Welding quality management device

Abstract

The purpose is to enable the use of existing spot welding guns without the need for dedicated external sensors, and to assist users in judging whether there are welding defects. The welding quality management device has a storage unit (13) and a retrieval unit (17). The storage unit (13) stores a plurality of welding data files related to the position of movable electrodes and the current value flowing between electrodes during the welding process, which are received from a plurality of welding robot bodies or their control devices (50) and jointly obtained by the plurality of welding robots. Together with the part number that identifies the part to be welded, the welding number that identifies the spot of the part to be welded, the program ID and date and time information specified by the program used to weld the part to be welded; the retrieval unit (17) retrieves the plurality of stored welding data files according to the retrieval conditions related to at least one of the part number, welding number, program ID and date and time information, and extracts a plurality of specific welding data files that match the retrieval conditions.

Description

Technical Field

[0001] This invention relates to a welding quality management device. Prior Technology

[0002] In recent years, the use of robotic devices equipped with spot welding guns for welding vehicle bodies and other components has become increasingly widespread. In spot welding operations, two workpieces to be welded are clamped between movable and fixed electrodes. A voltage is applied to the movable and fixed electrodes under a predetermined pressure, thereby welding the two workpieces. With the automation of welding operations, the detection of welding defects has become increasingly important. For example, techniques for determining abnormalities in the weld area based on data obtained from external sensors are known (e.g., Patent Document 1). [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2021-10925 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] Methods relying on external sensors for anomaly detection suffer from drawbacks. The accuracy and sensitivity of these sensors vary depending on the operating environment, potentially leading to inaccurate data and missed anomalies. Furthermore, the need for external sensors in welding robots for anomaly detection can result in incompatibility with existing welding robots, and the addition of expensive sensors further increases costs. Over-reliance on external sensors for anomaly detection diminishes the ability to accurately assess data for genuine anomalies. Therefore, there is significant room for improvement in anomaly detection, such as welding defects, in welding robots, particularly in the development of widely applicable technologies. [Methods used to solve problems]

[0006] According to the present disclosure, a welding quality management device includes a receiving unit, a storage unit, and a retrieval unit. The receiving unit receives from a plurality of welding robots or their control devices: a plurality of welding data files related to the position of the movable electrode and the current value flowing between the electrodes during the welding process, which are jointly obtained by the plurality of welding robots; a component number that identifies the component to be welded; a welding number that identifies the markings on the component to be welded; a program ID and date and time information specific to the program used to weld the component to be welded; the storage unit stores the plurality of welding data files in association with the component number, welding number, program ID, and date and time information; the retrieval unit retrieves the stored plurality of welding data files based on retrieval criteria related to at least one of the component number, welding number, program ID, and date and time information, and extracts a plurality of specific welding data files that match the retrieval criteria. [Effects of the Invention]

[0007] Based on this model, it can be applied to existing spot welding guns without the need for dedicated external sensors. By using graphs based on welding data archives collected from multiple welding robots, it can assist users in determining whether there are welding defects. Simple Explanation of the Diagram

[0008] [Figure 1] is a diagram showing a welding system including a welding quality management device according to this embodiment. [Figure 2] is a functional block diagram of the welding robot in Figure 1. [Figure 3] is a functional block diagram of the welding quality management device in Figure 1. [Figure 4] is a diagram showing an example of a welding quality management page provided by the welding quality management device of Figure 1. [Figure 5] is an example of a graph showing the time-varying electrode position as displayed on the welding quality management page of Figure 4. [Figure 6] is an example of a graph showing the variation in plate thickness for each component as displayed on the welding quality management page of Figure 4. [Figure 7] is an example graph showing the time variation of the gun shaft current value displayed on the welding quality management page of Figure 4. [Figure 8] is a graph showing the welding data files extracted based on the date and time associated with the welding data files specified by the user as search criteria. [Figure 9] is a graphical example showing a case where a welding data file with an anomaly flag exists. Implementation

[0009] The welding quality management device according to this embodiment will now be described with reference to the drawings. In the following description, constituent elements having substantially the same function and structure are labeled with the same reference numerals and will be described repeatedly only where necessary.

[0010] As shown in Figure 1, the welding quality management device 10 according to this embodiment is connected to a plurality of welding robots 20 (20a, 20b) via a network 70 such as a LAN. Each welding robot 20 (20a, 20b) consists of a welding robot body and a control device for controlling the welding robot body. The welding robot body is provided by a multi-joint arm mechanism 30 (30a, 30b) equipped with a spot welding gun 40 (40a, 40b). The control device consists of a robot control device 60 (60a, 60b) for controlling the multi-joint arm mechanism 30 and a welding gun control device 50 (50a, 50b) for controlling the spot welding gun 40. The robot control device 60 and the welding gun control device 50 are communicatively connected to each other.

[0011] As shown in Figure 2, the spot welding gun 40 comprises a fixed electrode 44, a movable electrode 45 positioned opposite the fixed electrode 44, a fixed arm 42 supporting the fixed electrode 44, a movable arm 43 supporting the movable electrode 45 by moving it along the gun axis, a servo motor 48 that generates the driving force for the movement of the movable arm 43, and an encoder 47 that detects the rotational position of the drive shaft of the servo motor 48. The output data of the encoder 47 is sent to the welding gun control device 50.

[0012] The welding gun control device 50 includes a drive control unit 51, a welding current control unit 52, a current detection unit 53, an electrode position specifying unit 54, a storage unit 55, and a communication unit 56. The drive control unit 51 controls the drive of the servo motor 48. Specifically, the drive control unit 51 sends a pressure command specified by the welding program to the motor control unit (not shown) at a time specified by the welding program. The motor control unit supplies current to the servo motor 48 to generate torque corresponding to the pressure command received from the drive control unit 51. Thus, the servo motor 48, which implements the indicated pressure, is driven with a predetermined torque, and the movable electrode 45 moves along the gun axis in a direction relative to the fixed electrode 44, either approaching or moving away from it. Furthermore, the drive control unit 51 can also be integrated into the robot control device 60.

[0013] The welding current control unit 52 controls the welding current supplied to the fixed electrode end 44 and the movable electrode end 45. Specifically, the welding current control unit 52 supplies welding current corresponding to the welding current command specified by the welding program to the electrode ends 44 and 45 at the times specified by the welding program.

[0014] The current detection unit 53 detects the value of the current flowing between the fixed electrode 44 and the movable electrode 45 when energized (hereinafter referred to as the gun shaft current value). Existing methods can be used to detect the gun shaft current value, such as using a current sensor.

[0015] The electrode position specifying unit 54 specifies the position (electrode position) of the movable electrode 45, which moves along the welding torch axis during welding, in each predetermined sampling cycle based on the output of the encoder 47. Here, welding period refers to the period from when the movable arm 43 starts moving from a predetermined initial position to when it returns to the initial position after welding. Since the electrode position is based on the output of the encoder 47, it corresponds to the amount of rotation of the drive shaft of the servo motor 48, rather than a parameter guaranteeing the absolute position of the movable electrode 45. During the period when the movable electrode 45 moves from its initial position towards the fixed electrode 44 to contact the part being welded, the electrode position corresponds to a physical absolute position. However, during the period when the movable electrode 45 contacts and is pressed into the part being welded, the electrode position does not correspond to a physical absolute position. Furthermore, the electrode position specifying unit 54 can also be assembled into the robot control device 60.

[0016] The storage unit 55 stores information related to the electrode position specified by the electrode position specifying unit 54 and information related to the gun shaft current value detected by the current detection unit 53.

[0017] The communication unit 56 controls the transmission and reception of various information between the control unit and the robot control device 60. Through the processing of the communication unit 56, the welding gun control device 50 sequentially sends information related to the electrode position or information related to the gun shaft current value to the robot control device 60, and receives control signals of the spot welding gun 40 such as pressure commands and welding current commands from the robot control device 60.

[0018] The robot control device 60 includes a processor consisting of a CPU and GPU, RAM serving as the processor's main memory and working area, and a storage device storing various programs and setting information. The storage device contains welding programs for the welding robot 20 to perform predetermined welding operations. These welding programs are prepared for each type of welding object. The welding program records the position of the welding points, the order of the welding points, the pressure commands during welding, and the welding current commands. The welding current is information including the position of the movable electrodes and the current value flowing between the electrodes.

[0019] The welding program is executed by a processor. The robot control device 60 functions as a welding robot control unit 61, a plate thickness variation calculation unit 63, an anomaly judgment unit 64, a welding data file generation unit 65, an input unit 66, a storage unit 67, and a communication unit 68.

[0020] The welding robot control unit 61 controls the welding robot 20. Specifically, the welding robot control unit 61 controls the multi-joint arm mechanism 30 according to the position and sequence of the welding dots specified in the welding program. Furthermore, the welding robot control unit 61 sends the pressure command and welding current command specified in the welding program to the welding gun control device 50 at the times specified in the welding program. In this way, the welding robot 20 performs the welding operation specified in the welding program.

[0021] The plate thickness variation calculation unit 63 calculates the variation in plate thickness before and after welding based on the time change of electrode position received from the welding gun control device 50. For example, the variation in plate thickness can be calculated based on the difference between the electrode position when in contact with the welding object and the electrode position when welding is completed.

[0022] The input unit 66 receives user input via input devices such as a keyboard, mouse, and teaching control panel, which then inputs user operations into the robot control device 60. Specifically, the setting information necessary for the welding robot 20 to perform a predetermined welding operation, as determined by the user, is input into the robot control device 60. This setting information includes the component type ID for a specific welding object and the program ID for the welding program used in that specific welding operation. The storage unit 67 stores various information received from the welding torch control device 50 (electrode position, torch shaft current value) and welding data files created by the welding data file creation unit 65 (described later). The communication unit 68 controls the transmission and reception of various information between the welding torch control device 50 and the welding quality management device 10. Through the processing of the communication unit 68, the robot control device 60 sends the welding data files related to the welding point to the welding quality management device 10 after the welding at the designated point is completed. Furthermore, the robot control device 60 sends the instruction values ​​specified by the welding program to the welding gun control device 50, and receives information related to the electrode position and information related to the gun shaft current value from the welding gun control device 50.

[0023] The welding data file creation unit 65 compiles data related to the welding torch current value, the electrode position during welding, and the change in plate thickness before and after welding as data body to create a welding data file. This welding data file associates the robot ID (identifying the welding robot 20), the component type ID (identifying the type of component in the specific welding object), the component number (identifying the component individually), the welding number (identifying the welding points of the components separately), the program ID (identifying the welding program used for welding specific components), and date and time information with the data body. The welding data file is created by the welding data file creation unit 65 each time welding at a point is completed, stored in the storage unit 67, and sent to the welding quality management device 10. The component type ID and program ID are input by the user. The component number is assigned as a serial number to each component in the welding object after welding begins. The welding number is defined by the welding program. The date and time information typically includes information related to the start and end dates and times of welding.

[0024] The anomaly determination unit 64 determines whether the welding was successful. For example, if a power outage or other abnormality occurs during welding operations, the anomaly determination unit 64 determines that an anomaly may have occurred during the welding operation, resulting in welding failure. In the welding data file corresponding to the points where the anomaly determination unit 64 determines that an anomaly occurred in the welding operation, there is an anomaly mark indicating that welding was performed under the anomaly determination.

[0025] The welding quality management device 10 has the same hardware as a general PC, including a processor, ROM, RAM, storage device, and input / output interface. The storage device contains the welding quality management program. The processor executes the welding quality management program, and the welding quality management device 10 functions as a control unit 11, input unit 12, storage unit 13, communication unit 14, display unit 15, search condition setting unit 16, search unit 17, graphics generation unit 18, and welding quality management page generation unit 19.

[0026] The control unit 11 provides overall control over all components that constitute the welding quality management device 10. The input unit 12 inputs user operations into the welding quality management device 10 via input devices such as a keyboard, mouse, and teaching control panel. Specifically, based on the user's operation, search criteria are input into the welding quality management device 10. The search criteria include at least one of the following: component type ID, component number, welding number, program ID, and date and time information.

[0027] The communication unit 14 is responsible for sending and receiving various information with the robot control device 60. Through the processing of the communication unit 14, the welding quality management device 10 receives welding data files from the robot control device 60. As explained, the data body of the welding data file contains data related to the electrode position during welding, the change in plate thickness of the welded component before and after welding, and the welding torch shaft current value during welding. The data body also includes robot ID, component type ID, component number, welding number, program ID, and date and time information. The welding data files received from the robot control device 60 are stored in the storage unit 13.

[0028] The search criteria setting unit 16 sets search criteria using various methods. Specifically, the search criteria setting unit 16 sets search criteria based on user operations via the input unit 12. Furthermore, the search criteria setting unit 16 sets at least one of the following as search criteria: robot ID, part type ID, part number, welding number, program ID, and date / time information associated with the welding data file containing the anomaly flag. The search criteria setting unit 16 also sets at least one of the following as search criteria: part type ID, part number, welding number, program ID, and date / time information associated with any welding data file arbitrarily specified by the user.

[0029] The retrieval unit 17 retrieves a plurality of welding data files stored in the storage unit 13 according to the retrieval conditions set by the retrieval condition setting unit 16, and then extracts a plurality of specific welding data files that match the retrieval conditions.

[0030] The graphics generation unit 18 generates multiple graphs representing the time-varying electrode positions during welding, graphs representing the change in plate thickness before and after welding for each component, and graphs representing the time-varying gun shaft current values ​​during welding, based on a plurality of specific welding data files extracted by the retrieval unit 17. When the plurality of specific welding data files include welding data files with anomaly flags, the graphics generation unit 18 generates a graph (picture) based on the welding data file with the anomaly flags attached, which is recognizable relative to the graph (picture) of the welding data file without the anomaly flags attached.

[0031] The welding quality management page creation unit 19 generates the data for the welding quality management page, which will be described later. The welding quality management page created by the welding quality management page creation unit 19 is displayed on the display unit 15.

[0032] The welding quality management page created by the welding quality management page creation unit 19 will be described below with reference to Figures 4 to 9. The welding quality management page is a page used by the user to confirm the welding quality of each weld point. As shown in Figures 4 to 7, the welding quality management page displays multiple search criteria for users to input. These criteria include "Robot ID," "Part Type ID," "Part Number," "Program ID," "Welding Number," and "Welding Date and Time." For example, if a user wants to check the welding quality of a specific spot on each part, they can enter the search criteria "Part Type ID" and "Welding Number." Furthermore, if they want to limit the welding period, they can enter the search criteria "Welding Date and Time." Furthermore, if they want to limit it to welding robot 20, they can enter the search criteria "Robot ID." Furthermore, if they want to limit it to the welding program used, they can enter the search criteria "Program ID." In this way, users can input search criteria according to the spot they want to check, thus setting their search criteria.

[0033] When users input search criteria, the welding quality management page displays data from multiple specific welding data files that match the search criteria in a tabular format. Users can review the data table to determine the likelihood of welding defects at any given point. Furthermore, when the graphical output button or other graphical display indicators are entered, as shown in Figures 4 to 7, graphs are displayed showing the time-varying electrode positions based on the multiple specific welding data files matching the search criteria, the variation in plate thickness for each component, and the time-varying gun shaft current value. In the graph showing the time-varying electrode positions shown in Figure 4, the vertical axis represents the electrode position, and the horizontal axis represents the elapsed time. These graphs can be switched on the welding quality management page shown in Figures 4 to 7 by changing the displayed data on the vertical axis or using tabs.

[0034] As shown in Figures 4 and 5, the multiple graphs representing the time-varying changes in electrode position generated by the graph generation unit 18 are displayed together by integrating and overlapping the time data. As shown in Figure 6, the multiple plots representing the variation in plate thickness are displayed together by using the component number as the horizontal axis and the variation in plate thickness as the vertical axis in order to compare specific welding data files. As shown in Figure 7, the multiple graphs representing the time-varying changes in gun shaft current value generated by the graph generation unit 18 are displayed together by integrating and overlapping the time data.

[0035] The welding quality management device 10 according to this embodiment can achieve the following effects. In other words, by inputting search criteria displayed on the welding quality management page provided by the welding quality management device 10, the user can extract welding data files that meet at least one of the following criteria: welding robot type, type of welding object component, individual components, marking points, date and time, and combinations thereof. The user can also view graphs showing the time variation of electrode positions, plate thickness variations, and torch shaft current values ​​for a plurality of welding data files that share at least some of the search criteria. By viewing these graphs, the user can determine the likelihood of welding defects at any marking point. In other words, the welding quality management device 10 according to this embodiment can support the user's judgment of welding defects.

[0036] Multiple graphs showing the time-varying changes in electrode position and multiple graphs showing the time-varying changes in gun shaft current value are integrated and overlaid together for display, and the variation in plate thickness for each component is also displayed. This allows users to more easily determine the presence or absence of welding defects. For example, as shown in Figure 4, if all the multiple graphs showing the time-varying changes in electrode position exhibit the same trend, the user can determine that there are no welding defects. On the other hand, as shown in Figure 5, if a graph shows a significantly different trend compared to the other multiple graphs showing the time-varying changes in electrode position, the user can determine that there is a possibility of welding defects.

[0037] Of course, the presence or absence of welding defects can also be determined by examining other types of graphs. As shown in Figure 6, the variation in plate thickness for part number "005" is significantly smaller than that for other part numbers. Therefore, in part number "005", it can be determined that the welding was not performed correctly and there is a possibility of an abnormality. Furthermore, for part numbers after "005", it can also be determined that the welding operation was performed under abnormal conditions. As shown in Figure 7, in the case where one of the multiple graphs representing the time variation of the gun shaft current value shows a significantly different tendency compared to the other multiple graphs, the user can determine that there is a possibility of welding defects.

[0038] Because the likelihood of welding defects can be determined from three types of graphs—graphs showing the time-varying changes in electrode position, graphs showing the variation in plate thickness for each component, and graphs showing the time-varying changes in gun shaft current—the probability of welding defects can be assessed more accurately, and the main causes of the welding defects can be analyzed from various perspectives. Furthermore, users can acquire knowledge of the trends in graphs when welding defects are present and the trends when welding defects are absent.

[0039] In this embodiment, the electrode position, the amount of variation in plate thickness, and the gun shaft current value are used as parameters for determining the likelihood of welding defects. The amount of variation in electrode position and plate thickness is calculated based on the output of the encoder 47 already equipped on the spot welding gun 40. The gun shaft current value is calculated based on the output of the current detection unit 53 of the welding gun control device 50 that controls the spot welding gun 40. In this way, since parameters that can be obtained in existing spot welding guns 40 are utilized, it is not necessary to equip the welding robot 20 with a dedicated external sensor just to determine the likelihood of welding defects. It can be applied to existing spot welding guns 40, which can be said to be very widely used.

[0040] If a welding robot 20 malfunctions, collecting welding data files from only a single welding robot 20 will not reveal the differences between the patterns, making it impossible to detect the anomaly and potentially leading to omissions. The welding quality management device 10 of this embodiment can collect multiple welding data files from multiple welding robots 20. Therefore, if multiple welding robots 20 are performing welding operations on the same type of component using the same welding program, welding anomalies caused by the welding robot 20 can be reliably detected by comparing data among the multiple welding robots 20.

[0041] The welding quality management device 10 according to this embodiment manages multiple welding data files generated by multiple welding robots 20 in one go. Users do not need to go to the site to operate the welding robots 20 in order to check the welding data files. Users can also access the welding quality management device 10 from a distance via the network 70 to check the welding data files.

[0042] According to the welding quality management device 10 of this embodiment, at least one of the robot ID, component type ID, component number, welding number, program ID, and date / time information attached to the welding data file of the data source of the plurality of graphics displayed on the welding quality management page, which is arbitrarily specified by the user, can be set as search criteria. For example, when a graphic (dot) with the potential for welding defects is found on the welding quality management page, the welding defect is highly likely to be caused by at least one of the welding robot type, component type, component, dot, welding program, and date / time specified in the welding information attached to the welding data file of the data source of the graphic. Dots that were welded under conditions common to at least some of the dot with the potential for welding defects also have the possibility of welding defects. For example, if the welding defect is caused by a power outage, dots that were welded during the same period may also be affected by the power outage and have welding defects. In addition, if the welding defect is in a specific welding robot 20, other dots welded by that specific welding robot 20 may also have welding defects.

[0043] As shown in Figure 7, by specifying the graphic among the multiple graphics represented on the welding quality management page that is presumed to be a welding defect, the welding information of the corresponding mark is displayed. Furthermore, at least one of these welding information items can be set as a search criterion. This eliminates the need for users to set search criteria and allows for the extraction of welding data files with a high probability of producing welding defects. Managing welding quality is a significant burden for managers when multiple welding robots are operating. Therefore, by extracting and confirming welding data files that indicate a potential welding defect from a single weld defect, welding quality management becomes easier, and the possibility of overlooking welding defects is reduced.

[0044] As shown in Figure 7, by specifying the date and time information in the search criteria, welding data files that match or are near the date and time "2022 / 09 / 18 11:35" of a specific graphic suspected of being a welding defect can be extracted. Furthermore, as shown in Figure 8, the graphic based on the extracted welding data file (extracted graphic) and the graphics based on multiple specific welding data files that match the extracted welding data file with the component type ID, welding number, and program ID can be overlaid and displayed together.

[0045] As shown in Figure 8, by reviewing the graphics of welding data files collected from each welding robot 20 at a specific date and time, the user can determine whether the graphics corresponding to the welded dots during the same period as the date and time when the welding defect occurred show the same trend or a significantly different trend compared to other graphics, thus judging whether a welding defect exists. Here, as shown in Figure 7, in welding robots 20 with robot ID "RO1" and "RO2", the graphics corresponding to the welded dots during the same period show a different trend compared to other graphics, thus allowing the user to infer whether an anomaly such as a power outage occurred throughout the factory at that date and time.

[0046] Thus, in the welding quality management page, when identifying graphs (dots) indicating a potential welding defect, by identifying these graphs (dots) and multiple graphs (dots) that share certain welding conditions, the root cause of the welding defect can be more efficiently identified. Furthermore, when assessing the likelihood of a welding defect, the occurrence of the same welding defect can be easily confirmed by component type, component, dot, program, and date / time, thus preventing the omission of welding defects.

[0047] In cases where the retrieval unit 17 extracts a plurality of specific welding data files, including those with anomaly markers, the graphics of the specific welding data files with anomaly markers are desirablely distinguishable from those of the specific welding data files without anomaly markers. For this purpose, for example, as shown in FIG9, graphics of welding data files with anomaly markers are represented by solid lines, while graphics of welding data files without anomaly markers are represented by dashed lines. Of course, identification can also be performed using the color of the lines, rather than the type of line. Therefore, the user can easily identify the graphics with anomaly markers.

[0048] The form of the welding quality management device 10 is not limited to that of the welding robot 20, as long as it can collect welding data from the welding robot 20. For example, the welding quality management device 10 can also be directly connected to the welding robot 20 via a cable. Alternatively, the welding quality management device 10 can also be connected wirelessly or via a wired connection to a control device such as a PLC that controls multiple welding robots 20 in a unified manner.

[0049] In this embodiment, the functions of the electrode position specifying unit 54 and the plate thickness variation calculation unit 63 are provided on the welding robot 20 side. However, as long as the electrode position and plate thickness variation can be calculated based on the output of the encoder 47, all or part of these functions can also be provided by the welding quality management device 10. In addition, some or all of the functions of the welding quality management device 10 can also be provided by the welding robot 20. Furthermore, some of the functions of the robot control device 60 and the welding quality management device 10, such as the function of the storage unit 13 of the welding quality management device 10, can also be provided by external devices.

[0050] In this embodiment, the welding data file includes three parameters: electrode position, plate thickness variation, and torch current value, which can be used to represent three different patterns. However, as long as the user can determine the possible presence of welding defects at the marked points, the parameters included in the welding data file only need to be at least one of the three parameters mentioned above.

[0051] In this embodiment, the welding data file includes robot ID, part type ID, part number, welding number, program ID, and date and time information. However, if the welding program is fixed and the part type is uniquely identified, the part type ID may not be included as supplementary information. Furthermore, even if the part type is the same, its performance may differ depending on the factory unit where it is produced. Therefore, the welding data file may include a batch ID to identify the production batch of the part type. Additionally, the spot welding gun 40 installed on the multi-joint arm mechanism 30 may be changed due to maintenance or other reasons. Therefore, the welding data file may include a gun ID to identify the spot welding gun 40. Moreover, the welding data file may also include various parameters that could potentially affect the welding operation, such as weather, temperature, humidity, the location of the welding robot 20, and the elapsed time since the welding robot 20 was maintained. These can be set as search criteria.

[0052] While some embodiments of the invention have been described, these embodiments are merely illustrative and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments, or variations thereof, are included, in the same way as those included in the scope or spirit of the invention, within the scope of the invention as described in the claims and their equivalents.

[0053] 10: Welding quality management device 11: Control Department 12: Input Section 13: Storage Department 14: Communications Department 15: Display Section 16: Search Criteria Setting Section 17: Retrieval Department 18: Graphic Design Section 19: Welding Quality Management Page Creation Department 20(20a,20b): Welding Robots 30: Multi-joint arm mechanism 40(40a,40b): Spot welding gun 42: Fixed arm 43: Movable boom 44: Fixed electrode 45: Movable electric pole 47: Encoder 48: Servo Motor 50(50a,50b): Welding gun control device 51: Drive Control Unit 52: Welding Current Control Department 53: Current Detection Section 54: Electrode position specific part 55: Storage Department 56: Communications Department 60(60a,60b): Robot control device 61: Welding Robot Control Department 63: Plate Thickness Variation Calculation Section 64: Anomaly Detection Department 65: Welding Data Archive Creation Department 66: Input Section 67: Storage Department 68: Communications Department 70: Internet

Claims

1. A welding quality management device connected to a plurality of welding robots, the welding quality management device comprising: a receiving unit receiving from the plurality of welding robots or their control device: a plurality of welding data files related to the position of movable electrodes and the current value flowing between electrodes during welding, obtained jointly by the plurality of welding robots; a component number for identifying the component to be welded; a welding number for identifying the dots on the component to be welded; a program ID for identifying the program used when welding the component to be welded; and date and time information; a storage unit storing the plurality of welding data files in association with the component number, the welding number, the program ID, and the date and time information; and a retrieval unit retrieving the stored plurality of welding data files based on retrieval criteria related to at least one of the component number, the welding number, the program ID, and the date and time information, and retrieving a plurality of specific welding data files that match the retrieval criteria; The graphics generation unit generates at least one of a plurality of graphics representing the time-varying position of the aforementioned movable electrode and a plurality of graphics representing the time-varying current value, based on the aforementioned extracted welding data file; and the display unit overlays and displays the plurality of graphics generated by the graphics generation unit together.

2. The welding quality management device as described in claim 1 further comprises: a search condition setting unit, wherein the setting is a value related to at least one of the aforementioned welding number, the aforementioned component number, the aforementioned program ID, and the aforementioned date and time information, based on user operation.

3. The welding quality management device as described in claim 1 further comprises: a search condition setting unit, which sets a value associated with at least one of the aforementioned welding number, the aforementioned component number, the aforementioned program ID, and the aforementioned date and time information, which are used as the aforementioned search conditions and are arbitrarily specified by the user in a welding data file; wherein, The aforementioned plurality of specific welding data files extracted by the aforementioned retrieval unit are, relative to the aforementioned designated welding data file, common to at least one of the aforementioned welding number, the aforementioned component number, the aforementioned program ID, and the aforementioned date and time information.

4. The welding quality management device as described in claim 1 further comprises: a search condition setting unit, which sets a value as the search condition that is associated with at least one of the aforementioned welding number, the aforementioned component number, the aforementioned program ID, and the aforementioned date and time information, which are attached to one of the aforementioned plurality of welding data files containing information indicating an anomaly in the welding operation; wherein, The plurality of specific welding data files extracted by the aforementioned retrieval unit are such that, relative to the aforementioned single welding data file, at least one of the aforementioned welding number, the aforementioned component number, the aforementioned program ID, and the aforementioned date and time information is common.

5. The welding quality management device as described in claim 1, wherein, The aforementioned welding data archive contains data related to the change in the thickness of the plate being welded before and after welding.

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