In its goal to produce quality CNC machine tools, Huffman Corporation, of Clover, South Carolina, has developed Laser Powder Fusion equipment. With this equipment, Huffman shows its ability to provide manufacturing process solutions for a variety of challenges, for example, the repair of components used in aircraft engines and similar gas turbine devices.
These components have a high intrinsic cost due to their sophisticated metallurgy and complex design. The expense of replacement makes refurbishment of worn parts attractive; yet despite their ability to withstand high operating temperatures, these components are prone to cracking and weakening when subjected to conventional welding methods.
Laser Powder Fusion permits the deposit of layers of metal onto the surfaces of complex components with a minimum of heat transfer. Huffman's HW-185 laser system combines a stream of powdered metal with a high-energy carbon dioxide laser. As the metal is melted by the laser beam, it is layered onto the surface being repaired in a process known as laser cladding.
The HW-185 was originally configured with three separate hardware systems to control the machine's laser, vision system and motion control. ASAP Inc. (Chagrin Falls, Ohio) ASIC-100 software permitted Huffman to perform all of these control functions within a single PC hardware platform.
Laser control is accomplished by interfacing an ActiveX software component provided by the laser manufacturer with ASIC-l00's database through the software's Dynamic Link Library. Sequential Function Charts (SFCs) within ASIC-100 are used to communicate commands to the laser.
The HW-185's vision system uses a PCI bus capture card to capture an image of the worn part. This image takes the form of a Device Independent Bitmap (DIB). The vision software allows the creation of tool paths by creating combinations of dynamic geometrical shapes (points, lines, splines, etc.) attached to graphical vision elements (edge detectors, centroids, etc.) that regenerate the unique contour of the captured image. Command codes (laser, motion and machine control) are embedded at appropriate places along the tool path, creating a part program in RS-274 language.
The part program's name is entered into the program control block in the ASIC-100 database, and commands are sent to generate the binary file that is fed by the ASIC-100 motion driver to the Delta Tau PMAC2 motion card for execution. ASIC-100 also provides the interfaces necessary to monitor axis position, feed rate, program status, executing block number and to ensure operation within safe limits.
ASIC-100 also provides an interface driver for an I/O located in a GE9030 10-slot rack. The I/O is used to interface components on an operator's pendant, powder feeder, door switches, lighting, lubrication system, fume exhaust system and numerous other machine functions. Each subsystem is implemented in a separate SFC, and execution can be monitored through ASIC-l00's program editor.
Direct bus integration of the HW-185's laser, vision and motion functions within a single host computer is one obvious advantage of ASIC-100 PC-based control software. Huffman Corporation's decision to incorporate open architecture controls has also yielded dramatic cost savings. The HW-185's smaller footprint covers less than half the floor space required for the previous unit, and it is offered at a lower price than the original machine.