JP2021085694A - Ball screw condition monitoring device and condition monitoring method - Google Patents

Abstract

To provide a ball screw condition monitoring device and a condition monitoring method, which allow for appropriately collecting data for accurately diagnosing the condition of a ball screw.SOLUTION: A condition monitoring device 20 provided herein monitors the condition of a ball screw 10 comprising a screw shaft 1, a nut 2, and a plurality of balls 3. The condition monitoring device 20 comprises: a period acquisition unit (signal acquisition unit 21) configured to acquire a period within an operating cycle of the ball screw 10, in which the screw shaft 1 and the nut 2 are moving relative to each other at a constant speed in one direction under no load as a data collection period; and a data collection unit 22 configured to collect physical quantities pertaining to the ball screw during the data collection period as data.SELECTED DRAWING: Figure 1

Description

The present invention relates to a ball screw condition monitoring device and a condition monitoring method.

Conventionally, a ball screw having a screw shaft, a nut, and a plurality of balls as rolling linear motion elements and in which the nut and the screw shaft move relative to each other via the balls is known. As a method of monitoring the state of the ball screw, for example, Patent Documents 1 and 2 disclose a method of detecting the vibration of the ball screw using a sensor and detecting an abnormality based on the detected vibration data. ..

In Patent Document 1, the data acquisition time T for capturing the output signal of the sensor is set to be equal to or longer than the cycle t in which the balls moving back and forth in the infinite circulation path enter the load passage from the no-load passage, and when the balls enter and exit the load passage. A technique for monitoring the state in consideration of the generated vibration is disclosed.
Further, Patent Document 2 has a technique of constructing a trigger signal for obtaining the measurement timing from an acceleration signal acquired from a vibration acceleration sensor, cutting out vibration measurement data only during steady-speed operation, and monitoring the state. It is disclosed.

Japanese Patent No. 6403743 Japanese Unexamined Patent Publication No. 2012-98213

Ball screws are used in various production equipment such as machine tools, conveyors, injection molding machines, etc., and the state monitoring of ball screws is performed in-line so as not to affect the production tact time in the above production equipment. Is desirable. However, this point is not taken into consideration in the techniques described in the above patent documents.
Therefore, the present invention provides a ball screw condition monitoring device and a condition monitoring method that can collect data for diagnosing the ball screw condition in-line without affecting the production takt time. The purpose.

In order to solve the above problem, the ball screw state monitoring device according to one aspect of the present invention is a ball screw state monitoring device that monitors the state of a ball screw having a screw shaft, a nut, and a plurality of balls. A period acquisition unit that acquires a period during which the screw shaft and the nut are relatively moving at a constant speed in one direction in a no-load state within the operation cycle of the ball screw as a data collection period. A data collecting unit that collects as data the physical quantity of the ball screw during the data collecting period acquired by the period acquisition unit is provided.
Here, the no-load state means a state in which the equipment provided with the ball screw does not perform the processing on the work and the ball screw is not subjected to the load due to the processing. For example, when a processing device such as a machine tool is provided with a ball screw, it means that the work is not processed in the processing device and the ball screw is not subjected to the load due to the processing of the work. That is, the no-load state here does not mean a state in which there is no load acting on the ball screw according to the device configuration and product specifications such as the preload and the load due to the weight of the table.
In this way, within the ball screw operation cycle, the period during which the nut is moving at a constant speed in one direction with no load is set as the data collection period, and the data during that period is collected, which affects the tact time in production. It is possible to collect data for diagnosing the condition of the ball screw in-line.

Further, in the ball screw condition monitoring device, the period acquisition unit may acquire the period in which the ball screw returns to the origin as the data collection period. In this case, it is possible to collect data when the nut moves to return to a predetermined position, for example, immediately after the equipment is started, when changing tools, when changing workpieces, and the like.
Further, in the ball screw condition monitoring device, the period acquisition unit may acquire the ball screw lubrication cycle as the data collection period. In this case, for example, after replenishing the lubricant (grease, oil), it is possible to collect data when the lubricant is agitated at a predetermined distance and at a constant speed.

Further, in the ball screw condition monitoring device, the period acquisition unit moves the nut in a load state during the operation of the equipment provided with the ball screw in the moving section in which the nut moves during the data collection period. The section may be included.
For example, when a processing device such as a machine tool is provided with a ball screw, abnormalities such as damage to parts are likely to occur in the section where the nut travels during processing. By including the section in which the nut travels during machining in the section for collecting data, it is possible to appropriately detect an abnormality.

Further, in the ball screw condition monitoring device, the period acquisition unit may periodically acquire the data collection period under the same conditions.
In this case, the collected data can be arranged in chronological order and the tendency can be monitored. Therefore, when the state changes due to the occurrence of an abnormality or the like, this can be appropriately detected. In addition, considering that the physical quantity (for example, vibration) related to the ball screw is different between the outward path and the return path, it is possible to collect data when the nut is moving in the same direction each time, and it is possible to improve the diagnostic accuracy. it can.

Furthermore, in the ball screw condition monitoring device, the physical quantity may be an axial vibration of the nut. In this case, the vibration generated in the nut can be appropriately detected.
Further, the ball screw condition monitoring device further includes a vibration sensor that detects the vibration data, and the vibration sensor is connected to the nut or the nut and can move relative to the screw shaft together with the nut. It may be fixed to the moving member. In this case, since the physical information of the monitoring target can be directly collected by the vibration sensor, highly accurate condition monitoring becomes possible.

Further, in the ball screw condition monitoring device, the driving unit is a servomotor that drives the ball screw, and the physical quantity may be at least one of the torque and the current of the servomotor.
In this case, since the torque and current of the servomotor need only be detected, complicated wiring for installing a sensor for detecting the physical quantity related to the ball screw is not required.

Further, the ball screw state monitoring device may further include an analysis unit that analyzes the data collected by the data collecting unit and monitors the ball screw state.
In this case, the data collected in-line can be used to appropriately monitor the state of the ball screw.

Further, in the ball screw state monitoring device, the analysis unit divides the data collected by the data collection unit into a plurality of data, and based on the analysis result of the divided data, the abnormal occurrence location of the ball screw. It may have an abnormal part identification part for specifying.
In this case, since it is possible to identify where the abnormality has occurred in the ball screw, maintenance of the ball screw or the like can be performed quickly.

Further, the ball screw state monitoring method according to one aspect of the present invention is a ball screw state monitoring method for monitoring the state of a ball screw having a screw shaft, a nut, and a plurality of balls, and the ball screw state monitoring method. Within the screw operation cycle, a step of acquiring a period during which the screw shaft and the nut are relatively moving at a constant speed in one direction under no load as a data collection period, and the ball screw during the data collection period. Includes a step of collecting the physical quantity of the as data.
In this way, within the ball screw operation cycle, the period during which the nut is moving at a constant speed in one direction with no load is set as the data collection period, and the data during that period is collected, which affects the tact time in production. It is possible to collect data for diagnosing the condition of the ball screw in-line.

According to one aspect of the present invention, it is possible to collect data for diagnosing the state of the ball screw in-line without affecting the production takt time.

FIG. 1 is a diagram showing a schematic configuration of a system including a condition monitoring device according to the present embodiment. FIG. 2 is a diagram showing an example of a ball screw. FIG. 3 is a functional block diagram of the condition monitoring device. FIG. 4 is a diagram for explaining a method of identifying an abnormality occurrence location.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention.

FIG. 1 is a diagram showing a schematic configuration of a system including a condition monitoring device 20 for monitoring the state of the ball screw 10.
As shown in FIG. 1, the ball screw 10 includes a screw shaft 1 and a nut 2. The rotating shaft of the servomotor 11 is connected to the screw shaft 1 via a coupling. The servomotor 11 is a drive unit that drives the ball screw 10. When the rotation of the servomotor 11 is transmitted to the screw shaft 1 and the screw shaft 1 rotates, the nut 2 is moved in the axial direction of the screw shaft 1.

FIG. 2 is a diagram showing an example of the ball screw 10.
The screw shaft 1 of the ball screw 10 is made of an elongated cylindrical metal member, and as shown in FIG. 2, a spiral rolling groove (spiral groove) 1a is formed on the outer peripheral surface of the screw shaft 1. ..
The nut 2 is made of a substantially cylindrical metal member having a circular through hole larger than the outer diameter of the screw shaft 1. A spiral rolling groove (spiral groove) 2a is formed on the inner peripheral surface of the nut 2 so as to correspond to the spiral groove 1a of the screw shaft 1. The spiral groove 1a of the screw shaft 1 and the spiral groove 2a of the nut 2 form a rolling path through which the ball 3 rolls.

Further, the nut 2 is formed with a linear ball return path 2b penetrating in the axial direction. The ball return path 2b is for returning the ball 3 from the end point of the rolling path to the start point.
Further, coma members 4 are embedded at both ends of the nut 2 in the axial direction. The top member 4 is made of, for example, a resin member. A direction change path 4a is formed in the coma member 4. The direction change path 4a is for communicating the rolling path and the ball return path 2b, and has a substantially arc shape. The top member 4 is not limited to the resin material but may be made of metal.

Circulation in which the ball 3 circulates in the rolling path formed by the spiral groove 1a of the screw shaft 1 and the spiral groove 2a of the nut 2, the ball return path 2b of the nut 2, and the direction change path 4a of the coma member 4. The route is configured. A large number of balls 4 are loaded in the circulation path, and the screw shaft 1 and the nut 2 move relative to each other via the balls 3 that roll in the rolling path in the circulation path. That is, in the circulation path, the rolling path formed by the spiral groove 1a of the screw shaft 1 and the spiral groove 2a of the nut 2 forms a load area where the ball 3 can receive an external load, and the ball return path of the nut 2. The direction change path 4a of the 2b and the top member 4 forms a no-load area.

Here, the ball 3 is loaded by an external load or preload applied to the ball screw 10 in the rolling path, and is made of a spherical metal member. The material of the ball 3 is not limited to metal, but may be ceramics or the like. Further, the rolling element included in the ball screw 10 is not limited to the spherical ball 3, but may be a roller.
Further, although the ball screw 10 including the top member 4 has been described here as shown in FIG. 2, the circulation member for circulating the ball 3 is not limited to the above. For example, the ball screw 10 of the tube type or the like may be used, and the circulation type may be used.

In this embodiment, a case where the ball screw 10 is applied to a processing device such as a machine tool will be described.
As shown in FIG. 1, a table 12 on which a work W, which is a work piece, is placed is connected to a nut 2 of a ball screw 10 via a bracket 13. The table 12 can reciprocate along with the nut 2 along the axial direction of the screw shaft 1. By moving the table 12, a desired position of the work W can be machined by a tool 30 such as a cutting tool. For example, by moving the nut 2 in the machining section A shown in FIG. 1, the entire surface of the work W can be machined.

Further, the vibration sensor 14 is fixed to the end face (nut flange end face) of the nut 2 in the axial direction. The vibration sensor 14 detects vibration in the traveling direction (axial direction) of the nut 2 as a physical quantity related to the ball screw 10. The physical quantity of the ball screw 10 detected by the vibration sensor 14 may be the vibration of the nut 2 in the circumferential direction. However, the axial vibration of the nut 2 is preferable as the physical quantity related to the ball screw 10.
The vibration data detected by the vibration sensor 14 is output to the condition monitoring device 20.

The condition monitoring device 20 can be configured by, for example, a microcomputer. The condition monitoring device 20 includes a CPU 20a, a ROM 20b, a RAM 20c, and a display unit 20d. The CPU 20a, for example, loads a necessary program or the like from the ROM 20b into the RAM 20c and executes the program or the like to realize various functional operations. Specifically, the CPU 20a realizes a monitoring function operation for monitoring the state of the ball screw 10 based on the vibration data obtained from the vibration sensor 14. The display unit 20d includes a display monitor such as a liquid crystal display.

FIG. 3 is a functional block diagram showing the configuration of the condition monitoring device 20.
As shown in FIG. 3, the condition monitoring device 20 includes a signal acquisition unit 21, a data acquisition unit 22, a storage unit 23, an analysis unit 24, and an output unit 25. The functions of the respective parts shown in FIG. 2 are realized by the CPU 20a shown in FIG. 1 executing a predetermined program.
The signal acquisition unit 21 acquires a trigger signal from the equipment side. Here, the trigger signal is a signal indicating a period during which the screw shaft 1 and the nut 2 are relatively moving at a constant speed in one direction in a no-load state within the operation cycle of the ball screw 10.
Here, the no-load state means a state in which the work is not machined in the machining apparatus and the ball screw 10 is not subjected to the load due to the machining of the work. That is, the no-load state here does not mean a state in which there is no load acting on the ball screw 10 according to the device configuration and product specifications such as the preload and the load due to the weight of the table 12.

The ball screw 10 performs an operation of returning to the origin position (origin return), for example, at the timing when the equipment is started, the timing when the tool 30 is replaced, the timing when the work W is replaced, and the like. Therefore, the signal acquisition unit 21 may acquire, for example, a trigger signal indicating a period during which the ball screw 10 returns to the origin.
Further, the ball screw 10 has a lubrication cycle, and after replenishing the lubricant (grease, oil), the ball screw 10 may be traveled at a predetermined distance and a constant speed in order to agitate the lubricant. Therefore, the signal acquisition unit 21 may acquire, for example, a trigger signal indicating that it is in this lubrication cycle.

For example, the signal acquisition unit 21 has a constant speed relative to the screw shaft 1 and the nut 2 in one direction in the operation cycle of the ball screw 10 in a no-load state for a certain period from the timing of receiving the trigger signal. It is a moving period, and the period can be acquired as a data collection period. The signal acquisition unit 21 may acquire the data collection period by receiving the trigger signal indicating the start timing of the data collection period and the trigger signal indicating the end timing. In the present embodiment, the signal acquisition unit 21 corresponds to the period acquisition unit.
In this way, the signal acquisition unit 21 acquires the period during which the nut 2 is moving in one direction as the data collection period, instead of reciprocating. Therefore, data can be collected in a relatively short time. Here, from the viewpoint of the SN ratio, it is desirable that the data collection period is a period in which the rotation speed of the screw shaft 1 is 100 rpm or more.

Further, in the moving section where the nut 2 moves during the data collection period, the section where the nut 2 moves under a load state during the operation of the equipment provided with the ball screw 10, that is, the nut 2 moves when the work W is machined in the machining apparatus. The section to be processed (processing section A in FIG. 1) can be included. In the moving section of the nut 2, the longer the distance, the larger the amount of data collected, and the noise component can be reduced by averaging. Therefore, it is desirable that the moving distance is long. The longer the travel distance, the more accurate the condition monitoring can be.

In the present embodiment, the signal acquisition unit 21 describes the case of acquiring the data collection period based on the trigger signal, but the method of acquiring the data collection period is not limited to the above. For example, the signal acquisition unit 21 may acquire the operation cycle information of the ball screw 10 and determine the data collection period based on the acquired information.

The data collection unit 22 collects the vibration data detected by the vibration sensor 14 during the data collection period acquired by the signal acquisition unit 21. That is, the data collecting unit 22 collects vibration data in synchronization with the operation cycle (machining cycle) of the ball screw 10 at the time of production.
The storage unit 23 stores the vibration data collected by the data collection unit 22 in a predetermined storage area.

In this embodiment, the condition monitoring device 20 periodically collects vibration data. At this time, the conditions for collecting vibration data (operation pattern, movement direction of nut 2, sampling time, data collection time, etc.) are the same each time.
In the ball screw 10, vibration occurs when the ball 3 rolls on the rolling path, vibration occurs when the ball 3 moves in and out of the load area and the no-load area of the circulation path, and the like. Then, in the ball screw 10, the position where the ball shifts from the load area to the no-load area and the position where the ball shifts from the no-load area to the load area are reversed depending on the direction in which the nut 2 moves. That is, the excitation position differs between the outward route and the return route. Therefore, the same vibration data is not measured on the outward route and the return route. Therefore, when collecting vibration data on a regular basis, the vibration data is collected under the condition that the moving direction of the nut 2 is always the same.

Considering the stability of the data, it is desirable to collect the data in the warm-up state. In addition, in order to properly grasp the occurrence of abnormalities, it is desirable that the data collection interval be at least once a day on working days.
Further, in FIG. 1, the arrow indicating the moving direction of the nut 2 is directed to the right, but the direction in which the nut 2 moves during the data collection period may be either.

The analysis unit 24 analyzes the vibration data stored in the storage unit 23 and monitors the state of the ball screw 10.
The output unit 25 outputs the state of the ball screw 10 diagnosed by the analysis unit 24 to the display unit 20d shown in FIG. 1, and presents the diagnosis result to the user.

The analysis unit 24 calculates the feature value based on the collected vibration data, and compares the calculated feature value with the reference value to diagnose the state of the ball screw 10 (whether or not an abnormality has occurred, etc.). .. Here, the feature value can include at least one of an RMS value, an overall value (OA value), a partial overall value (POA value), and a crest factor (CF). The feature value is not limited to the above, and can be appropriately selected. Further, if the threshold value of the feature value is set as the reference value in advance as the reference value, the abnormality can be easily and appropriately detected by comparing the feature value and the threshold value.

When analyzing the vibration data, the analysis unit 24 divides the vibration data into a processing section portion and a portion outside the processing section, and compares the analysis results (for example, the above-mentioned feature values) of the respective vibration data. May be good.
For example, as shown in FIG. 3, the analysis unit 24 may have a comparative diagnosis unit 24a, an abnormality location identification unit 24b, and a determination unit 24c. In this case, the comparative diagnosis unit 24a may compare the analysis results of the divided vibration data, and the determination unit 24c may determine the state of the ball screw 10 based on the comparison result by the comparative diagnosis unit 24a.
By comparing the feature value calculated from the vibration data of the machining section with the feature value calculated from the vibration data outside the machining section, it is possible to grasp the deterioration and damage state of the machining section.
Generally, in the ball screw 10, an abnormality is likely to occur in a machining section where a load is applied. Therefore, if it is determined in advance that an abnormality occurs only in the machining section and no abnormality occurs outside the machining section (that is, it is a normal value), the feature value of the machining section and the feature value outside the machining section (normal value) You can easily check the status without the time-series data of the feature values just by comparing. For example, condition monitoring is possible even in equipment where there are extremely few operation patterns suitable for the data collection period in order to shorten the tact time as much as possible. That is, the comparative diagnosis unit 24a shown in FIG. 3 may compare the feature values of the processed section and those outside the processed section.

Further, the analysis unit 24 may divide the vibration data of the entire region into data of a plurality of small sections and compare the analysis results (for example, feature values) of the divided vibration data. Thereby, the position where the state changes can be specified. For example, if there is a scratch on the rolling surface of the screw shaft 1, only the characteristic value when the nut 2 passes through the scratch fluctuates.
FIG. 4 is an example of characteristic values when there is a scratch on the rolling surface of the screw shaft 1. Each point (point) in FIG. 4 is a feature value calculated from the vibration data of each divided subsection. In this way, when there is a scratch on the rolling surface of the screw shaft 1, a portion (peak) where the feature value fluctuates greatly can be confirmed. Therefore, by specifying the location where the feature value fluctuates, the position where the screw shaft 1 is scratched (abnormality occurrence location) can be specified.
The abnormality location identification unit 24b shown in FIG. 3 divides the vibration data of the entire region into a plurality of data as described above, and identifies the abnormality occurrence location of the ball screw 10 based on the analysis result of the divided data. May be good.

Since the position of vibration due to the collision of the rolling elements changes between the outward route and the return route, it is desirable to consider the difference. Therefore, when collecting data in-line, it is desirable to collect only one data, one for the outbound route and one for the inbound route.

The analysis unit 24 diagnoses the state of the ball screw 10 by arranging the feature values calculated from the vibration data divided into the machining section and the outside of the machining section in chronological order and monitoring the change in the tendency. It may be. In this case, the state of the ball screw 10 can be diagnosed with higher accuracy.
Further, the analysis unit 24 may monitor the change in the tendency by arranging the feature values calculated without dividing the vibration data into the processing section and the outside of the processing section in chronological order. In this case, although simple diagnosis cannot be performed by comparing the machining section with the outside of the machining section, the calculation can be simplified and the memory required for analysis can be reduced.

In the present embodiment, the case where the condition monitoring device 20 includes each unit shown in FIG. 3 has been described. For example, at least a part of the storage unit 23, the analysis unit 24, and the output unit 25 is a device different from the condition monitoring device 20. May be provided. In this case, the condition monitoring device 20 transmits the data collected by the data collecting unit 23 to a device different from the state monitoring device 20, and a device different from the state monitoring device 20 analyzes the data to determine the state of the ball screw 10. You may diagnose.

As described above, in the state monitoring device 20 of the present embodiment, the period during which the screw shaft 1 and the nut 2 are relatively moving at a constant speed in one direction in a no-load state within the operation cycle of the ball screw 10. Is acquired as a data collection period, and vibration data during the data collection period is collected as data for monitoring the state of the ball screw 10.
In this way, the condition monitoring device 20 collects vibration data when there is no load, not when processing. Therefore, it is possible to collect vibration data that minimizes the influence of disturbance generated during processing. Further, since the data is collected within the operation cycle of the ball screw 10, it is not necessary to intervene in the diagnostic mode for data collection. Therefore, it is possible to prevent a decrease in productivity. Further, since the data collection range is not a round trip but a range in which the nut 2 is moving in one direction, the measurement time can be shortened. Further, since the data of the period during which the nut 2 is moving at a constant speed is collected, stable data measurement can be performed.

Further, the moving section in which the nut 2 moves during the data collection period can include a section in which the nut 2 of the ball screw 10 moves when machining is performed. As a result, the collected vibration data can include a signal when moving to a place where an abnormality is likely to occur. Therefore, for example, by comparing the feature value calculated from the vibration data of the machining section with the feature value calculated from the vibration data outside the machining section, it is possible to grasp the deterioration and damage state of the machining section. In this way, abnormality detection can be performed appropriately.

Here, the moving section and moving distance of the nut 2 during the data collection period can be set based on predetermined parameters (machining section A, etc.) such as the operation cycle of the ball screw 10 and the type of the ball screw 10. ..
For example, when the data collection time is set to be equal to or longer than the ball passing cycle as in the technique described in Patent Document 1, a system for grasping the ball passing cycle is required. On the other hand, in the present embodiment, it is not necessary to separately construct a complicated system for grasping the parameters required for setting the data collection period.

Further, in the present embodiment, by periodically collecting vibration data under the same conditions, the collected vibration data can be arranged in chronological order and the tendency can be monitored. Therefore, when the state changes due to the occurrence of an abnormality or the like, this can be appropriately detected. At this time, since the vibration data when the nut 2 moves in the same direction is collected each time, the diagnostic accuracy can be improved.
For example, when a trigger is constructed from an acceleration signal as in the technique described in Patent Document 2, it is not always possible to collect data under the same conditions every time. In the present embodiment, data is collected aiming at a period in which the nut 2 moves in a predetermined section at a constant speed in one direction, so that data under the same conditions can be collected each time.

As described above, since the measured value at no load during production is used in the present embodiment, data can be obtained during a series of operation cycles without stopping production even in equipment having a short tact time and operating for 24 hours. Can be collected. As a result, the state of the ball screw 10 can be monitored in-line without affecting the production takt time, and planned preventive maintenance can be performed.

(Modification example)
In the above embodiment, the case where the vibration sensor 14 is fixed to the nut 2 of the ball screw 10 has been described, but the position where the vibration sensor 14 is fixed is not limited to the above. If the vibration sensor 14 cannot be fixed to the nut 2 of the ball screw 10 due to the structure of the equipment, a moving member that can move relative to the screw shaft 1 together with the nut 2 as close to the nut 2 as possible. The vibration sensor 14 may be fixed. Examples of such a moving member include the table 12 and the bracket 13 shown in FIG. The vibration detected by the vibration sensor 14 may be axial vibration or circumferential vibration, but axial vibration is preferable.

Further, in the above embodiment, the case where the vibration of the nut 2 is detected as the physical quantity related to the ball screw 10 has been described, but the physical quantity may be the torque or the current of the servomotor 11. In this case, as compared with the case of detecting the vibration data, the wiring for installing the sensor for detecting the physical quantity related to the ball screw 10 becomes easier. However, while vibration data directly measures the physical information to be monitored, torque information and current data often contain information on other elements such as bearings and guide mechanisms, so vibration data is detected. Diagnosis accuracy tends to be slightly lower than in the case of.
In addition, the feature value was calculated based on the collected vibration data, and the feature value and the reference value were compared for judgment. However, instead of calculating the feature value, the waveform of the vibration data was directly referred to as the reference value waveform. They may be compared and judged.

Further, in the above embodiment, the case where the processing device such as a machine tool includes the ball screw 10 has been described, but the equipment provided with the ball screw 10 may be a transfer device, an injection molding machine, or other production equipment. .. Also in this case, similarly to the above embodiment, data for more accurately diagnosing the state of the ball screw 10 can be appropriately collected.

In the present invention, a program that realizes one or more functions of the above-described embodiment is supplied to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device program the program. It can also be realized by reading and executing. In this case, the program itself read from the recording medium realizes the function of the embodiment. In addition, the recording medium on which the program is recorded can constitute the present invention.
Further, by executing the program read by the computer, not only the function of the embodiment is realized, but also the operating system (OS) running on the computer is one of the actual processes based on the instruction of the program. The function of the above-described embodiment may be realized by performing a part or all of the processing.

1 ... Screw shaft, 1a ... Spiral groove, 2 ... Nut, 2a ... Spiral groove, 2b ... Ball return path, 3 ... Ball, 4 ... Top member, 4a ... Direction change path, 10 ... Ball screw, 11 ... Servo motor, 12 ... table, 13 ... bracket, 14 ... vibration sensor, 20 ... state monitoring device, 21 ... signal acquisition unit, 22 ... data collection unit, 23 ... storage unit, 24 ... analysis unit, 25 ... output unit, 30 ... tool, A ... Processing section, W ... Work

Claims (12)

A ball screw condition monitoring device that monitors the condition of a ball screw having a screw shaft, a nut, and a plurality of balls.
A period acquisition unit that acquires a period during which the screw shaft and the nut are relatively moving at a constant speed in one direction under no load in the operation cycle of the ball screw as a data collection period.
A ball screw condition monitoring device including a data collecting unit that collects as data the physical quantity of the ball screw during the data collecting period acquired by the period acquisition unit. The ball screw condition monitoring device according to claim 1, wherein the period acquisition unit acquires a period during which the ball screw returns to the origin as the data collection period. The ball screw condition monitoring device according to claim 1 or 2, wherein the period acquisition unit acquires the ball screw lubrication cycle as the data collection period. The period acquisition unit
Any one of claims 1 to 3, wherein the moving section in which the nut moves during the data collection period includes a section in which the nut moves under a load while the equipment including the ball screw is in operation. The ball screw condition monitoring device described in 1. The period acquisition unit
The ball screw condition monitoring device according to any one of claims 1 to 4, wherein the data collection period under the same conditions is periodically acquired. The ball screw condition monitoring device according to any one of claims 1 to 5, wherein the physical quantity is vibration in the axial direction of the nut. Further equipped with a vibration sensor for detecting the vibration data,
The ball screw condition monitoring device according to claim 6, wherein the vibration sensor is connected to the nut or a moving member that is connected to the nut and is movable relative to the screw shaft together with the nut. .. The drive unit is a servomotor that drives the ball screw.
The ball screw condition monitoring device according to any one of claims 1 to 7, wherein the physical quantity is at least one of a torque and a current of the servomotor. The ball screw state monitoring device according to any one of claims 1 to 8, further comprising an analysis unit that analyzes the data collected by the data collecting unit and monitors the state of the ball screw. .. The analysis unit
9. The claim 9 is characterized in that the data collected by the data collecting unit is divided into a plurality of data, and the ball screw has an abnormality location specifying unit that identifies an abnormality occurrence location of the ball screw based on the analysis result of the divided data. The ball screw condition monitoring device described in 1. A ball screw condition monitoring method for monitoring the condition of a ball screw having a screw shaft, a nut, and a plurality of balls.
In the operation cycle of the ball screw, a step of acquiring a period in which the screw shaft and the nut are relatively moving at a constant speed in one direction in a no-load state as a data collection period, and
A method for monitoring the state of a ball screw, which comprises a step of collecting as data a physical quantity of the ball screw during the data collection period. A program for causing a computer to function as each part of the ball screw condition monitoring device according to any one of claims 1 to 10.

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