Patent Publication Number: US-2022214311-A1

Title: Abnormality diagnosis system and abnormality diagnosis method

Description:
TECHNICAL FIELD 
     The present invention relates to a system that diagnoses an abnormality in equipment including a plurality of control shafts, and to an abnormality diagnosis method for the system. 
     BACKGROUND ART 
     In various apparatuses and the like, such as robots, machine tools, and semiconductor and liquid crystal manufacturing apparatuses, a component for guiding a movable part along a course of the movable part is used. For example, a linear guide is used at a location where a movable part moves in a straight line. In selection of such a component, a component with a load rating in excess of a load multiplied by a safety factor is selected in general. However, in recent years, attempts have been made to manage components in such a manner that the components are made more qualified, for example, by attaching a strain gauge to a component and calculating an actual load applied to the component (for example, see patent document 1). 
     Moreover, patent document 2 discloses a technology of diagnosing, with high accuracy, a product lifespan of a linear guide. According to the technology, for each virtual segment defined by dividing a rolling surface of a moving member along a direction of a track formed by a track member of the linear guide, a moving-time stress, which is a stress occurring in each segment when the moving member is moving, is calculated based on an amount of displacement of the moving member with respect to the track, and the number of occurrences of the moving-time stress, which repetitively occurs with waving when the moving member moves along the track, is calculated for each segment based on the amount of displacement. Then, the lifespan of the linear guide is diagnosed based on a magnitude of each moving-time stress and the number of occurrences of the moving-time stress that are calculated. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Document 1: Japanese Patent Laid-Open No. 2007-263286 
         Patent document 2: Japanese Patent Laid-Open No. 2018-109538 
       
    
     SUMMARY OF INVENTION 
     TECHNICAL Problem 
     Equipment, such as a robot or a machine tool, includes various parts. In general, a plurality of motors are mounted to cause the equipment to perform a desired operation, and each motor is caused to drive in line with the desired operation. To make the equipment operate in a preferred manner, it is necessary to quickly detect a malfunction that occurs, and to perform maintenance of the equipment at an appropriate timing. Since there are many driven members in general equipment, abnormal states can occur at many places in the equipment as a whole, and many detection devices such as sensors are required in order to detect the abnormal states. Accordingly, it is not easy to detect abnormal states in equipment on which a plurality of motors are mounted, and it is difficult to enhance accuracy in detection of abnormal states. 
     Regarding equipment maintenance, there are cases in which after equipment actually breaks down, breakdown maintenance is performed to handle the breakdown, and cases in which maintenance is performed at a time when no breakdown occurs, based on past operation experiences, an operation history, or the like related to the equipment. However, in such ways of maintenance, it is hard to say that efficient operation of equipment can be achieved, because equipment is stopped for a relatively long time, or equipment is unnecessarily stopped although the equipment is still able to stably operate. On the other hand, to achieve efficient operation of equipment, it is preferable to quickly detect an abnormal state, which is a predictive sign of a breakdown, before the breakdown occurs, and to lead such detection to performing maintenance. 
     The present invention has been made in light of the above-described problem, and an object of the present invention is to provide a technology that enables both appropriate maintenance and efficient operation of equipment. 
     Solution to Problem 
     In the present invention, to solve the problem, an abnormality diagnosis system of the present invention adopts a configuration in which a vibration sensor is provided for each of a plurality of control shafts included in equipment, and with such a simple configuration, an abnormality of each control shaft is diagnosed based on a distribution state of vibration levels corresponding to the plurality of control shafts. 
     Specifically, the present invention is an abnormality diagnosis system that diagnoses an abnormality related to each control shaft in equipment in which a plurality of control shafts, each including a motor and an output unit driven by the motor, are incorporated, the equipment being configured such that at least one of the plurality of control shafts receives transmission of vibration due to driving of the motor for at least one of the other control shafts when the motor drives, the abnormality diagnosis system including: a plurality of vibration sensors that are provided for the plurality of control shafts, respectively, and that detect vibration occurring in connection with driving of the motor corresponding to each control shaft; a calculation unit that calculates, for each of the plurality of control shafts, vibration levels in a plurality of predetermined frequency ranges, based on vibration information detected by each of the plurality of vibration sensors; and a diagnosis unit that diagnoses an abnormality related to each control shaft, based on a distribution state, across the plurality of predetermined frequency ranges and across the plurality of control shafts, of the vibration levels calculated by the calculation unit. 
     Advantageous Effects of Invention 
     Both appropriate maintenance and efficient operation of equipment can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a schematic configuration of a vertical machining center that is equipment according to an embodiment. 
         FIG. 2  illustrates a functional configuration of an abnormality diagnosis system according to the embodiment. 
         FIG. 3  is a flowchart of abnormality diagnosis control performed by the abnormality diagnosis system. 
         FIG. 4  is a first diagram illustrating distribution states of vibration levels used in the abnormality diagnosis control illustrated in  FIG. 3 . 
         FIG. 5  is a second diagram illustrating the distribution states of the vibration levels used in the abnormality diagnosis control illustrated in  FIG. 3 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An abnormality diagnosis system of an embodiment diagnoses an abnormality of each control shaft in equipment in which a plurality of control shafts are incorporated, the equipment being configured such that at least one of the plurality of control shafts receives transmission of vibration occurring when a motor for at least one of the other control shafts drives the at least one of the other shafts. The transmission of vibration between the control shafts here means that the equipment is configured such that vibrations mutually interact between the control shafts. Each control shaft includes a corresponding motor and an output unit. A single control shaft may include a plurality of motors or a plurality of output units. The output units of the control shafts do not necessarily need to coincide with output units of the equipment, and a combination of output units of a plurality of control shafts may be formed as an output unit of the equipment. 
     In the equipment thus configured, when a motor corresponding to a certain control shaft of the plurality of control shafts drives, vibration occurring due to the driving can act on another control shaft. Accordingly, the then vibration is detected by a vibration sensor provided for each control shaft. In other words, the plurality of vibration sensors respectively provided for the plurality of control shafts can detect vibration that transmits to the entire equipment when any of the corresponding motors, each provided for each control shaft, drives. Moreover, all vibration levels (magnitudes of vibration) detected by the vibration sensors respectively provided for the control shafts in the equipment are not the same and reflect a mechanical configuration of the equipment. 
     Here, in the equipment, a difference arises in mechanical condition, in terms of transmission of vibration, between a case in which a mechanical component of the equipment is in a normal state and a case in which the mechanical component is in an abnormal state. Note that an “abnormal state” in the present embodiment refers to a state that is related to an operation status of the equipment in terms of equipment maintenance, that requires maintenance to make the equipment continue to operate, and that is different from a so-called broken-down state in which the equipment is completely unable to operate. In other words, an abnormal state in the equipment means a state in which the equipment is still able to operate but requires maintenance such as replacing a part sooner or later, and a state that is discriminated from a normal state. In comparison with the equipment in the normal state, a vibration level detected on each control shaft varies according to a degree of an abnormal state (hereinafter, assumed to include presence or absence of an abnormal state) in the equipment. Moreover, depending on types of abnormal state that can occur in the equipment, mechanical conditions related to transmission of vibration in the equipment can also vary by the type, and therefore a distribution state of vibration levels, obtained when the control shafts are viewed as a whole, can be associated with each type of abnormal state. 
     Accordingly, in the abnormality diagnosis system of the present embodiment, to be able to distinguish each type of abnormal state that can occur in the equipment, a calculation unit calculates a vibration level in each of a plurality of predetermined frequency ranges, based on vibration information detected by each vibration sensor, and then a diagnosis unit diagnoses an abnormality related to each control shaft in the equipment, based on a distribution state of the vibration levels across all of the control shafts, obtained across the plurality of control shafts. The plurality of predetermined frequency ranges can be appropriately configured by taking into consideration the mechanical configuration of the equipment and a vibration characteristic (vibration resonant frequency or the like) for making it easy to detect a possible abnormal state in the equipment. The plurality of frequency ranges do not necessarily need to be consecutive frequency ranges, and the frequency ranges do not necessarily need to have the same widths. 
     As described above, in the abnormality diagnosis system, with a relatively simple configuration in which the vibration sensor is provided for each control shaft, an abnormality in the equipment can be diagnosed in a preferred manner by taking into consideration a fact that vibrations mutually interact between the control shafts. In particular, information subjected to abnormality diagnosis is information obtained as a result of the equipment actually operating and therefore accurately reflects a decree of an abnormal state in the then equipment, and accordingly, the abnormality diagnosis can be implemented in a preferred manner while the operation of the equipment is maintained favorably. As a result, a timing of performing maintenance, such as replacing a part of the equipment, can also be set appropriately. 
     Hereinafter, a specific embodiment of the present invention will be described based on the drawings. Sizes, materials, shapes, relative dispositions, and the like of constituent parts described in the present embodiment are not intended to limit the technical scope of the invention thereto, unless otherwise stated. 
     Embodiments 
       FIG. 1  illustrates a schematic configuration of a vertical machining center that is an example of equipment  1  to which the abnormality diagnosis system of the present embodiment is applied. In particular, an upper view (a) of  FIG. 1  represents an external appearance of a processing area of the equipment  1 , and a lower view (b) represents a schematic configuration of three control shafts included in the equipment  1 . The equipment  1  is a vertical machining center including the three control shafts of X shaft, Y shaft, and Z shaft, and the X shaft and the Y shaft are disposed on a horizontal plane while the Z shaft is disposed in a vertical direction. As illustrated in the upper view (a) of  FIG. 1 , a table  2  on which a workpiece is placed is arranged in the processing area of the equipment  1 . The table  2  is controlled according to the X shaft and the Y shaft. A cover  11  is arranged over the X shaft, and a cover  21  is arranged over the Y shaft. Moreover, a spindle  31  is arranged such as to be able to apply cutting and processing to a workpiece placed on the table  2 , and a position of the spindle  31  is controlled according to the Z shaft. Note that a main body of a motor for the spindle  31  is arranged inside a cover  32 . 
     Here, details of each control shaft will be described based on the lower view (b) of  FIG. 1 . On the X shaft, a motor  13  that is an actuator of the X shaft is arranged, an output shaft of the motor  13  is joined to a ball screw  14 , and a nut  15  corresponding to the ball screw  14  corresponds to an output unit of the X shaft. The X shaft is a control shaft that directly drives the table  2 , and movement of the table  2  along the X shaft is achieved by a rail  12   a  and a moving member  12   b  that supports the table  2  while sliding on the rail  12   a . Similarly on the Y shaft, a motor  23  that is an actuator of the Y shaft is arranged, an output shaft of the motor  23  is joined to a ball screw  24 , and a nut  25  corresponding to the ball screw  24  corresponds to an output unit of the Y shaft. The Y shaft is a control shaft that drives a composition of the table  2  and the X shaft, and movement of the composition along the Y shaft is achieved by a rail  22   a  and a moving member  22   b  that supports the composition of the table  2  and the X shaft while sliding on the rail  22   a . On the Z shaft, a motor  33  that is an actuator of the Z shaft is arranged, an output shaft of the motor  33  is joined to a ball screw  34 , and a nut  35  corresponding to the ball screw  34  corresponds to an output unit of the Z shaft. The Z shaft is a control shaft that drives the spindle  31  in the vertical direction, and movement of the spindle  31  along the Z shaft is achieved by a rail  32   a  and a moving member  32   b  that supports the spindle  31  while sliding on the rail  32   a.    
     In the equipment  1  thus configured, both the X shaft and the Y shaft are control shafts that implements movement of the table  2  on the horizontal plane, and the mechanical components related to the X shaft are arranged on the Y shaft. Accordingly, it can be understood that the X shaft and the Y shaft are configured such that vibrations occurring due to driving of the respective motors  13 ,  23  can be mutually transmitted. The Z shaft, unlike the X shaft and the Y shaft, is a control shaft that allows the spindle  31  to move in the vertical direction, and it can be understood that the Z shaft is configured such that vibration can also be transmitted between the Z shaft and each of the X shaft and the Y shaft via a housing of the equipment  1 , which is a machining center. Note that not all vibrations of the X to Z shafts are transmitted to each other, and there can be a vibration that is not transmitted between the control shafts substantially, depending on a characteristic (amplitude, frequency, or the like) of the vibration. 
     Moreover, each of vibration sensors  16 ,  26 ,  36  is arranged on each control shaft of the X to Z shafts, respectively, to detect vibration on the respective control shaft. Note that a direction of vibration detected by the vibration sensor  16  for the X shaft is an X-axis direction, a direction of vibration detected by the vibration sensor  26  for the Y shaft is a Y-axis direction, and a direction of vibration detected by the vibration sensor  36  for the Z shaft is a Z-axis direction. The vibration sensors  16 ,  26 ,  36  are arranged at end portions of the rails  12   a ,  22   a ,  32   a  included in the individual control shafts, respectively, so that movement of the output unit of each control shaft is not hindered. For the vibration sensors  16 ,  26 ,  36 , publicly known vibration sensors or acceleration sensors can be used, and a detailed description thereof is omitted. 
     Here, a configuration of the abnormality diagnosis system of the present embodiment will be described based on  FIG. 2 . The abnormality diagnosis system includes a processing apparatus  5 , and the vibration sensors  16 ,  26 ,  36  for the X to Z shafts electrically connected to the processing apparatus  5 . The processing apparatus  5  is substantially a computer including an operation processing device and a memory, and functional units illustrated in  FIG. 2  are formed by a predetermined control program being executed by the computer. Vibration information detected by each of the vibration sensors  16 ,  26 ,  36  is transferred to the processing apparatus  5 . 
     The processing apparatus  5  includes a calculation unit  51 , a diagnosis unit  52 , and a storage unit  53 . The calculation unit  51  receives vibration information on each control shaft from each respective one of the vibration sensors  16 ,  26 ,  36 , and calculates, for each control shaft, vibration levels in a plurality of predetermined frequency ranges, based on the vibration information. A plurality of possible abnormal states that may occur in the equipment  1  can be associated with various vibrations that occur at each control shaft. For example, there is a case in which vibration more easily occurs on the X shaft than the other control shafts in a first abnormal state, and vibration more easily occurs on the Z shaft than the other control shafts in a second abnormal state. Moreover, there is a case in which in a third abnormal state and a fourth abnormal state, vibration tends to occur on the Y shaft, compared to the other control shafts, but a frequency characteristic of the vibration (for example, resonant frequency of the vibration) occurring on the Y shaft varies. When various abnormal states occurring in the equipment  1  can be associated with characteristics of vibrations on the control shafts as described above, an abnormal state in the equipment  1  can be diagnosed by utilizing such vibration-related characteristics. The plurality of predetermined frequency ranges are set, with such a respect taken into consideration. In other words, each of the predetermined frequency ranges can be set as appropriate, based a vibration characteristic for making it easy to detect a possible abnormal state that may occur in the equipment  1 . 
     For example, in  FIG. 4 , which will be described later, five ranges (band 1 to band 5) are set as predetermined frequency ranges. Frequencies do not overlap between the frequency ranges, and for correlations between the frequencies belonging to the individual ranges, the relation of band 1&lt;band 2&lt;band 3&lt;band 4&lt;band 5 holds. The frequency ranges do not necessarily need to be consecutive frequency ranges, and widths of the frequency ranges (widths of the bands) do not necessarily need to be the same. Note that the set plurality of predetermined frequency ranges are used in common for each control shaft. 
     The calculation unit  51  performs fast Fourier transform (FFT) processing on the vibration information received from each of the vibration sensors  16 ,  26 ,  36  and, based on a frequency-related predetermined characteristic amount in a preset frequency range, calculates a vibration level in the frequency range. For the predetermined characteristic amount, for example, a peak value, a mean value, or the like of values obtained by the FFT processing in the frequency range may be adopted. The calculation unit  51  calculates a vibration level corresponding to each of the plurality of predetermined frequency ranges, for each control shaft, at the same timing. In the present embodiment, a vibration level is an index that is relatively calculated, on a basis of the above-described predetermined characteristic amount for each control shaft in the normal state in which no abnormal state occurs in the equipment  1 , for example, as in a following expression: 
       Vibration level=(actual predetermined characteristic amount)/(predetermined characteristic amount in the normal state). 
     Accordingly, for example, in an example illustrated in  FIG. 4 , the vibration level is determined to be “1” when the actual predetermined characteristic amount has the same value as the predetermined characteristic amount in the normal state, and values of the vibration level vary due to a fact that a degree of an abnormal state in the equipment  1  is reflected on the actual predetermined characteristic amount. In other words, a larger value of the vibration level that exceeds “1” means a higher degree of an abnormal state in the equipment  1 . 
     Next, the diagnosis unit  52  diagnoses an abnormality related to each control shaft, based on a distribution state, in each of the plurality of predetermined frequency ranges and across all of the control shafts, of the vibration levels calculated by the calculation unit  51 . Since a control shaft that is more susceptible to an effect and a frequency range in which the effect more easily appears change depending on a type of abnormal state in the equipment  1 , the distribution state can be said to be information reflecting a type of abnormal state in the equipment  1 . Accordingly, as described above, the diagnosis unit  52  can conduct abnormality diagnosis, based on the distribution state of the vibration levels. To conduct the abnormality diagnosis, vibration distribution information to be compared with the distribution state is stored in the storage unit  53 . The vibration distribution information is information associated with a possible abnormal state that may occur in the equipment  1 , and is information on a distribution of vibration levels formed based on vibration information detected for each control shaft on an assumption that the abnormal state occurs in the equipment  1 . In other words, the vibration distribution information is information related to a vibration distribution that discriminably represents an abnormal state occurring in the equipment  1  from other abnormal states. Accordingly, when a distribution state of vibration levels coincides with, or approximates to, certain vibration distribution information, the diagnosis unit  52  can make a diagnosis of occurrence of an abnormal state represented by the certain vibration distribution information in the equipment  1 . 
     Here, an example of processing related to abnormality diagnosis control by the processing apparatus  5  will be described based on a flowchart illustrated in  FIG. 3 . The abnormality diagnosis control can be performed at a predetermined timing, such as before workpiece processing is started or after workpiece processing is completed in the equipment  1 . First, in S 101 , driving of the motors  13 ,  23 ,  33  for the control shafts and the spindle  31  that are preset for diagnosis to detect an abnormal state in the equipment  1  is started. For example, one motor of the motors for the three control shafts or the spindle  31  may be caused to drive or driven, or the motors for the plurality of control shafts and the spindle  31  may be caused to drive and driven at the same time. By causing the motors and the like preset for abnormality diagnosis to drive in such a manner, abnormal states related to driving of the motors and the like can be narrowed down to some extent, and accuracy in detection of an abnormal state can be enhanced. When the processing in S 101  is finished, the processing advances to S 102 . 
     In S 102 , while the motors and the like started to drive in S 101  are driving, vibration on each control shaft is detected by the vibration sensors  16 ,  26 ,  36  provided for the control shafts, respectively, and the calculation unit  51  acquires vibration information related to the vibration. When the processing in S 102  is finished, the processing advances to S 103 . In S 103 , it is determined whether or not the driving of the motors and the like that are started to drive in S 101  is completed. When affirmative determination is made in S 103 , the processing advances to S 104 , and when negative determination is made, the processing in S 102  continues to be performed. 
     In S 104 , the calculation unit  51  calculates, for each control shaft, vibration levels in the plurality of predetermined frequency ranges, based on the vibration information on each control shaft acquired in S 102 . Subsequently, in S 105 , the diagnosis unit  52  generates a distribution state of the vibration levels, and further in S 106 , diagnoses a degree of an abnormal state in the equipment  1 , based on the generated distribution state. 
     Here, the diagnosis related to a degree of an abnormal state, conducted by the diagnosis unit  52  will be described based on  FIG. 4 .  FIG. 4  illustrates, at (a) to (c), distribution states of vibration levels generated in S 105  when three illustrative abnormal states occur in the equipment  1 . More specifically, an upper diagram (a) of  FIG. 4  represents a distribution state of vibration levels when an abnormal state occurs in the cover  21  on the Y shaft. The distribution state is detected and generated, due to the motor  23  for the Y shaft being caused to drive. In the abnormal state of interest, vibration levels based on vibration information from the vibration sensor  26  for the Y shaft, as affected by the cover  21 , are relatively high in the frequency ranges of the bands 1 to 3. Moreover, as described above, since the X shaft is arranged over the Y shaft in the equipment  1 , the vibration attributable to the abnormal state of the cover  21  is easily transmitted to the X shaft. On the other hand, if the abnormal state is of the cover  21 , the vibration attributable to the abnormal state is largely not transmitted to the Z shaft. As a result, in the frequency ranges of the bands 1 to 3, vibration levels of the X shaft are relatively high, similarly to the Y shaft, but are lower levels than the levels of the Y shaft. Moreover, vibration levels of the Z shaft are not affected by the X shaft or the Y shaft. As described above, the distribution state of the vibration levels illustrated in the upper diagram (a) of  FIG. 4  can be said to be associated with the abnormal state of the cover  21  on the Y shaft. 
     A middle diagram (b) of  FIG. 4  represents a distribution state of vibration levels when an abnormal state occurs in the spindle  31  on the Z shaft. The distribution state is detected and generated, due to the spindle  31  being driven. In the abnormal state of interest, it is assumed that cyclic mechanical vibration occurs in the spindle  31 . At the time, vibration levels based on vibration information from the vibration sensor  36  for the Z shaft are relatively high in the frequency ranges of the bands 1 to 2, but, on the other hand, the vibration is largely not transmitted to the X shaft or the Y shaft. As described above, the distribution state of the vibration levels illustrated in the middle diagram (b) of  FIG. 4  can be said to be associated with a certain abnormal state of the spindle  31  (that is, an abnormal state that causes the cyclic mechanical vibration). Moreover, a lower diagram (c) of  FIG. 4  also represents a distribution state of vibration levels when an abnormal state occurs in the spindle  31  on the Z shaft, but in the abnormal state of interest, it is assumed that friction between metals occurs in the spindle  31 . The distribution state is also detected and generated, due to the spindle  31  being driven. At the time, vibration levels based on vibration information from the vibration sensor  36  for the Z shaft are relatively high in the frequency ranges of the bands 4 to 5, which are relatively high frequency ranges, but, on the other hand, the vibration is largely not transmitted to the X shaft or the Y shaft. As described above, the distribution state of the vibration levels illustrated in the lower diagram (c) of  FIG. 4  can be said to be associated with a certain abnormal state of the spindle  31  (that is, an abnormal state that causes friction between metals). 
     As described above, abnormal states that can occur in the equipment  1  are associated with distribution states of vibration levels, as illustrated in  FIG. 4 . Accordingly, the diagnosis unit  52  compares such a distribution state with the vibration distribution information stored in the storage unit  53 , whereby based on a result of the comparison, when the distribution state coincides with any of the stored vibration distribution information, the diagnosis unit  52  can make a diagnosis of occurrence of an abnormal state represented by the coinciding vibration distribution information in the equipment  1 . When a generated distribution state differs from the stored vibration distribution information, but an amount of the difference is within a predetermined limit (for example, when a condition is met, such as that the number of frequency ranges that differ from certain vibration distribution information is equal to or smaller than a predetermined number), the distribution state may be regarded as approximating to the certain vibration distribution information, and a diagnosis of occurrence of an abnormal state represented by the certain vibration distribution information in the equipment  1  can be made. 
     As described above, according to the present abnormality diagnosis control, with a relatively simple configuration in which the vibration sensors  16 ,  26 ,  36  are provided for the control shafts, respectively, diagnosis of an abnormality in the equipment  1  can be conducted in a preferred manner, by taking into consideration the fact that vibrations mutually interact between the control shafts. In particular, information subjected to the abnormality diagnosis is information obtained as a result of the equipment  1  actually operating and therefore accurately reflects a degree of an abnormal state in the then equipment  1 , and accordingly, the abnormality diagnosis can be implemented while the operation of the equipment  1  can be maintained favorably. As a result, a timing of performing maintenance, such as replacing a part of the equipment  1 , can also be set appropriately. 
     Note that in the abnormality diagnosis control, although the driving of the motors and the like for abnormality diagnosis is performed in S 101 , such driving is not necessarily required processing. In other words, the acquisition of vibration information in S 102  may be performed when driving of motors and the like is performed for workpiece processing or the like in the equipment  1 . 
     Moreover, in  FIG. 4 , the distribution states of the vibration levels are represented by distributions of numerical values. However, instead of such a form, each vibration level may be represented by corresponding pictorial (image) information as illustrated in  FIG. 5 . In  FIG. 5 , vibration levels and images are associated such that as a vibration level is higher, an image has a darker shade of color. An upper diagram (a) illustrated in  FIG. 5  corresponds to the upper diagram (a) of  FIG. 4 , a middle diagram (b) illustrated in  FIG. 5  corresponds to the middle diagram (b) of  FIG. 4 , and a lower diagram (c) illustrated in  FIG. 5  corresponds to the lower diagram (c) of  FIG. 4 . By representing the vibration levels in the form of images as described above, it is made easy to use publicly known deep learning techniques involving image processing. As a result, it is made easy to determine coincidence or a degree of approximation between a distribution state of vibration levels and the vibration distribution information stored in the storage unit  53  by comparison, and accordingly, a degree of an abnormal state in the equipment  1  can be diagnosed in a preferred manner. 
     Modification 
     In the hitherto described embodiment, a degree of an abnormal state in the equipment  1  is diagnosed by comparing a distribution state of vibration levels with the vibration distribution information. Here, regarding an abnormal state that can occur in the equipment  1 , the abnormal state occurs suddenly in some cases, and the abnormal state gradually comes to appear, taking a certain amount of time, in some cases. In the latter case, it can be thought that a distribution state of vibration levels changes as an abnormal state in the equipment  1  changes, and when a distribution state of the vibration levels eventually coincides with or approximates to the vibration distribution state, a state is brought about in which the predetermined abnormal state occurs. 
     Accordingly, the diagnosis unit  52  can predict about when an abnormal state occurs, by using such changes in distribution state of vibration levels. Specifically, an abnormal state can be predicted, based on a history of driving of the respective motors  13 ,  23 ,  33  for the control shafts and the spindle  31  in the equipment  1 , and on changes in distribution state of vibration levels. For example, assuming that in a distribution state of vibration levels at a current point of time, numerical values related to the X shaft and the Y shaft in the bands 1 to 3 are half the numerical values indicted in the upper diagram (a) of  FIG. 4 , and that a history of driving of the motor  23  for the Y shaft up to the current point of time indicates 1000 hours, it can be predicted that the abnormal state indicated by the upper diagram (a) of  FIG. 4 , that is, the abnormal state of the cover  21  on the Y shaft can occur when the motor  23  is made to drive for another 1000 hours. 
     When an abnormal state is predicted by the diagnosis unit  52  as described above, a result of the prediction is notified from the processing apparatus  5  to a user, whereby the user can be advised to prepare for maintenance work. Moreover, the abnormality diagnosis control illustrated in  FIG. 3  is also performed, even if such prediction of an abnormal state is performed, whereby when the abnormal state actually occurs, the occurrence can be detected quickly. 
     REFERENCE SIGNS LIST 
     
         
           1  equipment 
           5  processing apparatus 
           13 ,  23 ,  33  motor 
           16 ,  26 ,  36  vibration sensor 
           31  spindle