When a critical piece of machinery operates effectively for more than a decade, the inevitable problem becomes aging controls, maintenance headaches, and fast-approaching obsolescence. At the Eaton production facility that supplies hydraulic lifters and associated components for the automotive market, a collaborative effort resulted in a retrofit program that rejuvenated an aging grinder and boosted production at the same time.
Eaton engineers Rick Gentry and Jim Guess report over 11 percent increases in the overall productivity of a retrofitted Heald grinder at the plant, and additional advantages of improved throughput and enhanced accuracy. Plus, the project required only six weeks to implement an effective solution.
Critical finishing operations
The Heald 1VL, an I.D. grinder utilized for the finish grinding operation on critical engine components, is a key machine tool in Eaton's operation. The grinder was originally equipped with an early generation Siemens 3G CNC used to control the X/Z linear axes, high-speed grinding and dressing spindles (60,000 and 54,000 rpm respectively) and an automatic load/unload device. And the original design of the machine incorporated size gauging and control.
The older CNC was specifically designed for the operational parameters of the grinder and had adequate power and flexibility for its time. But as with all controls, it eventually became more difficult to maintain, and downtime became an issue for Eaton engineers. After careful examination of the available controls, as well as the main frame and other mechanical components onboard, the decision was made to retrofit for improved efficiency and on-pace production.
In With The New: Grinder rejuvenated
with modern controllers uses 75 percent of existing software but gains
benefits from new CNC, digital drive, and absolute encoder
Eaton and Ex-Cell-O (www.ex-cell-o.com) collaborated on the retrofit project and approached the task as a joint venture. Ex-Cell-O managed the controls integration, machine software, interface design, electrical design and implementation of the new system, while Eaton handled the mechanical aspects of the project. Eaton provided new components not associated with the control system including relays, switches, terminals, and other items that would be reused from the original design where possible.
Since Siemens (www.siemens.com) no longer made a dedicated control for the grinder, the Sinumerik 810D CNC was selected from the current standard line of product. In the years since the original machine design, many control changes had taken place that benefited this application. A more compact design with drives and controls in the same package resulted in considerable space savings. Digital drives and absolute encoders minimized hardware and the compact design of the CNC control interface kept the control console in the same package. Siemens cycle programming also eliminated some programming of grinding cycles, and an embedded PLC controller enhanced the HMI protocol.
Out With the Old: Replacing aging
controls in a Heald grinder at Eaton Corp. with a new Sinumerik 810D CNC
increased production and eliminated maintenance
The original Heald grinder controls console required some redesign as the control panels are slightly wider than the original system. However, the redesign was achieved with the capability of mounting to the existing pendant support arm on the machine. The PLC interface was accomplished with Step 7 PLC logic with separate I/O Siemens hardware that provided a more compact design and easily interfaced with existing I/O terminal connectors.
The new CNC features an integrated NC, PLC and is capable of handling up to six axes and two spindles. The existing program format, used to maintain the operator compatibility, and the old program were approximately 75 percent transportable to the new CNC with modifications implemented in areas that required new functionality. This minimized operator impact with new equipment since the operator controls and the program parameters were basically the same as the old equipment.
Special operator interface screens were designed to match the original parameter values, reducing the need for extensive training of the operator interface system. Fault and operator messages were programmed to minimize downtime and give as much information as possible to the operator and maintenance personnel.