FI65184B - FOER FARERE FOER AVFORMNING AV HUVUDSAKLIGEN PLATTFORMIGA BETONGELEMENT - Google Patents

Description

1 65184

The present invention relates to a method for removing predominantly slab-like concrete elements from a mold.

In some known methods for removing concrete elements of the type described above from a mold, the concrete element is lifted out of the mold after a certain necessary curing by using a towbar or the like screwed into concrete-molded inserts or using elements which also engage nuts screwed into cast bolts. In addition to this, methods are known in which the concrete element is lifted out of the mold by means of suction cups placed on the upper surface of the concrete element. Common to these known methods is that the tensile strength of the concrete element must be able to withstand the effective load when lifted.

Since the tensile strength of root-cast concrete is minimal, a relatively long time must be allowed for the known methods to harden the concrete sufficiently to avoid damage to the freshly poured concrete. This results in a relatively long manufacturing cycle of the concrete elements and thus a low utilization of the mold capacity.

Attempts have been made to speed up the curing by introducing heat into the mold, for example by passing pressurized steam over or through the mold, and thus it has also been possible to considerably shorten the curing time and thus also the cycle time. However, heat conduction is a very energy-intensive measure which, of course, substantially increases production costs, which is why this solution is not widely used for economic reasons.

Swedish Offenlegungsschrift No. 379,668 discloses a method for removing slab-like concrete elements from a mold, in which the element is removed from the mold by acting on the lower side edge of the element with a vertical lifting force. The weight acts through a wall surface below the mold shaped as a lift, which, together with the vertical support frame, follows the concrete element to its storage location.

2 65184 This known method has the disadvantage that the lift, which, as mentioned, forms part of the mold, follows the concrete element and can only be removed when the strength of the concrete is sufficient.

The vertical lifting force of the lower side edge of the element also removes the element from the opened mold in accordance with SU patent publication 399,378. When operating in accordance with this patent, a lifting frame corresponding to the height of the element is placed in the opened mold, with means for gripping the upper edge of the element and applying a lifting force to the mold part detachable from the mold below the lower side edge of the element.

In this method, the lifting frame is available separately from the mold parts for lifting the next element immediately after the previous element has been received at the storage location. However, the mold part following the element remains under the element at the storage site and is not available for re-use until the element has hardened.

The object of the present invention is to provide a method for removing substantially plate-like concrete elements from a mold, in which method the mold parts following the element to be removed from the mold during the lifting step can be returned to casting immediately after the element has been transferred to its final curing warehouse.

This object is achieved by the method of the invention, in which the element is removed from the mold by acting on the lower mold surface of the element by vertical lifting compression while supporting the element mainly by the vertical mold side surface and the lifting frame. a mold in which lifting-pressing is provided by a plurality of lifting shoes located at the bottom of the lifting frame, transverse to the element, characterized in that the lifting shoes are placed under portions of the lower mold surface which are released from this mold surface by upward compression.

In this method, during the first step of removal from the mold, the element is guided by the mold side surface and the lifting shoes from the lower part of the concrete element. As soon as the upper edge of the concrete element is located a suitable distance above the upper end of the mold, the retaining mechanism is actuated and the concrete element is then securely held by the upper retaining mechanism and the lifting shoes at the lower side edge of the element.

Due to the lifting force acting on the lower side edge of the concrete element, the concrete element is subjected to pure compressive stress during lifting from the mold and since the compressive strength of freshly poured concrete is considerably higher than the tensile strength of freshly poured concrete. It has been found that for concrete elements made of concrete with 300 kg of cement / concrete, this time is reduced by about 3 hours, i.e. from 7.6 hours to about 4.5 hours, when using the method according to the invention. instead of using lifting hooks or the like.

The lifting frame which can be used to carry out the method according to the invention consists of a supporting frame, the height of which substantially corresponds to the height of the element and a laterally projecting pivoting bearing mechanism at the top the lifting frame is characterized in that the lower part of the lifting frame is provided with one or more lifting shoes projecting in the same lateral direction.

The lifting frame formed in this way consists of simple mechanical elements and is therefore a strong and secure mechanism, which is relevant in the use described above.

The invention will now be described with reference to the accompanying drawing, in which: Figure 1 shows a vertical section of the concrete element just before it is removed from the mold, and Figure 2 is the same when the concrete element has been partially removed from the mold.

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In the construction shown in the drawing, the plate-like concrete element 1 is placed in a substantially vertical position, whereby one of its surfaces rests on the mold surface 3 and its lower end rests against the U-shaped support beam 4.

As shown in the drawing, a lifting frame consisting of at least two horizontal beams 8 and at least two support beams 7 is suspended on the crane hook 2, to the lower ends of which support shoes a lifting shoe 5 is attached, which is adapted to contact the lower surface of the support beam 4. At the same time, in the position shown in Figures 1 and 2, the lifting frame 7, 8 supports the concrete element 1 from the side.

When the crane hook 2 is lifted, the lifting frame 7, 8 moves upwards, whereby the concrete element 1 slides along the mold surface 3 and whereby the lifting field 5 causes an upward compressive force on the concrete element via the support beam 4.

When the upper side edge of the concrete element is raised a suitable distance upwards from the mold 3 (Fig. 2), the retaining arm 6 mounted pivotally on the lifting frame 7, 8 can be suitably positioned against the upper edge of the concrete element 1 between the lower lifting shoe 5 and the side of the lifting frame parallel to the concrete element. In this position, the concrete element 1 can then be transported to the warehouse.

It should be noted that the method according to the invention can also be used with lifting frames or other devices than those shown in the drawing. It is essential, as mentioned above, that when the concrete element is lifted from the mold, a compressive load is provided.

The support beam 4 is part of the formwork wall used for casting the concrete element. This is attached to the mold surface 3, and the support beams 4 shown in the figures, which are moved along the mold surface 3 during removal, are then short parts of the fixed mold wall. There is one for each support 7 and thus trapezoidally cut off from the rest of the wall so that they can be easily detached from this.