Machine Design
1 The Landis centerless grinding machine is retrofitted with a new Flexium CNC system from NUM

1. The Landis centerless grinding machine is retrofitted with a new Flexium CNC system from NUM.

Intuitive HMI Facilitates Grinder Control

Over the past 20 years, a leading railcar-axle manufacturing company required two system upgrades for its heavy-duty Landis centerless grinders. Both times, it called upon APeC Integrated Services, Inc. to retrofit the grinders with a modern computer-numerical-control (CNC) system and implement controls that would make it easier to use, improve performance, and ensure precision and controllability.

The Landis centerless grinder’s axle workpiece and grinding wheel rotate in the same direction, inducing smooth grinding as the plunge grinder pushes the wheel into the workpiece. In the mid-1990s, APeC replaced the hydraulic actuation of the plunge grinder with servo motors that drove axis grinding at several feed rates and detected transition points by in-process gauging instruments. The tracer-type wheel dressing system was replaced with automated two-axis diamond-tipped tooling to dress the grinding wheel when necessary. The system used NUM’s Power 1060 platform for greater flexibility and easy programming. 

In the years after the first upgrade, APeC continued to support the grinder machines and work with operators to see what changes should be made next. In the following upgrade, APeC included Euro Machinery Specialists Inc. as well as NUM AG in the design process.  

Euro Machinery redesigned hydraulic and lubrication systems, and made any geometric rebuilds. NUM crafted a custom programmable logic controller (PLC) with an intuitive human-machine interface (HMI) that worked with NUM’s propietary Flexium platform. The HMI provides visual touchscreen controls, prompts, and monitoring tools. NUM also supplied the CNC kernel, touch-sensitive operator panel, servo drives, and motors.

In addition, APeC replaced the 1990s plunge grinder in-process gauging instruments with a linear encoder that delivers precise depth control and feedback to the user. The digital display receives taper-tolerance data from separate measurement probes on the length of the axle journal and displays it on the HMI’s virtual dials. Display screens are task-oriented and feature individual screens for each application. The Flexium CNC system runs with EtherCAT I/O communications and enables Extended Network Code Key Access (ENA) so that the user can control the CNC functions directly with the PLC.

2. The main control displays the axle-taper tolerance during grinding.

“A key project goal was simplifying machine operation as much as possible. NUM’s open Flexium CNC platform provides the control flexibility and HMI customization facilities that we needed to develop individual, task-oriented screens,” said Dave DeCoursey, President of APeC. “The user interface is consequently now much more ergonomic. Most operations, such as offset calculations, calibration, dressing and automatic grinding cycle initiation, are now performed using single, virtual pushbuttons that are only displayed when appropriate.”  

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