JP2011107030A - Operation state monitoring method and operation state monitoring device of rolling linear motion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation state monitoring method and an operation state monitoring device of a rolling linear motion device capable of monitoring accurately whether an operation state of the rolling linear motion device is normal or not. <P>SOLUTION: When monitoring whether an operation state of a ball screw 1 is normal or not, based on a signal outputted from a vibration sensor 4 provided on a ball circulation tube 1d of the ball screw 1, a peak value of the signal outputted from the vibration sensor 4 during operation of the ball screw 1 as long as a fixed distance is compared with a threshold set beforehand, and a total number of times of operation (i+n) of the ball screw 1 when a peak value exceeding the threshold appears and does not appear is used as a denominator, and the number of times of operation (i) of the ball screw 1 when the peak value exceeding the threshold appears is used as a numerator, to thereby calculate a high peak value appearance ratio (i/(i+n)), and if the calculated high peak value appearance ratio (i/(i+n)) exceeds a set value T set beforehand, it is determined that the operation state of the ball screw 1 is not normal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an operation state monitoring method and an operation state monitoring device for a rolling linear motion device for monitoring whether or not the operation state of the rolling linear motion device such as a ball screw or a linear guide is normal.

Sensors (eg, vibration sensors, acoustic sensors, etc.) provided on rolling linear motion device parts as a method for monitoring whether or not the operating state of mechanical equipment equipped with rolling linear motion devices such as ball screws and linear guides is normal. Based on the output signal, the specified physical quantity of the mechanical equipment is analyzed, and the result of the analysis is compared with the information that is used as a criterion for judging whether there is an abnormality in the mechanical equipment at each first time. Presence / absence judgment, based on the result of comparison / matching a predetermined number of times, or based on the result of comparison / matching every second time, comprehensive evaluation to determine that it is abnormal when the number of times of temporary determination is more than a threshold The method of performing is known (refer patent document 1).
According to the above-mentioned method, it is not necessary to periodically disassemble the machine equipment or to reassemble the machine equipment after disassembling in order to detect wear or damage to the rolling linear motion device parts. It is possible to perform maintenance and inspection of machinery and equipment without the need for such.

JP 2005-17128 A

However, since ball screw nuts and linear guide sliders repeat reciprocating movements under load, the sensor output changes sharply depending on the movement speed of the nuts and sliders or the load received from the machine equipment. Noise may occur in the sensor output due to the effects of various incidental facilities. For this reason, the number of times that an abnormality is temporarily determined increases due to a sudden change in sensor output, the influence of noise, etc., and when monitoring whether the operating state of the rolling linear motion device is normal using the method described above. Therefore, it is necessary to set a threshold value to a value that is not affected by a sudden change in sensor output or noise. However, if the threshold is set too low, it is determined that there is an abnormality when no abnormality has occurred, and if the threshold is set too high, there is no abnormality even though an abnormality has occurred. There was a problem of judging.
The present invention has been made paying attention to the above-mentioned problems, and its purpose is to operate the rolling linear motion device capable of accurately monitoring whether the operational state of the rolling linear motion device is normal. It is an object to provide a monitoring method and an operating state monitoring device.

  In order to solve the above-mentioned problem, an operation state monitoring method for a rolling linear motion device according to the first aspect of the present invention is a rolling linear motion device having a movable member that reciprocates in the axial direction through the rolling motion of the rolling element. A method for monitoring whether or not the operating state is normal, wherein a peak value of a signal output from a vibration detecting means attached to the movable member while the rolling linear motion device operates for a predetermined distance is obtained in advance. Compared with the set threshold value, the rolling when the peak value exceeding the threshold value appears and when the peak value exceeding the threshold value appears with the total number of times of operation of the rolling linear motion device when not appearing as the denominator Calculate the high peak value appearance ratio with the number of operations of the linear motion device as the numerator, and the operating state of the rolling linear motion device is not normal when the calculated high peak value appearance ratio exceeds the preset value And judging.

  According to a second aspect of the present invention, there is provided an operational state monitoring device for a rolling linear motion device, wherein the operational state of the rolling linear motion device having a movable member that reciprocates in the axial direction through the rolling motion of the rolling element is normal. Comparing means for comparing the peak value of the signal output from the vibration detecting means attached to the movable member while the rolling linear motion device operates for a certain distance with a preset threshold value And the operation of the rolling linear motion device when the peak value exceeding the threshold appears with the total number of operations of the rolling linear motion device when the peak value exceeding the threshold value appears and when the peak value does not appear as the denominator. A calculating means for calculating a high peak value appearance ratio with the number of times as a numerator, and an operating state of the rolling linear motion device when the high peak value appearance ratio calculated by the calculating means exceeds a preset value Characterized by comprising a determination means not to be normal.

  According to the present invention, the operation of the rolling linear motion device when the peak value exceeding the threshold value appears with the total number of times of operation of the rolling linear motion device when the peak value exceeding the threshold value appears and when it does not appear as the denominator. By calculating the high peak value appearance ratio with the number of times as a numerator and determining that the calculated operation state of the linear motion linear device is not normal when the calculated high peak value appearance ratio exceeds a preset value, Even if the threshold is set too low or the threshold is set too high, it is determined that there is an abnormality when no abnormality has occurred, or it is determined that there is no abnormality even though an abnormality has occurred. Less likely. Therefore, it is possible to accurately monitor whether or not the operating state of the rolling linear motion device is normal.

It is a figure which shows the operation state monitoring apparatus and ball screw which concern on the 1st Embodiment of this invention. It is a flowchart for demonstrating the operating state monitoring method of the operating state monitoring apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the waveform and threshold value of the signal output from a vibration sensor.

A first embodiment of the present invention is shown in FIG. In the figure, reference numeral 1 denotes a ball screw as a rolling linear motion device. A rotation shaft of a drive motor 2 for driving the ball screw 1 is connected to a screw shaft 1 a of the ball screw 1 via a coupling 3. ing.
The screw shaft 1b of the ball screw 1 has a spiral ball raceway groove (hereinafter referred to as “shaft side raceway groove”) 1c on the outer peripheral surface. The shaft side raceway groove 1c faces a spiral ball raceway groove (hereinafter referred to as “nut side raceway groove”) formed on the inner peripheral surface of a nut 1b as a movable member. A large number of balls (not shown) as rolling elements are incorporated between the nut side raceway grooves so as to be capable of rolling. These balls roll between the shaft side raceway groove 1c and the nut side raceway groove in accordance with the rotational movement of the screw shaft 1a (or nut 1b). The ball rolling between the grooves is introduced into a ball circulation tube 1d assembled to the nut 1b, and returned to its original position via the ball circulation tube 1d.

The ball screw 1 has a vibration sensor 4 as vibration detecting means for detecting vibration generated in the ball circulation tube 1d due to the rolling motion of the ball, and the signal output from the vibration sensor 4 is the first of the present invention. The operation state monitoring device 5 according to the embodiment is supplied.
The operation state monitoring device 5 includes a central processing unit (CPU) 5a, a read only memory (ROM) 5b, a random access memory (RAM) 5c, a display device 5d, and the like. The CPU 5a performs the operation of the ball screw 1 according to the flowchart shown in FIG. Whether the operating state is normal or not is monitored.

  That is, the CPU 5a first sets the number n of operations of the ball screw 1 when the peak value exceeding the threshold value does not appear in step S1 to n = 0 and the ball screw when the peak value exceeding the threshold value appears. After setting the number of operations i of 1 to i = 0, it is determined whether or not the ball screw 1 has started operation (step S2). Here, when the ball screw 1 does not start operation, it waits until the ball screw 1 starts operation. When the operation of the ball screw 1 is started, the process proceeds to step S3, the signal output from the vibration sensor 4 and the output signal of the encoder attached to the drive motor 2 are taken in, and the output signal of the vibration sensor 4 is converted to A / D-convert and store in the RAM 5c.

  When the signal output from the vibration sensor 4 is A / D converted and stored in the RAM 5c, the CPU 5a determines whether or not the ball screw 1 is in an operation stop state (step S4). Here, when the ball screw 1 is not in the operation stop state, the process returns to step S3, the signal output from the vibration sensor 4 and the output signal of the encoder attached to the drive motor 2 are taken in, and the output signal of the vibration sensor 4 is A. / D converted and stored in the RAM 5c.

If the ball screw 1 is in the stopped state, the process proceeds to step S5, where the working distance of the ball screw 1 is calculated based on the output signal of the encoder, and whether the calculated working distance has reached a predetermined working distance set in advance. It is determined whether or not (step S6). Here, when the working distance of the ball screw 1 has not reached the predetermined working distance, the process returns to step S2 and waits until the ball screw 1 is again in the working state.
If the working distance of the ball screw 1 has reached the predetermined working distance in step S6, the process proceeds to step S7, the output signal of the vibration sensor 4 stored in the RAM 5c is filtered, and the vibration sensor 4 is further processed in the next step S8. Frequency analysis of the output signal.

  When the output signal of the vibration sensor 4 is analyzed in this way, the CPU 5a detects the vibration peak and its peak value from the signal output from the vibration sensor 4 (step S9). Then, the detected peak value is compared with a preset threshold value (see FIG. 3), and it is determined in step S10 whether there is a peak value exceeding the threshold value. Here, when there is no peak value exceeding the threshold value, after n = n + 1 in step S11, the process proceeds to step S13 described later.

If there is a peak value exceeding the threshold, the process proceeds to step S12. After i = i + 1, the total number of ball screw operations (i + n) when the peak value exceeding the threshold appears and when it does not appear is calculated. It is determined in step S13 whether or not a predetermined number of operations N set in advance has been reached.
If the total number of operations (i + n) of the ball screw has not reached the predetermined number of operations N, the process returns to step S2 and waits until the operation of the ball screw 1 is started. If the total number of operation (i + n) of the ball screw has reached the predetermined number of operations N, the process proceeds to step S14, and the total number of operation of the ball screw when the peak value exceeding the threshold appears and when it does not appear. A high peak value appearance ratio (i / (i + n)) is calculated with the number of ball screw operations (i) as a numerator when a peak value exceeding the threshold appears with (i + n) as the denominator (step S15).

  If the high peak value appearance ratio (i / (i + n)) is calculated in this way, the CPU 5a compares the calculated high peak value appearance ratio with a preset set value I to obtain i / (i + n). It is determined whether or not ≧ I (step S15). Here, when the high peak value appearance ratio (i / (i + n)) does not exceed the set value I, the CPU 5a determines that the operating state of the ball screw 1 is normal, and displays the determination result on the display device 5d. (Step S16). On the other hand, when the high peak value appearance ratio (i / (i + n)) exceeds the set value I, the CPU 5a determines that the operating state of the ball screw 1 is abnormal, and displays the determination result on the display device 5d. Output (step S17).

As described above, when monitoring whether the operation state of the ball screw 1 is normal based on the signal output from the vibration sensor 4 provided in the ball circulation tube 1d of the ball screw 1, the ball screw 1 is constant. The peak value of the signal output from the vibration sensor 4 while operating for a distance is compared with a preset threshold value, and the total number of times the ball screw 1 is operated when a peak value exceeding the threshold value appears and when it does not appear ( Calculate the high peak value appearance ratio (i / (i + n)) with the number of operation (i) of the ball screw 1 as a numerator when a peak value exceeding the threshold appears with i + n) as the denominator, and the calculated high peak By determining that the operating state of the ball screw 1 is not normal when the value appearance ratio (i / (i + n)) exceeds a preset set value T, the threshold is set too low or the threshold is set high. Or it is determined at the stage of abnormal even in the case of too much does not occur there is an abnormality, or abnormality is also possible that or it is determined that no abnormality is low regardless of the to occur. Therefore, it can be accurately monitored whether or not the operation state of the ball screw 1 is normal.
In the first embodiment described above, the ball screw is illustrated as an application example of the present invention. However, the present invention is not limited to the ball screw. For example, it is also possible to monitor whether or not the linear guide is operating normally. The present invention can be applied.

1 Ball screw 1a Screw shaft 1b Nut 1c Shaft side raceway groove 1d Ball circulation tube 2 Ball screw drive motor 3 Coupling 4 Vibration sensor 5 Operating state monitoring device 5a CPU
5b ROM
5c RAM
5d display device

Claims (2)

  A method of monitoring whether or not the operating state of a rolling linear motion device having a movable member that reciprocates in the axial direction via the rolling motion of the rolling element is normal, wherein the rolling linear motion device operates for a certain distance. The peak value of the signal output from the vibration detection means attached to the movable member is compared with a preset threshold value, and the rolling is repeated when a peak value exceeding the threshold value appears and when it does not appear. When the peak value exceeding the threshold appears with the total number of operation of the moving device as the denominator, the high peak value appearance rate is calculated with the number of operations of the rolling linear motion device as the numerator, and the calculated high peak value appearance rate A method of monitoring the operating state of a rolling linear motion device, characterized in that it is determined that the operating state of the rolling linear motion device is not normal when a preset value exceeds a preset value.   A device for monitoring whether or not the operating state of the rolling linear motion device having a movable member that reciprocates in the axial direction via the rolling motion of the rolling element is normal, and the rolling linear motion device operates for a certain distance. Comparison means for comparing the peak value of the signal output from the vibration detection means attached to the movable member with a preset threshold value, and when the peak value exceeding the threshold value appears and when it does not appear A calculating means for calculating a high peak value appearance ratio with the total number of operations of the rolling linear motion device as a denominator and a peak value exceeding the threshold value as a numerator, and the calculation; Rolling means characterized by comprising: a judging means for judging that the operating state of the rolling linear motion device is not normal when the high peak value appearance ratio calculated by the means exceeds a preset set value. Operating status monitoring device of the linear motion apparatus.

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