High-tech drive concept improves reliability

GE Fanuc recently supplied to ELWEMA, one such specialised engineering manufacturer, an integrated high-tech drive concept for handling systems of four of its different machine types.

Mechanical engineers expect controller manufacturers to keep on providing innovative and cost-saving solutions.

GE Fanuc recently supplied to ELWEMA, one such specialised engineering manufacturer, an integrated high-tech drive concept for the handling systems of four of its different machine types.

When visiting the modern production facilities of leading automotive manufacturers, one will inevitably see assembly lines made by ELWEMA, a young company founded in 1979 and based in Ellwangen, Germany.

The reason for this is its high level of production quality as well as the proven technical reliability of the machines.

The company designs, develops and manufactures a variety of special machines, mainly for the automotive industry.

ELWEMA assembly lines, cold expansion machines, leak detectors, and machining tools are exported throughout the world.

The company recently developed and produced eight special machines, used to manufacture cylinder heads in two new production plants of one of the world's leading car manufacturers.

Each machine has up to 20 stations where working parts undergo various assembly and test cycles, with each processing step taking 23.5 seconds.

The partly machined working parts are positioned by up to five servo motors and moved with high speed to the next processing step by time-relay bars, lateral motion carriages and transfer units.

All the sequences are controlled by GE Fanuc's intelligent PowerMate H servo motor controllers.

The following four machine types are involved: Assembly machine: While running through 16 stations, the lubrication and water-coolant passages of the cylinder heads are checked for leakage.

Whenever a quality defect is detected, the faulty part is ejected.

This procedure is controlled by two PowerMate Hs linked together via Profibus.

Press fit machine: On this machine, one PowerMate H controls the conveyance of the engine parts through 20 stations where valve seat inserts and valve stem guides are pressed into the cylinder head.

Bearing cover machine: This type of machine has 18 stations where, using three PowerMate H modules, nuts are added to the cylinder heads and bearing covers are installed and fastened with nuts.

Closure assembly and test machine: The cylinder heads run through 20 stations where bores that are no longer needed are sealed off.

They then undergo a leakage test, with compressed air used to check whether the oil and water passageways are leak-proof.

On this machine the conveyance is controlled by two PowerMate H modules.

All system operation sequences for all the machines are controlled using a flow-chart-oriented soft-PLC, with communication at machine level carried out via Profibus.

Once a machine starts its work cycle, the 1-6 axes PowerMate H servo-motor controller takes over control.

With over 200 integrated closed loop and open loop control modules, its reliable and advanced functionality and its modular design, this servo controller is one of the best performing drive controllers available today.

Providing multiple-axis synchronisation, extensive motion control functions, electronic CAM functions, high-speed handling and integrated CNC/PLC/C programming, the PowerMate family is able to perform almost any drive control task in a wide variety of industries.

It also supports all current network standards (Profibus, DeviceNet, Ethernet, etc.).

With this controller module, Distributed Plant Automation is no longer an imaginary ideal but a reality.

Whether using PWM cabling or state-of-the-art distributed fibre-optic networks, whether it be a 30m or 100m distance to the drivers, the GE Fanuc Alpha Series servo motors will always receive the correct positioning or velocity commands.

ELWEMA uses Alpha servo motors with 3 and 6Nm rated torque.

The entire product family comprises a comprehensive range of digital precision servos with torques from 0.5Nm to 1000Nm.

Equipped with absolute digital encoders, these motors are able to perform drive tasks in almost any application.

Featuring durability, compact mechanical design with high power, IP65/IP67 rating, drive speed up to 5000 min-1 as well as excellent acceleration values, the PowerMate family places GE Fanuc at the front line of "global players" for advanced servo drive technology.

In today's high-speed production, it occasionally happens that a part of a motor jams or some other unpredictable malfunction blocks the operation sequences.

In order to avoid damage to any of the expensive manufacturing machine assemblies, up to now mechanical clutches have been used for protection.

A major disadvantage of these clutches, installed between the motor shaft and the drive unit, is that, after an interruption, the cycle needs to be reset and realigned manually, the drive control requiring a new reference base.

Frequently, two additional encoders are used to monitor the actual position of the drive unit.

The result is a loss of time and a significant increase in control work.

To guard against such malfunctions, GE Fanuc has developed a special collision protection function.

Basically, the PowerMate H monitors in real time the current torque of the controlled servo motor.

Whenever a time-critical sudden increase of the pre-set torque is detected (e.g when the time-relay bar is jammed), the drive motion is stopped without losing its absolute position.

After the blockage is eliminated, the machine or time-relay bar immediately restarts.

Manual realignment or referencing of the drive unit is no longer required.

With the real-time collision protection function, GE Fanuc was able to provide ELWEMA with an innovative solution.

Together they were able to convince the car manufacturer, as it provided not only reductions in manufacturing time, but also significant cost reductions in the overall drive system.

Anton Kurz, Project Manager, Electrical Construction at ELWEMA, describes his experience with GE Fanuc: "The first-class quality of GE Fanuc products and solutions is widely known.

I was very impressed by the rapid and efficient co-operation of GE Fanuc engineers involved in the development." As a strongly export-oriented company, ELWEMA can also rely on GE Fanuc's worldwide presence enabling GE Fanuc to offer them local services.

GE Fanuc Automation is a leading global supplier of automation controls.

These products and services include a wide range of CNCs, motion control products, micro to high-end PLCs, monitoring and control software products, and CO2 and YAG lasers.

GE Fanuc Automation is a joint venture between GE and FANUC Ltd and the company's European headquarters are at GE Fanuc Automation Europe in Luxembourg.

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