JP2015169626A - Diagnosis method and diagnosis system of bearing failure of travel carriage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diagnose bearing failure of a travel carriage before the travel carriage becomes unable to travel.SOLUTION: A diagnosis system includes a carriage unit, a travelling motor, and a main body part, and the body part diagnoses a bearing in the travel carriage supported by the carriage unit through a shaft and the bearing. The diagnosis system detects bearing failure on the basis of abnormal increase of the load of the travelling motor at the entrance or exit of a curve.

Description

  The present invention relates to diagnosis of a bearing failure of a traveling carriage.

  The applicant has developed and manufactured an overhead traveling vehicle that travels in a ceiling space such as a clean room. Such a structure of an overhead traveling vehicle is disclosed in, for example, Patent Document 1 (JP2002-308404A). In an overhead traveling vehicle, a pair of front and rear truck units travel on a rail, and the pair of truck units are connected to each other while leaving a degree of freedom of rotation about a vertical axis. The main body of the overhead traveling vehicle is supported by the bogie shaft from the pair of cart units, and the bogie shaft is supported by the cart unit by the bearing. The use of a pair of bogie shafts is a configuration for facilitating curve traveling.

  By the way, when an abnormality occurs in the bearing, an abnormal traveling load is generated on the curve, and the overhead traveling vehicle cannot travel. It is difficult to check the state of the bearing from the outside. For this reason, the overhead traveling vehicle stops, blocks the traveling route, and other overhead traveling vehicles may not be able to travel.

  To show related prior art, Patent Document 2 (JP2012-75293A) discloses monitoring motor current and counter electromotive voltage, or monitoring pulsation of motor current for detection of motor abnormality. Yes. However, this is not effective for detecting defective bearings.

JP2002-308404A JP2012-75293A

  An object of the present invention is to make it possible to diagnose a bearing failure of a traveling carriage before the traveling carriage becomes unable to travel.

  The present invention relates to a method for diagnosing the bearing in a traveling cart that includes a cart unit, a travel motor, and a main body, and the main body is supported by the cart unit via a shaft and a bearing. The bearing failure is detected from an abnormal increase in the load of the traveling motor at the entrance or exit of the motor. For example, a pair of front and rear shafts and bearings are provided.

  The present invention is also a system for diagnosing the bearing in a traveling cart that includes a cart unit, a travel motor, and a main body, and the main body is supported by the cart unit via a shaft and a bearing, Means are provided for detecting an abnormal increase in the load of the traveling motor at the entrance or exit of the curve.

  The present invention further includes a traveling carriage including a carriage unit, a traveling motor, and a main body, and the main body is supported by the carriage unit via a shaft and a bearing, wherein the traveling motor is provided at an entrance or an exit of a curve. And a means for detecting an abnormal increase in the load. The traveling carriage may perform self-diagnosis based on the detection result, or may output the detection result to a maintenance computer (diagnostic system computer) or the like and leave it for diagnosis on the ground side.

  The inventor has confirmed that if the bearing is defective, the torque of the traveling motor abnormally increases at the entrance and exit of the curve (FIG. 3). For this reason, if an abnormal increase in the torque of the traveling motor is detected at the entrance or exit of the curve, a bearing failure can be detected. The bearing failure may be determined by the overhead traveling vehicle itself, or data relating to running torque at the entrance or exit of the curve may be analyzed by a computer of the diagnostic system. In this analysis, the computer may make a diagnosis, or the operator may make a diagnosis by displaying data on the running torque at the entrance or exit of the curve on a monitor or the like.

  The traveling cart may be an automated guided vehicle or the like, but an overhead traveling vehicle including at least a pair of a cart unit, a shaft, and a bearing is important as an object of diagnosis. Since the overhead traveling vehicle travels at a high place, it is difficult for the operator to inspect the state of the bearing. When trouble occurs in an overhead traveling vehicle and the vehicle cannot travel, the rail itself cannot pass due to rail traveling. The bearings may be disposed at both ends of the shaft, for example, but are usually provided on either the cart unit side or the main body side. The bearing may be a roller bearing or the like, but it is important to diagnose a defect in the cross roller bearing which is suitable for an overhead traveling vehicle because of its excellent rigidity.

  If a running torque abnormality occurs once, it may be determined that the bearing is defective, but there is a possibility of making a wrong diagnosis. Moreover, in this invention, as shown in FIG. 4, it is possible to make a diagnosis at an early stage sufficiently before the traveling carriage becomes unable to travel. Therefore, it is preferable to diagnose the abnormality after collecting data indicating that the load has increased abnormally a plurality of times. In diagnosis, the peak value or average value of the output torque (travel torque) of the traveling motor at the entrance or exit of the curve may be used, or the frequency, frequency, etc., when the output torque exceeds the threshold for determining the failure. good.

Side view showing the overhead traveling vehicle of the embodiment and the notched rail Block diagram of bearing abnormality diagnosis system Diagram showing the running torque at the entrance of the curve with normal and abnormal bearings Diagram showing the relationship between bearing hardness and running torque Diagram showing model of rotational load at curve entrance Flow chart showing the diagnostic data collection algorithm for bearings Flow chart showing bearing diagnosis

  In the following, an optimum embodiment for carrying out the present invention will be shown. The scope of the present invention should be determined according to the understanding of those skilled in the art based on the description of the scope of the claims, taking into account the description of the specification and well-known techniques in this field.

  1 to 7 show an embodiment. Reference numeral 2 denotes an overhead traveling vehicle, which may be a traveling cart such as an automatic guided vehicle. Reference numeral 4 denotes a rail, which is provided, for example, in a ceiling space of a clean room. The overhead traveling vehicle 2 includes a pair of front and rear cart units 6, 6, a drive wheel unit 8 is disposed between the cart units 6, 6, and 10 is a main body of the overhead traveling vehicle 2.

  The driving wheel unit 8 includes a traveling wheel 12 that is a driving wheel and a traveling motor 14, and both front and rear ends thereof are supported by the carriage units 6 and 6 so as to be rotatable about a vertical axis. The pressure is applied so as to contact the tread surface 50 of the rail 4. The traveling wheel 12 causes the overhead traveling vehicle 2 to travel by frictional force with the tread surface 50. The cart units 6 and 6 include a driven wheel 20, guide rollers 22 and 24 for switching between branching and straight traveling, and a power receiving unit 28. The cart units 6, 6 support the main body 10 by a pair of front and rear vertical bogie shafts 31, 31 via cross roller bearings 30, 30. The cross roller bearing 30 may be changed to a ball bearing or the like, and the cross roller bearing 30 may be disposed between the bogie shaft 31 and the main body 10. Furthermore, the traveling motor 14 and the drive wheel 12 may be provided in each of the cart units 6 and 6, and the cart units 6 and 6 may be connected so as to be rotatable around the vertical axis.

  The overhead traveling vehicle 2 includes a linear sensor 32, reads a magnetic mark installed on the rail 4, and detects the absolute position of the overhead traveling vehicle 2. Furthermore, it communicates with a ground side controller by the communication unit which is not illustrated. The main body portion 10 includes a lateral unit 34, and the θ unit 36 and the hoist 38 are laterally moved in the horizontal direction at right angles in the traveling direction, and the θ unit 36 rotates the hoist 38 about the vertical axis. The hoist 38 moves the hand 40 including the chuck 41 up and down. The rail 4 includes treads 50 and 51, supports the litz wire by the litz wire holders 52 and 52, and supplies power to the power receiving unit 28 in a non-contact manner.

  FIG. 2 shows a bearing failure diagnosis system 60, in which the output torque of the traveling motor is input to the gate 62, and it is determined whether it is the entrance of the curve from the position of the overhead traveling vehicle on the map or the signal of the gyro sensor. Then, the output torque at the entrance of the curve is compared with the threshold value by the comparison unit 63. Then, the number of times that the threshold per day (NG number of times) is exceeded, the peak value of the output torque at that time, the position on the travel route, and the like are stored in the temporary memory 64. The position on the travel route here can be used, for example, for rail failure diagnosis. The NG number of the day with the maximum number of NGs per month, the maximum torque at the entrance of the curve in the range of January, and the like are stored in the storage unit 66 and used as diagnostic data.

  Using the data in the storage unit 66, the self-diagnosis unit 70 built in the overhead traveling vehicle may detect a defect in the cross roller bearing. However, in order to diagnose the failure more carefully, the diagnostic data is read from the input / output 68 to the personal computer 80 or the like in the maintenance area, and the diagnostic data is displayed on the monitor 81 so that the operator can diagnose the normality / defectiveness. It is preferable to do. In order to support the diagnosis, the statistical processing unit 82 is used to display the transition of the maximum number of NG times per month, the transition of the maximum torque, etc. on the monitor 81. Alternatively, the diagnosis may be performed by the diagnosis unit 84, and the diagnosis result, the transition of the maximum number of NGs per month, the transition of the maximum torque, and the like may be displayed on the monitor 81 to ask for the operator's confirmation. The threshold value of the comparison unit 63 may be constant, or may be generated individually from the value when the cross roller bearing is new.

  When the overhead traveling vehicle 2 travels in a curve, the bogie shaft 31 rotates about the vertical axis with respect to the carriage unit 6. When the defect of the cross roller bearing 30 progresses, the overhead traveling vehicle 2 becomes unable to travel in a curve. Therefore, it is possible to reliably diagnose the normality / defectiveness of the cross roller bearing 30 before the overhead traveling vehicle 2 becomes unable to travel. As data indicating the state of the cross roller bearing 30, the load on the traveling motor 14 in a curve, in other words, the output torque (traveling torque) of the traveling motor 14 was examined.

  FIG. 3 shows the output torque of the traveling motor 14 at the entrance of the curve. “Cross failure” indicates that a load equivalent to 50 N is applied to one of the pair of cross roller bearings 30 to make it difficult to rotate. A normal cross roller bearing 30 is shown. Even when a load of 50N was applied, the cross roller bearings rotated in a curve and could run on a curve. If the cross roller bearing 30 is defective, the running torque increases at the entrance of the curve.

  FIG. 4 shows the distribution (5 times) of the peak value of the running torque at the entrance of the curve when the load applied to the cross roller bearing 30 is changed in the range from 5N to 50N. When the cross roller bearing 30 becomes difficult to rotate, the peak value of the running torque increases, and the state of the cross roller bearing 30 can be diagnosed based on whether or not the running torque exceeds the threshold at the entrance of the curve.

FIG. 5 shows a model of the load that the traveling motor receives from the cross roller bearing at the entrance of the curve. R is the radius of curvature of the curve, and θ is the rotation angle on the curve. At the entrance of the curve, the front carriage unit 6f rotates counterclockwise by an angle β with respect to the line L connecting the front and rear cross roller bearings 30 and 30, and the rear carriage unit 6r rotates clockwise by an angle α. Rotate. When the rotational load of the cross roller bearings 30 and 30, that is, the moment of the force resisting rotation is Tbf and Tbr, the work amount Wb of the traveling motor by the cross roller bearing when entering the curve is
Wb = Tbf × β + Tbr × α (1)
Given in. When this is differentiated with respect to time, the output torque of the traveling motor is increased by entering the curve. Equation (1) confirms that the cross roller bearing failure can be detected from the increase in running torque at the entrance of the curve.

  3 to 5 have described the entrance of the curve, the same applies to the exit of the curve. Thus, the output torque of the travel motor may be monitored at both the entrance and exit of the curve, or one of them may be monitored.

  FIG. 6 shows a procedure for collecting diagnostic data. In step 1, it is detected that the vehicle is traveling at the entrance (or exit) of the curve. The number of times is incremented by 1, and the position on the travel route, the maximum torque, etc. are stored. Instead of the maximum torque, an average torque or the like at the entrance of the curve may be stored (step 3). For example, when the day ends (step 4), the number of NG times per day, the maximum value of torque at the NG location, the place where the maximum torque is generated, etc. are stored in the temporary memory (step 5). Then, for example, every month (step 6), the NG number of the day with the maximum number of NG times, the maximum value of the running torque at NG points in January, etc. are stored (step 7). Note that the maximum value of the running torque is auxiliary data for diagnosis, and may be an average value of running torque at the entrance of the curve. Further, the place where the maximum value of the torque is generated is auxiliary data for diagnosis of the rail state.

  The diagnosis data collected as shown in FIG. 6 is used, for example, when the overhead traveling vehicle arrives at the maintenance area, the diagnosis is performed according to the procedure shown in FIG. The transition of the diagnostic data collected in step 11 is displayed on, for example, a monitor, and the operator or the diagnosis unit diagnoses the normality / defectiveness of the cross roller bearing (step 12).

  In the embodiment, the running torque at the entrance of the curve is used, but the running torque at the exit or the running torque at both the entrance and the exit may be used. In addition, it is not necessary to collect all curves, for example, collect data only when the curve travel speed is the same and the empty / actual load conditions are the same except for the curves associated with branching / merging. Also good.

  In addition, since it is difficult to diagnose which of the pair of front and rear cross roller bearings is defective, for example, the operator determines from the backlash between the cross roller bearing and the bogie shaft. In equation (1), the angle β changes greatly at the entrance and exit of the curve first, and then the angle α changes greatly. It can be estimated which of the front and rear cross roller bearings is abnormal depending on whether it is significant.

2 Overhead traveling vehicle 4 Rail 6 Carriage unit 8 Drive wheel unit 10 Main body 12 Traveling wheel 14 Traveling motor 16 Energizing unit 20 Driven wheel 22, 24 Guide roller 28 Power receiving unit 30 Cross roller bearing 31 Bogie shaft 32 Linear sensor 34 Lateral unit 36 θ unit 38 hoist 40 hand 41 chuck 50, 51 tread surface 52 litz wire holder 60 bearing failure diagnosis system 62 gate 63 comparison unit 64 temporary memory 66 storage unit 68 input / output 70 self-diagnosis unit 80 personal computer 81 monitor 82 statistical processing unit 84 Diagnosis Department

R Curvature radius θ Rotation angle α, β Deviation from drive wheel unit
Tbf, Tbr Rotating load

Claims (5)

A method of diagnosing the bearing in a traveling cart that includes a cart unit, a travel motor, and a main body, and the main body is supported by the cart unit via a shaft and a bearing,
A method for diagnosing a bearing failure of a traveling carriage, wherein the bearing failure is detected from an abnormal increase in a load of a traveling motor at an entrance or exit of a curve.   2. The method for diagnosing a bearing failure of a traveling carriage according to claim 1, wherein the traveling carriage is an overhead traveling vehicle including at least a pair of the front and rear units, the shaft, and the bearing.   3. The method for diagnosing a bearing failure in a traveling vehicle according to claim 1, wherein the bearing is a cross roller bearing. A system for diagnosing the bearing in a traveling cart that includes a cart unit, a travel motor, and a main body, and the main body is supported by the cart unit via a shaft and a bearing,
A system for diagnosing a bearing failure of a traveling carriage, comprising means for detecting an abnormal increase in load of a traveling motor at an entrance or exit of a curve. A traveling carriage having a carriage unit, a traveling motor, and a main body, the main body being supported by the carriage unit via a shaft and a bearing;
A traveling cart comprising means for detecting an abnormal increase in load of a traveling motor at an entrance or exit of a curve.