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The EBC control on the Autocor damps unwanted boom vibrations.

Autocor eases pumping duties

01 February 2006

Through the launch of its revolutionary Autocor (automatic concrete placing on rail), Putzmeister has developed a trend-setting system for the automated delivery and placement of concrete in precast plants.

“The Autocor installation particularly makes sense in plants that process pumpable and preferably self-compacting concrete for medium and large-sized precast elements, and even if an expansion is planned for older plants, the Autocor system can be easily retrofitted,” says a spokesman for the German construction equipment giant.
He adds: “Provided there is requirement-compliant planning, the Autocor offers the precasting plant operator several advantages over traditional concreting with finishers, semi-gantry distributors or bottom discharge buckets. These include:
•  Consistent concrete quality;
•  Considerably higher emplacement performance;
•  Lower manpower requirements;
•  Consistent production even with formwork elements of different dimensions and varying heights; and
•  Cleanliness in the complete production process.
Another advantage of the new system is that it is composed of tried and tested systems, says the spokesman.
“An example is the rotor pump system that is well-known from the PUMI, flexible placing booms with a horizontal reach of 16 m to 28 m and a mixer drum with a capacity of 7 cu m as temporary storage. The complete unit is mounted on a rail-guided working platform and needs no support devices.
“In addition, there is the system’s control unit, which is integrated into the production process and the EBC system, which has proven its worth on PM truck-mounted concrete pumps. Among other things, the system dampens the movement of the concrete placing boom while shifting and rotating even at high output. Besides this, the EBC system can – if required – limit the working radius of the placing boom, so that it does not collide with any floor beams or other obstacles in the area.”

Working with Autocor
The spokesman continues: “A typical example of rational, automated concrete placement in precasting plants is the production of tower segments for wind power systems. Due to the varying diameter, the tower segments consist either of half-shells or of differently dimensioned one-piece ring elements. These parts are manufactured from pumpable standard concrete and from self-compacting concrete (SCC). To avoid the penetration of air during the processing of the SCC material, the concrete level is built up from the bottom when filling the differently-sized formwork units, the concrete level must be built up from the bottom, which means that the end hose is immersed deeply into the unset filled concrete. This is ensured at all times by the automated concrete placement performed by the Autocor system, which in connection with the EBC control unit and additional sensors, raises the placing boom automatically.
“A monorail overhead bucket transport system provides the Autocor with concrete from the mixing plant. The material is treated once again and homogenised with the previous batch in the Autocor mixer drum. In addition, the drum serves as a temporary storage facility and ensures that the Autocor can operate continuously. The concrete is delivered by a rotor pump, which Putzmeister offers in two versions – an optional flow rate of 60 or 80 cu m/h (maximum, theoretical) – for use in precasting plants. Due to the design, hardly any residual concrete arises with this pump system. The workshop remains clean because the concrete is transported within a closed system (overhead bucket transport system – mixer drum – pump – boom delivery line – formwork). When the machine is moved, a pneumatically-actuated squeeze valve attached to the end hose ensures that there is no concrete after-dripping during relocation.”
“Operating experience with Autocor is nothing but positive. According to customer information, production can be increased by up to 60 per cent compared with the previous method using automated concrete placement for precast elements. Due to the intensive treatment in the Autocor mixer drum a consistently high quality of unset concrete is also obtained. Any later labour-intensive reworking of the precastings, like smoothing and grinding, is reduced to a minimum. A change in the concrete type is also possible without difficulty,” he concludes.