Laser cutting of bus parts
the investment in laser cutting technology of I.C Co., Ltd. has paid off
you may not expect to find a high-tech and modern robot laser cutting system in Conway, Arkansas, a town about 20 miles away from the small stone city, which can also ensure the measurement results. However, this is a wholly-owned subsidiary of I.C., international truck and Engine Corporation, which is now a means of stamping 16 and 20 standard thickness galvanized sheet used in the manufacture of school buses and laser trimming and cutting of complex deep drawn parts. They have two six coordinate Motoman (located in West Carrollton, Ohio) up20 robots that use conventional technology to manufacture adhesives, usually electrical insulators. They can carry out precision laser cutting on more than 40 shapes, and will further improve the competitiveness of the size range market. The periphery of flat and abnormal parts with a width of 20.9 ~ 47.2 inches, a length of 93.7 inches, and a depth of 6 ~ 9 inches will be trimmed
Jim Krieger, the project manager of the excellent manufacturing center, who provides support to all branches, said, "the modern robot production center is a brand-new technology of the factory. The employees of the factory have accepted robots. The sheet metal parts manufacturing equipment works in two shifts every day, producing 82 sets of parts per shift. Robots have been proved to be very reliable."Krieger said, "flexible production centers have been designed to laser cut four kinds of school bus parts, including outer end caps, inner end caps, diaphragms and wheel sockets - they are used in Conway bus assembly plant and a sister bus assembly plant in Tulsa, Oklahoma."
motoman robot was installed in the second half of 2003, equipped with a complete set of TRUMPF (located in Primus, Michigan) hl703d nd:yag laser equipment, installed on the steel base support structure. Installing robots on these supporting structures can save ground space and make it easier to process large and complex parts - parts are fixed on a Motoman msr-1000 AC double station 180 degree indexing rotatable positioner. This high load positioner is equipped with an H-shaped frame table design, with a bearing capacity of 2200 pounds at each end and a graduation time of 7 seconds under full load. The opaque front wall located in the central part of the positioner and the unique automatic sealing protective device can protect the operator from laser radiation. The robot is completely sealed in a CDRH primary laser work unit sealing device with safety interlock door. This process is monitored by a CCTV camera and monitoring system. The equipment related to the laser is placed in a separate room
Figure 1: two robots use laser to trim the periphery of parts, and then use laser to accurately cut
to cut the different shapes required by the wheel socket
motoman also provides two sets of flexible clamps, one on each side of the indexing positioner. The parts are supported on the outer structure by the positioner and fixed in place by the vacuum cup after we become a behemoth. Although the same type of parts are generally processed on both sides of the locator, the system can also process different parts on both sides. The cycle time varies with different parts. The outer end cover takes about 300 seconds, while the wheel socket requires less cutting times, which takes about 110 seconds
the switching between the four parts types, namely, the outer end cover, the inner end cover, the diaphragm and the wheel socket, is completed manually, and it takes less than 15 minutes to switch the self positioning fixture. Parts are processed in batches, and the operator changes the number of parts in each batch by selecting the appropriate robot program for the parts to be processed - using a PC based color touch screen located on an independent base. Allen Bradley SLC 5/05 programmable logic controller (PLC) can provide comprehensive unit control and i/o monitoring, while the robot and positioner are controlled by Motoman XRC 2001 robot controller
two operators in each shift are responsible for loading and unloading large parts produced on the robot unit. The operator's operations include installing a part, cleaning the loading area monitored by the dual laser scanner, and starting the cycle start button on the operation station. When the current cycle is completed, the unit turntable will automatically index and transport the next part to the robot. The robot will perform peripheral trimming and laser cutting on each part for 6 ~ 110 times. The operator removes the cut parts and installs the parts to be cut on the fixture, and then repeats the processing process. The shape tolerance processed by the laser system is ± 0.030 inch, and the position tolerance is ± 0.060 inch
Figure 2: by using two robots to work at the same time, the laser cutting of the bathtub shaped outer
end cover with the most cutting processes takes about 300 seconds, while the processing of the wheel socket with less cutting processes takes only about 110 seconds
the unit also includes a 12 inch wide and 16 foot long electromagnetic belt conveyor with a waste chute that can collect and discharge laser cutting metal chips. In addition, it also includes an exhaust system composed of a blower with an exhaust speed of 9000 cubic feet/minute, a pressure blower system and an air duct to remove the smoke inside the unit
krieger added: "The cycle time of Motoman system is 10% faster than we planned. Before using robots, the production of these parts requires high manual labor intensity. Each part feature is manually plasma cut, manually installed on the punch, and trimmed by pneumatic shears. Before cutting, the style of the trimming line must be tracked. This process requires multiple stages, multiple operators, and in different stages A large amount of material handling is required between processes. By using robot units, many 'in-process' material handling operations are avoided. Robot automation improves the quality of final products. Precision control reduces the amount of scrap per part. In the original manual method, the noise is very loud. A band saw is used to cut the deep, bathtub shaped outer end cover into two parts. Through the new model, the space between the two parts to be trimmed is less than 1 inch, instead of the previous 6 inches. The laser system we chose requires little maintenance, and the loss cost of parts is far lower than the plasma based cutting method we have studied. "
the return on investment cycle of the robot system is about 2.5 years
mary Kay Morel is the full-time author of Motoman company in West Carrollton, Ohio. (end)