NO119671B - - Google Patents

Description

Method and machine for the production of elongated concrete objects.

It is known with horizontal sliding form filling to produce elongated concrete elements, such as beams, slabs etc., as concrete is fed out through an opening at the lower end of a container onto a flat surface. The container with concrete mixture is slowly moved forward on the surface. In the direction of movement calculated from the container, a slide equipped with a vibrator is placed, with which device the concrete layer formed on the substrate is vibrated and compressed. The container and the vibrating slide move at a constant speed over the surface. The sledge will thus slide over the concrete fed out from the container and laid out on the base and thereby compresses it. When the concrete leaves the vibrating sled, it is fully compacted and does not require any formwork. The method assumes that the holding strength of the concrete is so great when it leaves the vibrating sled, that the shaped product retains its shape without collapsing or cracking apart. Discharge of the concrete from the container must be very even and nby-like, otherwise you get a product that is uneven in terms of holding strength, density and dimensions. For this purpose, expensive and complicated pavers often have to be used. The method also assumes that the concrete has such a consistency and fluidity during vibration that the reinforcement, where this occurs, is completely reflowed and embedded.

From the container, the concrete must be laid out with a height HQ, which is adjusted so that the height H of the finished product, the beam, is the correct one. The ratio H/fcQ is inversely proportional to the ratio between the volume weight of the concrete in unpacked or packed state. The size of the ratio is approx. 0.5 - 0.6. In practice, this means that if you want to achieve a beam with the finished height of e.g. 20 cm, the concrete for the vibrating sled must be laid out to a height of approx. 40 cm. During the vibration, the concrete will be moved vertically downwards, which, particularly when it comes to the production of relatively thin beams, placed on one lengthwise edge, is a major disadvantage and significantly limits the method. On the one hand, the concrete must be so loose that it is able to completely flow around the rebars when the concrete moves downwards during compaction, and on the other hand there are difficulties in placing the concrete in the right amount. These difficulties increase with increasing height and/or decreasing width of the beam. The limit for the method currently seems to lie at beams with approx. 20 cm high and approx. 5 cm width. Before the reinforcement is to be embedded in the concrete to a sufficient extent, it is usually necessary to continuously bend the reinforcing bars to approximately the same extent as the concrete is moved downwards during the vibration. The same applies when using hole formers, i.e. when using, as a rule, tube-shaped rods for forming longitudinal holes in the shaped product.

The possibility of making the concrete so loose that it flows in the desired way under the vibrating sled is limited by the requirement for a relatively stiff consistency, because the manufactured product must retain its shape after compaction and before the concrete has set. From the point of view of holding strength, it is advantageous to have the stiffest possible consistency and the lowest possible water content. Another factor that limits the method is the friction between the concrete and the sides of the sliding form. If the height of the sides becomes too large in relation to the width of the shaped element, the concrete adheres to the side walls of the stop form below the vibrating slide, whereby cracks and voids can occur in the finished product.

Proposals have been made to remedy the above-mentioned disadvantages and to make it possible to produce elongated concrete objects with considerable height, e.g. 90 - 100

cm, and with a minimum thickness of approx. 4 - 5 cm. According to one proposal, the side surfaces of the concrete layer formed on the substrate are vibrated directly below the container filled with concrete mass, so that from this concrete mixture is fed to compensate for the volume of concrete required for the compression caused by the vibration in the lateral direction of the material formed under the container concrete layer. With this method, it is possible directly below the container in the lateral direction to compress the concrete layer to approx. 80 - 90% and possibly even more, which means that the concrete layer at the place where its upper surface is scraped off can be laid with a height HQ, which only exceeds the height H of the preformed element by 20 - 10% and possibly even less. subsequent vibrating sledge thus requires a compaction of the concrete layer in the vertical direction to be carried out only with approx. 10 - 5% or even less, while the final compression in the lateral direction is carried out by the side walls of the block mold below the vibrating slide. The concrete mass is fed or flows down from the container not only to fill the space between the side walls of the sliding form, but also to compensate for the compression provided by these. As the compression takes place by vibrating the side walls of the mould, you can get a very good vibrating effect. When beam-shaped elements are vibrated only from above, not nearly as great a compression effect can be achieved. Above all, regardless of the element's height, a homogeneous compression of the beam element in the vertical direction is obtained. When compacting only from above, the element is incompletely compressed in the lower part. Otherwise, higher water-cement numbers must be used to achieve a fully satisfactory compaction. You can work with concrete with a relatively low water-cement ratio, i.e. the weight ratio between the water and the cement in the concrete mixture. The water cement number can usually be kept as low as approx. 0.27 - 0.35 at a cement content of approx. 300 - 350 kg/m 3, which corresponds to a water content of approx. 100 - 120 l/m<3>. Thanks to this relatively low water cement number, a product with high holding strength is obtained. Another advantage of this relatively dry concrete is that an adhesion between the side surfaces of the shaped product and the sides of the stop mold is prevented. The strong vibration makes it possible to use a low cement content.

However, since the highly compressed concrete layer below the conveyor under the sliding form becomes relatively firm in consistency, it has proved difficult in front of the vibrating sled to wipe off the concrete mass at the upper edge of the shaped concrete object. This has shown a tendency to crack, and the cracks extend deep into the concrete object. An important purpose of the invention is to remedy this deficiency. According to the invention, the concrete layer compressed below the container is separated from the concrete mass remaining in the container by means of the windings of a rotating screw, which extends in the longitudinal direction of the sliding form and accompanies it during the advance. The screw is driven so that the concrete mass is fed backwards, i.e. in the opposite direction to the sliding form's forward movement direction, preferably so that the concrete mass is driven backwards by the screw somewhat faster than the sliding form is fed forwards. Thereby, a certain compression of concrete mass is achieved in the upper layer of the shaped object, because the vibrating slide carries out the vertical vibration. The risk of cracking in the shaped object is practically completely eliminated by the backward feed of the screw.

According to a further development of the invention, the longitudinal rebar, which is usually placed at the upper edge of the shaped concrete object, can be inserted through an axial bore in the screw during the forward movement of the sliding form. The rebar will then leave the hole in the screw at its rear end, i.e. at a place in the shaped concrete object, where the concrete mass has already been compressed to approx. 80%. In the case of the remaining 20% compression of the concrete mass - which compression essentially occurs by vibrating in the lateral direction of the side walls of the form below the vibrating slide - there will be no significant movement of the rebar in the concrete object, thereby ensuring that the rebar will retain its given position , i.e. gets the correct placement in the object or concrete bj oak.

The advantage of feeding the reinforcement in through the screw is not only that the final position is the correct one. If the reinforcement for the container is fed in over the edge, the reinforcement is pressed downwards by the descending concrete. If the reinforcement is not held up by the boiler or because it is stretched, it eventually moves all the way down to the bottom. On the other hand, if the reinforcement is held up (according to the above), it is pressed down by the concrete so much that, when the finished beam leaves the machine, it will spring back up. This results in very dangerous horizontal cracks in the beam. However, the input does not need to take place through the screw, but can take place e.g. through a special rudder. The main thing is that the actual feeding takes place after the container, as the compression has mostly already taken place.

However, during the vibration - both the vibration of the form walls in the lateral direction and the vibration of the vibrating sled in the vertical direction - which vibration has a backward reaction force, the concrete mass and the rebar will to a certain extent vibrate independently of each other. Thereby, there is a risk that the rebar will tear open a longitudinal cavity in the concrete mass, whereby of course the effect of the rebar in the finished concrete object is significantly reduced. For that purpose, according to a further feature of the invention, water is led around the rebar into the bore in the screw at its front end. The screw leans slightly backwards downwards, and the water therefore leaves the bore at the rear end of the screw. Here, the concrete mass is thus continuously softened to such an extent that it will settle well around the rebar, whereby the strength of the finished concrete element is increased to a considerable extent.

The method also enables the production of channel-shaped concrete elements, as two parallel, thin and relatively high side walls are produced by sliding mold filling according to the above and are formed continuously in a short time for a formed relatively thin layer of concrete, which, for example, according to the method specified in Swedish design document no. 309,556, has been laid out on a substrate.

The invention also relates to a machine for carrying out the method according to the above, which machine comprises a stand that can be moved over a base with one or more containers intended for receiving the concrete mixture with a discharge opening below for the concrete mixture and with side walls extending in front and behind the container for shaping of the side surfaces of the concrete layer formed on the substrate, of which side walls at least one is arranged to be vibrated laterally, as well as with a device for vertical vibration of the upper surface of the formed concrete layer. Characteristic of the invention is that at the bottom of the container there is a rotatably driven screw extending in the forward direction of the container, arranged to separate the concrete mass remaining in the container from the concrete object already formed under the container, vibrated in the lateral direction, during the sliding form filling with its windings.

Other characteristic features will be apparent from what follows with reference to the schematic drawings, where: Fig. 1 is a vertical longitudinal section through a machine according to the invention. Fig. 2 shows on a larger scale a vertical longitudinal section through the machine's rotatably stored screw.

rich. 3 is a side elevation, partly in longitudinal section, of a sliding form assembly for the production of channel-shaped concrete elements.

Fig. 4 shows the aggregate seen in plan.

Fig. 5 shows on a larger scale a vertical cross-section along the line V-V in fig. 3i and Fig. 6 show on an even larger scale a similar vertical cross-section through the left part of the aggregate according to fig. 5.

The one in fig. The molding machine shown in 1 and 2 consists of a container 1 with an opening 2 at the bottom for dispensing the concrete mixture 3 contained in the container. The container 1 is supported by a stand 4 (see fig.

6) with an idler wheel 5 for moving the machine on a level surface 6. Parallel side walls 8, which extend both forwards and backwards past the container 1, are used to shape the sides of the concrete layer or concrete object laid out by the machine 7 (see fig. 1). The machine is also provided with a sled 9 for shaping the upper surface 10 of the object 7. The sled 9 is provided with a vibrator 11 for compressing the concrete layer 7 in the vertical direction. The sled 9 is suspended on the stand 4 by springing member 12, so that it can perform vibrations in a vertical plane. 13 denotes a scraper at the rear edge of the container 1 of the opening 2, designed to level the upper surface of the concrete mass after it has left the container 1. At the rear end, the slide 9 is provided with a somewhat springy steel plate 14, which prevents the concrete layer at the rear end of the sled from forming a transverse wall, a so-called pressure bank. At least one mold wall 8, preferably the inner (according to Fig. 6 the right-hand) mold wall is provided with a vibrator 15 and is suspended by springing member 16 on the stand 4 so that it can vibrate in a horizontal plane. The vibrators 11 and 15 are arranged so that a

An obliquely backward force is applied to the upper surface of the formed concrete layer 7 or side surfaces 17. In order to prevent the formation of a transverse valley on the side surfaces 17 during the vibration of the side walls 8, the walls 8 at the rear end are also each provided with a springy steel plate 18 (fig. 4). Due to the vibration, the plates 14 and 18 also cause a certain so-called steel grinding of the concrete object 7.

The machine's traction over the substrate 6 is carried out by means of an electric motor 19 via a chain 20 to the running wheels 5.

In the opening 2, a screw 23 is rotatably stored with one end 21 in a bearing 22 in the longitudinal direction of the stand 4, sloping backward downwards. a bore 27, through which a rebar 28 can be fed. Above a chute 29 opening at the front end of the screw 23's bore 27 is a nozzle 31 connected to a pressurized water line 30, which supplies water through the bore 27 to the concrete mass at the far end 32 of the screw 23.

When the machine is moved in the direction of the arrow 33 in fig. 1, the relatively dry concrete mixture (water-cement ratio, for example 0.27 - 0.30) is fed or slides through the opening 2 onto substrates 6. On this are laid horizontal and vertically curved rebars 34 resp. 35. The space between the machine's side walls 8 is filled with concrete mass from the container 1. Due to the vibration, a strong compression of the concrete mass will take place in the lateral direction, and new mass continuously flows down from the container to compensate for the concrete mass consumed during the compaction. Below the scraper 13, where the concrete mass 7 has the height HQ, the object is thought to have already been compressed to approx. 90%. Further compaction of the concrete object takes place with the walls 8 below the slide 9. This compaction in the lateral direction is thought to take place with a further approx. 5%. With the slide 9, the remaining approx. 5%. This therefore means that the height and width dimensions of the cross-section of the concrete structure below the scraper 13 must be reduced by only approx. 10% or less. The finished object becomes very solid and homogeneous. The height H of this can therefore be increased considerably and the width relatively small. The already hard compacted mass below the container 1 is separated from the remaining concrete mass 3 in the container by means of the windings for the screw 23, which is driven at such a speed that the concrete mass is pushed backwards by the screw windings somewhat faster than the machine is moved forward (in the direction of arrow 33). At the same time, a rebar 28 is guided through the bore 27 in the screw 23 into the mould. As any significant further compression of the concrete object 7 does not occur in the vertical direction of the slide 9, the rebar 28 in the concrete object will occupy the correct distance from its upper surface 10, this distance 36 being determined by the inclination of the screw 23 and the height of the outlet. It may therefore be advantageous to make the bearing 22 for the screw 23 adjustable, so that the desired inclination of the screw

23 can easily be provided.

Due to the water inflow through the nozzle 31 to the concrete mass at the rear end 3 2 of the screw 23, the desired higher water cement number is obtained for the mass around the rebar 28.

In fig. 3-6 shows the production of a channel-shaped object 37 (fig. 5 - 6) made of concrete. This object 37 is a trough-shaped beam with a bottom part 38 and walls 39 rising from this. The bottom 38 is first produced on the substrate 6 and can preferably be lined with a sliding molding machine 40 (fig. 3 to the right), which is explained in more detail in Swedish design document no. .309,556. When moving the machine 40 in the direction of the arrow 41 in fig. 3, the relatively dry concrete mixture 42 flows, which in this case can have a water cement number as low as approx. 0.25 - 0.27, through the opening 43 in the container 44 down onto the substrate 6, a forward and downward sloping slope 45 of the concrete mixture 42 with a certain slope angle is formed below the front edge 46 of the opening. On this slope 45 water is sprayed from the nozzle 47 so evenly as possible. Part of the water then runs down towards the substrate 6, where the water cement number in the layer 48 is thus the largest. The concrete layer's upper surface is automatically leveled with the squeegee 49. The leading edge 46 is at a lower level than the squeegee 49. With the sled 50 of the machine 40, the concrete layer is compressed by vibrating with the sled's vibrator 51, whereby the desired density is obtained for the layer. During the compression, part of the water in the layer 48 is pressed upwards, so that a certain equalization of the water content in the entire layer is achieved. However, the water content at the upper surface never becomes so high that there is a risk of the slide 50 sticking to the layer. This ensures an even, firm layer on the finished bottom plate 38 also on the upper surface. The bottom plate becomes very firm, and there is no risk of it being deformed after the side walls 52 of the machine 40 have left it.

As shown in fig. 6, the longitudinal sides of the bottom plate 38 are provided with an upwardly directed part 53 with a height that exceeds the thickness of the bottom plate by, for example, two to three times. These raised parts 53 form, as will be seen from fig. 6, control for the walls 8 on the one in fig. 3 showed subsequent slide molding machine 54.

Immediately after the layer 48 has been compacted, two layers of concrete are laid out with two containers 1 located at some distance from each other and carried by a common stand 55, which are vibrated by the side walls 8 and the slides 9 on the front in connection with fig. 1 and 2 described way. With the unit according to fig. 3 and 4, it is thus possible to produce reinforced, channel-shaped beams with relatively thin and high walls 39 by means of sliding form filling. This beam thus, despite the relatively modest material consumption, has particularly high strength and load-bearing capacity.

Also the machine 54 for shaping the object 7, resp. the walls 39 can be provided with nozzles 47 (not shown) connected to a water line for spraying water towards the slope 56 of the concrete mass 3 flowing down from the machine's 54 containers 1. In

in this case, a small enrichment of water is obtained in the concrete mass near the upper surface of the shaped plate 38, i.e. on the upper side of the upright longitudinal parts 53 of the bottom plate. By the subsequent vibration and compression of the concrete mass with the side walls 8 and the slides 9, an equalization of the water content in the finished concrete object is achieved. In cases where the concrete walls 39 placed on the upper edge are to be provided with reinforcement at the lower edge, it is advantageous to have such a water spray of

the concrete mass 3 at the front end of the machine, as this ensures a good envelopment of the concrete mass around the rebars during the subsequent vibration.

The shown and described embodiments are to be regarded as examples only, and the slipform machines 40 and 54 can be constructively changed in several ways within the scope of the requirements. Thus, the machine rails 40, 54, instead of with running wheels 5, can be slidably supported by longitudinal beams or rails in the ceiling of the room, where the sliding forming is carried out. Instead of channel-shaped beams, with the aggregate according to the invention it is possible to produce L- or T-shaped ones in cross-section, in which case a single longitudinal wall 39 is stopped on the bottom plate 38.

If two mutually parallel rebars are to be placed at the upper edge of the walls 39, it may be appropriate to rotatably store two parallel, rotatably driven screws 23 provided with an axial bore 27 in the opening 2 of the container 1. The rebars can instead- for through a bore in the screw or screws are guided down into the stop mold through one or more rudders directed obliquely downwards to the rear, into the mouth of which water can possibly also be introduced.

The problem of removing the concrete mass without cracks occurring in the shaped object, the beam, is even more marked if the beam has a narrow web and this with a neck transitions into a wider section running along the upper part of the beam, where the actual pressure zone is located . In this case, the forces retained during shaping are significantly smaller than those that will push the concrete mass forward, as the pressure zone is wider than life. In this case, in order to get the material in the life sufficiently tightly packed and at the same time prevent the concrete mass from "pinching" in the neck, i.e. in the transition between the "wider upper part and the narrower lower part of the beam, the neck must be made to tilt backwards , downwards under the carriage 9 as can be seen from Fig. 1. Thanks to the use of the feed screw 23 and the backward inclination of the neck-forming part of the casting mold, a crack-free beam is obtained.

Claims (10)

1. Method for the production of elongated, particularly relatively thin, upright objects made of concrete using slip forming, where the concrete mass from a continuously moved container is fed onto a substrate and is formed under compression in the lateral direction below the container into a layer with mutually parallel longitudinal edges and an upwardly leveled surface by subsequent compaction in the vertical direction, characterized in that the laterally compressed concrete mass is separated from the concrete mass remaining in the container by means of the windings of a rotating screw. 2. Method as set forth in claim 1, characterized in that the rotating screw, which is stored in the container (1) so that it extends in the forward direction of the latter, is operated so that the concrete mass at the lower part of the container is fed backwards, i.e. opposite the forward direction of the container. 3. Method as stated in claim 1 or 2, where the stopped concrete object is provided with longitudinal reinforcement at its upper edge, characterized in that a reinforcing bar (28) is fed through an axial bore in the screw (23) during its and the container's (1) movement forwards. 4. Method as stated in claim 3, characterized in that through the bore (27) in the screw (23) water is also introduced together with the rebar (28) to increase the water cement number of the concrete mass around the iron in the stopped object. 5. Machine for carrying out some of the methods specified in the preceding claims, consisting of a stand that can be moved over a base with one or more containers intended for receiving concrete mixture with a discharge opening below for the concrete mixture and with side walls extending in front and behind the container for shaping the concrete formed on the substrate in f. layer's side surfaces, of which side walls at least one is arranged to be vibrated in a lateral direction, as well as with a slide or similar device for vertical vibration of the formed concrete layer's upper surface, characterized in that there is arranged at the bottom of the container (1) a rotatable driven in the forward direction of the container, the continuous screw (23), which, during the sliding form filling, separates the remaining concrete mass in the container from the laterally vibrated concrete object already formed under the container with its windings. 6. Machine as stated in claim 5, characterized in that the screw (23) is stored only at the front end (21) and rather preferably somewhat at an angle downwards to the rear. 7. Machine as stated in claim 5 or 6, characterized in that the screw is provided with a through-axial bore (27) for feeding through a rebar (28). 8. Machine as stated in claim 6 or 7, characterized in that it is provided with a device (31) for supplying water to the bore (27) at the front end of the screw (23). 9. Machine as specified in any of claims 5-8 for forming beams with a narrow body, which with a neck transitions into a wider upper part extending in the longitudinal direction of the beam, characterized in that a part of the mold forming the neck slopes downwards, backwards from the container (1) towards the slide (9). 10. Machine as stated in claim 9, characterized in that the sloping part of the stop mold also extends under the slide (9).