JP2007268590A - Apparatus for controlling spot welding robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for controlling a spot welding robot, which apparatus can efficiently detect the generation of defective welding, and also can predict the generation of the defective welding. <P>SOLUTION: A CPU of a robot controlling section extracts the data, which correspond to the searching condition input by an operator and include the range of the peak value of the generated temperature in a spot welding portion, from a logging table (step S180), and displays the data on a display screen (step S200). In this case, the generation of the defective welding is predicted by extracting the welding portion corresponding to the range wider than the range of the peak temperature to cause the defective welding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a spot welding robot that manages welding quality based on a peak temperature of a heat generation temperature of a spot weld.

2. Description of the Related Art Conventionally, a technique for checking welding quality by destructive inspection of a workpiece in a spot welding welding site performed in an automobile production line or the like is known. Such destructive inspection is performed by destroying the welded portion of the workpiece to be inspected periodically and checking the state of welding visually. By the way, the check of the welding quality by destructive inspection has a problem that productivity is lowered because the inspection man-hour increases. Therefore, as disclosed in Patent Document 1, a control device has been proposed in which a workpiece is inspected in a non-destructive state to manage welding quality. Such a control device checks the welding quality by utilizing the correlation between the peak temperature of the heat generation temperature of the welded portion during spot welding and the fixing force of the welded portion. In other words, the quality of the welding quality is determined by monitoring the heat generation temperature of the spot weld and comparing the peak temperature of the heat generation temperature with a predetermined threshold value. For this reason, it is possible to detect a welding failure when the peak temperature of the heat generation temperature is outside the threshold range, and it is possible to manage the total number of welding qualities in a non-destructive state of the workpiece.
JP 2001-38474 A

  By the way, the threshold value used in the control device as described above varies depending on the welding material conditions such as the type and thickness of the welding material. Moreover, since this threshold value varies depending on welding conditions such as the electrode shape of the welding machine and the applied pressure, it is difficult to set the threshold value. In general, the threshold value used for such determination is set by repeatedly performing preliminary experiments. However, if the peak temperature of the heat generation temperature is distributed in the vicinity of the threshold value, poor welding may occur. In spite of the fact that the performance is high, the worker may not be able to grasp such a state. That is, it is difficult to predict the occurrence of welding failure even if it is possible to identify the occurrence location of welding failure only by comparing the peak temperature and the threshold value, so that the management of welding quality becomes insufficient. There is a fear.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control apparatus for a spot welding robot that can efficiently detect the occurrence of welding failure and can predict the occurrence of welding failure. It is in.

  In order to achieve the above object, a control device for a spot welding robot according to the present invention is a control device for a spot welding robot that manages welding quality based on a peak temperature of a heat generation temperature of a spot weld, and is preset. A robot control unit that controls the operation of the spot welding robot according to a welding procedure; and a welding timer that outputs welding result data including at least the peak temperature in the welding step of the welding procedure, the robot control unit including the welding Storage means for associating and storing the welding result data acquired from the timer and the welding process, input means for inputting a search condition including at least the range of the peak temperature, and welding result data satisfying the input search condition Search means for searching the storage means, the searched welding result data, and the welding result data A display means for displaying on the display screen and a welding step of identifying, characterized in that it comprises a.

  According to this configuration, the control device for the spot welding robot includes a robot control unit that controls the operation of the spot welding robot according to a preset welding procedure, and a welding that includes at least a peak temperature of the heat generation temperature of the spot welding unit in the welding process. A welding timer for outputting the result data, and the storage means of the robot control unit stores the welding result data acquired from the welding timer in association with the welding process. For this reason, the robot controller can associate the welding process with the peak temperature and store the history data as history data.

  When a search condition including at least the peak temperature range is input, the robot controller searches the storage means for welding result data that satisfies the search condition, and finds the searched welding result data and the welding result data. The welding process to be specified is displayed on the display screen. For this reason, when the operator inputs a peak temperature range in which a welding defect is estimated to occur as a search condition, it is possible to grasp the welding result data corresponding to the range and the welding process. Therefore, it is possible to easily detect the workpiece and the welding location that are defective in welding from the history data accumulated in the storage means. In addition to the welding process, the welding date and time when the welding was performed may be displayed. If it does in this way, the workpiece | work and welding location which become a welding defect can be detected more easily.

  In addition, if an operator inputs a range wider than the peak temperature range where welding failure is estimated to occur as a search condition, welding with a peak temperature distributed in the vicinity of the range where welding failure is estimated to occur. When there is a process, the state can be grasped. For this reason, the operator can recognize that the possibility of poor welding occurring in the welding process is increased, and can adjust the welding conditions in the welding process in advance. In other words, since the operator can predict the occurrence of welding failure, it is possible to take measures to suppress the welding failure before the welding failure occurs. By configuring the control device for the spot welding robot in this way, even an inexperienced operator can easily detect a defective weld location and predict the occurrence of poor welds, thereby improving the welding quality. Can be managed.

  In the above configuration, the input unit may input a specific welding process or a specific period as a search condition, and the search unit may search for welding result data based on the search condition. .

  According to this configuration, the input means can input a specific welding process or a specific period as a search condition, and the search means searches for welding result data based on the search condition. By using a specific welding process such as a process or a specific period such as the last three hours as a search condition, the welding state in the welding process can be grasped. For this reason, it is possible to detect a defective welding location and predict the occurrence of defective welding according to the inspection location of welding quality or the inspection timing of welding quality.

  In the above configuration, the selection means for selecting the welding process displayed by the display means, and the history of acquiring the welding result data of the selected welding process from the storage means and displaying the result on the display screen in chronological order. Display means.

  According to this configuration, when the welding process displayed by the display means is selected, the welding result data of the selected welding process is acquired from the storage means and displayed in chronological order. It is possible to recognize the change in the welding state and its tendency from the time series data. For this reason, it is possible to suitably carry out post-mortem analysis when a welding failure occurs and a prior response before the welding failure occurs.

Hereinafter, with reference to FIGS. 1-8, one Embodiment which actualized the control apparatus of the spot welding robot which concerns on this invention is described.
FIG. 1 is a block diagram showing a configuration of a control apparatus 1 for a spot welding robot. The control device 1 includes a robot control unit 20 that controls the operation of the spot welding robot 10, a welding timer 30 that controls welding conditions such as welding time, and a teaching for creating a work program for teaching the spot welding robot 10. And a pendant 40. The robot controller 20 and the welding timer 30 are connected by a data bus 50 and are configured to be able to perform data communication with each other via a dual port RAM 51.

  The robot control unit 20 includes a CPU 21 that controls the spot welding robot 10, a ROM 22 that stores a system program for operating the CPU 21, and a RAM 23 that stores setting data such as work programs and welding conditions. The CPU 21 controls the operation of the spot welding robot 10 according to the teaching of the input work program and transmits welding conditions to the welding timer 30.

  The welding timer 30 includes a CPU 31 that controls welding conditions such as a welding time, a ROM 32 that stores a system program for operating the CPU 31, welding conditions received from the robot control unit 20 via the dual port RAM 51, and the like. RAM 33 to be stored. The CPU 31 controls the welding current supplied to the spot welding robot 10 and the energization time based on the welding conditions received from the robot controller 20. The contactor 60 supplies power to a welding transformer (not shown) of the spot welding robot 10 based on a command from the CPU 31.

  The teach pendant 40 is connected to the robot control unit 20 and includes an operation input unit 41 and a display screen 42 as input means. The teach pendant 40 is configured to be able to input welding conditions such as welding current, energization time, and pressure between electrodes from the operation input unit 41, and to display a welding result on the display screen 42.

  The control device 1 controls the spot welding robot 10 according to a work program created in advance, and manages the welding quality by detecting the peak temperature of the heat generation temperature of the spot weld in the welding process. Hereinafter, the control of the spot welding robot 10 performed by the control device 1 and the welding quality management method will be described.

  First, a method for creating a work program will be described. The creator of the work program operates the teach pendant 40 to position the spot welding robot 10 in the order in which welding is performed at a plurality of locations to be welded, and teach a welding command at that position. Further, the creator teaches that, at the position where welding is performed, an optimum welding condition is selected from a plurality of preset welding conditions, and welding is performed under the welding condition. As an example, in the case where the right door frame 70 of the vehicle body shown in FIG. 2 is a workpiece to be welded, the creator places the spot welding robot 10 at positions A1 to A5 of the right door frame 70 where spot welding is performed. Sequential positioning and teaching of welding instructions and welding conditions. Thereby, an operation program is created in which spot welding is performed in order from position A1 to position A5.

  FIG. 3 shows a processing table T1 of the work program created by the above procedure. “0101” described in the work program a indicates that this program is executed when the right door frame 70 is welded. Step b is the processing order of this work program, and instruction c represents processing executed in each step. Here, the step described as “LINE” indicates a moving process of the spot welding robot 10, and the step described as “SPOT” indicates a welding process by the spot welding robot 10. . That is, when the step is 2, spot welding is performed at the position A1 of the right door frame 70, and when the step is 3, 5, spot welding is performed at the positions A2 and A3. The welding condition number d is a number indicating a welding condition selected from preset welding conditions, and the welding condition such as the welding current and the pressure between the electrodes is indicated by this number. The work program processing table T1 created in this way is stored in the RAM 23 of the robot controller 20.

  The RAM 23 also stores work program processing tables for different work types. For example, not only the right door frame 70 but also a processing table of a plurality of work programs such as a case where a left door frame or an operation seat is a workpiece to be welded is stored. The processing tables for these work programs are created in the same procedure as in the case of the right door frame 70, and are registered for each work type. The creator who creates the welding procedure operates the teach pendant 40 to input the execution order of the work programs described above, and creates a correspondence table in which the work types and work programs are associated with each other.

  FIG. 4 shows the correspondence table T2. As shown in the figure, each work program f corresponding to the work type e and the execution order g of the work program are set by the correspondence table T2. For example, when the work type is the left door frame, three work programs “0201”, “0202”, and “0203” are executed in order. The correspondence table T2 created in this way is stored in the RAM 23 of the robot control unit 20.

  Next, control when the control device 1 automatically operates the spot welding robot 10 according to the work program will be described. When the automatic operation of the spot welding robot 10 is started, the robot control unit 20 controls the operation of the spot welding robot 10 according to the welding procedure of the processing table T1 of the preset work program. When the spot welding robot 10 performs the welding process, that is, when the command of the work program becomes “SPOT”, the robot control unit 20 outputs the welding condition number corresponding to the step of the work program and the welding start command. It transmits to the welding timer 30.

  The CPU 31 of the welding timer 30 controls the contactor 60 based on the received welding conditions and causes the spot welding robot 10 to perform spot welding. At this time, the welding timer 30 detects welding result data such as a peak temperature of the heat generation temperature (hereinafter simply referred to as a peak temperature) and an effective value of the welding current in the spot welded portion of the workpiece.

  The robot control unit 20 receives the welding result data from the welding timer 30 every time one welding process is completed, adds a work program number, a step number, and a welding date and time, and logs it to the RAM 23 of the robot control unit 20. To do. FIG. 5 shows a logging table T3 of welding results. As shown in the figure, when the work program “0101” for the right door frame is executed as the work program h, for the step i for performing the welding process, the welding date / time j at which the step was performed is stored, and The welding result data 1 such as the peak temperature k in the welding process is stored. In this way, the robot control unit 20 creates the logging table T3 by associating the steps of each welding process with the welding result data at that time, and stores the logging table T3 in the RAM 23 serving as storage means. In addition, the control device 1 executes each work program according to the welding order set by the correspondence table T2, and creates and stores a logging table in each work program by the same procedure as described above.

  Next, a procedure for detecting a workpiece with poor welding will be described. FIG. 6 shows a flowchart of a welding failure detection routine executed by the CPU 21 of the control device 1. The welding defect detection routine displays a welding result data satisfying the search condition and a welding process for specifying the welding result data when the operator of the production line operates the teach pendant 40 and inputs the search condition. 42 is displayed. The welding failure detection routine is executed when an operator inputs to the operation input unit 41 of the teach pendant 40 to start the routine.

  When the welding failure detection routine is executed, the CPU 21 of the robot control unit 20 requests input of search conditions for welding result data (step S110). This request is displayed on the display screen 42 of the teach pendant 40, and the operator operates the operation input unit 41 as input means to select a work type and input a check period and a peak temperature range. . The input of the peak temperature range is performed by setting a threshold value that is an upper limit value and a lower limit value.

  Then, the CPU 21 as the search means determines whether or not an input to start the search is made by the worker (step S120), and the search is performed based on the search condition set when the input to that effect is made. To start. When the search is started, the CPU 21 acquires all the welding locations of the selected work type from the processing table T1 and the correspondence table T2 stored in the RAM 23 (step S130).

  Next, the CPU 21 searches the logging table of the welding results with respect to all acquired welding locations, using the input check period and threshold as search conditions. That is, data is read from the welding result logging table T3 shown in FIG. 5 (step S140), and whether the data corresponds to the welding location of the selected work type (step S150) or within the check period (step S150). Step S160), it is determined whether the peak temperature is out of range (Step S170). Then, data corresponding to any search condition is extracted (step S180). If any of the search conditions is not met, the process proceeds to step S190.

  Next, the CPU 21 determines whether or not reading of all data has been completed (step S190). If reading of all data has not been completed, the CPU 21 performs step S140 to continue reading data. The process from is repeated. When the reading of all the data is completed, the CPU 21 displays the work program, the step, and the peak temperature on the display screen 42 from the data corresponding to the search condition (step S200). That is, the CPU 21 as the display means displays the welding result data such as the searched peak temperature and the welding process such as a step for specifying the welding result data on the display screen 42.

  FIG. 7 shows the display screen 42 at this time. For example, when a right door frame is selected as a search condition as a search condition, and a predetermined check period and threshold values that are an upper limit value and a lower limit value are input as 2000 ° C. and 1000 ° C., respectively, the work type corresponding to the search condition Data such as m, workpiece history number n, welding order o, welding date / time p, work program q, step r, peak temperature s, etc. are displayed in the lower part 42a of the display screen 42. Here, the work history number n is a number indicating the number of the work in the search range. In addition, on the upper stage 42b of the display screen 42, a work program and its steps corresponding to the welding location selected by the cursor of the lower stage 42a are displayed. After performing such display, the CPU 21 ends the welding failure detection routine.

  Here, in the welding failure detection routine described above, a welding process that is outside the range of the threshold value that is the upper limit value and the lower limit value of the peak temperature input by the operator is extracted. In general, it is known that when the peak temperature of the heat generation temperature of a welded part at the time of spot welding is equal to or higher than a predetermined temperature or lower than a predetermined temperature, the fixing strength of the welded part is reduced, resulting in poor welding. Yes. For this reason, if these predetermined temperatures are input as threshold values, it is possible to extract the target workpiece and the welding location that are defective in welding. In addition, since said predetermined temperature changes also with the conditions and welding conditions of a welding material, the threshold value input as search conditions is set by repeating a preliminary experiment. Further, in the above-described welding failure detection routine, the workpiece type (specific welding process) and the check period (specific period) can be input as search conditions, so that the inspection location of welding quality or the inspection timing of welding quality can be used. Accordingly, it is possible to efficiently extract a weld location that is a poor weld.

  Moreover, when the above-described welding failure detection routine is used, occurrence of welding failure can be predicted. When predicting the occurrence of welding failure, a value smaller than the upper limit value set from the peak temperature range that results in welding failure is used as the upper threshold value, and a value larger than the set lower limit value is used as the lower threshold value. Enter the search conditions. In this way, since it is possible to extract a welding location corresponding to a range wider than the peak temperature range that results in poor welding, a large number of peak temperatures are distributed in the vicinity of the range that results in poor welding at a certain welding location. In this case, the operator can recognize that there is an increased possibility that a welding failure will occur at the weld location. For this reason, the operator can adjust the settings of the welding conditions such as the welding current and the energization time in the welding process in which there is a possibility of welding failure before the welding failure occurs.

  Next, the history display function of the control device 1 will be described. The history display function as the history display means acquires the welding result data of the selected step from the logging table T3 by selecting an arbitrary welding location displayed by the execution of the welding failure detection routine, and the welding result. The data history is displayed. Since the control device 1 stores the welding result data in the RAM 23 in association with the welding date and time, the history of the welding result data can be displayed in chronological order.

  For example, as shown in FIG. 7, when the history display function is executed by selecting the step “4” in the work program “0101” with the cursor t as the selection means, the welding welded in the step “4” is performed. The history of result data is displayed on the display screen 42 in chronological order. FIG. 8 shows a display screen 42 at this time. As shown in the figure, for the step v of the selected work program, the work history number w, the welding date x, and the peak temperature y at the time of welding are displayed in chronological order. Thus, when the peak temperatures are displayed in chronological order, the operator can recognize the change in the welding state and the tendency thereof in the selected step.

According to the control device 1 of the spot welding robot of the embodiment, the following effects can be obtained.
(1) In the above embodiment, when the welding failure detection routine is executed, the CPU 21 inputs the welding temperature satisfying the search condition when the threshold value of the peak temperature of the heat generation temperature in the spot welded portion is input as the search condition. The logging table is searched, and the work program, step and peak temperature of the corresponding welding location are displayed on the display screen 42. For this reason, if an operator inputs the range of the peak temperature estimated that a welding defect generate | occur | produces as a search condition, the workpiece | work and welding location estimated to be a welding defect can be extracted easily. In addition, when the operator inputs as a search condition a range wider than the peak temperature range in which it is estimated that welding failure will occur, a large number of peak temperatures are distributed in the vicinity of the range where welding failure occurs at a certain welding location. In addition, the operator can recognize that there is a high possibility that a welding failure will occur at the weld location. For this reason, the operator can adjust the setting of the welding conditions in the welding process in which there is a possibility of welding failure before the welding failure occurs. In this way, not only searching for the peak temperature range that results in poor welding, but also searching for a wider range to predict the occurrence of poor welding and to suppress poor welding before the occurrence of poor welding. Can be taken. In addition, because it is possible to predict the occurrence of welding defects simply by entering search conditions, even an inexperienced operator can manage welding quality and ensure that poorly welded workpieces are shipped. Can be prevented.

  (2) In the above embodiment, when the work type and the check period are input as search conditions during the execution of the welding failure detection routine, the data of the welding locations corresponding to the search conditions are displayed. For this reason, according to the object workpiece | work which test | inspects welding quality, and the inspection timing of welding quality, a search object can be changed suitably and management of welding quality can be performed.

  (3) In the above-described embodiment, the control device 1 selects an arbitrary welding location displayed by executing the welding failure detection routine, thereby displaying a history of welding result data at that step in time-series order. Have For this reason, since the operator can recognize the change in the welding state and its tendency in the selected step, it is preferable to perform post-analysis when a welding failure occurs and pre-action before the welding failure occurs can do.

In addition, you may change the said embodiment as follows.
In the above embodiment, the control in the control device 1 is performed by the robot control unit 20 and the welding timer 30, but one control unit may perform the control collectively. The control may be shared in different ways.

  In the above embodiment, in the welding failure detection routine, the workpiece type, the check period, and the peak temperature range are input as search conditions, but the search condition only needs to include at least the peak temperature range, You may comprise so that other search conditions, such as a work program number, can be input.

-Moreover, the display of the display screen 42 shown in FIG.7 and FIG.8 of the said embodiment shows an example of the display mode, and you may make it display in another mode.
In the above embodiment, the control device 1 manages the welding quality based on the peak temperature of the heat generation temperature in the spot welded portion, but executes the welding failure detection routine using other parameters that can determine the welding quality. You may change it as you can.

The block diagram which shows the structure of the control apparatus of a spot welding robot. Schematic which shows a workpiece for welding. A processing table for work programs created by the control unit. Correspondence table created by the control unit. A logging table of welding results created by the controller. The flowchart of the welding defect detection routine which a control apparatus performs. Display screen when the welding failure detection routine is executed. Display screen when the history display function of the control unit is executed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Control apparatus, 10 ... Spot welding robot, 20 ... Robot control part, 30 ... Welding timer, 40 ... Teach pendant, 41 ... Operation input part, 42 ... Display screen, 60 ... Contactor.

Claims (3)

A control device for a spot welding robot that manages welding quality based on the peak temperature of the heat generation temperature of a spot weld,
A robot controller that controls the operation of the spot welding robot according to a preset welding procedure, and a welding timer that outputs welding result data including at least the peak temperature in the welding step of the welding procedure,
The robot control unit stores storage result data associated with the welding result data acquired from the welding timer and the welding process, input means for inputting a search condition including at least the peak temperature range, and the input Search means for searching the storage means for welding result data satisfying a search condition, and display means for displaying the searched welding result data and a welding process for specifying the welding result data on a display screen. A control device for a spot welding robot.   The said input means can input a specific welding process or a specific period as a search condition, and the said search means searches welding result data based on the said search condition. Control device for spot welding robot.   Selecting means for selecting a welding process displayed by the display means; and history display means for acquiring welding result data of the selected welding process from the storage means and displaying the result on the display screen in time series. The spot welding robot control device according to claim 1, comprising: a spot welding robot control device.

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