Assembly-friendly system solution for demanding machining centres

Profile

What was needed: Ready-to-install energy supply system for the spindle of machining centres
Requirements: Narrow bend radii, compact design, suitable chain and cables for high speed, long service life and easy installation
Product: readychain® harnessed energy chain
Field of application: Machining centre
Success for the customer: Assembly-friendly and compactly built complete solution from igus, which reliably guides more than 50 supply cables and can be retrofitted if required

About machining centres:The GS series of machining centres from Alzmetall is characterised by high dynamics and precision. It is mainly used for demanding machining tasks in high-volume production, tool and mould making, prototype construction and in the aviation industry.

The GS 800 was added to Alzmetall's family of machining centres in 2001 and immediately became a successful model, winning the German Federal Innovation Award in 2002 for its numerous innovative design features. In 2005, with the GS 1000, an upward expansion followed in two respects. On the one hand, the machining space has been expanded to 1070 mm in the A-axis, and on the other hand there is a choice of direct drives with torque technology or conventional servo drives for the two rotary axes. Both variants have been well received by users worldwide and have become a hit for Alzmetall.

In September 2006 the GS series was extended downwards. The GS 650 is specifically designed for users who demand precision and performance that cannot be met by conventional frame designs. This was first presented at the AMB in Stuttgart in autumn 2006. The machine is designed as a true gantry system and, in contrast to the GS 800 and GS 1000, is offered in A and C axis exclusively with highly dynamic and maintenance-free torque drives. High accuracies (Tp=0.007) and high machining speeds are available for use in single-part production and in volume production, in tool and mould making and in general mechanical engineering.

In addition to the 5-axis simultaneous version, there is a 3-axis version with a fixed table and optionally a 4th axis with counter bearing.
Integration into automated production systems can be achieved with a linear robot solution - the machine can be fully lifted from above - as well as with a pallet changer or an articulated arm robot for loading from the front, e.g. also with a zero-point clamping system.

The challenge

The machines require more than 50 supply cables for the spindle. This requires a compact design of the energy supply system or the complete system. Alzmetall requires that no cables are visible and that no components protrude from the machine.

The spindle, which operates at up to 30,000 min^-1, requires a total of 50 to 60 energy and signal cables - including electrical cables for servo drives, hydraulic hoses for the tool clamp, encoder and measuring system cables as well as supply cables for coolant and a compressed air supply to blow out the spindle. Therefore, here are required cables that allow small bend radii and are characterised by a long service life even under continuous movement stress.

Despite the compact type and tight bend radii, the chains and with them the cables move at high speed. In rapid motion, the spindle travels at up to 60 m/sec and achieves an acceleration of up to 10 m/sec². In free space, acceleration values of even up to 17 m/sec² are required: This places high demands on the quality of the cables and the energy chain.

Solution

igus was already involved in the development of the GS 800 at an early stage. Hans Jürgen Gizler: "The question was: What do you have to consider if you want to purchase a cost-effective, durable complete system? This question was answered satisfactorily by igus.

Therefore it seemed only logical to repeat this procedure with the new GS 650: igus supplies ready-to-connect, pre-assembled energy chains with integrated cable packages for every machine. This saves Alzmetall assembly time. And this is an important factor, because speed is considered a competitive advantage.

Compact design – movable in three axes
Due to the chain and the readychain principle it is possible to build in a very compact manner: The tight bend radii are only possible with chainflex cables. In addition, the requirement that no cables are visible and no components protrude could be achieved thanks to the igus e-chains.

The energy chain system of the GS 650 ensures mobility in three axes. The x-axis moves separately, while the y and z axis overlap. Installation is very simple, as all three chains end in a distribution box supplied by igus. The x-axis is designed horizontally and uses the upper machine cover as a support, on which it is supported by a bridge: a design detail that saves space and ensures optimum guidance of the chain.

The energy chain series used, the E 4/4 Light, is characterised by very compact external dimensions; for the same content, the chain is 20 mm narrower. It was precisely these 20 mm that ensured that the chain remained within the machine contour during all movements.

Ideal also for maintenance and retrofitting
Two variants were specified for the chain assignment: one for the standard versions of the GS 650, a second with additional cooling hoses for the more powerful spindle with 30,000 min-1. These variants, which are harnessed in Cologne, are delivered by igus just in time to Altenmarkt. Of course, additional cables can be integrated into the chain if required. This is even possible in retrospect - an argument that also convinced the designers at Alzmetall.

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Overview: Applications with readychain®

motion - magazine for energy chain systems®

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