Stäubli Robotics Posted 04/18/2012The customer in this case is in the early stages of including flexible automation in the processing of precision shafts, gears and housings. The plant uses dozens of machine tools, various heat treat and material treatment facilities and assembly equipment for the manufacture of power transmission equipment. The plant operates 24 hours per day, six days per week.
The quality standards set by the customer necessitated multiple QC checks and therefore significant human involvement from the receipt of raw material through final assembly. The manual handling steps or "touches" were the #1 source of scrap generation. Each of the 20 touches seen for making a typical part represented the opportunity to accomplish a QC check and to mark or nick a part.
The first step for the customer was to use of robotic automation for machine tending in the early process steps. These applications worked out very well for them so we moved further into the part making process.
Our deburring application started with the idea of using a robot to load and unload the machine tool and evolved to include integrated quality inspection and part clean up. The idea of also deburring the part and placing the finished part directly into the heat treat rack was added due to these key application facts:
-The part machining process time was long enough to allow for the added robotic process steps
-The tool changer for the handling tool to the deburring tool and floor detail for the addition of the heat treat rack into the cell were financially justifiable
-The automated deburring sequence produced superior dimensional and surface finish results
-Direct labor savings
-To deburr cut gear surfaces to a close tolerance
-Process eight part numbers with the ability to expand the range of parts to be processed in the future
-Run economically and effectively in small batches
-Create an operator friendly environment
-Load and unload the gear cutting machine tool and the part washer
-Load cut and deburred parts into a company standard heat treat basket
-Meet the financial goals set by the customer for payback
-Keep the operator employed as the operator of this cell and additional equipment
-Produce 70 parts per shift
-Do not nick the parts
-Eliminate as many human touches as possible
Description of the Solution:
TEC designed and built a two-shuttle infeed device with quick-change fixture plates. The fixtures used on the plates provide a solid and repeatable location for the robot to pick up incoming parts. The clever use of fixture location marking and the method used to "depalletize" the incoming parts created a robust and reliable part presentation scheme. The robotic end-of-arm tools included a handling tool and a deburring tool. The exchange from tool to tool was accomplished via an automatic tool changer. Once a part was unloaded from the machine tool, the robot sequence exchanged tools to the deburring tool.
A part finding technique was used to locate the exact detail needed to begin the deburring routine. A fixed and non-compliant deburring tool was used. The rigidity of the robot arm and the deburring tool resulted in superior machining of the parts. Once deburred, the tool changer is used to return to the handling end-of-arm tool, the part exchanged with the part resident in the part washer, and the final part placed into the heat treat rack located in a floor locating detail. The heat treat rack types also vary for the part sizes run in the cell; this device is the only manual set up piece of equipment in the cell.
TEC used the Staubli RX170 6-axis floor mounted robot with the CS8 controller, ATI tool changer, Schunk grippers and an Air Turbine 40,000 RPM pneumatic spindle for the deburring tool.
All of the stated and agreed to system requirements were met with these additions: -120 parts per shift realized, a 71% increase in throughput over the previous 70 parts per shift
-One human touch (down from five in the previous manual operation)
-Heightened operator involvement with part quality in lieu of simple repetitive handling routines
-Work in process in the area was reduced by 50%
-Elimination of any idea that this process step would be a bottleneck to the plant
-Strategically smart move and a viewable sales tool used often during plant tours