The invention relates to a method for producing concrete pipes in a vertical casting mould comprising a moulding space between a core and a mantle divided lengthwise and comprising mould sleeves which terminate the moulding space at the bottom and at the top, wherein pourable concrete is poured into the moulding space and the pipe body is demoulded after curing of the concrete by opening the mantle.
In contrast to a shaking pressing process, in a wet concrete casting method pourable concrete is poured into the moulding space of a casting mould, which has the result that the concrete body in the casting mould must cure before it can be demoulded. For the production of concrete pipes in vertical casting moulds this means that for demoulding the set concrete body, the divided mantle of the casting mould is either opened by expanding or radially pulling apart the mantle halves and the core is reduced in its diameter. Since the upper mould sleeve is assigned to the mantle, the upper mould sleeve must also be divided. However, the upper mould sleeve must allow a pouring of the pourable concrete into the moulding space from above which requires upper mould sleeves which are open on the front side, with the disadvantage that the end faces of the pipe body in the region of the open front sides of the upper mould sleeves must be smoothed by hand, and what is more, the setting behaviour of the pourable concrete poured into the moulding space can scarcely be taken into account. In the course of the setting process the air bubbles included in the pourable concrete escape upwards and can only partially escape via the open front side of the upper mould sleeve so that the air bubbles collecting in particular in the region of the outer circumferential wall of the upper mould sleeve cause undesired air pores in the region of the recessed front-side coupling attachments of the finished concrete pipes.
In order to be able to take into account the setting behaviour of concrete pipes produced by the shaking pressing method after demoulding, it is known (EP 0 476 245 A2) to press the upper mould sleeve in a shaping manner onto the compacted concrete body only after a compaction of the concrete caused by a shaking whilst displacing the excess concrete from the moulding space between mould core and mould mantle so that a uniformly compacted concrete body can be assumed even in the region of the coupling attachment formed by the upper mould sleeve. Apart from the fact that in a shaking pressing method, unlike a wet concrete casting method the difficulties caused by air bubbles ascending in the pourable concrete do not occur, in this known shaping pressing method to produce pipe bodies, the escape of the excess concrete from the moulding space should be seen as disadvantageous. In addition, a relative movement between the mould core and the mould mantle is required to be able to close the annular opening between the upper mould sleeve and the core, which annular opening is required to displace the excess concrete from the moulding space.
It is therefore the object of the invention to configure a wet concrete casting method to produce concrete pipes in the moulding space between a core and a mantle of a vertical casting mould so that not only the requirements for a true-to-size formation of the coupling attachments formed by the upper moulding sleeve are created but also the risk of the formation of air pores in the set concrete pipe can be avoided and the setting behaviour of the pourable concrete can be taken into account in a simple manner.
Starting from a method of the type described initially, the invention solves the formulated object in that the pourable concrete is poured into the moulding space in a predetermined quantity when the upper mould sleeve is removed and that the upper mould sleeve forming a closed ring is pressed in a shaping manner into the end face of the pipe body only after a setting time for a predefined setting volume of the cast pipe body between the core and the mantle.
Since the pourable concrete is cast in the moulding space when the upper mould sleeve is removed and the upper mould sleeve is pressed into the still pourable concrete only after a predefined setting time, the air bubbles ascending in the pipe body during the setting time can escape upwards unhindered through the upper mould sleeve, so that during the subsequent compression moulding of the front-side coupling attachment by pressing the upper mould sleeve into the still pourable concrete smooth wall surfaces can be formed not only in the circumferential region but also in the region of the front side. The waiting for the setting process for the concrete cast in the moulding space and the subsequent forming of the coupling attachment however requires a filling of the moulding space with a predefined quantity of pourable concrete in order to be able to ensure a predefined length of the concrete pipe to be produced. Accordingly a filling volume must be provided which exceeds the volume of the concrete pipe to be produced by the setting volume. The setting behaviour of different concrete compositions and therefore the respective setting volume to be taken into account can be determined simply for example by experiments. In practice, it has been found that even after a few minutes a setting is present which allows a compression moulding by the upper mould sleeve within a predefined manufacturing tolerance.
The compression moulding of the front-side coupling attachment of the concrete pipe to be produced can be assisted by turning the upper mould sleeve during and/or after the pressing into the pourable concrete.
The method according to the invention is explained in detail with reference to the drawings. In the figures:
As can be deduced in particular from
For demoulding a concrete pipe which has been produced, usually both the core 2 and also the mantle 3 are divided lengthwise. Whilst the mantle 3 must be withdrawn radially outwards from the concrete pipe to be demoulded, the core is to be drawn radially inwards to release the pipe body 7. This is achieved in a manner known per se whereby the longitudinal edges of the divided circumferential wall of the core 2 which run parallel to one another at a distance in the circumferential direction in the usage position of the core are pulled towards one another. In the case of a conical core configuration, a division of the core which is otherwise required can also be omitted. The longitudinal edges of the divided mantle 3 which abut against one another in the usage position of the mantle 3 are accordingly pulled apart. In the case of a one-piece design, the mantle 3 is thus widened whilst in the case of a two-part design the two mantle halves are pulled apart.
In order to produce a concrete pipe, pourable concrete is poured in a predefined quantity matched to the pipe to be produced into the moulding space 4 between the core 2 and the mantle of the casting mould when the upper mould sleeve 9 is raised usually from above according to
The air bubbles enclosed in the pourable concrete can escape upwards from the moulding space 4 during this setting time so that during the subsequent pressing of the upper mould sleeve into the pourable concrete between the core 2 and the mantle 3 the coupling attachment 8 is formed free from pores with smooth wall surfaces. Care should merely be taken to ensure that the air collecting above the pipe body 7 during insertion of the upper mould sleeve 9 into the moulding space 4 can escape from the mould sleeve 9 which is ensured by the necessary guide gap between the upper mould sleeve 9 and the core 2.
After a curing of the concrete necessary for demoulding, the pipe body 7 can be demoulded by opening the mantle 3 and pulling it apart radially outwards and pulling the core 2 radially in. The upper mould sleeve 9 can remain on the pipe body 7 during the demoulding but can also be removed beforehand.
Number | Date | Country | Kind |
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A 50881/2015 | Oct 2015 | AT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/AT2016/050260 | 10/13/2016 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2017/063010 | 4/20/2017 | WO | A |
Number | Name | Date | Kind |
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2334509 | Reeves | Nov 1943 | A |
3078539 | Duplessis | Feb 1963 | A |
3334390 | Steiro | Aug 1967 | A |
3461516 | Boucher | Aug 1969 | A |
20050269747 | Wuelfing | Dec 2005 | A1 |
20150246460 | Schluesselbauer | Sep 2015 | A1 |
Number | Date | Country |
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33 23 340 | Jan 1985 | DE |
2137924 | Oct 1984 | GB |
2014048684 | Apr 2014 | WO |
Entry |
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Espacenet. English-language abstract of DE 33 23 340 A1, Prinzing Georg GmbH Co. KG, Jan. 3, 1985. |
Number | Date | Country | |
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20180297234 A1 | Oct 2018 | US |