Where others tried and failed - automotive coil manufacturer Supreme Spring succeeded in creating the world's first intelligent servo drive application cold coiling line, a virtual reversal of the old hydraulic hot coiling line.
Because the system can be programmed using the supervisory control and data acquisition (SCADA) system, the line is vastly more economical, boasting dramatic reduction in change over times between recipes, mechanical setup times, as well as reduced scrap, human error and man-time expenses.
The R10 million investment in machinery, robotics and software was installed with the aid of Robotic Innovations, a Pretoria-based company specialising in industrial control and robotic production solutions; as well as programmable logic controllers (PLCs) and human machine interface (HMI) / SCADA systems. Adroit has been selected to be the SCADAS standard for Supreme Spring.
Attempts were under way in Japan to perfect this technology, but it was not until Supreme Spring commissioned the line and went live with automotive testing in August 2006 that it became a viable technology.
This pioneering move has resulted in a diversified strategy for the company going forward, Henk Viviers, project manager at Supreme Springs, explains: "It is a new technology in South Africa about which not much is known. Supreme Spring aims to put it in the global market, diversifying the company from an exclusive original equipment manufacturer (OEM) to a global leader in the sales and implementation of this process."
The rate of production is approximately one coil every eight seconds. With this capacity and improved reliability of the cold coil line, Supreme Spring won the contract to produce the export and domestic market with suspension coils for the new Toyota line of 133L vehicles launching in 2007.
"The accuracy of the robotics and the resulting reduction in human error has resulted in a boom in this type of technology in the automotive industry," says Viviers.
In this application, Adroit is an interface to the operator, providing intuitive access to the 127 different types of coils that can be produced by the cold coiling line. The touch-screen makes it simple for operators to see the code for each and select the desired recipe that includes compressing distance, load window, and more. These recipes are stored in the PLC and accessed via the Adroit SCADA HMI.
After the recipe has been selected, the system auto-updates using the new data and adjusts elements such as the height of the conveyor to fit the coil diameter when implementing the new recipe. The PLC also auto-updates the registers when a recipe is changed in the Adroit SCADA.
At Supreme Spring, the Adroit software is used more as an HMI than a typical SCADA system, and sits on top of a PLC, to which it connects directly via TCPIP to the tags inside the Allan Bradley PLC. The PLC in turn connects to four robots, a hot shot peener and defector machine. The set-up also allows for the possibility of adding an interface with the coiling machine later.
Robotic Innovations has visually split the manufacturing process into two areas on the SCADA, with the tempering furnace machine linking the two sections. In this way, faults can be identified more easily. The first area has monitoring and control functionality for its collective parts that include a straightening device, defector machine, cold coiling machine and robot manipulator.
The line originates with a straightening process. Previously, the metal was supplied in the form of rods, but with the cold coiling method, it is delivered in reels. From there it passes through a defector machine to test for defects in the steel, and then onto a sliding table. Manual labour is used to off-load the springs onto the sliding table. This is the only place on the line that is not automated. Planning is being done to fully automate this section.
The second area automatically detects where the parts are in the system and work according to the data; this includes the scragger, three robots, hot-shot peener, and the cooling tower. All the sections are connected via a DeviceNet network to the PLC, the oven has its own controller that the Adroit system monitors and logs because of its criticality to the process. The Adroit SCADA enables the operator to view each step in the process in sequence, and each component can be more closely viewed by touching on the image on the touch screen.
Next, the parts are put through a tempering furnace to release mechanical stresses. The function of the scragger is to compress the spring to give correct tension - along with temperature monitoring; this is one of the most crucial stages of the process. Using the automated system, Supreme Spring can achieve greater production accuracy by setting the exact compressing distance of the spring up to 0.001mm.
Stress testing is a critical element of coil production, and using the hot-shot peener with temperatures of approximately 300^0C, Supreme Spring is able to get a better penetration depth of the tiny blasted steel particles, and hence improved stress relief. The system also boasts shot peener relay logic between the shot peener PLC and the SCADA PLC. The coil is next placed on a cooling conveyor before it is removed to a bin.
Cold coiling offers many benefits over the old hot coiling system, it eliminates lengthy repair times and dramatically reduces human error, with only one person required to work on this entirely automated line, versus five personnel for the hot coiling system.
The new cold coiling line also boasts a significant reduction in the amount of scrap, with the help of Adroit. The system automatically monitors and logs the coils press distance for load testing. The system automatically notifies the robots what to reject at the load testing stage. Coils that fall below the specified parameters are automatically rejected as scrap, while those that fall above the parameters are automatically sent to the second scragger, which auto-adjusts and reworks the spring to the desired parameters, thereby reducing scrap.
Andries Malherbe, senior software engineer for Robotic Innovations, says: "We are using Adroit's latest version - 6 on a Windows XP platform. We chose the system because of the simplicity of the user interface, its flexibility, and especially its product support."
Robotic Innovations configured the Adroit system with security levels that record who is logged on to the system and what changes they make. User security is integrated into the event viewer, to ensure product quality, and provide a paper trail of faults and the accountable parties.
The Adroit SCADA provides data logging for each load, as well as for all heating furnace temperatures. The operator can retrieve and view these statistics or drawn down on them for reporting purposes as far back as six months.
"We also selected the Adroit soft licence over that with the dongle because it comes standard with the touch-screen PC," Malherbe explains. The 17-inch touch-screen forms the sole workstation on this line and is used with Adroit tag licences.
The graphics where created in a computer-aided design (CAD) program named CATIA by Robotic Innovations and added to the SCADA packaging giving the graphics a 3D, realistic and instantly recognisable feel. Robotic Innovations also compiled a comprehensive online help function, to ensure the operator gets maximum utility out of the system.
There is a manual operations screen, servo drive screen, and a manual interface built in. The system supports new auto-correction intelligence that sets itself up according to the logging done. Direct messages are sent from the drive to the PLC, and then to the SCADA which notifies the operator of faults in the drive.
Faults must first be acknowledged by the system operator, before the Adroit SCADA will reset the system via the Agent Server. As part of the Adroit standard package offering, a one hour time licence provides redundancy.
"Because of Adroit's versatility and power, we reduced the scan tags from 1 661 to approximately 53 scan tags," says Malherbe.
The Marshall Agent in Adroit enabled Robotic Innovations to compress the number of tags used, without compromising on quality, and thereby reducing their total licensing costs. The company bought a 75 scan point licence and used 53 for the project, four of which are analogue tags that are being used for logging and trending.
"We compressed a lot of information into the Marshall Agent to service 16 digital bits, instead of using 16 individual tags," says Malherbe. Two of the tags are also being used to export data to Excel - for use in graphs and reports.
Robotic Innovations used compression inside the PLC as well, for example, when a recipe is chosen, the PLC selects the block inside itself to be activated.
"Robotic Innovations, Supreme Spring, and Adroit have brought together their knowledge and expertise to once again prove that South African companies have the ability to deliver innovative solutions to the worlds challenges," says Dave Wibberley, managing director of Adroit Technologies.
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