Most people, especially those in heavy industry, such as the automotive industry, have difficulty immediately linking the term “manufacturing automation†to the picking, packaging and storage of cotton. However, like any other manufacturing industry, the cotton processing industry is also struggling with the pressures of cost and efficiency. With this in mind, a company in Kennesaw, Ga., developed a unique cotton baling system that improved overall consistency while reducing the time and expense of the packaging process. “We originally adopted SERCOS interface technology because of its outstanding performance,†Olten said. “This is the first automated packaging system, and we want to be able to handle any control requirements that may arise.â€
Developed by Factory Solution (a subsidiary of Interstate Electrical Supply), the Ultra-Twist system enables the gin to more efficiently produce a neatly shaped bale. The company claims that the Ultra-Twist system uses Schneider Electric's integrated motion control components, including motion controllers, networking and programmable logic controllers, to fully automate the packaging process.
The Ultra-Twist system was developed for International Fiber Packaging, a division of ginner supplier Leggett & Platt, and is being used on approximately 15 gins in Texas and Georgia. Steve Phillips, vice president of Interstate Electric, said the system has been fully operational through a three-year trial recently completed.
Complex function
James Dutton, department manager at Factory Solution, points out that many complex moves are required for packaging. First, a work box with three to six baling joints is moved into position, and the baling wire provided by the reel passes through a guide groove around the cotton bale and is folded back to the joint where the baling wire stops at a predetermined position. The bale is then tensioned, cut from the roll and wound onto the Ultra-Twist to knot the knot a predetermined number of times. The positional error is accurate to 1 inch (1 inch = 2.54 cm), ensuring that the cotton is tied and not damaged by the bale.
“The motion control system is optimized to maximize the variety of functions,†Dutton said. “This is very important because it requires control of up to 13 independent shafts.â€
Cotton treatment begins even before the harvested agricultural products have left the farmland. After the cotton is picked, it is pressed into a cotton piece of up to 21.3 meters (70 feet) by a well-known cotton molding machine. Cotton swabs are loaded onto trailers and transported to nearby gins. These gins are usually operated 24 hours a day during the harvest season to help farmers quickly transport their produce.
The "cotton block" was dismantled into a separate cotton peach in the cotton gin. It is then transported to a number of different machines that remove the cotton, extract the cotton fibers, clean and identify the moisture levels.
The cotton fibers are then transported to the baler and hydraulic technology is used to create a cotton hull of approximately 227 kilograms (50 pounds). (Phillips said that these cotton blocks are very dense and require a hammer to knock the nails in). Finally, the cotton pieces are weighed, bagged and transported to the warehouse for storage.
A high-volume cotton gin can process up to 60 bales per hour, so Factory Solutions is looking for ways to ensure that the gin is operating as efficiently and cost-effectively as possible. The use of steel wire instead of plastic tape is one of the many features that are applied.
Packaging control
Bundling cotton bales with steel wire is the old idea that is now emerging, Phillips said. Prior to the widespread use of plastic strips, the cotton processing industry used flat steel straps to bundle bales, but these strips were bulky and required large joints on the baler and required clips to secure the joints. The development of round steel wires with sufficient tension to hold the bales enabled Factory Solution to reintroduce steel technology during the packaging process. Because steel is recyclable, each wire is as much as 50 cents cheaper than a plastic strip, Phillips said.
“When you consider the fact that a cotton gin can produce 100,000 bales in a quarter, it will save a lot of money,†he said.
Most packaging systems are bundled with plastic straps. However, changes in temperature in the warehouse can loosen the belts, causing the bales to deform and even spread out in some cases, Phillips said.
"That's a mess, but it's even worse if a cotton bag is on fire. The plastic strip will melt and the fire will spread. But the metal won't be damaged, so the fire will be suppressed in a few bales. â€
In addition, by introducing advanced motion control capabilities into the Ultra-Twist system, Factory Solution has significantly improved the operation and strapping performance of bales. All motion control components are manufactured by Schneider Electric, including servo drives, brushless motors, and programmable logic controllers (PLCs).
Mark Olten, business development manager for Schneider Electric's motion control products, explains that the use of servo motors is the key to speed and accuracy in the Ultra-Twist system.
“With servo technology, you can quickly specify the motion of the device with a high resolution. In other words, the system knows exactly where 'where' compared to systems that use other motors,†Olten said. “These features are accompanied. Rapid and accurate acceleration and deceleration movement shortens the time of the strapping cycle, which means that cotton can be processed faster."
The Ultra-Twist system also works in fully automatic mode. The semi-automatic and manual systems require three people to operate, Olten said.
The components on the Factory Solutions baler control panel need to be tested before installation. The wires on the control panel are used to connect peripherals including servo motors to simulate actual operation.
Network-based interactive control
Factory Solution manufactures two sizes of Ultra-Twist systems - high performance models with six packaged joints and standard models with three joints. The high-performance models were originally controlled by Schneider Electric TSX PremiumPLC, which uses the SERCOS protocol for motion control based on fiber optic conduction.