Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B17/00—Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
  • B28B17/0063—Control arrangements
  • B28B17/0081—Process control
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B21/00—Methods or machines specially adapted for the production of tubular articles
  • B28B21/02—Methods or machines specially adapted for the production of tubular articles by casting into moulds
  • B28B21/06—Methods or machines specially adapted for the production of tubular articles by casting into moulds into moulds having sliding parts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B21/00—Methods or machines specially adapted for the production of tubular articles
  • B28B21/02—Methods or machines specially adapted for the production of tubular articles by casting into moulds
  • B28B21/10—Methods or machines specially adapted for the production of tubular articles by casting into moulds using compacting means
  • B28B21/22—Methods or machines specially adapted for the production of tubular articles by casting into moulds using compacting means using rotatable mould or core parts
  • B28B21/24—Methods or machines specially adapted for the production of tubular articles by casting into moulds using compacting means using rotatable mould or core parts using compacting heads, rollers, or the like
  • B28B21/26—Methods or machines specially adapted for the production of tubular articles by casting into moulds using compacting means using rotatable mould or core parts using compacting heads, rollers, or the like with a packer head serving as a sliding mould or provided with guiding means for feeding the material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B21/00—Methods or machines specially adapted for the production of tubular articles
  • B28B21/02—Methods or machines specially adapted for the production of tubular articles by casting into moulds
  • B28B21/10—Methods or machines specially adapted for the production of tubular articles by casting into moulds using compacting means
  • B28B21/22—Methods or machines specially adapted for the production of tubular articles by casting into moulds using compacting means using rotatable mould or core parts
  • B28B21/24—Methods or machines specially adapted for the production of tubular articles by casting into moulds using compacting means using rotatable mould or core parts using compacting heads, rollers, or the like
  • B28B21/28—Methods or machines specially adapted for the production of tubular articles by casting into moulds using compacting means using rotatable mould or core parts using compacting heads, rollers, or the like combined with vibration means

Definitions

• the invention concerns a slip-form machine for casting hollow objects, in particular pipes of concrete or a similar material, substantially vertically by means of successively progressive zonewise vibration compression, comprising inner and outer slip-form mould parts, respectively, which are slidingly displaced along the already cast part of the hollow object during the casting process, the inner mould part being divided into at least two sections interconnected via one or more elastic spacers, the uppermost one of said sections containing at least one vibrator.
• the vibrator is positioned right at the top of the inner mould part, and the two mould parts are displaced axially with respect to each other during casting.
• This displacement can take place e.g. in that the outer mould part is stationary, while the inner mould part continuously rises from below up into the outer mould part, while the mould is simul ⁇ taneously successively filled with so much fresh concrete that a specific layer of concrete is constantly disposed around the area of the top of the mould part where the vibrator is present.
• This layer which moves upwardly in the mould together with the rise of the inner mould part, will substantially be in the same state of vibration in all the levels of the mould and will moreover be vibrated for the same period of time, so that the vibration compression process can be controlled better and the finished pipe can have a more uniform quality in the longitudinal direction.
• the previously mentioned drawbacks associated with casting in stationary mould parts are not eliminated completely. The reason is that the vibrations propagate from the top down through the inner mould part and thereby still bring the concrete into vibration states, which depend on the level of the concrete in the mould, during the course of the overall casting process, just as, in this case too, the concrete is vibrated for a longer time downwardly in the mould than upwardly.
• this improved method to cast a concrete pipe which fully satisfies the requirements which are today made with respect to a well-defined high and uniform quality of a concrete pipe throughout its overall length.
• the method requires huge investments in the many moulds which a manufacturer with a reasonably great range of goods must necessarily have in store, because a set of associated mould parts can only be used for a specific diameter and a specific length, and because the tools themselves are moreover very expensive since both mould parts must at least have the same length as the cast hollow body or pipe.
• the object of the invention is to provide a machine of the type mentioned in the opening paragraph, which, with a minimum energy consumption for the vibration compression process and relatively modest investments in moulds, is capable of making a great range of cast hollow objects, in particular concrete pipes, within a shorter working cycle than before, which have a perfect uniform quality through ⁇ out the longitudinal direction, and which also carefully observes the prescribed tolerances longiditudinally as well as transversely.
• the inner mould part is elastically suspended from the upper section of the mould part, and it is therefore present in a labile state in itself, in which it is not capable of absorbing transverse forces.
• the lower section is nevertheless kept safely in place in the transverse direction by the outer mould part via the compressed quiet concrete in the zone between the outer mould part and the lower section of the inner mould part.
• the concrete is kept in a form of liquid state by the vibrations, so that the concrete is distributed evenly and uniformly along the periphery.
• the concrete will enter the underlying quiet concrete zone and ensure that the lower section of the inner mould part is constantly kept in a position concentric with the outer mould part, so that the wall thickness of the finished pipe is completely uniform along the periphery.
• the outer mould part may thus be built as a sheet iron structure which has natural frequencies in itself that differ significantly from the vibration frequency.
• This structure may in turn be provided with a heavy mass of e.g. concrete, which imparts natural frequencies to the overall outer mould which are so much below the vibration frequency that the outer mould cannot keep up with the applied rapid vibrations and therefore remains standing in a quiet state.
• the outer mould part may therefore be suspended freely from e.g. wires or be rigidly suspended from machine parts, whose mass then contributes to determining the natural frequency of the outer mould part to a certain extent.
• the vibrations entail that the concrete is brought into a form of liquid compressible state.
• the volume of the concrete is reduced during the compression, and in the prior art this causes vertical transport of material to take place in the ring gap between the two mould parts, so that filling of the mould and the compression of the concrete are impeded significantly because of the friction between the concrete and the mould parts.
• the uppermost section of the inner mould part has an upper conical portion with a conicity which downwardly narrows the cross sectional area of the ring gap between the conical portion and the inner side of the outer mould part in a proportion which is substantially inversely propor ⁇ tional to the increase in density which the compression simultaneously imparts to the concrete during the relative axial displacement between the two mould parts.
• Compression of the concrete requires that the concrete is loaded with a suitable static pressure, which conventio- nally just consists of the weight of the overlying column of concrete.
• a suitable static pressure which conventio- nally just consists of the weight of the overlying column of concrete.
• loading of the narrow vibration zone, which does not have any greater amount of concrete disposed thereover is relatively small, and, according to an advantageous embodiment of the invention, the inner mould part is therefore suspended rotatably, and the conical portion of the upper section is equipped with a generally multi-thread screw, which serves to transport the concrete downwardly and to simultaneously apply to the concrete a predetermined downwardly directed static pressure during the compression process, which can thus be controlled optimally by means of a suitable selection of the pitch of the convolutions and the speed of rotation o the inner mould part.
• a profile ring is usually employed, having the same nominal inside diameter as the pipe.
• the convolu ⁇ tions are dimensioned with an outside diameter which is throughout at least slightly smaller than the inside diameter of the profile ring opening, so that the upper ⁇ most section can pass upwardly through this opening durin the final phase of the casting.
• a rotating vibrator is used, imparting rotating horizontal vibrations to the uppermost section.
• another type of vibrator is used, imparting horizontal vibrations to the uppermost section with directions of deflection which lie in a predetermined fixed plane through the axis of the section. This additionally reduces the amount of concrete which vibrates, and since the deflection plane follows th rotation of the section it is simultaneously ensured that the concrete is vibration-compressed completely uniformly around the periphery of the pipe.
• the machine of the invention has been given a pattern of motion where the mould parts are displaced suc that the lower edge of the part of the outer mould part which contacts the already cast part of the hollow body o the concrete pipe, is constantly at a lower level than partly the actual vibrated zone of the concrete, partly the upper edge of the lowermost section of the inner mould part after said section has contacted the concrete.
• the machine of the invention lends itself to casting of hollow objects or concrete pipes having a cross-section which is uniform or varies longitudinally.
• concrete pipes are generally provided with a socket at one end and a spigot at the other which mates with the socket of an adjoining pipe. Therefore, the two mould parts of the machine do not always move together during the casting process, the machine having a pattern of motion where the mould parts are mutually displaced upwardly in dependence on the cross-sectional shape which is desired in each individual case in a specific casting level.
• the uppermost section of the inner mould part moreover has a cylindrical portion which is in continuation of the conical portion, and which, by a intermediate elastic sealing ring, is continued by the lower, likewise cylindrical section of the mould part.
• the cylindrical portion of it acts as a trowel that smooths the concrete and imparts a tight and smooth inside surface to the finished pipe.
• a surface improving material is pumped via a pipe connection out through at least one opening in the uppermost section.
• this opening describes a screw line, whereby the surface improving material is applied to or incorporated in the concrete surface evenly and uniformly.
• useful surface improving materials include fine concrete, plastics or water.
• fig. 1 shows a set of mould parts for normal casting of concrete pipes with stationary or mutually displaceable mould parts
• fig. 2 shows a set of mould parts for slip-form casting
• fig. 3 shows the slip-form mould parts of fig. 2 suspended in a casting machine
• fig. 4 is an enlarged, partly sectional view of a concrete pipe being cast by means of the set of slip-form mould parts shown in fig. 2,
• figs. 5a-p are partial axial sectional views of various stages in the casting of a concrete pipe with a socket end and a spigot end by means of a set of slip-form mould parts and an upper profile ring firmly arranged in the outer mould part for shaping the spigot end,
• figs. 6a-p are partial axial sectional views of various stages in the casting of a concrete pipe with a socket end and a spigot end by means of a set of slip-form mould parts and a freely displaceable upper profile ring for shaping the spigot end,
• fig. 7 is a side view of the top of a rotating inner mould part according to the invention with incorporated sensor
• fig. 8 shows the same, but in a partial axial section, where the sensor is clearly visible
• fig. 9 is a side view of the top of an inner mould part according to the invention with the outer wall partly removed so that a pipe connection to a surface improving material is visible, and
• fig- 10 shows the same, but in a partial axial section.
• Fig. 1 shows a set of mould parts 1, 2, which may be for traditional casting of concrete pipes with stationary mould parts, or for casting with displaceable mould parts, as described e.g. in the applicant's Danish Patent
• the mould parts must have a length at least equal to the finished pipe, and it is moreover usually necessary to provide a separate set of mould parts for each pipe length within a specific dimension. These casting methods therefore require huge investments in moulds, if the concrete product manu ⁇ facturer is to be capable of producing and supplying a reasonably great range of goods.
• the set of slip-form mould parts 3, 4 shown in fig. 2 is relatively short and therefore inexpensive and the overall investments in moulds are reduced additionally to a significant degree, because a set of mould parts can be used for pipes in all lengths, provided that the pipes have the same diameter and are otherwise shaped in the same manner at the ends, e.g. with uniform socket and spigot ends.
• the slip-form mould parts facilitate handling and transport of the moulds, as well as switching from one pipe length to another within a specific diameter, because such switching now does not require laborious exchange of the mould parts, but merely quick and simple adjustment of the casting length of the machine.
• Fig. 3 shows the set of mould parts 3, 4 of fig. 2 suspended in a casting machine which is generally designated 6.
• the mould parts are displaced upwardly during casting and finally leave the finished and demoulded pipes standing on a bottom ring, ready for being transported to a curing site by means of e.g. a fork truck.
• the slip-form casting can also take place by lowering the pipe with respect to the mould parts, which will therefore just have to be dis ⁇ placed mutually to the extent necessary for casting the socket and spigot ends of the pipe.
• Fig. 4 shows on an enlarged scale how a concrete pipe 8 is cast by means of an outer slip-form mould part 9 and an inner slip-form mould part 10.
• the outer mould part 9 is built as a sheet iron structure with internal and external shells 11, 12 which are connected with upper and lower plate rings 13, 14.
• This structure per se has a natural frequency which is either considerably greater or con ⁇ siderably smaller than the vibration frequency.
• the cavity of the structure is filled with concrete which, together with the iron structure, imparts such a great overall mass to the outer mould part that the natural frequency of the mould part will be much below the vibration frequency.
• the outer mould part may be rigidly suspended from an axially displaceable machine part which is associated with the machine 6, and which will thereby contribute to the overall mass of the outer mould part to a certain degree.
• other materials than concrete may be used for filling the cavity of the sheet iron structure.
• lead may advantageously be used for limiting the outer diameter of the mould part, or a liquid such as water or oil which can be drained when the mould part is to be transported or be stored for an extended period of time.
• the inner mould part 10 is suspended from an axially displaceable machine part 16 and is divided into an upper section 17 and a lower section 18.
• the upper section 17 moreover contains a vibrator (not shown), the vibrations themselves being indicated by the symbol 19.
• the lower section 18 is suspended from the upper section 17 by means of a plurality of elastic spacers, which are rubber buffers 20 in the shown case, but may also suitably be springs.
• the gap between the two sections 17, 18 is outwardly sealed with a sealing ring 21 of e.g. rubber or an elastic plastics material.
• Casting of the concrete pipe 8 now takes place by filling fresh concrete into the ring gap between the two mould parts 9, 11 as these are displaced upwardly in the direction indicated by the arrows.
• the vibrator is constantly activated during this, as indicated by the symbol 19, and the vibrator thereby vibrates the upper section 17, said section in turn bringing the surrounding concrete into vibrations.
• the vibrations are not capable of propagating out to the outer mould part 9 because of the great difference between the natural frequencies of said outer mould part and the vibration frequency, and the outer mould part will therefore hang quietly in the wires 15, while it is successively displaced vertically upwardly during the casting process.
• the concrete pipes can therefore be cast with an unprecedented uniformity and precision in the transverse direction.
• the lower section 18 of the inner mould part 10 which calibrates the pipe interiorly, cannot absorb transverse forces owing to its elastic suspension from the rubber buffers 20 and therefore cannot by itself assume a position concentric with the outer mould part 9.
• the outer mould part which stably supports the inner mould part via the intermediate quiet concrete zone, which was formed as a concentric ring already during the immediately preceding vibration compression, in which the concrete was in a form of liquid state, said ring being sufficiently strong, because of the compression, to be capable of transmitting transverse forces between the outer mould part 9 and the lower section 18 of the inner mould part 10.
• the outer mould part is determined, as explained previously, and when the inner mould part is of the non-rotatable type, the correct coaxial position of the upper section can be ensured by means of a sufficiently rigid suspension in the casting machine, so that the axis of the upper section, force controlled, will coinside with the defined pipe axis during the vertical displacement of the inner mould part.
• Such forced control is not necessary when the inner mould part rotates during the casting process.
• the inner mould part may be suspended from e.g. a vertical rod which is suffi ⁇ ciently dimensioned to transmit the necessary torsional moment to overcome the frictional forces between the inner mould part and the concrete without, however, being capable of absorbing major transverse forces.
• the outer mould part is given a natural vibration frequency which, in addition to being signifi ⁇ cantly different from the vibration frequency, is pre- ferably considerably lower than the number of revolutions of the inner mould part, such that the outer mould part is not vibrated because of the rotation of the inner mould part.
• the lower edge of the outer mould part is flush with the lower edge of the lower section.
• the two lower edges can extend in any other manner with respect to each other, but the lower edge of the outer mould part must never be in the immediate vicinity of or above the upper edge of the lower section or at the same level as the actual, vibrated zone of the concrete. This would entail that the lower section would no longer be duly supported by the outer mould part, and that moreover there would no quiet, vibration- insulating concrete zone above the exposed pipe, which would therefore be deformed or collapse.
• the upper section 17 is provided with an upper conical portion 22 whose conicity is adapted such that the cross sectional area of the ring gap is narrowed downwardly in a proportion which is inversely proportional to the increase in density which the compression simul ⁇ taneously imparts to the concrete during the relative axial displacement between the two mould parts.
• the concrete For the compression to take place, the concrete, as ex ⁇ plained above, must be brought into a liquid state by the vibrations, and the concrete must be affected by a verti- cal static pressure which is usually provided by the weight of the overlying column of concrete.
• this column is usually relatively low, and the static pressure on the concrete is therefore small and also varies greatly with just small changes in the filling rate.
• the inner mould part 10 can therefore be caused to rotate during casting in the direction shown by the arrow, and the conical portion 22 of the upper section is moreover provided with preferably several convolutions which, at a specific speed of rotation, apply to the concrete a predetermined downwardly directed pressure which is considerably greater than the pressure from the overlying concrete column.
• This pressure can be regulated by changing the speed of rotation and by means of a suitable selection of the pitch of the convo- lutions. It has been found that the optimum pressure im ⁇ pact on the concrete can be obtained best when this pitch is relatively small and when there are several convolu ⁇ tions which together form a multi-thread screw.
• the conical portion 22 of the upper section 7 downwardly merges into a cylindrical portion 23, which, via the elastic sealing ring 21, continues in the lower section 18 which, as mentioned before, i.a. serves to calibrate the pipe interiorly, but which also serves as a trowel smoothing the surface of the concrete during the rotation of the inner mould part. If the height of the lower section 18 is too low, the calibration will be incomplete, since it can then partly take place in the transition zone to the not yet finish-compressed concrete, and if the cylindrical portion is too high, too great friction forces can easily occur between the portion and the concrete, which is thereby affected by a torque which can entail deformation in the pipe.
• the best solution to these conflicting conditions is that the height of the lower section 18 is between 0.1-1.0, preferably between 0.3-0.7 and in particular between 0.4-0.6 times the diameter of the portion.
• Figs. 5a-p show various stages in the slip-form casting of a concrete pipe 24, said pipe being in this case provided with a socket 25 and a spigot 26.
• the outer part is indicated by the reference numeral 27 and the inner mould part by the reference numeral 28.
• the outer mould part 27 is suspended from wires 29 in the same manner as the outer mould 9 shown in fig. 4, but it may also be suspended from a rigid, but vertically displaceable machine part, as shown in fig. 3.
• a profile ring 30 for shaping the spigot end 26 is firmly mounted upwardly in the outer mould part 27, and a filling hopper 31 is in turn mounted on top of the profile ring.
• the outer mould part Downwardly, the outer mould part has an inside expansion 33, which corresponds to the outer side of the pipe socket 25, and which, together with a bottom ring 32 for supporting the cast pipe 24, serves to shape the pipe socket 25.
• the machine In order to be able to cast the pipe 24 with the socket 35 and the spigot end 26, the machine must be adapted such that the mould parts 27, 28 has a quite specific pattern of motion during the casting process, which depends on th specific shape of the pipe in each individual case.
• the mould parts 27, 28 are present in their starting positions in which the lower end of the outer mould part contacts or is positioned in the immediate vicinity of the bottom ring 32, and the inner mould part 28 is in the opening of the bottom ring with the conical portion positioned slightly above the upper side of the bottom ring.
• the mould is thus closed downwardly and can therefore be filled with concrete, as shown in figs. 5b, c and d, the position of the outer mould part being unchanged, while the inner mould part, which now rotates and simultaneously vibrates, is displaced upwardly during casting of the socket 25.
• the shank of the pipe is cast, the outer mould part now following the continued upward displacement of the inner mould part, until the outer mould part has reached its upper casting position in fig.
• FIG. 5f in which the shank of the pipe is finished by and large, and casting of the spigot end is to begin.
• Figs. 5g, h and i show how the spigot end is cast, while the outer mould part stands still and the inner mould part continues its upward displacement through the opening of the profile ring until the mould part has emerged completely from the opening in fig. 5i.
• the concrete in the area of difficult access just below the profile ring is compressed during this by the multi-thread screw on the conical portion of the inner mould part, and the excess concrete is collected in a compressed state in the filling hopper 31.
• the pipe is now finished, and then the vibrator is stopped, as shown in fig. 5j, while the outer mould part is displaced upwardly, as shown in fig.
• Figs. 6a-f show how the casting of the socket and shank of the pipe takes place by means of exactly the same pattern of motion as is shown in figs. 5a-f, which will therefore not be described more fully again.
• the upper profile ring 35 is already on its way to the position shown in figs.
• Figs. 60 and p show a variant of the casting process in which a reinforcement 36 is placed on the bottom ring 32 before the mould parts are returned to their starting positions. This reinforcement will then be embedded in the pipe during the subsequent working cycle, which takes place in quite the same manner as described above.
• the inner mould part 28 must be capable of passing the opening of the profile ring 30; 35, and the convolutions of the mould part must there ⁇ fore have an outside diameter which is slightly smaller than the diameter of this opening.
• the vibrator used may be a rotating vibrator, which rotates in the same or opposite direction of the inner mould part.
• the vibrations take place with a frequency of between 50 and 250 Hz, and the inner mould part rotates at a rate of up to 200 rotations per minute.
• a rotating vibrator it is possible to use a vibrator which just brings the uppermost section of the inner mould part into horizontal vibrations with directions of deflection which lie in a fixed plane through the axis of the inner mould part, and which therefore rotate with the same speed of rotation as this mould part.
• this vibrator type is used, the mass of the concrete amount subjected to vibrations at a given moment is additionally reduced to a significant degree with the consequent advantages in the form of e.g. reduced energy consumption.
• the optimum vibration compression conditions which are capable of keeping the density of the concrete at the desired level during the entire casting process, can be provided by adjusting one or more of the parameters, the relative speed of displacement between the mould parts, the speed of rotation of the inner mould part, as well as the frequency and/or amplitude of the vibrations. These parameters are controlled by a preprogrammed computer in response to the signals from a sensor 37, which is positioned in the upper section 17, as shown in figs. 7 and 8.
• the sensor may e.g. be adapted to measure the rate of an ultrasonic pulse during the passage to and fro through the wall of the cast pipe to the inner side of the outer mould part 9 (fig.
• the sensor system is then to be constructed as a transceiver system measuring the time delay of the reflected signal from the outer mould part.
• the sensor 37 describes a screw line because of the simultaneous rotation and rise of the inner mould part 10.
• the wall of the cast concrete pipe is hereby inspected completely in its entire extent, and the mentioned ultrasound rate can be used as a measure of the quality of the compression by comparison with reference values known in advance, and the quality of the compression can thus not only be registered passively, but also be controlled actively if desired.
• ultrasound sensors may be used, but also other suitable forms of sensors, e.g. X-ray sensors.
• Figs. 9 and 10 show a pipe connection 38 which terminates in an outlet opening 39 in the upper section 17.
• the pipe connection 38 is connected with a reservoir (not shown) of a surface improving material, which can thereby be con ⁇ veyed to the outlet opening 39 by means of e.g. a pump (not shown).
• a surface improving material which can thereby be con ⁇ veyed to the outlet opening 39 by means of e.g. a pump (not shown).
• a surface improving material may be fine concrete or plastics which settles as a thin layer on top of the concrete, or e.g. just water which brings the outermost surface of the concrete into a liquid state which can easily be smoothed to an even and tight layer.
• the machine of the invention now makes it possible to cast e.g. a concrete pipe in a shorter working cycle, with much smaller investments in moulds, and with a smaller energy consumption than known before.
• the machine ensures that the cast pipe has a completely uniform quality both in the longitudinal direction and along the periphery, and that the pipe can be cast with much narrower longitudinal and diameter tolerances than before.
• the process is moreover self-adjusting, such that a uniform quality is ensured from pipe to pipe in series of a desired size.
• the process can be switched easily and quickly from one quality to another by changing the production parameters via the control system.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Automation & Control Theory (AREA)
• On-Site Construction Work That Accompanies The Preparation And Application Of Concrete (AREA)
• Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8096673

Family Applications (1)

Country Status (3)

Cited By (4)

Citations (6)

• 1991
  • 1991-04-19 DK DK71291A patent/DK71291D0/da not_active Application Discontinuation
• 1992
  • 1992-04-15 WO PCT/DK1992/000127 patent/WO1992018308A1/en active Application Filing
  • 1992-04-15 AU AU16858/92A patent/AU1685892A/en not_active Abandoned

Patent Citations (6)

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