JP2007029994A - Deterioration diagnosing device, and deterioration diagnosing method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To diagnose deterioration of an electric-powered spot welding gun by finding out a sign of deterioration of the gun. <P>SOLUTION: A deterioration diagnosing device 1 is provided with: a pressurizing time-obtaining means 22 for obtaining a pressurizing time from the time of driving start of an electrode 161 until the time when electrodes hold members with predetermined force; a pressurizing position-obtaining means 23 for obtaining a position of the electrode 161 in the state that the electrodes hold members with the predetermined force; an analyzing means 24 for analyzing, by a statistical method, analysis data 421, which are determined by the pressurizing time and the pressurizing position of a spot welding gun 16 in an analysis section; and deterioration diagnosing means 25, 26 for diagnosing the deterioration of the spot welding gun 16 by diagnostic data 422, which are determined by the pressurizing time and the pressurizing position of the spot welding gun 16 in a control section, based on the analysis result of the analysis data 421 by the analyzing means 24. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a deterioration diagnosis apparatus, a deterioration diagnosis method, and a program for diagnosing deterioration of a spot welding gun in a welding robot that performs spot welding.

In an industrial robot, characteristic data of each axis of the robot can be collected and statistically analyzed to diagnose deterioration of the robot arm (see, for example, Patent Document 1). This is because characteristic data such as cycle time, average torque, and reduction gear life is accumulated from the past to the present, and this is analyzed by statistical methods to show signs of deterioration before the reduction gear replacement period arrives. It is something to be detected.
On the other hand, in an electric spot welding gun connected to an industrial robot, wear of a fulcrum shaft and wear of a ball screw in a drive system occur due to aging. At present, pressurization control that keeps the motor current constant is the mainstream, so the actual pressurization decreases due to these deteriorations, which can cause spatter and dust when energized, which can cause poor welding quality.
JP 2005-148873 A

  However, when trying to catch these signs of deterioration using a method such as Patent Document 1, it is difficult to find the influence of the spot welding gun on the cycle time due to the variation in the work position. Since control is performed to keep the flowing current constant, there is a problem that it is difficult to find signs of deterioration of the spot welding gun in terms of average torque and maximum torque. Therefore, even if the deterioration of the robot body axis can be diagnosed, the deterioration diagnosis of the electric spot welding gun cannot be performed.

  Accordingly, the present invention has been made to solve the above-described problem, and a deterioration diagnosis device capable of diagnosing deterioration of an electric spot welding gun by finding a deterioration sign of the electric spot welding gun. An object is to provide a diagnostic method and a program.

The invention according to claim 1 is a degradation of a spot welding gun in which an electrode is driven by an electric motor and a current is passed in a state in which members to be joined are sandwiched between the electrodes with a predetermined pressing force to join the members together. In the deterioration diagnosis apparatus, the pressurization time acquisition means for acquiring the pressurization time from the start of driving the electrodes to the state where the members are sandwiched by the predetermined pressurizing force, and the members are connected to the predetermined Pressure position acquisition means for acquiring the position of the electrode in a state of being sandwiched by the applied pressure, and the pressure time and pressure position acquired by the pressure time acquisition means in a predetermined operation section of the spot welding gun Based on the analysis result of the analysis data determined by the statistical method, the analysis data determined from the pressurization position acquired by the acquisition means, and based on the analysis result of the analysis data by the analysis means The spot welding is based on diagnostic data determined from the pressurization time acquired by the pressurization time acquisition means and the pressurization position acquired by the pressurization position acquisition means in a section after a predetermined operation section of the welding gun. And a deterioration diagnosis means for diagnosing deterioration of the gun.
Here, the predetermined operation section is a section in which analysis data is collected and stored for analysis by a statistical method before performing deterioration diagnosis, and is a so-called analysis section.
The section after the predetermined operation section is after the analysis section, that is, after obtaining a regression equation, and collecting and accumulating diagnostic data for performing deterioration diagnosis of the spot welding gun based on the regression equation. This is a section, which is a so-called management section.

  According to a second aspect of the present invention, in the deterioration diagnosis apparatus according to the first aspect, the analysis means calculates an nth-order (n is a natural number) regression equation based on the analysis data. .

  According to a third aspect of the present invention, in the degradation diagnostic apparatus according to the second aspect, the degradation diagnostic unit is configured to provide a distance between a regression line based on the regression equation of the nth order (n is a natural number) and the diagnostic data. And the deterioration of the spot welding gun is diagnosed based on the calculated distance.

  According to a fourth aspect of the present invention, in the deterioration diagnosis device according to any one of the first to third aspects, the welding gun control device is connected in communication with a welding gun control device that performs drive control of the spot welding gun. Communication means for receiving pressurization time data relating to the pressurization time and pressurization position data relating to the pressurization position.

  According to a fifth aspect of the present invention, in the deterioration diagnosis apparatus according to the fourth aspect, the communication means is configured to be communicably connected to a plurality of welding gun control apparatuses, and the deterioration diagnosis means acquires the pressurization time. And the pressurization position acquisition means are capable of simultaneously diagnosing deterioration for each spot welding gun based on analysis data and diagnosis data acquired from a plurality of welding gun control devices via the communication means. To do.

  The invention according to claim 6 is a deterioration of a spot welding gun in which electrodes are driven by an electric motor and members to be joined are sandwiched between the electrodes with a predetermined pressure, and current is passed to join the members together. In the deterioration diagnosis method, a pressurization time acquisition step of acquiring a pressurization time from the start of driving of the electrodes to a state where the members are sandwiched with the predetermined pressurizing force, and the members between the predetermined A pressurization position acquisition step of acquiring the position of the electrode in a state of being sandwiched between the pressurization pressures, a pressurization time acquired by the pressurization time acquisition step in a predetermined operation section of the spot welding gun, and the pressurization position Based on the analysis process for analyzing the analysis data determined from the pressure position acquired in the acquisition process by a statistical method, and the analysis result of the analysis data in the analysis process, Spot welding based on diagnostic data determined from the pressurization time acquired by the pressurization time acquisition step and the pressurization position acquired by the pressurization position acquisition step in a section after a predetermined operation section of the welding gun A deterioration diagnosis step of diagnosing deterioration of the gun.

  According to a seventh aspect of the present invention, in the program, spot welding is performed such that, in the program, the electrodes are driven by an electric motor and the members to be joined are joined with each other with a predetermined pressure applied between the members to be joined. A computer for diagnosing deterioration of a gun, a pressurization time acquisition function for acquiring a pressurization time from the start of driving of the electrodes to a state where the members are sandwiched with the predetermined pressure, and the members Pressurization position acquisition function for acquiring the position of the electrode in a state sandwiched by a predetermined pressurizing force, pressurization time acquired by the pressurization time acquisition function in a predetermined operation section of the spot welding gun, and the pressurization Based on the analysis function for analyzing the analysis data determined from the pressurization position acquired by the position acquisition function by a statistical method, and the analysis result of the analysis data by the analysis function And the diagnostic data determined from the pressurization time acquired by the pressurization time acquisition function and the pressurization position acquired by the pressurization position acquisition function in a section after the predetermined operation section of the spot welding gun. And a deterioration diagnosis function for diagnosing deterioration of a spot welding gun.

According to the first aspect of the present invention, in the predetermined operation section of the spot welding gun, the pressurization time from the start of driving the electrodes to the state where the members are sandwiched with the predetermined pressurization force by the pressurization time acquisition means And the position of the electrode in a state in which the members are sandwiched with a predetermined pressure by the pressurization position acquisition means. Here, the pressurization time and the pressurization position acquired in a predetermined operation section of the spot welding gun are used as analysis data.
Then, when the analysis means analyzes the analysis data by a statistical technique, the deterioration diagnosis means is acquired by the pressurization time acquisition means in a section after the predetermined operation section of the spot welding gun based on the analysis result of the analysis data. The deterioration of the spot welding gun is diagnosed based on the diagnostic data determined from the applied pressurization time and the pressurization position acquired by the pressurization position acquisition means.

That is, the deterioration diagnosis of the spot welding gun is performed based on the pressurization time and pressurization position of the electrode, and it is not necessary to find a sign of deterioration from the cycle time affected by the variation in the work position. Further, it is not necessary to find a sign of deterioration from the maximum torque that is affected when control is performed to keep the current flowing through the motor constant.
Therefore, it becomes possible to find the deterioration sign of the electric spot welding gun from the data regarding the electrode of the spot welding gun, and the deterioration diagnosis of the electric spot welding gun can be performed.

  According to the second aspect of the present invention, the analysis means calculates an nth-order regression equation (n is a natural number) based on the analysis data, and performs deterioration diagnosis of the electric spot welding gun based on the regression equation. Therefore, deterioration diagnosis can be performed by a simple method, and the load on analysis can be kept low.

  According to the invention of claim 3, the deterioration diagnosis means calculates the distance between the regression line based on the regression equation of nth order (n is a natural number) and the diagnostic data, and spots based on the calculated distance Since the deterioration of the welding gun is diagnosed, the deterioration diagnosis can be performed by a simple method, and the load on the analysis can be kept low.

  According to the fourth aspect of the present invention, since the pressurization time data and the pressurization position data can be received via the communication means, the deterioration diagnosis can be performed even if the deterioration diagnosis device and the welding gun control device are separated. By operating the apparatus, the pressurization time data and the pressurization position data can be taken into the deterioration diagnosis apparatus.

  According to the invention described in claim 5, the deterioration diagnosis device simultaneously diagnoses deterioration for each spot welding gun based on the analysis data and the diagnosis data acquired from the plurality of welding gun control devices via the communication means. Therefore, it is not necessary to provide a deterioration diagnosis device for each spot welding gun, and cost can be reduced and management can be facilitated.

According to the sixth and seventh aspects of the present invention, in a predetermined operation section of the spot welding gun, the pressurization time acquisition function is used until the member is sandwiched with the predetermined pressure from the start of driving the electrodes. The pressure time is acquired (pressurization time acquisition step), and the position of the electrode in a state where the members are sandwiched with a predetermined pressure by the pressurization position acquisition function is acquired (pressurization position acquisition step). Here, the pressurization time and the pressurization position acquired in a predetermined operation section of the spot welding gun are used as analysis data.
Then, when the analysis data is analyzed by a statistical method using the analysis function (analysis process), the deterioration diagnosis function is used to pressurize in a section after a predetermined operation section of the spot welding gun based on the analysis result of the analysis data. Deterioration of the spot welding gun is diagnosed based on diagnostic data determined from the pressurization time acquired by the time acquisition function and the pressurization position acquired by the pressurization position acquisition function (deterioration diagnosis step).

That is, the deterioration diagnosis of the spot welding gun is performed based on the pressurization time and pressurization position of the electrode, and it is not necessary to find a sign of deterioration from the cycle time affected by the variation in the work position. Further, it is not necessary to find a sign of deterioration from the maximum torque that is affected when control is performed to keep the current flowing through the motor constant.
Therefore, it becomes possible to find the deterioration sign of the electric spot welding gun from the data regarding the electrode of the spot welding gun, and the deterioration diagnosis of the electric spot welding gun can be performed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode of a deterioration diagnosis apparatus, a deterioration diagnosis method, and a program according to the present invention will be described below in detail with reference to the drawings.
<Configuration of spot welding robot>
First, the configuration of a spot welding robot that is diagnosed for deterioration by the deterioration diagnosis apparatus will be described.
FIG. 1 is a diagram showing a schematic configuration of the spot welding robot 10.
The spot welding robot 10 is configured such that drive control is performed by the robot control device 11, and a plurality of spot welding robots 10 and 10 are provided to constitute a robot system.
The spot welding robot 10 includes a base 12 as a base, a plurality of manipulators 14 connected by joints 13, servo motors (not shown) as drive sources provided at the joints 13, and shaft angles of the servo motors. And an encoder (not shown). A spot welding gun 16 is provided at the tip 15 of each connected manipulator 14.

Each joint 13 includes a swing joint that pivots one end of the manipulator 14 and pivotally supports the other end, and a rotary joint that pivots the manipulator 14 so that the manipulator 14 can rotate about its longitudinal direction. Composed. That is, the spot welding robot 10 corresponds to a so-called articulated robot. In addition, the spot welding robot 10 includes six joints 13 and can position the tip portion 15 at an arbitrary position.
As shown in FIG. 2, the spot welding gun 16 includes two electrodes 161 and 162, one electrode 161 is fixed together with the arm 163, and the other electrode 162 is attached to one electrode 161 by a ball screw 165. It is comprised so that it may drive with the arm 164 toward. That is, the members to be joined can be held by driving the ball screw 165 to narrow the distance between the electrode 161 and the electrode 162. The ball screw 165 is driven and controlled by the robot control device 11, and the robot control device 11 functions as a welding gun control device.
As the spot welding gun, a spot welding gun 17 as shown in FIG. 3 may be used. The spot welding gun 17 includes two electrodes 171 and 172, one electrode 171 is provided on the arm 173, and the other electrode 172 is provided on the arm 174. The arm 173 and the arm 174 are connected via a fulcrum shaft 175, and the arm 173 is brought into contact with and separated from the arm 174 by driving of the drive transmission arm 176. That is, by driving the drive transmission arm 176 and narrowing the distance between the electrode 171 and the electrode 172, the members to be joined can be sandwiched.

<Configuration of deterioration diagnosis device>
Next, a deterioration diagnosis apparatus that performs deterioration diagnosis of the spot welding robot 10 will be described.
FIG. 4 is a block diagram illustrating a configuration of the deterioration diagnosis apparatus 1.
The deterioration diagnosis apparatus 1 is connected in communication with a diagnosis control apparatus 2 that performs control relating to deterioration diagnosis, an input apparatus 5 that receives user operation instructions, and a robot control apparatus 11 that performs drive control of the spot welding robot 10. Deterioration diagnosis result by control of the communication device 6 as communication means for receiving pressurization time data regarding the pressurization time of the spot welding gun 16 and pressurization position data regarding the pressurization position from the control device 11 and control of the diagnostic control device 2 And a display device 7 for displaying.

(Diagnostic control device)
The diagnosis control device 2 includes a CPU 3 that executes each process in accordance with a process program related to deterioration diagnosis, and a memory 4 that stores a process program, process data, and the like for executing each process.
The memory 4 is provided with a program area 41 in which a program necessary for performing deterioration diagnosis is stored, a data area 42 in which data necessary for performing deterioration diagnosis is stored, various work memories and counters, and the like. A work area 43 in which each process is performed is formed.

The program area 41 stores a pressurization time acquisition program 411 that realizes a function of acquiring a pressurization time from the start of driving of the electrode 162 until the member is sandwiched with a predetermined pressure.
The program area 41 stores a pressurization position acquisition program 412 that realizes a function of acquiring the position of the electrode 162 in a state where the members are sandwiched with a predetermined pressure.

  In the program area 41, there is an analysis program 413 that realizes a function of analyzing the analysis data 421 determined from the pressurization time and the pressurization position acquired in a predetermined operation section of the spot welding gun 16 by a statistical method. It is remembered. Here, the predetermined operation section is a section in which the analysis data 421 is collected and accumulated for analysis by a statistical method before the deterioration diagnosis, and is a so-called analysis section. The statistical method refers to a method of performing regression analysis from the pressurization time and the pressurization position acquired in the analysis section to obtain an nth-order (n is a natural number) regression equation. In this embodiment, a linear regression equation is obtained. The regression equation is not limited to a linear one, and a secondary regression equation or a cubic regression equation may be obtained by performing multiple regression analysis.

  Further, in the program area 41, for diagnosis determined from the pressurization time and the pressurization position acquired in a section after a predetermined operation section of the spot welding gun 16 based on the analysis result of the analysis data 421 by the analysis program 413. A deterioration diagnosis program 414 that realizes a function of diagnosing deterioration of the spot welding gun 16 based on the data 422 is stored. Here, the section after the predetermined operation section is after the analysis section, that is, after the regression equation is obtained, the diagnostic data 422 is collected to perform the deterioration diagnosis of the spot welding gun 16 based on the regression equation. , A section to be accumulated, a so-called management section.

In the data area 42, analysis data 421 is stored. The analysis data 421 is determined by the pressurization time data 423 and pressurization position data 424 collected and accumulated by the execution of the pressurization time acquisition program 411 and the pressurization position acquisition program 412 in the analysis section for obtaining the regression equation. It is data.
In the data area 42, diagnostic data 422 is stored. The diagnosis data 422 is data determined by the pressurization time data 425 and the pressurization position data 426 collected and accumulated by the execution of the pressurization time acquisition program 411 and the pressurization position acquisition program 412 in the management section in which the deterioration diagnosis is performed. is there.

FIG. 5 is a block diagram illustrating functions of the deterioration diagnosis apparatus 1.
The diagnosis control apparatus 2 executes the pressurization time acquisition program 411 so that the pressurization time for acquiring the pressurization time from the start of driving the electrode 162 to the state where the members are sandwiched with a predetermined pressurizing force is obtained. It has the acquisition part 22, and this pressurization time acquisition part 22 functions as a pressurization time acquisition means.
In addition, the diagnostic control device 2 includes a pressurization position acquisition unit 23 that acquires the position of the electrode 162 in a state where the members are sandwiched with a predetermined pressurizing force by the CPU 3 executing the pressurization position acquisition program 412. The pressurization position acquisition unit 23 functions as a pressurization position acquisition unit.
In addition, the diagnostic control apparatus 2 includes an analysis unit 24 that analyzes the analysis data 421 acquired in the analysis section by regression analysis by the CPU 3 executing the analysis program 413, and obtains a regression equation. 24 functions as an analysis means.
Further, the diagnosis control device 2 causes the CPU 3 to execute the deterioration diagnosis program 414 to calculate the distance between the regression line based on the regression equation obtained by the analysis unit 24 and the diagnostic data 422 acquired in the management section. The distance calculation unit 25 has a calculation unit 25 and functions as a deterioration diagnosis unit.
Further, the diagnosis control device 2 includes a deterioration diagnosis unit 26 that diagnoses deterioration of the spot welding gun 16 based on the distance calculated by the distance calculation unit 25 by the CPU 3 executing the deterioration diagnosis program 414. The deterioration diagnosis unit 26 functions as a deterioration diagnosis unit.
Further, the diagnosis control device 2 displays the diagnosis result of the spot welding gun 16 by the deterioration diagnosis unit 26 on the display device 7 having a function as the display unit 27.

<Deterioration diagnosis processing>
Next, the deterioration diagnosis process of the spot welding gun 16 using the deterioration diagnosis apparatus 1 will be described. Since this degradation diagnosis process includes an analysis section in which analysis data 421 is acquired and analyzed, and a management section in which diagnosis data 422 is acquired and deterioration diagnosis is performed, the process will be described separately for each section.
(Analysis section)
FIG. 6 is a flowchart showing the flow of processing in the analysis section in the deterioration diagnosis of the spot welding gun 16 by the deterioration diagnosis apparatus 1.
When the deterioration diagnosis device 1 is activated, the CPU 3 develops the pressurization time acquisition program 411 and the pressurization position acquisition program 412 in the work area 43 and executes them for analysis from the robot control device 11 via the communication device 6. Pressurization time data 423 and pressurization position data 424 to be data 421 are acquired (pressurization time acquisition process, pressurization position acquisition process, step S101). Here, the acquired pressurization time data 423 and pressurization position data 424 are stored in the data area 42 as analysis data 421.

  Next, the CPU 3 determines whether or not the acquired analysis data 421 has acquired the number n of data necessary for performing regression analysis (step S102). If the CPU 3 determines that the number of acquired data is less than n (step S102: NO), the CPU 3 returns to the process of step S101 and acquires the pressurization time data 423 and the pressurization position data 424. To do. On the other hand, when the CPU 3 determines that the number of data in the analysis data 421 is n or more (step S102: YES), the CPU 3 determines whether the number of data in the analysis data 421 is n. (Step S103).

In step S103, when the CPU 3 determines that the number of data of the analysis data 421 is n (step S103: YES), the CPU 3 expands and executes the analysis program 413 in the work area 43, thereby adding. A regression analysis is performed based on the pressure time data 423 and the pressure position data 424 to obtain a primary regression equation (analysis process, step S104). Specifically, as shown in FIG. 7, the analysis data 421 is plotted with the pressurization time (sec) on the vertical axis and the pressurization position (mm) on the horizontal axis, and a regression line is obtained from each analysis data 421. A regression equation that minimizes the sum of distances to L is obtained. In the present embodiment, since the linear regression equation is used, the regression line L is linearly approximated.
After calculating the regression equation, the CPU 3 returns to step S101 and further acquires analysis data 421.

  In step S103, when the CPU 3 determines that the number of data of the analysis data 421 is not n, in other words, when the number of data of the acquired analysis data 421 exceeds n (step S103: NO). The CPU 3 calculates the sum of the distances from the analysis data 421 to the regression line L (step S105), and determines whether or not the analysis data 421 has been acquired for a predetermined group size (step S105). S106). If the CPU 3 determines that the analysis data 421 has been acquired by the size of the group (step S106: YES), the CPU 3 calculates the X bar (average value) and R (range) of each analysis data 421. (Step S107). On the other hand, when the CPU 3 determines that the analysis data 421 is not acquired by the size of the group (step S106: NO), the CPU 3 returns to step S101 and further acquires the analysis data 421.

In step S107, the reason why the X bar (average value) and R (range) are calculated is that the deterioration diagnosis in this embodiment is managed by the X bar-R control chart.
Specifically, the X bar is the average value of the distance between the data obtained in step S105 for each group and the regression line, and R is the range.

  Next, the CPU 3 determines whether or not the number of acquired analysis data 421 has reached the number of groups in the analysis section (step S108). Here, when the CPU 3 determines that the number of acquired analysis data 421 is the number of groups in the analysis section (step S108: YES), the CPU 3 calculates a management limit line (step S109). On the other hand, when the CPU 3 determines that the number of acquired analysis data 421 is not the number of groups in the analysis section (step S108: NO), the CPU 3 returns to step S101 and further analyzes data. 421 is acquired.

Here, the management limit line is an upper management limit line UCL indicating an upper management limit with respect to the management center line CL passing through the average value, and a lower side indicating a lower management limit with respect to the management center line passing through the average value. Using the control limit line LCL, the total X bar of the X bar and the average R bar of the range R obtained from the X bar calculated in step S107 are obtained by the following equations, respectively.
CL = X bar bar UCL = X bar bar + k * R bar LCL = X bar bar-k * R bar Here, k is a coefficient determined by the size of the group.
With the above processing, an analysis section, that is, a criterion for performing deterioration diagnosis is determined.

(Management section)
FIG. 8 is a flowchart showing the process flow of the management section in the deterioration diagnosis of the spot welding gun 16 by the deterioration diagnosis apparatus 1.
When the processing in the analysis section ends, the CPU 3 develops the pressurization time acquisition program 411 and the pressurization position acquisition program 412 in the work area 43 and executes them for diagnosis from the robot controller 11 via the communication device 6. Pressurization time data 425 and pressurization position data 426 to be data 422 are acquired (pressurization time acquisition process, pressurization position acquisition process, step S201). Here, the acquired pressurization time data 425 and pressurization position data 426 are stored in the data area 42 as diagnostic data 422.

  Next, the CPU 3 calculates the sum of the distances from the respective diagnostic data 422 to the regression line L obtained in the analysis section (step S202), and whether or not the diagnostic data 422 has been acquired for a predetermined group size. Is determined (step S203). If the CPU 3 determines that the diagnostic data 422 has been acquired by the size of the group (step S203: YES), the CPU 3 calculates the X bar (average value) and R (range) of each diagnostic data 422. (Step S204). On the other hand, when the CPU 3 determines that the diagnostic data 422 is not acquired by the size of the group (step S203: NO), the CPU 3 returns to step S201 and further acquires the diagnostic data 422.

The reason why the X bar (average value) and R (range) are calculated in step S204 is that the deterioration diagnosis in this embodiment is managed by the X bar-R control chart.
Specifically, the X bar is the average value of the distance between the data obtained in step S202 and the regression line for each group, and R is the range.

  Next, the CPU 3 determines whether or not the calculated X bar and R are between the upper control limit line UCL and the lower control limit line LCL calculated in the analysis interval, that is, whether or not they are within the control ( Step S205). Here, when the CPU 3 determines that the X bar and R are between the upper control limit line UCL and the lower control limit line LCL (step S205: YES), the CPU 3 determines that the spot welding gun 16 has not deteriorated. And the processing of the management section is terminated. On the other hand, when the CPU 3 determines that the X bar and R are not between the upper control limit line UCL and the lower control limit line LCL (step S205: NO), the CPU 3 indicates that the spot welding gun 16 has deteriorated. It is determined that there is, and that effect is displayed on the display device 7 (step S206).

<Operational effects of the deterioration diagnosis device and the deterioration diagnosis method>
According to the deterioration diagnosis apparatus 1 and the deterioration diagnosis method using the deterioration diagnosis apparatus 1 in the above embodiment, the analysis data 421 (pressurization time data 423, pressurization position data 424) is acquired in the analysis section, and the analysis program By executing 413, a regression equation is obtained by regression analysis based on the analysis data 421, and then, by executing the deterioration diagnosis program 414, diagnostic data 422 (pressurization time data 425, The deterioration of the spot welding gun 16 is diagnosed based on the pressure position data 426).
That is, the deterioration diagnosis of the spot welding gun 16 is performed based on the pressurization time and pressurization position of the electrode 162, and it becomes unnecessary to find a deterioration sign from the cycle time affected by the variation of the work position. Further, it is not necessary to find a sign of deterioration from the maximum torque that is affected when control is performed to keep the current flowing through the motor constant.
Therefore, the deterioration sign of the spot welding gun 16 can be found from the data related to the electrode 162 of the spot welding gun 16, and the deterioration of the spot welding gun 162 can be diagnosed.

Further, since regression analysis is used as a statistical analysis method and deterioration diagnosis is performed based on the distance between the diagnostic data 422 and the regression line L, the load on the analysis and deterioration diagnosis processing can be kept low.
In addition, since the pressurization time data 423 and 425 and the pressurization position data 424 and 426 can be received via the communication device 6, even if the deterioration diagnosis device 1 and the robot control device 11 are separated, the deterioration diagnosis device. By operating 1, the pressurization time data 423, 425 and the pressurization position data 424, 426 can be taken into the deterioration diagnosis device 1.

<Others>
The present invention is not limited to the above embodiment. For example, each program may be created separately for each function, or all programs may be created integrally along the processing flow to form one program. Further, not all of the processing is processed by software by a program, but part or all of the processing may be processed by hardware. In addition, substitution and change are possible freely within the scope of the invention.

It is a figure which shows schematic structure of a spot welding robot. It is a figure which shows schematic structure of a spot welding gun. It is a figure which shows schematic structure of another spot welding gun. It is a block diagram which shows schematic structure of a deterioration diagnostic apparatus. It is a block diagram which shows the function of a deterioration diagnostic apparatus. It is a flowchart which shows the process of the analysis area by a deterioration diagnostic apparatus. It is the graph which represented the relationship between a pressurization position and pressurization time with the regression line. It is a flowchart which shows the process of the management area by a deterioration diagnostic apparatus.

Explanation of symbols

1 Deterioration diagnosis device 6 Communication device (communication means)
16 Spot welding gun 22 Pressurization time acquisition part (Pressurization time acquisition means)
23 Pressurization position acquisition part (Pressure position acquisition means)
24 Analysis unit (analysis means)
25 Distance calculator (degradation diagnostic means)
26 Deterioration diagnosis unit (degradation diagnosis means)
161 Electrode 162 Electrode 411 Pressurization time acquisition program 412 Pressurization position acquisition program 413 Analysis program 414 Degradation diagnosis program 421 Analysis data 422 Diagnosis data 423 Pressurization time data 424 Pressurization position data 425 Pressurization time data 426 Pressurization position Data L regression line

Claims (7)

In the deterioration diagnosis device for diagnosing deterioration of a spot welding gun that drives electrodes by an electric motor and flows current in a state in which the members to be bonded are sandwiched between the electrodes with a predetermined pressurizing force.
A pressurization time acquisition means for acquiring a pressurization time from the start of driving of the electrodes to a state where the members are sandwiched by the predetermined pressurizing force;
A pressure position acquisition means for acquiring a position of the electrode in a state where the members are sandwiched by the predetermined pressure force;
Analytical data determined by the pressurization time acquired by the pressurization time acquisition means and the pressurization position acquired by the pressurization position acquisition means in a predetermined operation section of the spot welding gun is analyzed by a statistical method. Analysis means to
Based on the analysis result of the analysis data by the analysis unit, acquired by the pressurization time and the pressurization position acquisition unit acquired by the pressurization time acquisition unit in a section after a predetermined operation section of the spot welding gun. Deterioration diagnosis means for diagnosing deterioration of the spot welding gun based on diagnostic data determined from the applied pressure position;
A deterioration diagnostic apparatus comprising:   2. The deterioration diagnosis apparatus according to claim 1, wherein the analysis unit calculates an nth-order regression equation (n is a natural number) based on the analysis data.   The deterioration diagnosing means calculates a distance between a regression line based on the n-th order (n is a natural number) regression equation and the diagnostic data, and diagnoses deterioration of the spot welding gun based on the calculated distance. The deterioration diagnostic apparatus according to claim 2, wherein:   Communication means connected to a welding gun control device for controlling driving of the spot welding gun and receiving pressurization time data related to the pressurization time and pressurization position data related to the pressurization position from the welding gun control device. The deterioration diagnostic apparatus according to any one of claims 1 to 3, further comprising: The communication means is configured to be communicably connected to a plurality of welding gun control devices,
The deterioration diagnosis unit is configured to detect spot welding guns based on analysis data and diagnosis data acquired by the pressurization time acquisition unit and the pressurization position acquisition unit from a plurality of welding gun control devices via the communication unit. 5. The deterioration diagnosis apparatus according to claim 4, wherein deterioration diagnosis is possible simultaneously. In the deterioration diagnosis method for diagnosing deterioration of a spot welding gun that drives electrodes by an electric motor and flows currents in a state where the members to be joined are sandwiched by the electrodes with a predetermined pressure, and joins the members.
A pressurization time acquisition step of acquiring a pressurization time from the start of driving of the electrodes to a state where the members are sandwiched by the predetermined pressurizing force;
A pressurization position acquisition step of acquiring a position of the electrode in a state where the members are sandwiched by the predetermined pressure force;
Analytical data determined from the pressurization time acquired by the pressurization time acquisition step and the pressurization position acquired by the pressurization position acquisition step in a predetermined operation section of the spot welding gun is analyzed by a statistical method. Analysis process to
Based on the analysis result of the analysis data by the analysis step, acquired by the pressurization time acquired by the pressurization time acquisition step and the pressurization position acquisition step in a section after a predetermined operation section of the spot welding gun. A deterioration diagnosis step of diagnosing deterioration of the spot welding gun based on diagnostic data determined from the applied pressure position;
A degradation diagnosis method comprising: In a computer that diagnoses the deterioration of the spot welding gun that drives the electrodes by an electric motor and passes the current in a state where the members to be joined are sandwiched by the electrodes with a predetermined pressure, and joins the members.
A pressurization time acquisition function for acquiring a pressurization time from the start of driving of the electrodes to a state in which the members are sandwiched with the predetermined pressurizing force;
A pressurization position acquisition function for acquiring the position of the electrode in a state in which the members are sandwiched by the predetermined pressing force;
Analytical data determined by the pressurization time acquired by the pressurization time acquisition function in the predetermined operation section of the spot welding gun and the pressurization position acquired by the pressurization position acquisition function by a statistical method Analysis function to
Based on the analysis result of the analysis data by the analysis function, acquired by the pressurization time and the pressurization position acquisition function acquired by the pressurization time acquisition function in a section after a predetermined operation section of the spot welding gun A deterioration diagnosis function for diagnosing deterioration of the spot welding gun based on diagnostic data determined from the pressed position,
A program to realize

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