Title:
MONITORING APPARATUS OF LIFETIME OF BALL SCREW
Document Type and Number:
Japanese Patent JP3185066
Kind Code:
B2
Abstract:
PURPOSE: To enable exact estimation of a residual lifetime by storing beforehand the relationship between an axial load of a ball screw and a motor current value and a fundamental motion rated load of the ball screw and by computing a rated fatigue lifetime value on the basis of a variation coefficient value measured in each sampling.
CONSTITUTION: After a ball screw is incorporated in a machine tool or the like, a motor is driven, first sampling is executed and a motor current value I and a rotational speed N in a very short time set by dividing a sampling time (t) are read in a sampling device 26. The current value I is converted into an axial load P with reference to a stored relation formula, subjected to A/D conversion together with the rotational speed N and transferred to a computing device 30. The device 30 calculates a rated fatigue revolution number R and a rated fatigue lifetime L from these data, divides a rated fatigue revolution number R'1 determined by subtracting a revolution number γi accumulated in a work amount metering device 27 from the revolution number R, by an average revolution speed Nm1, and thereby a rated fatigue lifetime L1 at that time is determined. The above-stated procedure is repeated, and when the value of this lifetime becomes smaller than an alarm value Z'1, an alarm is issued.
Inventors:
Izumi Yonekawa
Application Number:
JP22657291A
Publication Date:
July 09, 2001
Filing Date:
August 12, 1991
Export Citation:
Assignee:
Kuroda Seiko Co., Ltd.
International Classes:
G01M13/00; G01M13/04; (IPC1-7): G01M13/00
Domestic Patent References:
| JP459474B2 |
Attorney, Agent or Firm:
Masahisa Takahashi (1 person outside)