Octopus locking bush for a simple mechanical solution works with the hydraulic pressure available on a tablet compaction simulator to give a compact assembly easy to connect and disconnect.

Huxley Bertram Engineering design and make special purpose industrial machinery. When their new tablet compaction simulator needed a holding brake, the need was met by an ETP Octopus locking bush for a simple mechanical solution. The ETP Octopus works with the hydraulic pressure available on the machine and gives a compact assembly that is easy to connect and disconnect.

Huxley Bertram, based at Cottenham near Cambridge, UK, developed their new two-pillar machine for pharmaceutical companies to use in the development of new commercial drugs, or to mimic the performance of production compaction machinery for the purpose of investigating production problems.

Typical output rates are 1-2 tablets per minute.

A hopper filled with powder is positioned over the die-plate in the centre of the machine.

Powder falls into the die and the hopper is retracted when the level, confirmed by a laser sensor, is correct.

At the final compaction stage where maximum force is applied, a locking brake is needed to stop the tendency of the hydraulic oil compressing and giving a bounce effect.

The lower actuator is locked by a bush called the Octopus.

ETP, a Swedish company, is the manufacturer.

They specialise in hydro-mechanical connection technology.

The Octopus is a hydraulic actuated joint with a flanged end and, in this application, it is rigidly fixed under the die plate.

When the tablet is compressed and the machine hydraulic pressure of 280-bar applied, the inner sleeve of the cylinder contracts and rigidly grips a split collet, which transmits the force through to the 45mm actuator rod.

The action is fast and repeatable with a life of about 500,000 cycles.

With the bottom actuator locked, final compaction can be carried out using the top actuator.

Then the tablet is ejected into an output carousel.

Designed to transmit both torque and axial forces, the Octopus bush is rated at 67kN axially, safely above the maximum piston force of 50kN.

Lenze supply ETP Octopus bushes in a standard range to clamp shafts between 30 and 100 mm and special designs are possible.

Other application areas include the locking of machine slides and tool holders in machining centres.