Advancing to perfection
New concept for the clamping unit of the EBLOW from BEKUM
Berlin, 07/10/10: The global premiere of the EBLOW electric blow moulding machine at the K'07 sees BEKUM take a new technological path. The findings of several thousand operating hours in the development lab in Berlin and constructive advice from our customers were all used in the further development of the EBLOW x07 D series. The more powerful EBLOW x07 D now has mould plate widths of 350 mm to 700 mm and a clamping force of 80 to 240 kN as a single and dual-station unit. The core of the EBLOW x07 D is a precise and energy-efficient clamping unit that has been newly developed by the Berlin-based company and which is also available for hydraulic blow moulding machines.
The construction is based on highly-efficient electric drives at the main axis of the blow moulding machine. The electro-mechanical axis were designed and built to meet the special requirements of the respective functions.
New clamping unit with symmetric force distribution
In addition to this the very important function of the clamping unit of the EBLOW x07 D has been redeveloped. Optimised clamping force generation and distribution have perfected the squeezing of the parison waste portion. The heart of the new clamping unit is the C – base frame, which, like all main components, was subjected to FEM analysis. The design of the C – base frame, which utilises closing plates that move along precise, low-friction linear guides, enables completely symmetrical force distribution over the entire mould area while maintaining high parallelism of the closing plates.
New unit improves operational usage
The calibration point always stays in exactly the same position after closure of the mould – the mould parting line. The construction of the new system also allows optimal installation of bottom calibration station which raises production output. The system is downwardly compatible: besides the proven mould quick-change function, the mould attachment points have also been retained. Thus nearly all standard moulds of previous BEKUM series can be adapted.
Movement of the moulds in the new clamping unit
The mould closing motion utilises a patented and thus exclusive drive technology featuring a combination of a servo motor and hydrostatic transmission. This drive technology performs the “closing and opening movement on the mould carrier unit positioned on linear guides” cycle very quickly. The dead times of the overall process are considerably reduced by this. The consistently high and precise distribution of force during the squeezing process results in ideal formation of the article. The user can always make full use of the clamping force without adjustment and irrespective of the mould thickness. The clamping force and speed can be adjusted to meet the process requirements exactly.
Fast carriage movement in the new clamping unit
The carriage movement “transfer of the clamping unit from blower head position to calibration position” is performed using a simple, low-maintenance, robust crank drive. This enables positioning of the carriage precise to 0.01 mm without mechanical stop at an average speed of 680 mm/s, i.e. a 300 mm stroke requires just 0.44 seconds. According to BEKUM, the highly dynamic and precise electromechanical axis sets new standards in blow moulding machine technology.
Hybrid drive combines dynamism and force
The hybrid drive for the closing system, which was developed together with Bosch-Rexroth, not only fulfils the dynamic requirements of the axis but also the need for fast, stroke-independent force generation when the mould closes as well as ensuring the energy consumption and noise emission levels expected of modern machines. The drive can retain forces for a long time and gently absorb fast force changes. The drive system works in an energy efficient manner and closes precisely, reducing noise emissions to 68 dB. The two development partners have broken new ground with this system, which does not require a classical hydraulic system with a tank and displacer.
Hybrid drive reduces load with high retention forces
A hydraulic transmission was placed between the electric drive and linear axis for the BEKUM closing system. This serves to convert the rotary motion into linear motion. This facilitates an intelligent switching between speed and power strokes. This significantly reduces the load on the drive side and the ball screw drive. A blocking function in the hydraulic transmission means that the clamping force can be retained without drive torque – just as with a conventional hydraulic machine.
Series design for hydraulic and electric blow moulding machines
The new clamping unit was developed as part of an overall solution for economical high-performance blow moulding machines. It is available for the EBLOW x07 D series of electric blow moulding machines and will shortly be available for the BM x07 D series of hydraulic blow moulding machines. This technology enables energy-efficient, quiet and smooth operation, resulting in less wear and tear for the blow mould machine and moulds, which in turn extends the life of the unit.
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