Quality process controls bearing surface finish

A patented Generating Bearing Quality process allows manufacturers to precisely remove amorphous material layers and control surface finish, bearing ratio, geometry and even size of bearing journals.

The patented Impco GBQ (Generating Bearing Quality) process allows manufacturers to precisely remove amorphous material layers and control surface finish, bearing ratio, geometry and even size of bearing journals.

It is optimised by Impco's WorldStar Microfinishing System, which is manufactured under license in Europe by Tamworth-based Evans and Price.

When a leading French car manufacturer had a requirement for a fine finishing machine for one of its new, high performance, four cylinder, diesel production lines, the turnkey solution provided by Evans and Price included the use of Siemens control equipment including a Simodrive 611U universal drive system, FK7 servo motor, PH7 spindle motor, Simatic S7-315 PLC and an MP270 multipanel HMI.

The system is configured so that the drives are connected to the PLC via Profibus while production line characteristics are modified by the HMI.

"In many automotive applications, pressures inside cylinder bores are increasing," explains Mark Hendel, sales manager at Evans and Price.

"In turn, better surface geometry is required to reduce chatter and lobing on crankshaft bearing journals".

"The customer required a process that would remove the chatter and at the same time improve roundness".

"We suggested the WorldStar 1640, which is a special purpose automatic micro finishing machine for crankshaft finishing with load and unload via a gantry system." As GBQ has the ability to microfinish parts within tenths of a micron, control and drive of the WorldStar crankshaft machines for the customer was a key issue, prompting Mr Hendel to contact Siemens Automation and Drives for advice".

""We had yet to break into the French automotive market so this was a critical point in the project," he says.

Account manager at Siemens, Jim Fernley, takes up the story: "While cost was an issue, one of the main requirements was to keep the system as simple as possible for the operator".

"So although we could have proposed a full CNC system, we looked at the process and the variables and knew that a 611U/PLC system would be capable of performing the required tasks." Key features of the Simodrive 611 universal ensure it is: configurable for speed/torque controls as well as position controls; suitable for synchronous and induction motors; and able to communicate with Profibus-DP, the most widely deployed field bus standard in the world.

In terms of its integrated positioning functionality, it is possible to enter up to 64 separate traversing blocks and store them in the drive, while jerk limitation, acceleration, speed and target position (absolute or relative) can be programmed individually in each traversing block.

The Simatic S7-300 series of modular PLC platforms are specifically optimised for high performance machine automation, facilitating integrated system solutions in centralised and distributed architectures.

Its Micro Memory Card concept enables it to store and access information in nearly any file format, and its integrated functions such as high speed counting, positioning, loop control, on-board I/O and simple motion control helps eliminate the need for ancillary devices.

Even though the machine would be set to run a primarily part type, certain dimensions would require accurate positional control.

Changes could be accomplished by storing the basic program on the 611U and changing values for specific components using the HMI, making life very easy for the operators".

""We've used Siemens equipment in the past, for machines supplied to Audi (for the TT crankshaft) and VW (for the w-engine crankshaft)," adds Mr Hendel".

""When the customer enquiry came along, we spoke at length to the customer and agreed, if the solution and the price was right, that Siemens should be appointed as a lead partner on the project." Such has been the success of the Siemens-controlled machine at the manufacturing site, the customer is now taking the GBQ process and applying it to all its existing crankshaft lines.

Evans and Price has been rewarded with an order for three additional machines, plus a further machine for their motorsport arm.

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