Patent Number: 
Section: claims

1. A maintenance system that calculates a timing to make a visit for maintenance work of consumable parts of a machine to be maintained; the system comprising:a visit-interval calculating section for calculating a visit interval to make a visit for maintenance work for each consumable part on the basis of a failure rate distribution;a replacement-interval calculating section that calculates a replacement interval to replace the consumable parts for each consumable part on the basis of the failure rate distribution; anda visit-timing calculating section that calculates a timing to actually visit the machine to be maintained on the basis of the visit interval calculated by the visit-interval calculating section and the replacement interval calculated by the replacement-interval calculating section. 2. The maintenance system according to claim 1, further comprising:a failure-rate-distribution calculating section that calculates the failure rate distribution of each consumable part on the basis of maintenance historical data, that is, history information on maintenance work performed for the machine to be maintained, whereinthe visit-interval calculating section calculates the visit interval to make a visit for maintenance work for each consumable part on the basis of the failure rate distribution calculated by the failure-rate-distribution calculating section and the maintenance historical data; andthe replacement-interval calculating section calculates the replacement interval to replace the consumable parts for each consumable part on the basis of the failure rate distribution calculated by the failure-rate-distribution calculating section and the maintenance historical data. 3. The maintenance system according to claim 1, wherein:the visit-interval calculating section calculates the visit interval at random, and the replacement-interval calculating section calculates the replacement interval at random; andthe visit-timing calculating section obtains a combination of a visit interval and a replacement interval in which a predetermined cost is the minimum, on the basis of the visit interval calculated by the visit-interval calculating section and the replacement interval calculated by the replacement-interval calculating section. 4. The maintenance system according to claim 3, whereinthe visit interval calculated for each consumable part by the visit-interval calculating section is set longer than the replacement interval calculated by the replacement-interval calculating section. 5. The maintenance system according to claim 3, whereinthe predetermined cost is the sum of labor costs for the maintenance work by a serviceman, material costs for the consumable parts, and the loss due to the reason that the user cannot use the machine to be maintained. 6. The maintenance system according to claim 1, whereinthe visit-timing calculating section obtains a combination of a visit interval and a replacement interval in which a predetermined cost is the minimum by search processing using a Monte Carlo method or a generic algorithm on the basis of the visit interval calculated by the visit-interval calculating section and the replacement interval calculated by the replacement-interval calculating section. 7. The maintenance system according to claim 1, whereinthe visit-timing calculating section calculates a list of a next visit timing and consumable parts to be replaced at the next visit timing on the basis of the visit interval calculated by the visit-interval calculating section and the replacement interval calculated by the replacement-interval calculating section. 8. The maintenance system according to claim 1, whereinthe visit-interval calculating section and the replacement-interval calculating section calculate values close to intervals at which the failure rate is estimated to be higher than a predetermined rate, on the basis of the failure rate distribution of each consumable part, which is calculated by the failure-rate-distribution calculating section. 9. A maintenance method for calculating a timing to make a visit for maintenance work of consumable parts of a machine to be maintained, the method comprising:a failure-rate-distribution calculating step of calculating the failure rate distribution of each consumable part on the basis of maintenance historical data, that is, history information on maintenance work performed for the machine to be maintained;a visit-interval calculating step of calculating a visit interval to make a visit for maintenance work for each consumable part on the basis of the failure rate distribution calculated in the failure-rate-distribution calculating step and the maintenance historical data;a replacement-interval calculating step of calculating a replacement interval to replace the consumable parts for each consumable part on the basis of the failure rate distribution calculating in the failure-rate-distribution calculating step and the maintenance historical data; anda visit-timing calculating step of calculating a timing to actually visit the machine to be maintained on the basis of the visit interval calculated in the visit-interval calculating step and the replacement interval calculated in the replacement-interval calculating step. 10. The maintenance method according to claim 9, whereinin the visit-interval calculating step, the visit interval is calculated at random, and in the replacement-interval calculating step, the replacement interval is calculated at random; andin the visit-timing calculating step, a combination of a visit interval and a replacement interval in which a predetermined cost is the minimum is obtained on the basis of the visit interval calculated in the visit-interval calculating step and the replacement interval calculated in the replacement-interval calculating step. 11. The maintenance method according to claim 10, whereinthe predetermined cost is the sum of labor costs for the maintenance work by a serviceman, material costs for the consumable parts, and the loss due to the reason that the user cannot use the machine to be maintained. 12. The maintenance method according to claim 10, whereinin the visit-timing calculating step, a combination of a combination of a visit interval and a replacement interval in which a predetermined cost is the minimum is obtained by search processing using a Monte Carlo method or a generic algorithm on the basis of the visit interval calculated in the visit-interval calculating step and the replacement interval calculated in the replacement-interval calculating step. 13. The maintenance method according to claim 9, whereinin the visit-timing calculating step, a list of a next visit timing and consumable parts to be replaced at the next visit timing is calculated on the basis of the visit interval calculated in the visit-interval calculating step and the replacement interval calculated in the replacement-interval calculating step. 14. The maintenance method according to claim 9, whereinin the visit-timing calculating step and the replacement-interval calculating step, values close to intervals at which the failure rate is estimated to be higher than a predetermined rate are calculated on the basis of the failure rate distribution of each consumable part, which is calculated in the failure-rate-distribution calculating step. 15. A computer-readable storage medium storing a maintenance program for a computer to execute a process of calculating a timing to make a visit for maintenance work for consumable parts of a machine to be maintained, the maintenance program including instructions which, when executed, cause the computer to perform actions comprising:a failure-rate-distribution calculating step of calculating the failure rate distribution of each consumable part on the basis of maintenance historical data, that is, history information on maintenance work performed for the machine to be maintained;a visit-interval calculating step of calculating a visit interval to make a visit for maintenance work for each consumable part on the basis of the failure rate distribution calculated in the failure-rate-distribution calculating step and the maintenance historical data;a replacement-interval calculating step of calculating a replacement interval to replace the consumable parts for each consumable part on the basis of the failure rate distribution calculated in the failure-rate-distribution calculating step and the maintenance historical data; anda visit-timing calculating step of calculating a timing to actually visit the machine to be maintained on the basis of the visit interval calculated in the visit-interval calculating step and the replacement interval calculated in the replacement-interval calculating step. 16. The computer-readable storage medium according to claim 15, whereinin the visit-interval calculating step, the visit interval is calculated at random, and in the replacement-interval calculating step, the replacement interval is calculated at random; andin the visit-timing calculating step, a combination of a visit interval and a replacement interval in which a predetermined cost is the minimum is obtained on the basis of the visit interval calculated in the visit-interval calculating step and the replacement interval calculated in the replacement-interval calculating step. 17. The computer-readable storage medium according to claim 16, whereinthe visit interval calculated for each consumable part in the visit-interval calculating step is set longer than the replacement interval calculated in the replacement-interval calculating step. 18. The computer-readable storage medium according to claim 16, whereinthe predetermined cost is the sum of labor costs for the maintenance work by a serviceman, material costs for the consumable parts, and the loss due to the reason that the user cannot use the machine to be maintained. 19. The computer-readable storage medium according to claim 16, whereinin the visit-timing calculating step, a combination of a visit interval and a replacement interval in which a predetermined cost is the minimum is obtained by search processing using a Monte Carlo method or a generic algorithm on the basis of the visit interval calculated in the visit-interval calculating step and the replacement interval calculated in the replacement-interval calculating step. 20. The computer-readable storage medium according to claim 15, whereinin the visit-timing calculating step, a list of a next visit timing and consumable parts to be replaced at the next visit timing is calculated on the basis of the visit interval calculated in the visit-interval calculating step and the replacement interval calculated in the replacement-interval calculating step.