3D concrete printing with the aid of AKO pinch valves from the VMP series

AKO supplies a pinch valve for prototypes of a 3D concrete printing robot. The valve from the VMP series with a nominal size of DN 25 was supplied with an anti-abrasive sleeve to guarantee a long and reliable service life. In addition, a safety arrangement (protection circuit) was installed on the pinch valves that keeps the valve closed in the event of a loss of compressed air.

The printing robot fitted with the AKO pinch valve works with high-performance concrete that is mixed with additives with sizes ranging from 0.3 mm – 1 mm (0.12 line – 0.39 line). This is why an abrasion-resistant pinch valve sleeve made out of high-performance natural rubber is used with this abrasive medium.

The world's first 3D concrete printing robot has been in the development phase for around two years and should be launched on the market at the end of 2018. After it has launched on the market, it will be possible to directly produce a wide range of concrete elements on-site with the aid of the printing robot – including the installed AKO pinch valve. The 3D printer will be able to produce small precast concrete parts through to wall cladding elements on order.

The 3D printing robot is as tall as a man and has a six-axis arm mounted on a gantry crane that allows it to complete its assigned tasks quickly and flexibly. The concrete is sprayed through a printing nozzle (diameter: around 10 mm / 0.39 in) in a pendulum motion to produce the desired dimensions. The robot is thus able to “print” the desired form or three-dimensional object layer by layer. The AKO pinch valve from the VMP series is installed before the printing nozzle and is responsible for the correct dosing and reliable shutting off or releasing of the high-performance concrete. Due to its abrasion-resistant sleeve, the pinch valve is resistant to the abrasive properties of the concrete mixed with additives.

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The first initial tests using a valve with a pneumatic cylinder raised some safety concerns because there was no safe way to reliably divert excess pressure that may have built up within the system without causing any damage because the excess pressure would have made the pneumatic cylinder uncontrollable.

Many different alternatives were considered until the company finally decided on the currently installed pinch valves from the VMP series from AKO. By releasing compressed air from the pinch valve, it is possible for the excess pressure to escape from the system unhindered without damaging any components or making them unusable. If the pressure rises to a dangerous level, it can automatically escape via the pinch valve because it starts to open automatically from a certain differential pressure. Another advantage was the weight reduction that could be achieved by installing a pinch valve. The total weight of the old control valve exceeded 40 kilograms (88.18 lb), while the VMP pinch valve weighs just 500 grams (1.1 lb). The manufacturer was thus able to make weight savings of more than 98% in this area.
The research engineer responsible for the project:

  "We are very satisfied with the installed pinch valve and particularly impressed with the range of products offered by AKO. It is good to know that the process can be scaled up in the future should we require larger valves."