Using Bosch Rexroth IACR-R integrated axis controller proportional valves, Ingersoll CM Systems made its crankshaft deepfillet rolling machine 25% smaller.

Ingersoll CM Systems Inc., Midland, Mich., develops and builds crankshaft manufacturing systems and machinery. Among the company’s special products is its crankshaft deep-fillet rolling machine. These machines induce residual compressive stress at and below the surface of the crankshaft being rolled to improve its fatigue strength. As the name implies, the crankshaft deep-fillet rolling machine rolls or cold-works the fillets or undercuts located at each end of a crankshaft’s bearing surfaces. Deep-fillet rolling is the name given to the process of rolling under high loads. The term originated because of the depth to which the material is strengthened — up to 0.125 in. To achieve the required strength, the machine revolves the crankshaft a specific number of times while a specified force is applied.

Depending on whether the crankshaft is for a 4- or 5-cylinder engine, the rolling machine may involve from nine to 13 arms of independent rolling axes. Each arm applies a different force at a different point along the length of the crankshaft. Older Ingersoll rolling machines used separate control cards for each of the 13 axes of motion. This called for a large processing area on the machine, cabinet space for the individual controllers, and extensive wiring for components and I/O devices.

A smarter, leaner generation
Ingersoll wanted its next generation of crankshaft-rolling machines to be more compact, while still producing the crankshaft strength and precision its industry demands. They called upon Bosch Rexroth Corp.’s Hydraulics and Electric Drives and Controls technology groups to develop a new control system. Ingersoll’s control-package requirements for the crankshaft deep-fillet rolling machine were primarily that the system supply incremental, precise pressure variations to generate forces as high as 30 kN within a ±1% tolerance band. In addition, programmed force changes had to be achieved in one-tenth of a second by the hydraulic actuator.

Depending on the specific crankshaft requirements, the crankshaft deep-fillet rolling machine includes from nine to 13 arms of independent rolling axes per machine.

The resulting design assigns one Rexroth IAC-R proportional hydraulic servo solenoid valve to each rolling axis of motion. In contrast to traditional designs that require a separate controller for each axis, the IAC-R valve has a programmable, fieldbus-compatible, 32-bit digital motion controller packaged right on board. (The robust cast-aluminum housing containing the on-board valve electronics package allows the IAC-R to be rated for IP 65 sealing, EMC compatibility, and sustained 25-G vibration for 12 hours in all three dimensions.) The axis feedback devices — including position, pressure, and force — plug directly into the valve’s electronics. The result is a completely integrated assembly for electrohydraulic motion control that significantly cuts panel space and wiring requirements. Using the IAC-R valves reduced field wiring by 25% and eliminated one of the four previously required electrical panels, saving Ingersoll approximately 15% in machine control costs.

Another benefit of the new control design is PLC communication with the motion axes over a Profibus network. This — coupled with distributed intelligence in the valves — removes limitations in control performance commonly associated with continuous closed-loop control concepts over a fieldbus. Logic execution and synchronization are much faster. Ingersoll achieves a PLC scan time of less than 2 msec — more than ten times faster than the other controls they have used.

All setup parameters for the IAC-R digital controller are saved in flash memory on the valve and are stored at the machine-level control. This allows quick configuration of machines and minimum downtime in the field in the event of machine replacement. All parameters can be saved and uploaded or downloaded as needed. (This formerly required a manual adjustment.) As a result, field changes can easily be made from one machine to another, taking less than half the commissioning time required in previous designs.

Simplified controls
A Rexroth IndraMotion MTX CNC controller (that can control as many as to 64 axes of motion) controls the overall machine and tightly integrates the multi-tasking PLC with the CNC. The performance CNC card running the CNC motion and all machine logic is installed in a Bosch Rexroth IPC40 located in the main electrical enclosure. A single cable connects the 15-in. display panel in the operator console, providing keyboard, machine key, USB, and mouse functionality. The operator console is lightweight, rugged, and slim. In addition, the Rexroth IndraWorks software package used with the MTX controller contains all the tools necessary to engineer, commission, and operate the machine. The operator interface can easily adapt to fit both the machine and operator requirements using an integrated WinStudio custom screen editor.

The installation uses a slim yet rugged operator console connected with a single cable to the main electrical enclosure.

Compared to other CNCs, the MTX controller provides fast PLC program execution and expedient processing of NC-blocks and auxiliary functions for reduced controller-related time delays and improved machine productivity. The MTX uses SERCOS with fiber-optic cable to control all servo and spindle motion, and Profibus DP to permit fast control of distributed I/O and hydraulic axis control via the IAC-R valve. The IAC-R valve has five modes of operation — open loop flow control, closed loop pressure or force control, position control, alternating control (closed loop position and pressure), and onboard NC functionality. Feedback devices can be either analog, SSI, EnDAT, or one-volt p-p sine wave. Each valve counts and stores the powered-on time, operation time, and fault history — as well as first, last, and next service dates for troubleshooting and preventive maintenance. A 64-character device description can also be assigned to each valve and, like all parameters, can be read by the PLC or other control system units via fieldbus.

Inter-machine communications between all control elements is a key benefit of moving to the IAC-R valve. The change from analog communication to communication via Profibus minimizes the machine’s wiring, eliminates noise, and gives Ingersoll a digital interface to the proportional valves. Ingersoll’s customers can check processes frequently, monitor forces daily or weekly, adjust and calibrate as needed via the operator interface, and send information directly to the valve.

For more information, contact Bosch Rexroth Corp. at (800) 739-7684 or visit www.boschrexroth-us.com.

Integrated digital axis controllers
Integrated axis controllers (IACs) from Bosch Rexroth’s Industrial Hydraulics business unit take advantage of decentralized intelligence for hydraulic drive technology. Compact, pre-tested assemblies are based on Rexroth’s proportional directional and high-response valves and communicate with the control via field bus. They offer simple integration in control concepts as well as a variety of axis control functions, including pressure, pQ, force, position, and alternating control.

IAC-R high-response proportional valve has an integrated digital axis controller and fieldbus interface.

The integration of IACs in the existing control structure eliminates the need for an additional controller assembly, reducing required cabling. They signal error messages via field bus to higher-level machine control where they are evaluated by remote diagnosis. User-friendly PC commissioning is available.

The IAC family is available in two variants, as IAC-R on the basis of high-response valves and as IAC-P on the basis of proportional directional valves. The IAC-R combines the advantages of highly accurate servo solenoid valves with completely digital on-board electronics. Both offer functionalities adapted to specific requirements of electrohydraulic drive technology.

For both types, up to four analog sensors for pressure and position, an incremental position measuring system (1Vss or EnDat), and two analog sensors or an SSI position measuring system and two analog sensors can be connected to integrated axis controllers.