Drives help achieve a 40% reduction in machining times

04 January 2021

Machining times in a complex seven-station drilling unit have been reduced by more than 40% following the introduction of variable frequency drives (VFD) into the process.

Jafs Machines of Colombia produces a range of products for manufacturers of machined components. These include the Octo-Drilling Machine, a seven-station unit with an indexable turret.
The machine allows simultaneous machining of components via seven individually controlled spindles within the turret. In addition to drilling, some of the spindles tools need to thread components meaning reversible movement is also required.
The spindles rotate individually on the turret powered by 1.5HP three-phase motors at 220v. But they have to rotate at different speeds, with stop/start, depending on the station and tool being used. This included being reversible for the process of threading components.  The difficulty with the process was that the indexable turret and its movement was not easy to connect to the control of the drives through individual wiring.
The solution was found with Invertek’s Optidrive E3 VFDs .Eight of the VFDs have been employed to accurately control the speed of the spindles and the indexing rotation of the turret. These were connected through a Modbus RS-485 communications network in order to avoid the physical wiring of the drives individually, which would have been impossible through the movement of the turret.
This type of connection means only two signals are sent to the eight drives (RS-485 + and RS-485 -) by means of slip rings. The E3 drives are configured to be controlled through Modbus communication, via a PLC.”
The drives not only control the multiple motors on the moving turret but have also helped increase machining times by 40%. “Excellent response speeds were achieved which also allowed changes in the rotation of the threading stations without damaging the tapping tool. The response in speed, on and off, and change of rotation met all the requirements of the process.

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