Continuous Cold Strip Mill Complex: ASRS & AGV

IPACT defined the functional scope of how the various subsystems were to interface to the Complex Coordinator (Level III).  This functional scope established the ground rules and architecture for all ASRS and AGV data communications within the complex.  IPACT engineers participated in the review of ASRS and AGV vendors and helped develop the overall plan for integrating AGVs and ASRS into a safe, maintainable, state-of-the-art manufacturing facility.

To ensure timely material flows with the ASRS and AGV systems, extensive simulation was done by constructing models of the facility.  Inputs to the model were the rated capacities of the production and shipping facilities at extremes of the product size.  The model simulated product flow and demands of the total material handling system for thousands of coils and show areas of bottleneck, which impacted the facility performance.  By making changes to the flows and patterns in the model, many potential problems were eliminated by incorporating the improvements into the real world system.

When implemented and later expanded, the coil storage and retrieval parts of this cold mill complex consisted of three areas with storage capacities of 2000, 1800 and 1300 coils and each with a separate ASRS and AGV system.  The two, large areas each had three (3) automated cranes while the smaller ASRS had two such cranes.  Each area was controlled by DEC VAX computers with two (2) A/B PLCs for each crane, one on-board and the other on the ground to facilitate coordination and communication.

An IPACT engineer performed general automation troubleshooting and software maintenance on the DEC computers in these storage and retrieval systems for a period of approximately seven (7) years.  This required understanding in detail the functionality of all of the automated equipment and the interfaces between the various pieces.

These interfaces were designed to provide a seamless operation as the material flows:

• from core equipment to wrap line (paper or stretch wrap)
• to storage or to the inspection line/slitter and then to storage
• and finally to the loading dock

To facilitate quick retrieval of the coil for truck or rail shipment, a shipping lineup is prepared.  Immediately after input of truck driver identification:

• one transaction prints shipping tags and Bill of Lading
• as the coil is being automatically retrieved

When the coil is loaded onto the truck, manual confirmation is performed and entered into the system for a three-way match between:

• coil storage tag,
• ship tag, and
• Bill of Lading documents (no mixed steel).

If required, test results are printed as 'Page 2' of the ship tag (solving a major customer issue) and an Advanced Shipping Notice (ASN) is automatically faxed as the truck leaves the facility.

Two of the ASRS facilities included rail-shipping capability (usually an evening activity), and one of these includes rail receiving and storage of substrate from off-site locations.

To achieve all this, the process systems were connected through a common tracking and HMI system and a local real-time Level III (distributed business system) was provided for quality conformation and coil release, scheduling of loads, complete order information, unified inventory management, shipping document management and detailed coil genealogy.  In a system of this type, the tracking system must be able to handle every possible situation, including coils on the ground.

The Level III is interfaced to the remote mainframe business system.  However, all facility coordination and all data completeness and correctness is controlled locally through use of this system which was designed by process control engineers using a process control architecture.

Integrated Process Automation & Control Technologies