FIELD OF THE INVENTION

The present invention relates to an improved method to cut autoclaved aerated blocks from moulded cakes.

BACKGROUND OF THE INVENTION

It is known that autoclaved aerated blocks are manufactured by aerating a mixture of Cement and Siliceous material of required specification, combined with water. Such mixture is poured in a mould and after aeration and hardening, a cake is formed and is cut to blocks (Figure 1).

The length (L) Height (H) and Width (W) of the Cake is determined according to the size of the mould. The Cake is trimmed to a height of 600 mm or less, that becomes the length of the blocks cut from the Cake.

Various methods are known to be used to cut the cake into blocks of 600 mm (L) x Width (W) x Thickness (T). Width of 200 or 250 mm, for example, forms the height of the block and thickness is cut as per requirements.

The simplest method used in prior art, is to cut the cake on the same base after removing the four sides of the mould. When the cake is hard enough to remain without losing its shape, I is then cut to length wise and width wise. The top of the cake is trimmed to a height, say 600 mm (see Figure 2).

There is no problem with the method of figure 1, that is to say, to cut the Cake width wise but when length of the cake is more than 2.5 meters, the wire for cutting undergoes a sagging that could leave the middle of the cake uncut, while the wire touches the bottom of the mould at edges. Hence, the length of the cake is limited generally to about 2.5 meters to avoid such problem.

Such restriction on size of the cake limits the production and also reduces effective utilization of Autoclave capacity as many trolleys of small size have to be sent to the Autoclave.

For greater efficiency various methods are also used in the prior art to enable manufacturing of longer cakes up to 6 or 8 meters.

In one known method to cut these longer cakes (see Figure 3), the cakes are turned by 90° to stand on its height of 600 mm. The cutting wire then needs to be just above 600 mm so that the cutting of the cake becomes easier and cakes up to 8 meters can be handled this way.

The drawback in this method is, any inaccuracy or jerky operation can result in developing cracks in the cake.

In yet another known method, the whole block is lifted and placed on a cutting bench (Figure 4). In both these methods the block is distributed from its case position and hence strength and care in such manipulations is necessary and with a possibility of cracks and rejections, when not done properly.

Patent NL 7010674 of 17-7-1990, described a cutting system wherein a block is of tilted onto a cutting bench which again manipulates the natural position of block.

Patent 3734,991 of May 22, 1973, teaches use of grippers to lift a cake so as to pass a cutting frame through the cake. The precision of the grippers' pressure is important to keep integrity of the cake and also the blocks tend to move after cutting relative to the multiple thickness of the wires.

The patent application IN 1717/CHE/2014 describes a cutting bench for cutting a cake from the bottom. This process needs a special lifting device to lift the cake and place on the cutting bench. This process needs well designed mechanism to lift the cake which is still plastic and also the cake should be made strong enough for such operations.

US Patent 891,949 dated 12-8-1960 describes a method of constructing a mould base with laths screwed in with a space to accommodate a cutting wire to be pulled through cake. The Patent does not disclose the complete cutting system in particular the block to be done in longitudinal and cross wire direction. Also Laths are used to avoid oiling, which suffer from wastages when repeatedly sent into the autoclaves. Further, filling the slab with wax is not practical for production line. The Laths need periodical replacement.

All above deficiencies of the prior art are overcome in the present Patent. Also the mass productive needs are to be met.

OBJECTS OF THE INVENTION

It is therefore an object of the invention to propose an improved method to cut aerated blocks from moulded cakes.

Another object of the invention is to propose an improved method to cut aerated blocks from moulded cakes which minimizes handling of the cake.

A still another object of the invention is to propose an improved method to cut aerated blocks from moulded cakes which allows cutting of longer sized cakes on the moulded itself.

A further object of the invention is to propose an improved method to cut aerated blocks from moulded cakes which is simple and cost effective.

SUMMARY OF THE INVENTION

Accordingly, there is provided an improved method to cut autoclaved aerated blocks from moulded cakes in a cutting apparatus, the cutting apparatus consisting of a base frame having a plurality of longitudinal channels, the base frame provided with multiple gaps corresponding to the blocks to be cut, a cutting frame inserted in the base frame to allow several cutting wires to be disposed each within said gaps, and a moving mechanism causing the cutting wires to travel up and down, the upward movement of the cutting wires enabling the autoclaved cake cut along the length, the method comprising the steps of spreading a thin film on the base frame, placing the mould slidably into the base frame; pour slurry and after hardening, to remove side walls. Then activating the moving mechanism for cutting the cake by passing the cutting frame with said multiple wires relatively into the slots from top to down direction, wherein relative movement between the cutting wires and the cake is achieved either by the moving cutting wire into the stationary cake or moving the cake against the stationary cutting wires, and wherein the cutting wires are oscillated at a speed in proportion to speed of the cutting the cake.

BRIEF DESCRIPTION OF THE ACCOMPNYING DRAWINGS

Figure 1 - shows a prior art method of moulding a cake and cutting of the block.

Figure 2 - shows a prior art cutting method in which the length of the cake is restricted to avoid uncut portion.

Figure 3 - shows a prior art method in which longer size blocks are cut with margins.

Figure 4 - illustrates another prior art method in which the cake is lifted along with the side plates of mould.

Figure 5 - shows a device to support the cake for cutting the cake according to the invention.

Figure 6 - shows a mould with fabricated bottom.

Figure 7 - shows a cutting frame corresponding to the base frame of the device of Figure 5, the cutting frame being longer than the size of the cake.

DETAIL DESCRIPTION OF THE INVENTION

In the subject invention to cut the AAC green cake, the base plate is so constructed to allow cutting of the cakes even longer than 2.5 meters with wires traveling through the cake and into gaps provided in the base plate or alternatively by cutting the cake from the bottom when a cutting wires/blades are inserted in the base plate.

In both cases, on the base plate, a water proof film is spread before the side walls of the mould are placed on the base plate to avoid leakage of slurry into the gaps of the base plate.

A typical structure of a bottom plate is made consisting of two long beams at either end joined by cross beams. On the cross beams, parallel sectors are welded with gaps to receive a cutting wires of bench or frame. These channels (parallel sections) correspond to the length of the cake anywhere between two meters to six meters typically but not restricted in length.

The gap between the channels should be more than that of the wires in cutting bench. These longitudinal gaps are fixed for the dimension of height of block during construction and hence can have one pre determined dimension. Usually 200 mm or 250 mm height of blocks are used.A cutting bench or frame is constructed using wires or thin blades, the lengths of which correspond to that of the cake.

This bench is so constructed that the cutting wires or blades can sit in the gaps or grooves. It is necessary to keep distance corresponding to the height of the block in usage.

With this arrangement it is also possible to cut the cake from top, passing through the cake into these slots. Alternatively, the frame can be pre-introduced in the mould and the cutting frame can be moved up using similar mechanism.

This method will be understood by the illustrated explanation for construction of base plate in the new method to enable cutting with long wires.

A suggested structure is made of two long beams at either end joined by several cross beams at intervals to present rigid frame work. However other methods of supportive structure can be used (Figure 5).

Above the cross members, the channel sections are attached or welded to all cross members. Length of these channels correspond to the length of the cake; say 6 meters along with necessary margins for cutting (Figure 7).

Between these channel sections a gap of 1 mm (typical) is left corresponding to width of wire or blade used for cutting. The base plate thus constructed is fitted on any conveying mechanism such as a trolley on rails. It can also be moved on rollers.

To correspond to such base frame, a cutting frame (Figure 6) is constructed with the dimensions bigger than the length and width of the cake.

This frame will have wires or blades at intervals corresponding to the gaps in the channels of the base and the frame so that the wires or blades can enter into these gaps after or before the cake is cut, illustrated below.

The wire or blades are tensioned using a spring or other suitable pulling means, say by pneumatic cylinders. Once the side plates are removed, the cutting frame is brought down by a movable mechanism, preferably with to and fro motion, the wires are moved down through the cake until they enter the gap between the channels of the fabricated base plate. This way, the wires travel to a position even below the bottom of the cake so that the cake is cut even when the wire sags. The frame is then moved up to a rest position.

Alternatively, the cutting wires or blades are inserted into the grooves even before the mould box is fitted so that cutting wires are in place in the grooves. The frame of the cutting wires , rests on the base plate. In this way, travel through the cake is limited to one way only i.e. up from bottom. When the cake is ready for cutting, the mould box is removed and the movable mechanism moves the cutting wire of frame upwards preferably with to and from motion, until the cutting frame moves up after completely cutting the cake lengthwise. The cutting frame is then detached from the mechanism and inserted into the free base plate for subsequent operation.

In either case, on the base plate a thin film of material such as polythene sheet is inserted on top of the base plate before the mould box is placed to avoid leakage of material through the gaps between the channels.

The sequence of operation is thus given below On the fabricated base plate, a thin film of sheet is placed to cover the gap between the channels, the size of which exceeds the dimension of the mould box. The Mould box contains seals at bottom to avoid leakage of slurry. After the slurry is poured and after it is ready for cutting, the mould box is removed and the cutting operation as described, is done.

In case of alternative method, the cutting frame is inserted into the base plate and then the film of sheet is placed to cover the gaps between the channels.

After the cake is ready to cut, the cutting frame is moved down with blades for cutting the cake including the film and then, the cutting frame moves into grooves of the base frame.

The cutting frame is moved up so that from the grooves the cutting wire moves up until the film and the cake are cut longitudinally. The cutting frame is then detached and is placed in another base frame for repeat operation. In either case, the sag of the wire does not affect full cutting of the cake throughout its length. Cross cutting of the cake is done as per well established procedure into various thicknesses as required. This is possible as the length of the wires for this cutting is not selected to be more than 1.6 metres.

It is also possible to cut the grooves in the longitudinal channels, and insert the wires into these slots before placing the film on the base plate so that the wires can travel from bottom.

This disclosed method allows cutting of the cake without moving it from the base plate and eliminates the need to make a stronger green cake structured for green handling.

CLAIM

1. An improved method to cut autociaved aerated blocks from moulded cakes in a cutting apparatus, the cutting apparatus consisting of a base frame having a plurality of longitudinal channels, the base frame provided with multiple gaps corresponding to the blocks to be cut and a cutting frame, suitable frame to allow several cutting wires to be disposed each within said gaps, and a moving mechanism causing the cutting wires to travel up and down, the upward movement of the cutting wires enabling the autociaved cake cut along the length, the method comprising the steps of: spreading a thin film on the base frame, placing the mould suitably on to the base frame; cutting a frame suitable to insert into the base frame and allowing several cutting wires to travel from top into the multitude gaps or to travel upwards from within base frame, such travel enabling the pre autociaved cake cut along the length; activating the moving mechanism for cutting the cake after removal of side walls, by passing the cutting frame with said multiple wires relatively into the slots from top to down direction, wherein relative movement between the cutting wires and the cake is achieved either by moving the cutting wire into the stationary cake or moving the cake against the stationary cutting wires.

2. The method as claimed in claim, wherein the cutting wires are oscillated at a speed in proportion to the speed of cutting the cake.

3. The method as claimed in claim 1, wherein the cake is not moved off the base plate until the cut blocks are autoclaved and gain strength.