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Besides presenting Control Engineering's entire print editions, Control Engineering Online also delivers daily news, Web Exclusives, and Online Extra articles that add value to in-print features. Here are highlights of some articles recently posted online at www.controleng.com.
Besides presenting Control Engineering's entire print editions, Control Engineering Online also delivers daily news, Web Exclusives, and Online Extra articles that add value to in-print features. Here are highlights of some articles recently posted online at www.controleng.com .
Vision system, motion control help assemble toilet seats
To help keep up with increasing commode production, systems integrator Phoenix Automation (Norcross, Ga.) recently built an automated machine that assembles up to 24,000 toilet seats every 10 hours, or 40 seats per minute. This sequential operation requires two indexing pallet conveyors. Placing bumpers into predrilled holes molded into the covers and seats required integrating vision with motion control.
The entire system has 23 servo-controlled drives, two vision systems, nine 16-valve air banks, more than 300 photocell and proximity sensor inputs, and four Siemens human-machine interfaces (HMIs), controlled by a Siemens PLC and communicating via Profibus. The Phoenix engineering team reviewed several companies' vision systems and chose Siemens VS710 vision system, which met performance and accuracy specifications and also had a Profibus interface.
Find and troubleshoot control valve problems 'on the fly'
The best time to determine control valve performance is on-line. Top Control's George Buckbee, P.E., presents some simple techniques to determine control valve performance during normal operation. There are many ways for control valves to degrade process performance. Most common are stiction, hysteresis and backlash, and improper valve sizing.
Fixing stiction problems requires: ensuring the valve actuator and positioner are properly sized for the force required to move the valve; verifying that air supply to the valve is correct; and checking torque on the valve packing gland.
Hysteresis refers to overall response and backlash refers to that portion of hysteresis caused by lost motion on valve and positioner mechanical parts. By far, the most common causes of hysteresis and backlash are loose or worn mechanical linkages between the positioner, actuator, and/or valve. A positioner can remove hysteresis. If a positioner exists, conduct a thorough physical inspection of sources of lost motion, such as positioner-, actuator- and valve-linkages, and repair as needed.
For more information, or visit TopControl at www.topcontrol.com .
Realistic off-vehicle test of transmission parts
A new automatic transmission test rig with controls developed by COM Inc. (Dexter, Mich.) uses two dynamometers—one to drive the component under test and another simulating real-world load conditions. The test unit is instrumented with strain gauges and thermocouples that, when connected to a telemetry collar, provide real-time information from the rotating part.
A key factor in making this system affordable is its use of Microstar Laboratories' (Bellevue, Wa.) data acquisition processor, which runs real-time operations independent of the non-real-time graphical user interface (GUI). This approach increases reliability, and—using COM's Finite State Machine software—saves the $20,000 to $30,000 that would otherwise be required for a programmable logic controller (PLC) system to provide safety monitoring and machine control.
Automated line aids coffee creamer bulk bag filling, reduces waste
To lessen aeration and improve accuracy, Anchor Products (Reporoa, New Zealand) recently installed an automated packing line for filling bulk bags with sodium caseinate. The new line reportedly eliminates aeration experienced by rotary sack fillers, cuts dust and packaging waste by 90%, and achieves bag weight accuracy of 1%
The powder is automatically transferred and filled by a system that includes two flexible screw conveyors, a 390-gallon capacity surge hopper, and a bulk bag filler. The 1,500-lb bags are automatically conveyed from the filler to a heat sealer and then to bulk storage. The PLC-controlled system is also tied to the plant's PLC.
The new line was designed, built and commissioned over two months by Flexicon Corp.'s (Phillipsburg, N.J.) licensee Fresco Systems Ltd. (Auckland, New Zealand) and New Zealand's B.W. Murdoch engineers. Anchor selected flexible screw conveyors as the most effective method for moving the difficult-to-convey powder in a restricted 33 x 23-ft space. Flexible screw conveyors gave Anchor and its engineers a method for overcoming the semi-free flowing powder's tendency to aerate.
For more information, visit Flexicon Corp. at www.flexicon.com .
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