Condition Detection Apparatus, Condition Detection Method, Condition Detection Program, Information Recording Medium Therefor, and Condition Display Apparatus, Condition Display Method, Condition Display Program, Information Recording Medium Therefor

• US 20080065354A1
• Filed: 08/30/2005
• Published: 03/13/2008
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: THK Company Limited
• Original Assignee: THK Company Limited
• Inventors: Honjo, Yoshiyuki, Yoshioka, Takeo, Watanabe, Shigeo
• Granted Patent: US 7,546,211 B2
• Time in Patent Office: Days
• US Class Current: 702/183
• CPC Class Codes: F16C 2233/00 Monitoring condition, e.g. temperature, load, vibration
• CPC Class Codes: F16C 29/00 Bearings for parts moving only linearly F16C32/06 takes precedence; incorporated in flexible shafts F16C1/28 ; parts of bearings in general and special methods for making bearings or parts thereof in general F16C33/00
• CPC Class Codes: F16C 29/0633 with a bearing body defining a U-shaped carriage, i.e. surrounding a guide rail or track on three sides
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

A condition detection apparatus comprising an AE sensor 1 that detects AE waves, which elastically-occur when a plurality of balls included in an LM system self-rotate and revolve within a circulation section at the same time, and generates detection signals Sae, and a signal processing unit 4 that generates a first parameter indicating an intensity of the AE waves based on the generated detection signals Sae, generates based on the detection signals Sae a second parameter by weighting only detection signals Sae temporally-continuously detected among the detection signals Sae, generates based on the detection signals Sae a third parameter by weighting only detection signals Sae temporally-discontinuously detected in correspondence with the movement of the balls among the detection signals Sae, and judges contents of an operational condition of the LM system using any one of the first, second or third parameter, is provided to enable prognosis of occurrences of failures in the LM system, to improve maintainability for a user of the LM system, and to contribute to the prolonging of the operation life of the LM system as well as performance assurance and quality improvement of apparatuses or devices incorporated with the LM system.

Claims

1. A condition detection apparatus that detects a current operational condition of a linear rolling motion guide apparatus, the condition detection apparatus characterized by comprising:

a detection device that detects elastically-occurring undulations which are attributable to at least any one of collisions between the rolling members and a rolling surface included in the linear rolling motion guide apparatus, slippages at a contact section of the rolling surface and the rolling members, collisions between rolling members or slippages between rolling members at a contact section, or a crack occurring at least either one of the rolling members or the rolling surface, occurring when a plurality of rolling members included in the linear rolling motion guide apparatus self-rotate and revolve at the same time, and generates an electric detection signal corresponding to a detected undulation;

a first generation device that generates a first parameter indicating an intensity of the undulation based on the generated detection signal; and

a judgment device that judges the operational condition to be normal when the generated value of the first parameter is below a first threshold that is preset for the first parameter.

2. The condition detection apparatus according to claim 1, characterized by further comprising:

a second generation device that weights only detection signals temporally-continuously detected among the generated detection signals, based on the detection signals, to generate a second parameter; and

a third generation device that weights only detection signals temporally-discontinuously detected in correspondence with the movement of the rolling members among the generated detection signals, based on the detection signals, to generate a third parameter,

wherein

the judgment device is arranged to perform judgment on the above-described contents using at least either the second parameter or the third parameter when the generated value of the first parameter is equal to or greater than the first threshold.

3. The condition detection apparatus according to claim 2, characterized in that:

if X_i is a measurement obtained by sampling the detection signals and N is a total number of such measurements, then the first parameter P₁ is a parameter which may be expressed as

$\begin{array}{cc}{P}_1=\sqrt{\frac{1}{N}<br><br>\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>{\left(X_i\right)}^2};<br><br>& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>1\right]\end{array}$

if a constant K (volts) is a maximum input range at the detection device, then the second parameter P₂ is a parameter which may be expressed as

$\begin{array}{cc}{P}_2=\frac{1}{\sqrt{\frac{1}{N}<br><br>\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>{\left(K-X_i\right)}^2}};<br><br>\mathrm{and}& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>2\right]\end{array}$

if M is a number of extractions used as the measurement, then the third parameter P₃ is a parameter which may be expressed as

$\begin{array}{cc}{P}_3=\frac{\sqrt{\frac{1}{M}<br><br>\underset{j=1}{\overset{M}{\sum <br><br>}}<br><br>{\left(X_j\right)}^2}}{P_1}.& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>3\right]\end{array}$

4. The condition detection apparatus according to claim 2 or 3, characterized in that

the judgment device judges that the operational condition is a condition of insufficient lubrication in the event that the generated value of the first parameter is equal to or greater than the first threshold, the generated value of the second parameter is equal to or greater than a second threshold that is preset for the second parameter, and the generated value of the third parameter is below a third threshold that is preset for the third parameter.

5. The condition detection apparatus according to claim 2 or 3, characterized in that

the judgment device judges that the operational condition is a condition in which the circulation section is contaminated by a liquid other than the lubricant in the event that the generated value of the first parameter is equal to or greater than the first threshold, the generated value of the second parameter is equal to or greater than the second threshold that is preset for the second parameter, and the generated value of the third parameter is equal to or greater than the third threshold that is preset for the third parameter.

6. The condition detection apparatus according to claim 2 or 3, characterized in that

the judgment device judges that the operational condition is a condition in which a crack has occurred at least either one of the rolling members or the rolling surface in the event that the generated value of the first parameter is equal to or greater than the first threshold, the generated value of the second parameter is below the second threshold that is preset for the second parameter, and the generated value of the third parameter is equal to or greater than the third threshold that is preset for the third parameter.

7. The condition detection apparatus according to claim 1, characterized by further comprising

a notification device that notifies any of the operational conditions judged by the judgment device.

8. A condition detection method for detecting a current operational condition of a linear rolling motion guide apparatus, the condition detecting method characterized by comprising:

a detection step for detecting elastically-occurring undulations which are attributable to at least any one of collisions between the rolling members and a rolling surface included in the linear rolling motion guide apparatus, slippages at a contact section of the rolling surface and the rolling members, collisions between rolling members or slippages between rolling members at a contact section, or a crack occurring at least either one of the rolling members or the rolling surface, occurring when a plurality of rolling members included in the linear rolling motion guide apparatus self-rotate and revolve at the same time, and generating an electric detection signal corresponding to a detected undulation;

a first generation step for generating a first parameter indicating an intensity of the undulation based on the generated detection signal; and

a judgment step for judging the operational condition to be normal when the generated value of the first parameter is below a first threshold that is preset for the first parameter.

9. The condition detection method according to claim 8, characterized by further comprising:

a second generation step for weighting only detection signals temporally-continuously detected among the generated detection signals, based on the detection signals, to generate a second parameter; and

a third generation step for weighting only detection signals temporally-discontinuously detected in correspondence to the movement of the rolling members among the generated detection signals, based on the detection signals, to generate a third parameter, wherein

judgment is performed on the above-described contents in the judgment step using at least either the second parameter or the third parameter when the generated value of the first parameter is equal to or greater than the first threshold.

10. The condition detection method according to claim 9, characterized in that:

if X_i is a measurement obtained by sampling the detection signals and N is a total number of such measurements, then the first parameter P₁ is a parameter which may be expressed as

$\begin{array}{cc}{P}_1=\sqrt{\frac{1}{N}<br><br>\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>{\left(X_i\right)}^2};<br><br>& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>4\right]\end{array}$

if a constant K (volts) is a maximum input range at the detection device, then the second parameter P₂ is a parameter which may be expressed as

$\begin{array}{cc}{P}_2=\frac{1}{\sqrt{\frac{1}{N}<br><br>\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>{\left(K-X_i\right)}^2}};<br><br>\mathrm{and}& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>5\right]\end{array}$

if M is a number of extractions used as the measurement, then the third parameter P₃ is a parameter which may be expressed as

$\begin{array}{cc}{P}_3=\frac{\sqrt{\frac{1}{M}<br><br>\underset{j=1}{\overset{M}{\sum <br><br>}}<br><br>{\left(X_j\right)}^2}}{P_1}.& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>6\right]\end{array}$

11. The condition detection method according to claim 9 or 10, characterized in that

the operational condition is judged in the judgment step to be a condition of insufficient lubrication in the event that the generated value of the first parameter is equal to or greater than the first threshold, the generated value of the second parameter is equal to or greater than a second threshold that is preset for the second parameter, and the generated value of the third parameter is below a third threshold that is preset for the third parameter.

12. The condition detection method according to claim 9 or 10, characterized in that

the operational condition is judged in the judgment step to be a condition in which the circulation section is contaminated by a liquid other than the lubricant in the event that the generated value of the first parameter is equal to or greater than the first threshold, the generated value of the second parameter is equal to or greater than the second threshold that is preset for the second parameter, and the generated value of the third parameter is equal to or greater than the third threshold that is preset for the third parameter.

13. The condition detection method according to claim 9 or 10, characterized in that

the operational condition is judged in the judgment step to be a condition in which a crack has occurred at least either one of the rolling members or the rolling surface in the event that the generated value of the first parameter is equal to or greater than the first threshold, the generated value of the second parameter is below the second threshold that is preset for the second parameter, and the generated value of the third parameter is equal to or greater than the third threshold that is preset for the third parameter.

14. The condition detection method according to claim 8, characterized by further comprising

a notification step for notifying any of the operational conditions judged in the judgment step.

15. A condition detection program characterized in that the program enables a computer included in a condition detection apparatus that detects a current operational condition of a linear rolling motion guide apparatus to function as:

a detection device that detects elastically-occurring undulations which are attributable to at least any one of collisions between the rolling members and a rolling surface included in the linear rolling motion guide apparatus, slippages at a contact section of the rolling surface and the rolling members, collisions between rolling members or slippages between rolling members at a contact section, or a crack occurring at least either one of the rolling members or the rolling surface, occurring when a plurality of rolling members included in the linear rolling motion guide apparatus self-rotate and revolve at the same time, and generates an electric detection signal corresponding to a detected undulation;

a first generation device that generates a first parameter indicating an intensity of the undulation based on the generated detection signal;

a second generation device that weights only detection signals temporally-continuously detected among the generated detection signals, based on the detection signals, to generate a second parameter;

a third generation device that weights only detection signals temporally-discontinuously detected in correspondence to movement of the rolling members among the generated detection signals, based on the detection signals, to generate a third parameter; and

a judgment device that judges contents of the operational condition using at least any one of the first parameter, the second parameter or the third parameter.

16. An information recording medium, characterized in that the condition detection program according to claim 15 is recorded thereon so as to be readable by the computer.

17. A condition display apparatus characterized in that the apparatus displays a current operational condition of a linear rolling motion guide apparatus, the condition display apparatus comprising:

a detection device that detects elastically-occurring undulations which are attributable to at least any one of collisions between the rolling members and a rolling surface included in the linear rolling motion guide apparatus, slippages at a contact section of the rolling surface and the rolling members, collisions between rolling members or slippages between rolling members at a contact section, or a crack occurring at least either one of the rolling members or the rolling surface, occurring when a plurality of rolling members included in the linear rolling motion guide apparatus self-rotate and revolve at the same time, and generates an electric detection signal corresponding to a detected undulation;

a sampling device that samples the generated detection signals and generates detection data;

a first generation device that respectively generates, based on respective detection data contained in detection data groups composed of a plurality of detection data obtained during a preset detection period, a first parameter obtained by performing weighting on only detection data corresponding to detection signals that have been temporally-continuously detected among the generated detection signals, for each of a plurality of detection data groups corresponding to different detection periods;

a second generation device that respectively generates, based on respective detection data contained in the detection data groups, a second parameter obtained by performing weighting on only detection data corresponding to detection signals that have been temporally-discontinuously detected in correspondence to movement of the rolling members among the generated detection signals, for each of the plurality of detection data groups corresponding to the different detection periods; and

a display control device that displays a graph, obtained by using a value of the first parameter and a value of the second parameter obtained for each single detection data group and repeating for each detected data group a procedure in which the single detection data group is displayed as a single plot point on a graph using values of the first parameter as a first axis and values of the second parameter as a second axis, onto a display device.

18. The condition display apparatus according to claim 17, characterized in that:

if X_i is a value of each detection data, N is a total number of detection data contained in the corresponding detection data group, and a constant K (volts) is a maximum input range at the detection device, then the first parameter P₂ is a parameter which may be expressed as

$\begin{array}{cc}{P}_2=\frac{1}{\sqrt{\frac{1}{N}<br><br>\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>{\left(K-X_i\right)}^2}};<br><br>\mathrm{and}& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>7\right]\end{array}$

if M is a number of extractions used as the detection data, then the second parameter P₃ is a parameter which may be expressed as

$\begin{array}{cc}{P}_3=\frac{\sqrt{\frac{1}{M}<br><br>\underset{j=1}{\overset{M}{\sum <br><br>}}<br><br>{\left(X_j\right)}^2}}{P_1}.& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>8\right]\end{array}$

19. A condition display method for displaying a current operational condition of a linear rolling motion guide apparatus, the condition display method characterized by comprising:

a detection step for detecting elastically-occurring undulations which are attributable to at least any one of collisions between the rolling members and a rolling surface included in the linear rolling motion guide apparatus, slippages at a contact section of the rolling surface and the rolling members, collisions between rolling members or slippages between rolling members at a contact section, or a crack occurring at least either one of the rolling members or the rolling surface, occurring when a plurality of rolling members included in the linear rolling motion guide apparatus self-rotate and revolve at the same time, and generating an electric detection signal corresponding to a detected undulation;

a sampling step for sampling the generated detection signals and generating detection data;

a first generation step for respectively generating, based on respective detection data contained in detection data groups composed of a plurality of detection data obtained during a preset detection period, a first parameter obtained by performing weighting on only detection data corresponding to detection signals that have been temporally-continuously detected among the generated detection signals, for each of a plurality of detection data groups corresponding to different detection periods;

a second generation step for respectively generating, based on respective detection data contained in the detection data groups, a second parameter obtained by performing weighting on only detection data corresponding to detection signals that have been temporally-discontinuously detected in correspondence to movement of the rolling members among the generated detection signals, for each of the plurality of detection data groups corresponding to the different detection periods; and

a display control step for displaying a graph, obtained by using a value of the first parameter and a value of the second parameter obtained for each single detection data group and repeating for each detected data group a procedure in which the single detection data group is displayed as a single plot point on a graph using values of the first parameter as a first axis and values of the second parameter as a second axis, onto a display device.

20. The condition display method according to claim 19, characterized in that:

if X_i is a value of each detection data, N is a total number of detection data contained in the corresponding detection data group, and a constant K (volts) is a maximum input range at the detection device, then the first parameter P₂ is a parameter which may be expressed as

$\begin{array}{cc}{P}_2=\frac{1}{\sqrt{\frac{1}{N}<br><br>\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>{\left(K-X_i\right)}^2}};<br><br>\mathrm{and}& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>9\right]\end{array}$

if M is a number of extractions used as the detection data, then the second parameter P₃ is a parameter which may be expressed as

$\begin{array}{cc}{P}_3=\frac{\sqrt{\frac{1}{M}<br><br>\underset{j=1}{\overset{M}{\sum <br><br>}}<br><br>{\left(X_j\right)}^2}}{P_1}.& \left[\mathrm{Formula}<br><br>\text{\hspace{1em}<br><br>}<br><br>10\right]\end{array}$

21. A condition display program characterized in that the program enables a computer included in a condition display apparatus that display a current operational condition of a linear rolling motion guide apparatus to function as:

a detection device that detects elastically-occurring undulations which are attributable to at least any one of collisions between the rolling members and a rolling surface included in the linear rolling motion guide apparatus, slippages at a contact section of the rolling surface and the rolling members, collisions between rolling members or slippages between rolling members at a contact section, or a crack occurring at least either one of the rolling members or the rolling surface, occurring when a plurality of rolling members included in the linear rolling motion guide apparatus self-rotate and revolve at the same time, and generates an electric detection signal corresponding to a detected undulation;

a sampling device that samples the generated detection signals and generates detection data;

a first generation device that respectively generates, based on respective detection data contained in detection data groups composed of a plurality of detection data obtained during a preset detection period, a first parameter obtained by performing weighting on only detection data corresponding to detection signals that have been temporally-continuously detected among the generated detection signals, for each of a plurality of detection data groups corresponding to different detection periods;

a second generation device that respectively generates, based on respective detection data contained in the detection data groups, a second parameter obtained by performing weighting on only detection data corresponding to detection signals that have been temporally-discontinuously detected in correspondence to movement of the rolling members among the generated detection signals, for each of the plurality of detection data groups corresponding to the different detection periods; and

a display control device that displays a graph, obtained by using a value of the first parameter and a value of the second parameter obtained for each single detection data group and repeating for each detected data group a procedure in which the single detection data group is displayed as a single plot point on a graph using values of the first parameter as a first axis and values of the second parameter as a second axis, onto a display device.

22. An information recording medium, characterized in that the condition display program according to claim 21 is recorded thereon so as to be readable by the computer.