US3480705A

US3480705A - Method for casting,lifting and setting blocks

Info

Publication number: US3480705A
Application number: US539192A
Authority: US
Inventors: Josef Vogele
Original assignee: Hebel Gasbetonwerk GmbH
Current assignee: Hebel Gasbetonwerk GmbH
Priority date: 1965-04-03
Filing date: 1966-03-31
Publication date: 1969-11-25
Anticipated expiration: 1986-11-25
Also published as: CH457242A; GB1137031A; FR1472782A; NL6604070A; SE312517B; AT255953B; NL143457B; DE1584426B1

Description

J. VOGELE Nov. 25, 1969 METHOD FOR CASTING, LIFTING AND SETTING BLOCKS Filed March 31, 1966 INVENTOR. JQSZF 1/6 6151:

United States Patent Int. Cl. 1529c /00,7/00,- B28b 7/10 US. or. 26490 2 Claims ABSTRACT OF THE DISCLOSURE A method is provided for casting, lifting, transporting, and setting down a large porous concrete block wherein concrete is placed in a casting frame comprising four vertical walls positioned on a stationary base. A hood is placed over the mold with the concrete therein? and a vacuum is drawn in the hood and above the concrete to prevent the concrete from cracking or sagging during lifting and transportation of the mold walls and concrete to a cutting station. The vacuum is replaced by a positive pressure in order to force the casting frame up and off the cast block after positioning at the cutting station.

The invention relates to a method for the casting, lifting and setting down of mass blocks which are] still in plastic condition, in particular porous concrete blocks, by means of a casting or mould frame which can be placed on a stationary casting base and is lifted off the mould base together with the mass block, after the same has been cast, and, to allow the setting down of this block, after it is transported to a cutting device. For this purpose, a mould is known which is composed of four side boards, fitted at the inside with bottom bars or bottom angles, on which the mass block is intended to rest while being lifted and transported. These bottom bars provide, however, an insufficient support to the very sensitive and relatively large-size plastic block of porous concrete, so that the block sags in its central area thereby causing damage and cracks.

A further disadvantage of this known mould is that it must be dismantled on the cutting device, after the mass block has been set down. This is not only a tedious procedure, but also causes the risk of damaging the sensitive mass block, since the side boards of the mould because of the bottom bars, have to be removed from the mass block in the lateral direction.

The object of the invention is to avoid the above mentioned disadvantages and, using a casting frame which can be placed on a stationary mould base, lift off the mass block together with this casting frame without causing any damage, and transport it to the cutting device without the casting frame having to be dismantled after the setting down of the mass block. According to the inven tion, this problem is solved by a pneumatic depression (vacuum), also referred to as a negative pressure, which is produced within the casting frame, before the same is taken off the casting base, and acts on the top face of the mass block, and is maintained to allow the setting down of the block; then, a pneumatic overpressure, also referred to as a positive pressure, is produced which acts on the top face of the mass block and causes the casting frame to come clear off the block, so that it is pushed up and is then taken off and removed.

This method, with the combined effect of adhesion and vacuum forces, permits a safe transportation of the sensitive porous concrete block without the formation of cracks. The block can be already lifted off the casting base while still being in a relatively non-rigid, very plastic Patented Nov. 25, 1969 condition, whereby not only time! is gained for the primary hardening, but also the withdrawal of the suspensionfbars which hold the reinforcement, and the cutting of the block into units (slabs or bricks) become easier, and'damage to the block (e.g. crumbling away) during these operations is prevented. A further advantage of this novel method is that the setting down of the block and the removal of the casting frame are achieved in a most simple manner by means of compressed air, and no dismantling of the casting frame is required in this case, which means that a sealed casting frame composed of four side boards, tightly fastened to each other, can be used for the casting as well as for the overhead transportation.

For the overhead transport, a relatively low vacuum suffices. It is desirable to provide a vacuum per surface unit which is approximative to the weight per surface unit of the mass block. Assuming a specific gravity of approximately 1.0 for the porous concrete block while it is still in a plastic state, and a height of approximately 50 cm. of the porous concrete block, this gives a gravity per surface unit (cm?) of the mass block of approximately 0.05 kg., so that, in order to maintain the equilibrium, a vacuum of only 0.05 kg./cm. approximately, is required.

The method according to the invention is advantageously worked in conjunction with a fan in such a manner that the casting frame, prior to being lifted off the casting base, is connected to the suction line of the fan and, after the setting of the block, to the blower line of the fan.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a cross-section of a mould for casting a porous concrete block, with a vacuum-powered lifting device; and

FIGURE 2 shows a component of the mould according to FIGURE 1 in a modified design.

In the drawings, 1 denotes a stationary level casting base, which may be reinforced by cross and longitudinal bracing girders 2, 3. A rectangular casting frame 4, which is composed of four perpendicular side boards 4a, tightly fastened to each other, is placed, but not fixed onto this casting base. These, preferably sealed, casting frame side boards are denoted 4a, the lower part of which may be formed by hollow stay members 5, and their upper end may be fitted with bracing L- or U-beams 6 which are suitably interconnected to the hollow stay members 5 by perpendicularly props 7.

The porous concrete block, cast into this casting frame or mould, is denoted 8. This block is separated at a later stage by a cutting device into construction elements, e.g. slabs. These cutting lines are indicated by dash-dotted lines 9. The reinforcement where used of a slab is shown at 10, in which case this reinforcement is held by a suspension bar 11. These suspension bars are led through a cross beam 12 which rests with its legs 12a on the profiles 6 of the mould 4. This mould is in an air-tight connection with the hood 13, which is' connected to a source of suction and compressed air, preferably a fan 14, in such a manner that a pneumatic depression or an overpressure can be produced selectively in this hood 13, and, thus, in the mould 4. The suction line 15 and the pressure line 16 of this fan communicate, via a control device 17, with the duct 18 which opens into the hood 13. This control device includes a push rod 19 which can be moved in direction of the arrow A, and by which the control flaps 21, pivoted around the axis 20, can be shifted from the position indicated by the full lines, into the position marked by the broken lines 21. With these control flaps in the position 21, the air current is in direction of the arrows drawn in unbroken lines, i.e. causing a pneumatic depression in the hood 13, whereas in the broken-line position 21', the air current is in reverse direction (arrows with broken lines), i.e. causing an" overpressure in the hood 13.

To lift the casting frame, a suitable hoisting device, which is shown at 22 in the form of a crane hook, may engage with the hood 13, but may as Well be applied directly to the casting frame 4.

The hood 13 is advantageously connected to the casting frame 4 in a readily detachable manner. For this purpose, the end profiles 23 of the hood can be fitted with holdfast jaws 25 which are hinged at the axis 24 and provided with thumb screws 26, so that the hood 13 and the casting frame 4, with the aid of these holdfast jaws 25, can be coupled to each other in a rigid and air-tight connection, as is shown in the drawing. The bottom edge of the hood is fitted with an inverted U-section 27 with a resilient seal 28, which rests on the vertical flange of the profile 6, thereby providing an air-tight connection between the hood and the mould.

When a pneumatic depression is produced in the hood 13 and the hood, together with the casting frame, is then lifted off the mould base 1, this lifting operation is achieved under the combined effect of the depression forces and the adhesion forces which exist between the mass block 8 and the walls 4a, of the casting frame. To boost these forces, the inward sides of the casting frame walls 412 can be fitted with spring-type blades 29, as is shown in FIGURE 2, and may be, for instance, in the form of vibrating diaphragms; under the effect of the ambient atmospheric pressure (with a vacuum in the hood 13), these are pressed inward against the mass block 8, and, therefore, increase the friction forces which are present between the block and the casting frame. On the other hand, when an overpressure is generated in the hood 13 to allow the setting down of the mass block, this cannot cause any damage to the mass block, since the blades 29 rest against the side boards 4a and the perpendicular props 7.

To eliminate or reduce the adhesion forces that are present between the mass block and the casting base, when lifting the casting frame 4 off the casting base 1, the casting frame 4, prior to being lifted, may be slightly shifted off the casting base 1 in laterial direction. Instead, the casting frame 4 can be first lifted off the casting base at one side only, as indicated by the arrow B, so that a small gap exists between the mass block and the casting base at 30, and, (with a vacuum building up in the hood 13), the atmospheric pressure can become effective at this point on the bottom face of the block.

After being transported with the pneumatic depression supporting the block 8- from above, the casting frame 4 together with the block 8 is set down on the table of a cutting device, and, with an overpressure building up in the hood 13, the casting frame 4 is then separated from the block 8 and pushed upward. To improve removal of the casting frame from the block 8, the walls 4a, 5 of the casting frame may be slightly inclined from the vertical plane towards the inside, as indicated by the dashdotted line 4a and the angle a in FIGURE 1, so that the casting frame widens towards its bottom in a tapered shape.

As the casting frame is separated from the block 8 by means of overpressure and the crane hook 22, the cross beams 12 are hoisted so that the suspension bars 11 are drawn out of the block 8. If required, the bars 11, prior to this hoisting operation, can be loosened in the block 8, i.e. slightly pulled out. To this effect, the hood 13 can be provided with servo-lifting devices 32, to be operated from the outside, e.g. by means of pivoting levers 31, and in conjunction with eccentric components, by which the cross beams 12 are slightly hoisted. An unlocking system can be coupled with these servo-lifting devices 32, by which the suspension bars 11 are turned simultaneously around their axis and thus loosened from the reinforcements 10.

I claim:

1. A method for casting, lifting, transporting and setting down of a large porous concrete block in a plastic state comprising the steps of:

placing a casting frame having four vertical walls on a stationary mould base and filling same with concrete to define a porous concrete block;

after the block has been cast, but while the block is still in a relatively non-rigid, very plastic condition fitting a vacuum-overpressure hood over the top of the casting frame and securing it thereto;

supplying a negative pressure below atmospheric pressure to the hood and of a value for preventing sagging and consequent cracking of the still plastic concrete block due to gravitational force acting on the block as while the bottom of the block is otherwise unsupported, said negative pressure at least assisting in holding the block in fixed vertical position within the casting frame;

lifting the casting frame, hood and therewith the concrete block off the mould base and without requiring delay transporting same to a cutting device and setting the hood, casting frame and still plastic block down as a unit thereon with the bottom of the block supported on the cutting device;

urging the hood upwardly away from the top of the block for sliding the casting frame upwardly off the block while exerting a downward force upon and distributed at least substantially uniformly over the top of the block by discontinuing the negative pressure and applying a positive pressure above atmospheric pressure to the hood, so as to leave the block setting on the cutting device free of the casting frame and ready for cutting.

2. A method according to claim 1, wherein the negative pressure has a value per unit area substantially equal to the weight per unit area of the top surface of the concrete block.

References Cited UNITED STATES PATENTS 2,046,867 7/1936 Billner 264l01 2,629,135 2/1953 Johnson 264-335 X 3,178,791 4/1965 Dickson 25-120 X ROBERT F. WHITE, Primary Examiner I. H. SILBAUGH, Assistant Examiner US. Cl. X.R.