Method and apparatus for issuing repair alerts in a transmission mechanism

• US 7,369,964 B2
• Filed: 09/26/2006
• Issued: 05/06/2008
• Est. Priority Date: 09/28/2005
• Status: Active Grant

• Current Assignee: Toshiba Kikai Kabushiki Kaisha
• Original Assignee: Toshiba Kikai Kabushiki Kaisha
• Inventors: Tokuyama, Harumichi, Morita, Tomonori, Nishizawa, Makoto
• Primary Examiner(s): Barlow, Jr.; John E.
• Assistant Examiner(s): Washburn; Douglas N
• Application Number:
  US11/535,098
• Publication Number:
  US 20070093976A1
• Time in Patent Office: 588 Days
• Field of Search: 702/71, 702/82, 702/184, 702/182
• US Class Current: 702/184
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01M 13/028 Acoustic or vibration analysis
• CPC Class Codes: G05B 23/0283 Predictive maintenance, e.g. involving the monitoring of a system and, based on the monitoring results, taking decisions on the maintenance schedule of the monitored system; Estimating remaining useful life [RUL] preventive maintenance, i.e. planning maintenance according to the available resources without monitoring the system G06Q10/06

Abstract

White noise is applied to a servocontrol system of a servomotor in order to measure a frequency characteristic of a mechanical component in an electric injection molding machine, and a signal from an encoder is applied to a fast Fourier converter. Data from the fast Fourier converter is applied to a memory unit, and the content of the memory unit is displayed on a display unit in the form of a board diagram. Repair announcement is issued when a deviation of the resonant frequency of each mechanical component with respect to data at an initial setting time exceeds a predetermined value.

Claims

1. A method for issuing a repair alert for a transmission mechanism that transmits a driving force of a servomotor, comprising:

measuring a first frequency response characteristic of the transmission mechanism at installation of the transmission mechanism by applying white noise to a servocontrol system of the servomotor and measuring a feedback of rotation of the servomotor with an encoder;

determining a first resonance frequency of the transmission mechanism from the first frequency response;

measuring a second frequency response characteristic of the transmission mechanism after a predetermined operating time elapses by applying white noise to the servocontrol system of the servomotor and measuring a feedback of rotation of the servomotor with the encoder;

determining a second resonance frequency of the transmission mechanism from the second frequency response; and

issuing a repair alert for the transmission mechanism when a deviation between the first resonance frequency and the second resonance frequency exceeds a predetermined allowable value.

2. The method according to claim 1, further comprising storing the first frequency response as a first frequency response data in a memory, reading the first frequency response data from the memory, and displaying the first frequency response data on a board diagram on a screen of a display device.

3. The method according to claim 2, further comprising repeating the measuring of the second frequency response characteristic of the transmission mechanism to obtain a plurality of frequency response measurements at different times, and writing the plurality of measurements on the board diagram on the screen of the display device so as to display a change of the second frequency response characteristic over time.

4. A repair alerting apparatus configured to issue a repair alert for transmission mechanism that transmits a driving force of a servomotor, comprising:

a first device configured to measure a first frequency response characteristic of the transmission mechanism at installation of the transmission mechanism by applying white noise to a servocontrol system of the servomotor and measuring a feedback of rotation of the servomotor with an encoder;

a second device configured to determine a first resonance frequency of the transmission mechanism from the first frequency response;

a third device configured to measure a second frequency response characteristic of the transmission mechanism after a predetermined operating time elapses by applying white noise to the servocontrol system of the servomotor and measuring a feedback of rotation of the servomotor with an encoder;

a fourth device configured to determine a second resonance frequency of the transmission mechanism from the second frequency response; and

a fifth device configured to issue a repair alert for the transmission mechanism when a deviation between the first resonance frequency and the second resonance frequency exceeds a predetermined allowable value.

5. A repair alerting apparatus according to claim 4, wherein the first device includes:

a servomotor arranged in an electric injection molding machine;

a servocontrol system in communication with the servomotor, the servocontrol system being configured to control the servomotor;

a white noise generator in communication with the servocontrol system, the white noise generator being configured to generate white noise to be applied to the servocontrol system;

an encoder in communication with the servomotor, the encoder being configured to feedback a rotation of the servomotor;

a fast Fourier converter in communication with the white noise generator and the encoder, the fast Fourier converter being configured to receive a difference between white noise from the white noise generator and an output of the encoder and apply fast Fourier conversion to the difference;

a memory unit in communication with the fast Fourier converter, the memory unit being configured to store output data from the fast Fourier converter; and

a display device in communication with the memory unit the display device being configured to display contents of the memory unit.

6. The repair alerting apparatus according to claim 5, wherein the memory unit includes:

a first memory area configured to store output data from the fast Fourier converter; and

a second memory area configured to store data of the first memory area, a resonance frequency of the transmission mechanism calculated based on the data, and a deviation value of the resonance frequency with respect to data at initial setting time of the transmission mechanism.

7. The repair alerting apparatus according to claim 6, wherein the memory unit further includes a program which converts data of the first memory area and stores the converted data in the second memory area.

8. The repair alerting apparatus according to claim 7, wherein the memory unit further includes a program which displays data of the second memory area on a screen of the display device in the form of a board diagram.

9. The repair alerting apparatus according to claim 5, further comprising a servocontrol system mode changing device in communication with the servocontrol system, the servocontrol system mode changing device being configured to change the servocontrol system to a measurement mode so as to activate the first device.