JPS6255712A - Method for diagnosing trouble of machine - Google Patents

Abstract

PURPOSE:To detect quickly and completely the factor of a trouble when the working of a machine is stopped and to improve the working efficiency of the machine, by collating a logic equation stored in a diagnosis data area with the input/output state of a sequence controller and discriminate each working element or the state of a detector to detect the trouble area. CONSTITUTION:A sequence controller PC reads a trouble diagnosis logic equa tion LG having equation number (N=1) out of those equations LG stored in the trouble diagnosis data area of a data storing part 2. Then the controller PC refer to the input/output state table of a table part 3 to check whether or not both right and left members of the equation LG are satisfied. The equa tion number N receives +1 in the trouble diagnosis data area and the next equation LG is checked in case the left member is not satisfied and both right an left members are satisfied respectively. Then the abnormal states of both output and input elements OUT and IN of the equation LG are displayed on a display control panel 4 when the right member is not satisfied although the left member is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a fault diagnosis method for diagnosing a fault in a machine that operates in sequence according to commands from a sequence control device.

"Prior Art" Generally, in a machine that performs this sequence operation, as shown in FIG. When a function command, other workpiece loading signal, etc.) is input, a logic (expressed by a logical formula for sequence operation) SLY indicating the relationship with the status of other operating elements at that time is determined, and this logical formula SLI
When this is established, a command output OUT 1 is sent from the sequence control device M, PC to the machine MAK, which is the controlled object, [and the operating element (for example, cylinder) Al corresponding to this command output 0UTIK operates, and then this operation When the sensor (for example, a cut switch) attached to the manufacturer 1 becomes the input INI for the operation of the next stage of operation 11A2, each of the operation elements AI and A2 operate in sequence, resulting in a series of mechanical operations. is now being carried out. Usually, when designing a control circuit for a machine that operates in sequence, each logical formula for the sequence operation is determined from a time chart (indicating the operating order of each operating element and the relationship between each operating element). The machine is sequence-controlled by designing SLI, SL2, and SL3 and connecting these logical expressions S L 1 , SL2, and SL3. in this case,
If each operating element AI, A2 or the sensor attached to these is normal, each input INI corresponds to the command output 0UT1.0UT2 for each operating element AI, A2.
, IN2 are input to the sequence control device PCK, and the actuation lines Al and A2 are not directly related to each other and are operated separately according to commands from the sequence control device PC.

``Problems to be Solved by the Invention'' By the way, machines that perform the above-mentioned sequential operations tend to become larger and more complex, and as a result, maintenance work in the event of a failure of the machine requires a great deal of effort and time. The problem is that the downtime (the downtime from when the machine stops operating due to a breakdown until the machine can be operated again after repairs and adjustments are completed) increases, resulting in a reduction in operating time. There is. For this reason, the above-mentioned machines have traditionally been inspected regularly and replaced parts at intervals of usage.
Efforts have been made to prevent machine failures, but for example, electric parts used to control machine tool grips, such as limit switches and solenoid valve solenoids, are used in harsh environments where they come into contact with chips, coolant oil, etc. This problem cannot be dealt with through periodic maintenance and replacement, and as a result, there is currently a problem in that machines often stop operating due to failures in the electrical components mentioned above.

In recent years, with the spread of microcomputers, programmable sequence controllers (programmable sequence controllers) using microcomputers have been adopted as control devices for machines that operate in sequence. Search methods are becoming more difficult. In other words, the method of processing sequence logic is completely different between a sequence control device that combines conventional relay circuits and a control device that uses the above-mentioned microcomputer, and it is difficult for maintenance personnel to use this microcomputer. Because the internals of the sequence control device are often unknown (black box), if a certain output element does not operate in response to the commands of the sequence control device, the logic condition for that output element will be changed. On the other hand, a method of checking the on/off state of a relay along an electric circuit (a fault diagnosis method conventionally used in sequence control devices incorporating a relay circuit)
The problem is that it cannot be used.

In view of the above circumstances, the present invention aims to solve the problem that most failures in machines that operate in sequence occur in the electrical system, especially in limit switches, solenoids, etc. installed in locations with poor operating environments, and that It was developed with a focus on interruptions in operation, and its purpose is to quickly and reliably discover the cause of failure when a sequence-controlled machine stops operating.
An object of the present invention is to provide a method for diagnosing machine failures that can improve the operating rate of machines.

"Means for Solving Problems" In order to achieve the above object, the present invention stores in advance in a diagnostic data area a logical formula that holds true when a machine that operates in sequence operates normally, and During sequence operation of the machine, the command output that the sequence control device outputs to each operating element of the machine and the detection input of each detector that is input to the sequence control device are stored in an input/output state table, respectively. Then, based on the failure diagnosis start command, the logical formula stored in the diagnostic data area is compared with the input/output status of the sequence control device stored in the input/output status table, and each of the operating elements or It determines the status of the detector and discovers the location of the machine's failure.

"Operation" In the fault diagnosis method of the present invention, at the start of fault diagnosis,
The logical expressions that hold true during normal operation of the machine, stored in the diagnostic data area in advance, are compared with the input/output status of the sequence control device during actual operation stored in the input/output status table, and each operating element or detection To determine whether the condition of a machine is normal or abnormal, and quickly and reliably identify the location of a machine failure.

"Embodiment" Hereinafter, an embodiment of the present invention will be described based on FIGS. 7 to 6.

In FIG. 2, the PC is a programmable sequence control device, and this sequence control device RPC is used for checking sequence operation data (logic formulas for sequence operation) and controlling output according to the input state. A program storage unit (ROM) 1 stores a program and a block diagram for failure diagnosis for performing failure diagnosis processing, a data storage unit 2 stores the sequence operation data and failure diagnosis data, and stores input and output states. A table section 3, a display panel 4 for registering or changing abnormal conditions, input conditions, sequence operation status, etc., sequence operation data, or failure diagnosis data, and A central processing unit (which performs stock sequence control or trouble diagnosis processing)
CPU) 5 and the input signals from each detector 6 are passed through BU.
It is comprised of an input interface 7 that sends out to the central processing unit f5 via S, and an output interface 9 that sends command output from the central processing unit 5 to each operating element 8. In addition, the above failure diagnosis data is stored in ROM.
(read-only memory), and RAM (iF read-out memory) is used to store the input/output status.

Sequence control device fit PC configured as above
In this process, before sequence control of the machine is performed, failure diagnosis data (logical formulas) are registered in the data storage section 2 in advance. This logical formula for fault diagnosis is similar in form to the pool algebraic formula normally used for designing sequential circuits, but
The content is different.

That is, the logical formula for failure diagnosis is the sequence control device P.
The relationship between the command output OUT output by C and the detection input IN input to the sequence control device *pc based on this command output OUT is described in the form of a pool algebraic expression. The command output OUT is written in combination with the command output OUT, and the input group that changes when the command output is sent is written in combination on the right side. Note that this format (pool algebra format) is intended to make it easier for those who design sequence logical formulas to create or test logical formulas for fault diagnosis, and it is not necessary to stick to this format. It is not necessary to have a command output, as long as the command output and input are associated with each other.

For example, in order to supply fluid to both ends of one cylinder 10, as shown in FIG. 00UTO
A pair of limit switches (detectors) a/, detecting the movement of the piston front 10a of the cylinder 10 when outputting 0OUTI, Detection of human power 0INO,0
The relationship with INI is expressed in the above logical formula for fault diagnosis as follows. That is, 00UTOGO=OIN10F(1).

0INO0N(2); ......(1)00UT
IGO=OINOOF<1>.

0INI ON<2); Song... (2) Now, to explain the above equation α), the sequence control device *
pc is the solenoid busy excitation signal 00UTO of the above solenoid valve.
When output (GO), fluid is supplied to the proximal end side of the cylinder 10 (the left end side in Figure 1), the piston rond 10a moves forward, and first, the detection protrusion 10b attached to the tip of the piston rond 10a moves forward. However, due to the trap of separating from the actuator a of the limit switch 6', the detection input QINI of the limit switch 6' becomes OFF state [Formula (
1), the detection protrusion 10b contacts the actuator of the limit switch 6', thereby turning on the detection input OINO of the limit switch 6'. become a state. In addition, the above (2)
), when the sequence control device PC outputs (GO) the excitation signal 00UTI to the solenoid of the solenoid valve, fluid is supplied to the piston rod end side of the cylinder 10 (the right end side in Figure 1), and the piston rod 10
a retreats and the detection protrusion 10b separates from the actuator of the IJ limit switch 6', so that the detection input 0INO of the limit switch 6' is turned off.
Next, the detection protrusion 10b contacts the actuator aK of the limit switch 6', thereby causing the limit switch 6'
The detection human power 0INll is turned on. in this way,
The above equations (1) and (2) describe the relationship between the input and output states regarding the cylinder IOK. Then, each formula (1
), (2) 1 as shown in FIG.
Register it in the data area for failure diagnosis in .

As described above, if the relationship between output and input is described for each unit of configuration (operating element) of the machine to be controlled and stored in the data storage unit 2, the necessary fault diagnosis can be performed. data can be obtained.

These failure diagnosis data (logical formulas) are easily created from drawings expressing the relationship between machine operations and detectors such as limit switches, such as time charts, hydraulic diagrams, and machine assembly drawings. For example, as shown in FIG. 3, logical formulas LG for failure diagnosis are stored in the data storage unit 2 in correspondence with large numbers N=1 to 22, respectively. In the figure, m.

UT3. m and Nn respectively indicate a command output from the sequence control device PC and an input to the sequence control device PC, GO indicates sending of a command output, and ON and OF indicate input on and off, respectively.

Also, kuO〉 indicates that the condition is a trap when the left side is satisfied, and <1>, <2>, and <3>.

... indicates the order in which each element on the right side holds true when the left side holds true. Furthermore, in the logical formula r/J,
r=J, r, J, r; J, rφ" indicate "or", "formula delimiter", "element delimiter", "terminal force of expression", and "terminal force of data", respectively. . For example, the fault diagnosis logical formula LG stored in the large number N=3, that is, 00U
TOGO=OINOON<O>, 0INION<1>,
0IN20 N < 2 > p is the left side element 00UT
When +100UT1 is output (GO), the input element 0INO is turned on (ON), then OINI is turned off (OFF), and KSOIN2 is turned on (ON). .

As described above, after storing the failure diagnosis data in the data storage unit 2, the sequence system a device pc performs the following steps as before.
Sequence processing is performed based on the sequence program stored in the program storage unit IK. That is, the sequence control device NPC first searches the sequence operation data (logical formula for sequence operation) stored in the data storage section 2, and stores the element states of the logical formula in the input/output state table of the table section 3. If the logical expression is established based on the status of each input/output stored, the sequence control device PC sends the result as a command output OUT to the operating element 8 of the machine to be controlled, and also outputs the result as a command output OUT. Store in the output status table. Then, each logical formula for sequence operation stored in the sequence control device 1t, the PC C, and the data storage unit 2 is sequentially searched, and a command output OUT is sent out each time each logical formula is established. For this,
As shown in FIG. 9, the input/output status table of the table unit 3 includes [, each input/output 0INO, 0INI, 0IN2, ・
, 0OUTO, 0OUTI, . . . are recorded.

In this way, the sequence control device PC performs sequence control on the machine to be controlled, but if a failure occurs and the machine stops operating during this sequence processing, the program memory of the sequence control device PC The fault cutout program stored in section 1 is activated. As a result, the sequence control device & PC executes the fault diagnosis logic formula LG stored in the fault diagnosis data area of the data storage unit 2, as shown in step 5PIK in FIG. 6, based on the above fault diagnosis program. Among them, the one with the largest number N=1 is read out, and with reference to the input/output status table of the table section 3, the fault diagnosis 1aJffi formula I is determined.
, it is checked whether the left-hand side terms and right-hand side terms of G hold true (see steps SP2 and SP3).

Then, if the left-hand side term does not hold true, or if both the left-hand side term and the right-hand side term hold true, the process proceeds to step SP4, where the equation number N in the fault diagnosis data area is incremented by 1 and the next fault is set. If the term on the left side holds true while the term on the right side does not hold true when the diagnostic logical formula LG is calculated, the fault diagnosis logic with 1 not true is created as shown in step SP5. The abnormal state of the output OUT and input 4I of the formula LG is displayed on the display operation panel 4, and the abnormality lamp is lit. Based on the displayed content, maintenance personnel replace mechanical parts (solenoids, limit switches, etc.) that are defective. For example, in Figure 1, the command output 00UTO is sent from the sequence control device PC (GO).
1 limit switch 6' detection input 0IN
limit switch 6 even though I was turned off.
’ detection human power 0INO is not turned on,
Since the on signal of the detected human power 0INO of the limit switch 61 is not input to the sequence control device 1tPc, seek yxllyl1m! H1PC is the detection input O of the limit switch σ, which is the input to the next sequence operation.
Sequence control is stopped when the INO ON signal is not input. As a result, the machine to be controlled stops operating. In this state, when you start the fault diagnosis program, the sequence control device [PC
Although the left-hand side term (OOUTOGO) of the equation holds true, the right-hand side term (OlN0ON<2>) does not hold, so it is determined that this limit switch 6' is defective. In this case, the excitation signal (command output 00UTO
Each limit switch el when is output (GO),
There are the following 9 cases for the state of 6# detection human power 0INO, 0INI.

Table 1 In Table 1, the determination of whether the machine is normal or defective is explained based on the assumption that the defective location in formula (1) above is a hole, but in reality, failures may occur at multiple locations. There is. In this case, even if the fault diagnosis method according to the present invention is carried out, it may not be possible to discover all the faulty parts in - times of inspection, but after repairing the faulty parts displayed on the display operation panel 4, By repeating the operation of activating the fault diagnosis program again, all faulty parts are reliably discovered and repaired.

In this way, when a failure occurs in a machine that is sequence-controlled by the sequence control device W or the PC, the failure diagnosis data stored in advance in the data storage unit 2 (
Since the fault location is automatically searched by comparing the logical formula) LG with the input/output status recorded in the table section 3, the fault location is systematically searched and the fault is detected quickly and reliably. location is discovered. Therefore, the time required to discover a fault location is significantly shortened, and the operating rate of the machine is improved. Furthermore, the failure diagnosis data is easily created from the structure of the machine (from time charts, hydraulic diagrams, machine assembly drawings, etc.), and there is no hassle or difficulty in creating the data.

In addition, in the above embodiment, the sequence control device RPC
K. Although the machine has been described as having a sequence control function and a failure diagnosis processing function, a failure diagnosis device may be provided separately from the sequence control device mpc that performs sequence control.

"Effects of the Invention" As explained above, the present invention stores in advance in the diagnostic data area a logical formula that holds true when a machine that operates in sequence operates normally, and when the machine operates in sequence, The control device stores commands output to each operating element of the machine, and then, based on the failure diagnosis start command, the logical formula stored in the diagnostic data area and the sequence control stored in the input/output status table. The purpose is to compare the input and output status of the device to determine the status of each of the operating elements or detectors mentioned above, and to discover the location of the machine failure. Each operation 12' is determined by comparing the logical formula that holds during normal operation of the machine with the input/output status of the sequence control device during actual operation stored in the input/output status table.
To determine whether the condition of the A or detector is normal or abnormal, the failure location of the machine can be quickly identified and the downtime of the machine can be suppressed. , which has the excellent effect of significantly improving the operating rate of the machine.

[Brief explanation of drawings]

1 to 6 show an embodiment of the present invention,
Fig. 7 is a schematic configuration diagram of the sequence control device, Fig. 1 is an explanatory diagram showing the input/output relationship, Fig. 3 is an explanatory diagram explaining the data area for failure diagnosis, and Fig. 9 is an explanatory diagram explaining the input/output status table. 3 is an explanatory diagram showing an example of a logical formula for fault diagnosis stored in the data area for fault diagnosis; FIG. 6 is a flowchart for explaining the contents of the fault diagnosis process; and FIG. 7 is for explaining sequence control. FIG. PC...Sequence control device, LG...
・Logical formula for failure diagnosis, 3... Table section, 6.
...Detector, 8...Operating element, OUT.
...Command output, IN...Detection input. Agent: Patent Attorney Masatake Shiga ;l:',. Figure 1 @ Figure 2 Oα BA O0OLJTI Figure 3 Figure 5 22 BOLFTIGO-201JT1ON (e>,
1lN3ON<1>, 21N2ON<2>;#

Claims (1)

[Claims] In a fault diagnosis method for diagnosing the failure of a machine that operates in sequence according to commands from a sequence control device, a logical formula that holds true when the machine is in a normal operating state is stored in the diagnostic data area in advance, and the machine During sequence operation, the command output that the sequence control device outputs to each operating element of the machine and the detection input of each detector that is input to the sequence control device are stored in an input/output state table, respectively. Then, based on the failure diagnosis start command, the logical formula stored in the diagnostic data area is compared with the input/output status of the sequence control device stored in the input/output status table, and each of the above is determined. A method for diagnosing a machine failure, characterized by determining the state of an operating element or a detector and discovering a failure location in the machine.