DEH0011340MA - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

Registration date: February 5, 1952. Advertised on May 3, 1956

GERMAN PATENT OFFICE

The invention relates to a method and a device for producing hollow bodies from Concrete or the like with prestressed reinforcement. Fling. According to the procedure. Will first be a The molding surrounding the reinforcements placed in the mold thanks to the low centrifugal effect formed, and the method is characterized in that the preform for tensioning the ring reinforcement by the pressure during the ίο centrifuging filled in granular filler and the concrete is exposed to a high degree of centrifugal force.

It has previously been proposed to spin-form a preform first and then Stopping the spinning at a standstill, prestressing the reinforcement under static pressure. A rigid outer mold was used and a relatively liquid cement mixture attached to the inner wall thereof before the preform is molded from concrete. If then the static pressure is admitted, you get a little expansion and possibly a low tension of the reinforcement, if not the centrifugal effect already the liquid one Compressed mixture as much as possible. In doing so, however, water and possibly also air are pressed out of the mixture and penetrates into the concrete and deteriorates

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its properties. An inferior product with low reinforcement tension is obtained.

In contrast, the invention offers great advantages:

According to the invention, hollow bodies made of concrete or the like are produced quickly and cheaply Reinforcement can be given any desired prestress. The most expensive part of the for making The required equipment can quickly be released after a hollow body has been thrown out to produce new hollow bodies. So the production capacity is high. During the the time required for hardening of the completely centrifuged hollow body is, only a behavior- ' requires cheap equipment.

Furthermore, according to the invention, prestressed hollow bodies with a smaller wall thickness than before can be used getting produced.

The short production time, during which the products according to the invention are spun, has the consequence that the cement mortar cannot stick to the molds, which can therefore be easily cleaned after a pipe has been produced, which on the other hand with such production methods is not the case in which the concrete pipe may be locked in its shape during an entire work shift (e.g. during the greater part of 8 hours).
The invention is described below with the aid of a number of figures, further features characteristic of the invention being dealt with.

Fig. Ι shows a vertical longitudinal section through an apparatus for producing prestressed pipes according to the invention;

Fig. 2 is a cross section through a device, according to the invention;

Fig. 3 is a detail section in the radial direction. along the line III-III in Fig. 2;

Figure 4 is an alternative cross-section to that shown in Figure 2;

Fig. 5 is a vertical longitudinal section through a device according to the invention;
FIGS. 6 to 8 illustrate different moments in the manufacturing process, for example in connection with FIG. 5;
'Fig. 9 is a vertical sectional detail through

a pipe wall during casting; '
Fig. 10 is a cross-sectional view of an internal mold having a channel system with cavities;

Figures 11 and 12 are alternative cross sections by a device for the production of pipes according to the invention;

Fig .; 13 is a longitudinal section through a device according to the invention.

'Fig. Ι shows a device according to the invention for centrifuging a concrete pipe, 1 is a centrifugal drum with a horizontal axis i _a . 2 indicates the concrete pipe during manufacture. 3 is a filler, 4 denotes end disks which are connected to end rings 5. 6 is an elastic bandage between the centrifugal drum and its support rings 7, which can run on a bed of rollers (not shown).

The manufacture of a prestressed concrete pipe using the equipment shown in FIG takes place as follows:

Concrete is spun into the spinning mold, which is driven by the centrifugal drum 1 and the end rings 5 is formed. The concrete fills / thereby the form and encloses it in the form introduced framework of reinforcement - preferably both ring reinforcement and longitudinal reinforcement - Which during the manufacture of the concrete pipe in the transverse direction and optionally should also be prestressed in the longitudinal direction. The centrifugal drum can be tight or be permeable to water. If the concrete is prepared with an excess of water to a satisfactory To maintain light fluid in connection with the spreading of the concrete in the form, so the excess water goes in during the spin and then through the Inner surface of the concrete pipe and, if the outer shape is permeable, also through the outer shape.

When the spinning has been carried out so long that the fresh concrete in the desired Has stabilized to the degree, the centrifugal drum is brought to a standstill. At the inner Surface of the concrete becomes an elastic membrane, for example in the shape of an original flat, thin rubber blanket. Then the end disks 4 are attached, and the spinning is carried out again with the addition of filler 3 along the axis of the centrifugal drum, which filler can be of any type, e.g. B. sand, iron silt, heavy balls, but also Clay or other material. The centrifugal drum then expands at the appropriate time - It is assumed that this consists of a number of elements extending in the longitudinal direction the drum extend -, the fresh concrete pipe 2 also having a larger diameter receives so that the concrete also presses the ring reinforcement outwards and the same at the same time tense. The expansion of the concrete pipe is not only caused by the centrifugal forces that the Mass of the pipe generated during the revolution, but also by that of the trapped Filling forces exerted on the pipe. The resulting centrifugal forces are Transferred to the support rings 7 via the elastic bandages 6.

It is assumed that measures for a slow, gradual expansion of the Centrifugal drum are taken, so that the deformation of the concrete pipe from a non-prestressed to a prestressed, fresh concrete pipe takes place slowly enough, which both for the stress distribution within the reinforced pipe as well as its density is advantageous.

The manufacturing method described above can be modified as follows. After the diameter of the concrete pipe has been enlarged to the final size in a suitable manner, with

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If further liquid has been able to escape through the permeable drum, the central cavity is completely or partially filled with filler - if this has not already been done. One filling the whole pipe _; - which, however, is not often necessary - ■ can e.g. B. be done by introducing a feed pipe for the filler from the side in the central axis of the drum. The supply then takes place through this pipe, for example by pneumatic means.

The prestressed, fresh concrete pipe can then, after the centrifuging has stopped and the parts of the centrifugal drum have been separated in the required manner, be removed from the drum, the pipe sitting on a core body consisting of the end plates 4 and the filler 3 , which with or without a continuous cylindrical opening in the center line withstands the forces of the reinforcement of the pipe, for example by a more or less pronounced arching effect within the filling.

After that supported in this way, fresh, pre-stressed concrete pipe has been transported away from the centrifugal drum, this can immediately prepared for spinning a new pipe.

The end disks 4 can be connected to one another through an attached in their center and with openings . provided pipe be connected through which the supply of the filler can take place. ■

It has not been mentioned above the manner in which there is a gradual change the diameter of the centrifugal drum according to the invention are taken. This can e.g. B. by Change in the speed of rotation of the drum can be achieved, the elastic bandages 6 at increased Speed of the drum are compressed, causing an expansion of the concrete pipe he follows.

It is assumed that the bars I ₆ - apart from the part 6 - are connected to one another by means of elastic spacers or the like.

Fig. 2 shows a detail of a centrifugal device, ij denotes the centrifugal drum, which is here in the form of a number of profile beams, is preferably made of light metal, which rest against the elastic bandage 6 on the outside. It is assumed here that the bandage 6 consists of a rubber ring that is connected with Liquid or gas can be filled and pressurized. 8 is a ring reinforcement, and 9 is a longitudinal reinforcement.

Fig. 3 is a section along the line HI-III in Fig. 2. It shows a basic embodiment of the elastic bandage 6 and illustrates how the centrifugal drum is supported by the support ring 7 is supported against a number of rollers 10 , their shafts 11 preferably take up firm positions during spinning. .

In comparison with FIG. 2, FIG. 4 shows an alternative embodiment of a centrifugal drum with several parts. The centrifugal drum 1 consists here of a rigid tube during all the centrifugal moments, for. B. a steel pipe in which there is an elastic outer shape 12 (outer shape in relation to the concrete pipe 2). The elastic outer shape is provided with drainage strips 13 located in radial planes, which lead 70 from the surface of the concrete pipe 4 to channels 14 with axial extension located within the elastic outer shape, which channels have the task, among other things, of removing excess water from the concrete.

The resilient form 12 may be made of a material having a low modulus of elasticity, e.g. B. rubber, and the deformability of the elastic. The shape can be further increased by a channel system (not shown in FIG. 4) which is arranged in the same and is completely or partially filled with an agent (e.g. liquid or gas). It is assumed that the channel system is provided with devices for changing the pressure within the same. With such a change in pressure, the volume of the elastic form is changed, and consequently the diameter of the concrete pipe to be produced also changes, provided that sufficiently large centrifugal forces are active. 4 can be viewed as a cross section through the centrifugal device shown in FIG. 1, with the fundamental modification that the parts and 7 are interchanged and extend over the entire length of the tube.

With the device described in FIGS Prestressed concrete pipes can be produced according to the following production plan.

1. Concrete is poured into the casting mold with the reinforcement framework for the concrete pipe installed therein, either while the mold is stationary or while it is rotating at a certain speed. The concrete fills the shape and embeds the reinforcement framework. In order to be able to work with concrete that is pliable from the start, it is advantageous to provide a not insignificant excess of water, which has to be removed later. This can e.g. (Mentioned in relation to the speed which hang below in connection with 11.0 subsequent production steps) example by spin coating at a relatively low speed to happen.

2. The stabilization of the poured concrete pipe can also be done while the centrifugal drum stands still, whereby you can use an elastic. Innenform that under the action of a internal overpressure is stretched. In those cases where water comes out of the freshly poured Concrete pipe drains, the water can be in one or both sides, i. H. either through the outer shape or flow inwards towards the center or in both directions.

3. After the poured concrete pipe in required Once the degree has been stabilized, it may be desirable on the inner side of the concrete pipe a case of some kind, for example

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a coherent, elastic membrane or a separating layer of another kind, which changes shape allowed to attach.

4. It is then spun using a relatively high speed, with the Outer shape automatically gives way or is caused to stretch, in which cases the concrete pipe also expands to a larger radius. During this moment the concrete is so tight that it pretensions that reinforcement that has a component in the cross-sectional planes granted. .

The outer shape can be, for. B. from a one-piece or from one composed of individual longitudinal parts, consist of tubular steel that can be dismantled into its components. You can not have an interior lining own or equipped with an inner lining in the form of an elastic outer shape 12 be stiff or stretchable or made of a layer of filler. The like. Consist can.

5. The fresh, expanded concrete pipe is used to remove the outer shape more quickly by means of an internally supplied filling of a suitable type, e.g. B. a friction material, such as Sand or the like, stabilized. This filling presses against the inside of the during spinning concrete pipe to be produced and is compacted vigorously even during centrifugation.

It can be advantageous to cover this inner, stabilizing filling with an insulating layer of to separate the concrete. Such a layer may be in the form of a slurry, e.g. B. of cardboard or from some other fibrous material in water. Under centrifugation this becomes Slurry causes slurry to spread evenly on the inside surface of the fresh concrete pipe. After the slurry has dehydrated to some extent and has become sufficiently solid, an internal, stabilizing sand filling or the like is attached under centrifugation, which does not adhere to the concrete under these circumstances.

Instead of the slurry mentioned in the previous section, other materials, e.g. sawdust - or another material

. '. , with a low modulus of elasticity - fine sand, etc. can also be used.

6. After the stabilizing filling is in place, the pipe, etc. is out of the outer shape removed and moved to a place where its further solidification can take place. The stabilizing The filling does not necessarily need the whole *. Fill in the tube, just one

.55 part of the same, for example in the form of a shell around a cylinder serving as a recess. the (especially a sheet metal pipe with a small diameter in relation to the concrete pipe), which also used to lift the pipe out of the mold and to transport it away from the outer mold can be.

While above in connection with Fig. 1 to 4 initially the spinning in the horizontal position 5 to 9 and 13 relate to spinning about a vertical axis.

In FIG. 5, 6 denotes an elastic bandage in the form of a layer covering the entire inner surface of the centrifugal drum, for example made of raw rubber or sponge rubber. 15 is an elastic inner mold for the concrete pipe 2, which is in the stage of shaping using the form plate 16, which is lifted during concreting - preferably with vibration - with the concrete pipe between the beams I ₆ of I-profile or the like . (Which bars form the parts of the centrifugal drum here) and the elastic inner shape 15 is created. The inner mold 15 is placed on the inner surface of the concrete pipe formed by the shield 16 under the action of the unstraining forces of a filler 3 which is filled up at the top using a funnel 17. The elastic inner form 15 can be laterally supported above the shield 16 in a suitable manner (not shown in the figure). The filling of filler, which takes place here, as shown, without overpressure, can also, as can easily be seen, take place under overpressure (for example in such a way that the filler 3 is surrounded by water or air under overpressure); in this case the funnel 17 is closed, provided with a lock and tightly connected to the elastic inner mold 15.

18 denotes a lower metal funnel which is connected to the outer rigid centrifugal drum 1 via the slice i8 _a and connected by bolts 19th 20 is a disk, preferably of a slightly conical shape, which is used to fasten the longitudinal reinforcement 9 at the top, which is fastened to the lower sheet metal funnel 18 at the bottom. The longitudinal reinforcement is anchored here above and below by means of nuts 21. 22 indicates rings made of strong elastic material. 23 denotes end rings from. Steel for the finished concrete pipe, which are shown here as angle iron, but which can also be designed in the form of tapes, ie can only consist of flat iron rings that are cast into the outer surface of the pipe.

After the concreting has been completed, the shield 16 is lifted and along with the Funnel 17 is removed, and instead an upper sheet metal funnel 24 is attached by means of nuts 25.

If the concreting (the primary shaping), which has been described above, is referred to as the first production stage, the second now follows, which comprises stabilization of the poured concrete pipe by centrifuging, with any excess water leaving the concrete pipe and through the cavity in or flows through outflow openings 26 between the bars I _6. In order to avoid wasting the water containing the binding agent, which is concerned here, either a fixed screen can be arranged or the water can be pumped away in such a way that the centrifugal device is centered

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leaves in the central axis. The second production stage is illustrated schematically in Fig. 6, wherein, the arrows mark the internal overpressure on the inner mold 15. After doing this The preliminary stabilization of the cast concrete pipe has taken place, followed by a possible one Third processing stage, in which the filler is emptied, the elastic inner mold is removed and through a separating layer 27 of the simplest type is replaced, in which new filler is added. The order is that indicated in FIG. 7 schematically.

The fourth production stage is centrifuging in a vertical position, the speed being selected so high that the elastic bandage 6 is slowly compressed, causing a slow expansion of the poured concrete pipe, which takes the ring reinforcement with it (which is preferably in the form of a Spiral reinforcement is carried out) and the same tensioned. When this process has lasted long enough, the spinning is interrupted, and you then have the fresh, prestressed concrete pipe, which surrounds a core of highly compressed filler. The concrete pipe can then be detached from the centrifugal drum ί with the associated elastic bandage 6 and bars i _b. The concrete pipe 2 in addition to the filling 3 is, for. B. upward, pulled and the lower sheet metal funnel 18, the disc 20 and the upper sheet metal funnel 24 (in which devices for lifting can be provided), the compressed filling 3 is able to absorb anchoring stresses also from the longitudinal reinforcement. The transport of the not yet tied, prestressed concrete pipe and a few small parts, which do not represent any noteworthy costs, is referred to here as the fifth processing stage.

1 The next processing stage is the storage, during which the setting of the concrete takes place, as well as the further increase in the strength of the concrete. During the storage period, the filling serves as a pressure-absorbing element both for prestressing the ring reinforcement and for prestressing the longitudinal reinforcement. The sixth . Processing stage can be referred to as the primary storage.

50. The seventh processing stage involves removal the inner filling (and also the possibly existing elastic inner shape) what can be done once the concrete of the pipe has reached such a degree of strength that it only forces resulting from the prestressed reinforcement in one or both directions able to absorb. However, according to the invention, this can also be done without any disadvantage at a later date Point in time. In connection with the removal of the inner filling (except an optionally used elastic inner mold 15) the two sheet metal funnels 18 and 24, the Disc 20 and the elastic rings 22 free so that they can be used again immediately for manufacture can be.

The final and eighth processing stage can be post-treatment of the concrete pipe to achieve the highest quality of the area and, in connection with it, its final storage, testing etc. before it is delivered to the buyer.

Fig. 9 is a detail which shows how the concreting can be carried out when using a rigid or relatively rigid inner shape in such a way that the inner shape and the outer shape are axially displaced in relation to one another, for example in such a way that the inner shape in relation is lowered to the fixed (attached in a fixed position) outer shape. 28 is an annular concrete funnel. An advantage of this arrangement is, for example, that it enables the use of an inner mold of the type shown in Fig. 10, which is implemented as a relatively rigid cylinder in resilient material and provided with devices for drainage which are basically of the type has been specified in the external shape shown in FIG. The advantage of the in F ^ g. Described device 9 and 10, ^v is the fact that the stabilization of the cast concrete pipe can be accelerated, as soon as the excess water it has the opportunity to flow away in either direction, both outwardly between the external shaping elements I ₆ and inward via the drainage channels 14 through which the liquid can be carried away either by its own overpressure (under the effect of centrifugation) or by pumping.

In addition to the devices that have been described above, the invention also relates to devices which allow the production of a prestressed concrete pipe in a centrifugal drum, the axis of which is rotatable about another axis (in particular a horizontal axis), the centrifugal drum in any desired inclined position can be adjusted so that the drum assumes a horizontal position during certain manufacturing moments and a vertical position during other manufacturing moments. In such cases, the drum is preferably arranged within a rigid framework of framework or the like, which carries the rollers 10, wherein ^! the rigid frame is rotatably mounted about a horizontal axis which can be located outside the centrifugal drum or inside the same (viewed from the side) and preferably in or near the center (viewed from the side) of the centrifugal drum. The machinery for driving the centrifugal drum is preferably permanently attached to the framework. In this case, the processing stages can be as follows:

1. Concrete pouring in a horizontal position Under spinning, which is a primary stabilization of the cast pipe brings about.

2. Bringing the frame carrying the centrifugal drum into a vertical position.

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3. A suitable separating layer is applied to the inside of the concrete pipe.

4. Filler is placed inside the release liner.

5. Spin is performed while the concrete pipe is given an opportunity to slowly expand.

6. The concrete pipe is taken out of the outer mold, the same being the compressed one Filling surrounds that with. is provided with suitable end pieces.

Fig. 11 shows an elastic outer shape inside the centrifugal drum 1 in the form of a steel pipe. The elastic sleeve, which is in tension-free Condition can have an outer diameter that corresponds to the inner diameter of the steel pipe is very close to each other, is hydraulic at the beginning by means of fluid pressure in the Channels 29 stretched so that it is radially from

ao pushes steel tube inwards. After the concrete pipe has been poured, expansion can occur through (or take place simultaneously with) reduction of the volume of the elastic sleeve.

Fig. 12 shows how a particular axially draining layer - e.g. B. in the form of filler - Has been inserted between the concrete pipe to be produced and the elastic outer mold 12. the Arrangement allows a very high degree of drainage of the poured concrete pipe, which, after it came out of its outer shape in the shape of a fresh, not yet set concrete pipe is taken out, e.g. B. can be treated by grinding steel to the desired uniform To maintain surface quality.

FIG. 13 shows a somewhat modified embodiment of the device according to FIG. 5. The upper sheet metal funnel 24 according to FIG. 5 is replaced by a filling tube 31 according to FIG. 13, which has a number of internal annular flanges 32 is provided .. During the spinning, new material flows centrally down in the filler tube 31, the flanges of which prevent the filler from inside of the concrete pipe is pressed upwards when the spinning stops, so that the filler 3 den Absorbs the pressure of the prestressed reinforcement.

It should be emphasized that each Kind of material comes into question, which is used in connection with the Schleu-. the additional burden that is desired in certain cases the · concrete pipe can be used in its manufacture. The filler can thus be a liquid or solid body, preferably granular material, spheres, etc. The filler can also contain all occurring volume weights (density including voids) have e.g. From 0.5 and upwards, e.g. B. to 8 to 10.

Among the slightly different working methods,

which the device permits, the following may be mentioned:

i. Spin with a fixed outer shape and an elastic inner shape.

2. Change the outer shape so that it is compliant (so that the radius can be increased can) while increasing the radius of the inner shape at the same time. The latter can be done in two ways be achieved:

a) through increased spin effect (increased speed),

b) by a means mounted in the inner mold, e.g. B. a filler (if applicable a liquid) and especially a heavy filler (e.g. sand, iron silt, lead balls or the like).

Another production scheme - in connection with vertical installation - ■ is the following:

1. Concreting with loose cement mortar (concrete mortar) against an inner form that is expedient can be an elastic form. The inner shape should preferably be in the Relation to the outer shape can be lowered, which latter is provided with devices for vibrating.

2. Spin, with excess water - with a certain cement content - inwards against the center goes off and flows off in the axial direction towards one or both ends.

3. Filling - especially heavy - within the interior mold.

4. Removal of the filling in the inner mold and also removal of the inner mold itself and insertion of new interior filling. Then spin, after which the outer shape (which is preferably - in Cross-section seen - in several parts. leads) can be removed. .

5. What one has thus achieved in a short while is a transversely - ₍ and preferably also in the longitudinal direction - prestressed, fresh concrete pipe, the inner and outer forms of which can be removed while the concrete pipe hardens, whereby it is against you Core is supported by cheap filler that can be reused later.

A modified embodiment is as follows:

1. Quick pour vertically with wet concrete the reinforcement framework with simultaneous attachment of an internal, finely perforated, elastic shape (or elastic shape / which is provided with longitudinal outer channels).

2. Slow spin with drainage. ,

3. Increasingly vigorous spinning, advantageously with the introduction of filler or something else Material in the inner mold.

4. Expansion of the outer shape, the loading. reinforcement framework (especially the ring reinforcement), e.g. B. is tensioned by increasing the speed.

5. Remove the outer shape.

6. After the pipe has obtained a satisfactory strength, the interior filling is made as well removed the inner shape.

Alternatives to 4th, 5th and 6th are:

4 a) The inner mold is removed.

Sb) Internal filling is attached.

6 a) The outer shape is stretched under vigorous spinning.

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7 a) The outer shape is removed, and the tube with the inner filling is taken away.

According to the invention one has the possibility

.5 that after using an elastic Internal form under vibration a primary stabilization of the poured concrete pipe is done called elastic inner shape can be removed during spinning. This can e.g. B. thereby happen that the elastic inner mold is evacuated during the rotation, with them becomes free from the inner surface of the concrete pipe. Here, the elastic inner shape of a vertical or horizontal center stand that is on the same axis as the centrifugal drum attached and suitably stored. The elastic inner shape can be in the mentioned case can also be detached from the poured concrete pipe in a simple manner in such a way that that it is stretched in the axial direction, being underdeveloped in elastic elongation by the action of contraction in the transverse direction which causes expansion in the longitudinal direction ! brings about, separates. Once the elastic inner form has been completely removed from the inside of the concrete pipe has been, it is possible to still use the filler that you have while spinning wants to use to feed, so that it later forms the load-bearing core, which the fresh, prestressed Concrete pipe carries and possibly also, so that the filling contributes to the centrifugal effect.

It is · to be noted that as well as a elastic inner molded envelope can be removed during the centrifugation, such as can be attached to the inside of the concrete pipe during centrifugation. If So for some reason you see the inner shape during the formation of this concrete pipe replacing, this can easily be done while spinning.

It can be made according to the invention further arrangements, so as to allow a certain Wieg a zwangläufige in all respects DeIinung of the forming concrete pipe, for which preferably a uniform displacement of the beam is made possible versclhiedtenein I ₆ to außien.

The filler can be supplied in a heated state. The invention also includes devices according to which the filler during the manufacturing process heat, e.g. B. by Steam supply, can be supplied.

If, in special cases, a further sling is required, for example to increase the height of the degree of prestressing, this can be done by inserting the concrete pipe once into the 'The centrifugal drum is inserted.

In the examples chosen, it is first described that the centrifugal drum is on rollers is hung up. The drum can, however, also by means of one or more bearing journals in the Center line be rotatably mounted.

In the examples chosen, it has been indicated how the filling takes the tension forces from the pre-tensioned one Receives longitudinal reinforcement. In the . Cases where the longitudinal reinforcement is not prestressed it may be advantageous to use a central connecting element - e.g. B. in the form of a Pipe - -between the two end discs (sheet metal funnels etc.), which encloses the filling, seen in the longitudinal direction of the pipe.

It should be emphasized that a draining form on one or both sides of the to Forming concrete pipe can be used, with the liquid either in radial or in can flow in the axial direction.

In the event that the inside (or outside) surface of the pipe becomes rougher than desired, can, preferably before the concrete pipe has reached an appreciable age (for example while it is not yet. 24 hours old), a supplementary, cementitious layer, for example in a vertical position on the pipe, whereby the application of the additional layer is always in full over- ' can be done according to the casting method described in connection with Fig. 5. The elastic sleeve, which is used to apply the very thin finished layer on the inside of the rough concrete pipe is used can be removed after a very short while.

Packing of filler can be done from the center during spinning, for example using a screw mounted in a feed tube for the filler, the sidh rotates, which means that the filling is forced through its axial conveyance is compressed.

According to the invention, various types of filler can come directly into question the inner surface of the pipe and at various distances from it. In loading, In special cases, the last filling at the center line can be made of a concrete cast or the like.

The elastic inner (and possibly the outer shape) can consist of a number of steel strips or 'like. exist, the mutual position of which is slightly changed during the pipe pressing, whereby they act as an "elastic form".

Under "press water" or the like, a liquid mixed with a binder is very generally used Roger that.

It should be noted, for example when spinning in a horizontal position, that the The filler that is added is sufficient to create the required counterpressure against the concrete can, either in that the cavity of the tube is completely filled with filler or by the fact that the arching within the filler is so large that it is possible is to provide an open channel in the middle. ,. ■.

In connection with the final removal of the interior of the concrete pipe it can be advantageous to use the filler, which is firmly

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Is packed together, for example by means of a specially designed drilling device remove.

According to older methods of making prestressed Pipes, the production consists in the fact that the hoop stresses (for example via the smell concrete) should be transferred to a fairly long remaining interior shape. This disadvantage, which has a low production capacity and

ίο causes high costs, is according to idler invention completely avoided.

The invention is concerned with a device and · a method of casting structures and units for the building industry in concrete or similar material with tensioned (prestressed, etc.) reinforcement, in particular of prestressed pipes, the concrete (the concrete wall :) after being poured in a mold; but has not yet set and received strength, subjected to lateral pressure and thereby is deformed and stresses the reinforcement, and is characterized by the fact that the concrete of a passive back pressure is kept in the deformed position, this passive pressure within a filler that is spun is formed.

The manufacturing method according to the invention allows the fresh concrete pipe, if it is taken out of the outer form, treated on the outside, so that the Bumps that drained in the manufacture of pre-stressed pipes against an external one Form normal arise, in a simple 'way Can turn away - 'for example by grinding steel - a Behänd treatment, which can easily turn automatically by pulling the tube while it is rotated and at the same time in its Shifted longitudinally wind, · brought into contact with a rotating grinding wheel or the like will.

When it comes to pipes with small diameters, it can according to the invention 'in The question arises of filling the inner mold completely with concrete - expediently in a vertical position - and then carry out the spinning - advantageously in a horizontal direction -, with the excess concrete at the ends starting from τ. flows. After this has taken place and stabilization has taken place, sand or the like is poured in, and the speed is increased with expansion and preload. In this way, z. B. light masts with a wall thickness of z. B. 2S 20 mm can be produced.

Among the areas of manufacture in which the

.55 Invention is used, the following are mentioned: prestressed pipes, e.g. for water pipes, furthermore Posts, masts and beams of various kinds. In the latter context, it should be emphasized that that, although the above description only deals with round external shapes have been, the invention is not limited to such. The invention also allows Execution of prestressed units, which - seen in cross section - angular, for example have a square shape and are provided, for example, with beveled corners.

A prestressed mast of outer conical shape can, for. B. in a horizontal position with gradually variable inside diameter, using rings at intervals that stay where they are, if that Tube is removed from the outer mold. This procedure is particularly useful at extremely thin-walled constructions.

In contrast to the pre-stressed pipe manufacturing methods, which serve the purpose initially to produce a pipe, which is later surrounded with tensioned reinforcement that is plastered becomes, resulting in very different stresses in the different concrete layers leads, the manufacturing method according to the invention has the advantage that. one gets a concrete, which has a much more uniform load across the entire concrete cross-section. '

For example, when spinning with a horizontal axis, the free inner surface of the Betorube during the first shaping turn it leveled in the same way as it was during manufacture from hurled (non-prestressed pipes) go is common.

It may be possible to use several spinners, one of which is for the implementation of one processing stage and another for the implementation of another processing stage is specially constructed.

It is assumed that the spinner is designed such that the outer shape so extended can turn or the different parts can be removed from each other so that the molded concrete pipe with the other parts made of dbr outer shape -free or without significant friction can be removed. Another possibility is to choose the outer shape from a number assemble of parts into which they can be dismantled to take out the pipe. The separation of the parts of the outer shape is also important in connection with the Shape, e.g. B. by rinsing.

Combinations of spinning and static compression can be considered.

Furthermore, a device can also be used by which the filler vibrates at high frequencies wind, in order to increase the degree of packing, especially directly on the central axis.

If, after a period of storage, an increased degree of packing of the filling is desired, this can be done z. B. od by pressing in tapered rods. Like. From both ends or by use Another device that allows the expansion of the concrete pipe to be achieved.

Whereas in the past in the manufacture of pre-stressed pipes after the primary concrete stabilization the iron was brought to a tension O ₁ , which sank _{to the value of σ 2} after the removal of the inner form -

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The latter value, together with the course of the strength increase of the concrete for the point in time at which the removal of the inner shape of this pipe could take place, was of decisive influence - according to the invention, for example, a first tension of the ring reinforcement to a value of bring about σ ₃ > O ₁ and allow the remaining tension of the ring reinforcement to reach a value of σ ₄ 7> O ₂ ,

ίο because the method according to the invention without economic Disadvantage 'allows the hardening of the concrete to a higher degree before the; Removal of the inner shape takes place. From the economic point of view, it is z. B. not excluded, postpone the removal of the inner shape of the tube for a week or at least several days. Of course, the choice of prestressing of the concrete is largely similar free, and you can, if desired, achieve a higher preload than before.

The invention is not limited to the details of the device described and shown and the manufacturing method according to the invention, but also extends to all any possible combinations of the individual solutions disclosed.

Claims (8)

PATENT CLAIMS: i. Process for the production of hollows of concrete or the like. With prestressed reinforcement by centrifugation, after which first put the ingredients in the mold . the preform that surrounds them low centrifugal force is formed, thereby characterized in that the preform for tensioning the ring preservation by the pressure granular filler poured in during spinning and the concrete of a high spinning effect is exposed. 2. The method according to claim 1, characterized in, that the 'granular filler during! the south oar through one in the feed tube for the filler acting screw or by pneumatic or hydraulic means is put under additional pressure. 3. The method according to ■ claim 1 and 2, characterized characterized in that the hollow body immediately after completion of the spinning out of the mold taken out and during! des, setting continue to leave under the pressure of the filler will. 4. The method according to claim 1 to 3, characterized in that the spinning ^{device is pivoted through about 90 0} after the completion of the spinning and the hollow body is then removed from the mold. 5. Device for performing the method according to claim 1 to 4 with a rotary, and: expandable outer shape, characterized by end walls (4, 18, 24) on the outer shape (1). 6. Apparatus make claim 5, characterized in that the end walls (18, 24) on Hollow body (2) itself detachably attached and. with this and the filling (3) from the outer Form (1) can be removed after spinning is finished. 7. Apparatus according to claim 5 and. 6, characterized in that the rotatable outer Form (1) is mounted with its axis of rotation in a frame, which in turn around another Axis is pivotable, which forms an approximately right angle with the axis of rotation. 8. Apparatus according to claim 5 to 7, characterized by, the end walls of the Form connecting tube in the middle of the filling. Referred publications: German patent specifications No. 801 700, 657 155, 745, 607 424; U.S. Patents Nos. 2,474,660, 2,349,213, 2429012; Swiss patent specification No. 229 572. 1 sheet of drawings