Methods and systems for scheduling work

A method for scheduling operations in a steel mill, comprising the steps:

• reading all the orders that must be produced in a certain period of time, and creating the necessary number of slabs to satisfy the orders;
• reading all the virtual slabs to be produced and their due dates as hot coils, and generating an ideal rolling sequence of slabs;
• reading an ideal rolling sequence of slabs and generating a set of heats to be produced;
• reading the real slabs to be produced, generating a plurality of hot coil schedules, and writing hot coil schedules into a hot coil schedule memory;
• and
• reading a plurality of solutions from the hot coil schedule memory, extracting common parts from the plurality of solutions, and using the extracted parts as an initial partial solution for a hot strip mill sequencing algorithm.

A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for scheduling operations in a steel mill, the method steps comprising:

• reading all the orders that must be produced in a certain period of time and creating the necessary number of slabs to satisfy the orders;
• reading all the virtual slabs to be produced and their due dates as hot coils, and generating an ideal rolling sequence of slabs;
• reading an ideal rolling sequence of slabs and generating a set of heats to be produced;
• reading the real slabs to be produced, generating a plurality of hot coil schedules, and writing hot coil schedules into a hot coil schedule memory;
• reading a plurality of solutions from the hot coil schedule memory, extracting common parts from the plurality of solutions, and using the extracted parts as an initial partial solution for a hot strip mill sequencing algorithm.

A system for scheduling work orders in a plant, comprising:

• means for grouping the orders into heats;
• means for creating a reference list for the heats, from which the heats are pulled to be scheduled;
• means for identifying current plant conditions;
• means for testing a best value of an objective function for taking B possible heats to be scheduled next;
• means for forming sequences up to P heats to be scheduled in order;
• means for taking the best sequence and fixing the first heat of the sequence as scheduled, after testing a number of possibilities;
• and
• means for removing the heat fixed as scheduled from the reference list.

A method for scheduling work orders in a plant, comprising the steps:

• grouping the orders into heats;
• creating a reference list for the heats, from which the heats are pulled to be scheduled;
• identifying current plant conditions;
• testing a best value of an objective function for taking B possible heats to be scheduled next;
• forming sequences up to P heats to be scheduled in order;
• taking the best sequence and fixing the first heat of the sequence as scheduled, after testing a number of possibilities;
• and
• removing the heat fixed as scheduled from the reference list.

A method for scheduling production processes in a plant, comprising the steps:

• a) reading information regarding what the plant has done, and the situation of metallic units and processing units in the plant;
• b) identifying what each processing unit will be doing with the metallic units;
• c) reading the next step to be executed in the route assigned to each metallic unit;
• d) assigning a virtual time indicator and increasing the virtual time until a metallic unit is released by a processing unit;
• e) checking the next routing step of the metallic unit, and placing the metallic unit in the set of the processing units that can execute the step;
• f) verifying if all the metallic units of the same type of the one just finished are complete;
• g) if not all the metallic units are complete, then assigning the next metallic unit to the processing unit;
• h) if all the metallic units are complete, then selecting, from among all the types of materials available for that processing unit, which one is the best type to go next;
• i) defining the best order of the metallic units in the selected group;
• j) assigning the first metallic unit to the processing unit;
• and
• k) evaluating the processing time of said first metallic unit.

A system for scheduling production processes in a plant, comprising:

• means for reading information regarding what the plant has done, and the situation of metallic units and processing units in the plant;
• means for identifying what each processing unit will be doing with the metallic units;
• means for reading the next step to be executed in the route assigned to each metallic unit;
• means for assigning a virtual time indicator and increasing the virtual time until a metallic unit is released by a processing unit;
• means for checking the next routing step of the metallic unit, and placing the metallic unit in the set of the processing units that can execute the step;
• means for verifying if all the metallic units of the same type of the one just finished are complete;
• means for assigning the next metallic unit to the processing unit, if not all the metallic units are complete;
• means for selecting, from among all the types of materials available for that processing unit, which one is the best type to go next, if all the metallic units are complete;
• means for defining the best order of the metallic units in the selected group;
• means for assigning the first metallic unit to the processing unit;
• and
• means for evaluating the processing time of said first metallic unit.

A method for scheduling work in a hot strip mill, comprising the steps:

• establishing conditions for all processing units in the host strip mill area and for the available slabs in stock;
• grouping the slabs with similar routes, and identifying the critical sequences for each route;
• evaluating the buffer size of the last step of a non-critical sequence so that a minimum lot size is reached before starting a critical sequence;
• selecting slabs to be assigned to the buffers;
• scheduling slabs for the processing units in the non-critical and in the critical sequences;
• and
• if a conflict is detected, delaying the processing starting time of buffer to eliminate the conflict.

A system for scheduling work in a hot strip mill, comprising:

• means for establishing conditions for all processing units in the host strip mill area and for the available slabs in stock;
• means for grouping the slabs with similar routes, and for identifying the critical sequences for each route;
• means for evaluating the buffer size of the last step of a non-critical sequence so that a minimum lot size is reached before starting a critical sequence;
• means for selecting slabs to be assigned to the buffers;
• means for scheduling slabs for the processing units in the non-critical and in the critical sequences;
• and
• means for delaying the processing starting time of buffer, if a conflict is detected, to eliminate the conflict.