Fig. 2: Isometric view of the mould The rectangular box, i. e. the skeleton of the mould (1) consists of a lower frame and a side frame on each of the 4 sides. All 5 frames are reinforced with diagonal metal profiles, so that the head of the mould (2) is fitted to the skeleton.

At the corners of the mould are boxes (pillars) made of 4 sides. The inner sides (3A) are fixed and are attached to the head of the mould and to the skeleton, and the two external sides (3B) are detachable.

The pillars are open at the top and closed at the bottom, ready to receive the concrete. At the bottom of the pillar, on its lower catch, there is a metal cone (7) whose function is to create a conical opening at the base of the pillar of the pre-cast element. Underneath it is another shelf which is attached to the mould (8), on which may be placed a mechanical or hydraulic jack in order to help in extracting the pre-cast element from the mould.

The skeleton of the mould (1) is supported on leveling legs (6), which may be used to level the mould so that it is horizontal even if the surface of the ground is not level.

The head of the mould is surrounded by horizontal sides which close off the head of the mould (6). These sides are detached before extracting the element, and are closed before pouring the concrete.

Figs. 3 and 4 These diagrams illustrate the pre-cast concrete element which is extracted from the mould.

Fig. 3 is an isometric view of the element and Fig. 4 is a vertical section across the width of the element.

(2A) is the top of the element, which consists of an upper surface (11) and a lower frame of beams (10), which surrounds it. The frame has a step around it, which is used to support adjacent pre-cast elements (9).

The element is supported by 4 pillars (12).

(4A) is an internal slope which gives the head of the element the shape of the inverted bath. The entire element, the surface, the beams, the step and the pillars are a single monolithic concrete unit which is produced as a result of the unique structure of the mould, which forms the subject of this invention.