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CNC boosts boring-mill productivity.

Randolph Machinery Operations, a division of Alcoa Packaging Equipment, Randolph, NY, makes machinery for the canmaking industry. Products are large, and cast steel workpieces can weigh up to 2 tons. The workpiece in the photos, for example, is a semifinished carrier wheel for a can testing machine that weighs 1000 lb and requires boring of 60 1 3/8" and 1" holes, plus drilling and tapping of another 150 holes. The workpiece mounts on two cast-iron box angle plates or knees on the boring-machine table. The company uses carbide tools to maximize machine feeds and speeds while holding the required tolerances.

Randolph had been purchasing NC-reader replacement units for punched-tape readers, and this led to a brainstorming session with a sales engineer from Shop Control Systems, Chagrin Falls, OH, to find a way to upgrade the company's existing Giddings & Lewis horizontal boring mill. It was an older machine--circa 1968--and the original controls used individual transistors. Control codes were downloaded via paper or Mylar punched tape.

The Shop Control system is designed specifically to upgrade NC boring mills to full CNC machines. According to Shop Control's Walter Marsh, the system is a plug-in replacement for the old control cabinet and magnetic unit, with state-of-the-art electronics and computer technology. The only change in the machine-tool hardware is the retrofit of new shaft encoders and Farrand scale preamplifiers where applicable to bring the position-reporting function up to current standards.

"The boring mill made a nice application for a new control," says John Flood, plant manager at Randolph. "Shop Control retrofitted the CNC and eliminated the old logic cabinet as well as the magnetics cabinet. The new control's computer interfaces directly to the transmission solenoids in the machine tool."

The Shopcon system uses an IBM AT-compatible computer to provide machine control. A tool-path program editor called SCEDIT allows direct communication between the control and the machine and facilitates all of the operator-interface capabilities of the program so it can create, edit, communicate, and manage tool-path programs interactively while running the machine tool. A hard-disk drive lets the computer store thousands of tool-path programs on-line. Tape use is eliminated.

SCEDIT and the control program operate in four basic modes: (1) Basic Editor, (2) Machine MDI (manual data input), (3) Manual Pulse Coder, and (4) Full Automatic. M, G, S, and F codes also are provided. Because the main control element is a personal computer, it can be replaced inexpensively and the software reloaded, should a computer failure occur.

The format of the tool-path program commands is identical to the format used by Fanuc controls. Within the limits of the machine-tool hardware, a point-to-point program written for a mill with a Fanuc control will execute on the Shopcon system.

Engineers claim the Shopcon package is unique in its design, capabilities, and low price of $38,495 for complete installation, training, and post-sale support. This compares with a retrofit cost of $80,000 to $100,000, a used-machine price tag of several hundred thousand dollars, or a brand-new boring mill for $1 million.

One of the immediate improvements resulting from the updated control was reduced downtime, says Mr Flood. "The new control solved the downtime problems we had with loose connections on the plug-in boards caused by pulling them in and out, and by environmental factors. It's better to have permanent boards, so connections won't loosen from vibration, pollution, high humidity, temperature, etc. We had a lot of maintenance costs, and parts were becoming less obtainable. The new control eliminated that total control package and its problems.

"Another important benefit is the ability to correct program errors or incorporate changes on the floor," he adds. "With the old system, the operator couldn't correct the program at the machine; he had to take it up to the office for change by a programmer, followed by reloading back on the tape reader or NC unit.

"Now, the operator can program most parts right at the machine using the manual data input (MDI) feature. On the other hand, programs for complex workpieces are still made in the office using a CAD/CAM system operated by specially trained programmers."
COPYRIGHT 1993 Nelson Publishing
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Copyright 1993 Gale, Cengage Learning. All rights reserved.

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Title Annotation:computer numerical control
Publication:Tooling & Production
Date:Jul 1, 1993
Previous Article:Machine accuracy by the numbers.
Next Article:Ceramic grinding: the next generation.

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