JP4441367B2 - Method of welding workpieces using a welding robot - Google Patents

Description

The present invention relates to a welding method for performing welding on a workpiece (workpiece) using a welding robot .

  Conventionally, there is a welding robot that joins a plurality of workpieces to be welded by, for example, arc welding. In this welding robot, a so-called teaching & playback system is often used. In this teaching & playback method, the movement trajectory of the welding torch along the workpiece welding position is set in advance by a worker or the like as teaching data, or the welding position of the workpiece is detected by detecting the welding position by a sensing operation of a laser sensor, for example. This is a method in which the movement trajectory of the welding torch along the position is set as teaching data, and the teaching data is used for welding work by the subsequent welding torch.

  On the other hand, in the welding operation, when it is installed on a welding work table or the like for welding the workpieces, positional displacement may occur for each workpiece due to the tightening condition of the jig. For example, in the publication of Patent Document 1, welding is performed with an accurate movement trajectory by detecting a positional deviation of a workpiece in advance before welding and reflecting the detected positional deviation amount in preset teaching data. A method of obtaining has been proposed.

Japanese Patent Laid-Open No. 5-200551

  In the control in this publication, the following method is used when detecting a displacement in advance before welding. That is, in this welding robot, in addition to the welding torch, a touch sensor and a pin for detecting contact with the workpiece are provided substantially in parallel with the welding torch. The workpiece is marked in advance, and an operator or the like inputs the amount of movement manually or from an operating device having a keyboard or the like so that the pins of the welding robot move toward the marking. When the pin comes into contact with the work piece, the touch sensor detects it, takes the position of the pin at that time as position data, and compares it with position data input in advance to calculate the amount of displacement. Yes.

  However, in the control in the above publication, when the pin is moved toward the marking of the workpiece, the movement operation is performed manually or by an input operation from the operation device. For example, it was troublesome.

The present invention has been conceived under the circumstances described above, and uses a welding robot that can easily carry out the detection operation when detecting a positional deviation of a workpiece before welding in advance . It is an object of the present invention to provide a workpiece welding method .

  In order to solve the above problems, the present invention takes the following technical means.

A workpiece welding method using a welding robot provided by the present invention includes a welding torch attached to the tip of an arm and a workpiece position detecting means for detecting a positional relationship of the workpiece installed on a welding workbench with respect to the welding torch. A welding method for workpieces, in which welding is performed while moving the welding torch along a welding location of the workpieces to each of a plurality of workpieces sequentially installed on the welding work table using a welding robot equipped with A plurality of movement positions indicating a movement locus at the time of welding by installing a reference work as a reference of the plurality of works on the welding work table and moving the welding torch along a welding position of the reference work. A first step of teaching data as teaching point data, and the reference work set on the welding work table, the welding torch is connected to the reference work The position information of the operation start point for specifying the movement line to be moved toward and the direction indication point indicating the movement direction of the welding torch between the operation start point and the reference workpiece is respectively set for the plurality of movement lines. A second step of setting, and moving the welding torch on a plurality of movement lines specified by the operation start point and the direction indication point set in the second step, respectively, and the workpiece position on each movement line When the positional relationship of the reference workpiece with respect to the welding torch detected by the detection means becomes a predetermined positional relationship, a third step of acquiring positional information of the reference workpiece based on the positional relationship at that time, and the welding operation When each of the plurality of workpieces is installed on a table as a workpiece to be welded, the operation start point and the direction set in the second step are set to the welding torch. When the positional relationship of the workpiece to be welded with respect to the welding torch detected by the workpiece position detecting means on each movement line is the predetermined positional relationship by moving on the plurality of moving lines specified by the indicated points, respectively, A fourth step of acquiring the position information of the workpiece to be welded based on the positional relationship of the time, a plurality of pieces of position information of the workpiece to be welded acquired in the fourth step, and the third step The obtained position information of the reference workpiece is compared with the obtained position information on the same movement line, the difference between the two is calculated, and the teaching taught in the first step based on the difference is calculated. A fifth step of correcting the point data, and the welding torch while moving the welding torch by the welding robot based on the teaching point data corrected in the fifth step. And a sixth step of causing welding to be performed on the workpiece (claim 1).

The operation start point may be a retreat point that is set in advance in order to retract the welding torch from the movement trajectory during the welding when a welding operation is not performed (Claim 2).

Further, the predetermined positional relationship between the reference workpiece and the workpiece to be welded with respect to the welding torch is a positional relationship in which the welding torch contacts the reference workpiece and the workpiece to be welded, and the workpiece position detecting means includes: Further, it is preferable that the welding torch detects that the welding torch is brought into contact with the surface of the workpiece and becomes conductive, and the moving position detecting means detects the moving position of the welding torch at that time .

Moreover, the the predetermined positional relationship of the reference workpiece and the welding object work for welding torch, the distance between the welding torch and the surface of said workpiece is to a predetermined distance, said work position The detecting means may be a moving position detecting means for detecting a distance from the welding torch to the surface of the workpiece by an optical sensor and detecting a moving position of the welding torch at that time .

According to this configuration, when teaching the movement trajectory of the welding torch at the time of welding using the reference workpiece, in order to identify the movement line for moving the welding torch toward the reference workpiece , the welding torch of each movement line is specified . When an operation start point and a direction indication point indicating the movement direction of the welding torch between the operation start point and the reference workpiece are set and input by, for example, an operator, the operation start point and direction for each movement line Move the welding torch toward the reference workpiece on a straight line passing through the indicated point . By its movement, the welding torch, for example, if it has contact with the surface of the reference workpiece is detected, Ru acquired position of the welding torch when the detected as the reference position data. In addition, when welding to a plurality of workpieces to be welded, the welding torch is moved on the plurality of movement lines specified by the operation start point and the direction indication point in the same manner as the reference workpiece for each workpiece, When the welding torch contacts the surface of the workpiece on the movement line, the position of the welding torch at that time is acquired as position data of each workpiece.

By performing the above-described operation, for example, when detecting the position deviation of the workpiece before welding, the position data of each workpiece for detecting the position deviation with respect to the position of the reference workpiece can be easily and reliably acquired. . Conventionally, the movement operation of pins and the like for detecting the positional deviation of each workpiece has been performed manually or by input operation from an operation device, so it takes a very long time and is troublesome for an operator or the like. However, these problems can be solved by the above configuration.

As the position data, the reference position data for the reference workpiece and the position data for each workpiece to be welded are acquired. However, when the reference position data is obtained again, the welding torch has already been acquired when the previous reference position data is acquired. Since the operation start point and the direction indication point for instructing the moving direction of the first and second directions are taught, it is not necessary to teach these points again, and the welding torch can be immediately moved to acquire the position data.

According to a preferred embodiment, the plurality of movement lines to be set may be parallel to each other (claim 5).

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram showing a control system including a control device for a welding robot according to the present invention. This control system performs welding on a workpiece (workpiece to be welded) using a welding torch provided in a welding robot. In particular, this control system performs the welding of each workpiece before welding a plurality of workpieces. The present invention provides a method for detecting misregistration, so-called pre-sensing control.

  This control system is roughly constituted by a welding robot 10, a robot control device 20, and a welding power supply device 30.

  The welding robot 10 automatically performs, for example, arc welding on the workpiece W. The welding robot 10 includes a base member 11 fixed to a floor or the like, six arms 12 connected to the base member 11 via six axes, and six arms 12 provided at both ends or one end of the six arms 12. A drive motor (servo motor) 13 (partially omitted) is configured.

  The welding robot 10 is provided with a welding torch 14 at the distal end portion of the arm 12 provided on the most distal end side. The welding torch 14 guides a welding wire 15 having a diameter of, for example, about 1 mm as a filler material to a predetermined welding position of the workpiece W.

  A wire feeding device 16 is provided on the upper portion of the welding robot 10. The wire feeding device 16 is for feeding the welding wire 15 to the welding torch 14. The wire feeding device 16 includes a reel (not shown) around which the welding wire 15 is wound, and a feeding motor 17 that rotates the reel. The feeding motor 17 is rotationally driven by a welding power source device 30.

  A coil liner 19 for guiding the welding wire 15 is connected to the wire feeder 16, and the tip of the coil liner 19 is connected to the welding torch 14. The welding wire 15 projects outward from the welding torch 14 and functions as a consumable electrode. That is, welding is performed on the workpiece W by generating an arc between the tip of the welding wire 15 and the workpiece W by the welding power source device 30 and melting the welding wire 15 with the heat.

  Each of the six drive motors 13 is rotationally driven by a drive signal from the robot controller 20, and each of the drive motors 13 is rotationally driven, whereby each arm 12 is displaced, and as a result, the welding torch 14 moves up and down. It can be moved back and forth and left and right.

  Each drive motor 13 is provided with an encoder (not shown). The output of the encoder is given to the robot control device 20, and the rotation position of each drive motor 13 is detected by the output of the encoder. Therefore, the robot controller 20 recognizes the displacement state of each arm 12 from the rotational position of each drive motor 13 and the current position of the welding torch 14 attached to the arm 12 at the tip.

  The robot control device 20 is for controlling the operation of the welding robot 10. The robot control device 20 drives and controls each drive motor 13 of the welding robot 10 based on a work program stored in advance, current position information from an encoder (not shown), and the like, and moves the welding torch 14 from the operation start point to the workpiece. The welding point of W is moved from the welding point to another welding point or from the welding point to the retraction point (position).

  The welding power source device 30 includes a welding power source (not shown), and the welding power source supplies a welding voltage between the welding torch 14 and the workpiece W. Moreover, the welding power supply device 30 also has a function of driving the feeding motor 17 of the wire feeding device 16 at a predetermined timing.

  FIG. 2 is a block diagram showing the configuration of the robot control device 20 and its peripheral devices. The robot control device 20 includes a control unit 21 configured by a microcomputer or the like, a memory unit 22, a servo drive unit 23, a current position monitoring unit 24, a welding control unit 25, and a contact detection unit 26. An operation device 27 is connected to the control unit 21. Six drive motors 13 provided in the welding robot 10 are connected to the servo drive unit 23, respectively. Six encoders 28 respectively provided in the six drive motors 13 are connected to the current position monitoring unit 24. In addition, a welding power source device 30 is connected to the welding control unit 25 and the contact detection unit 26.

  The control unit 21 is a control center of the robot control device 20, and is based on a work program stored in advance in the memory unit 22, an operation signal from the operation device 27, current position information from the encoder 28, or the like. Then, by performing predetermined data processing and giving an operation command to the servo drive unit 23, the drive motor 13 is driven to rotate and the welding torch 14 is moved.

  Further, as will be described later, the control unit 21 performs welding based on the operation start point A (see FIG. 4) of the welding torch 14 and the operation start point A input by an operator or the like in pre-sensing control. It has a function of moving the welding torch 14 based on position data indicating a direction indicating point B (see FIG. 4) indicating a direction in which the torch 14 moves. This movement control of the welding torch 14 is for bringing the welding torch 14 into contact with the workpiece W.

  Moreover, the control part 21 is based on the output from the contact detection part 26 which detects that the welding torch 14 and the workpiece | work W contacted, and the output from the encoder 28 of the six drive motors 13 at the time of the detection. The contact position of the welding torch 14 is stored in the memory unit 22 as position data. That is, when the welding torch 14 contacts the workpiece W, the control unit 21 stops the movement of the welding torch 14 and stores the rotational position of each drive motor 13 detected by the six encoders 28 at that time as position data. Store in the unit 22. Furthermore, it has a function of correcting the positional deviation of each workpiece W based on the position data of the welding torch 14 when the welding torch 14 and the workpiece W come into contact with each other. This will be described later.

  The memory unit 22 stores a work program that defines a series of movements and operations of the welding robot 10. The work program includes a welding start command for starting welding, a collision detection process, a stop process, and the like along with such a movement command.

The memory unit 22 stores data necessary for executing the work program. For example, the memory unit 22 stores position data indicating the operation start point A and the direction indication point B of the welding torch 14 described above. In addition, teaching point data of a movement locus that is a welded portion of the workpiece W is stored. Furthermore, position data for correcting the positional deviation of each workpiece W is stored (details will be described later). Note that the position data, the teaching point data, and the position data for correcting the positional deviation of the operation start point A and the direction indication point B are specifically the movement start point A, the direction indication point B, This is a data group indicating the rotational positions of the six drive motors 13 output from the six encoders 28 when set at the teaching position or the like.

  The servo drive unit 23 outputs a drive signal to each drive motor 13 based on the drive signal from the control unit 21.

  The current position monitoring unit 24 monitors the current position of the welding torch 14 based on a detection signal from the encoder 28 disposed in each drive motor 13.

  The welding control unit 25 causes the welding power source device 30 to perform welding by the welding torch 14 based on various commands from the control unit 21 and a position signal from the current position monitoring unit 24.

  The contact detection unit 26 detects contact between the welding torch 14 and the workpiece W based on a control signal (voltage) from the welding power supply device 30. Specifically, the welding torch 14 is detected by detecting changes in the presence / absence of energization (including both a state changing from “present” to “not present” and a state changing from “not present” to “present”). A contact position with the workpiece W is detected. The detection signal from the contact detection unit 26 is sent to the control unit 21 so that the control unit 21 recognizes that the welding torch 14 and the workpiece W are in contact with each other.

  The operation device 27 has a plurality of operation buttons (not shown), and enables various operations such as selection, activation, start, and stop of the automatic operation mode or manual mode during welding by operation by the user. The control unit 21 receives the operation signal from the operation device 27 and performs predetermined data processing. In the present embodiment, for example, position data indicating the operation start point A and the direction indication point B is input from the operation device 27 or an instruction to perform pre-sensing control is performed by an operation by an operator or the like.

  Next, the operation of the above configuration will be described with reference to the drawing showing the work procedure in FIG. 3, the perspective view of the workpiece W in FIG. 4, and the flowchart shown in FIG.

  In this embodiment, when the workpiece W is welded by the welding robot 10, the robot controller 20 controls the workpiece W according to the following procedure, and detects a positional shift in each workpiece W.

  That is, as shown in FIG. 3, as the first step, the robot controller 20 is set to the teaching point data input mode and actually welded to a reference workpiece W (hereinafter referred to as “reference workpiece Ws”). Teaching point data necessary for the acquisition is acquired.

  Next, as a second step, position data (hereinafter referred to as “reference position data”) that is set as a reference by pre-sensing control for the same reference workpiece Ws with the robot control device 20 set in the reference position data input mode. To be acquired.

  Next, as the third step, the robot control device 20 is set to the target position data input mode and is different from the reference workpiece Ws, and the workpiece W to be originally welded (hereinafter referred to as “welding target workpiece Wp”). By performing the pre-sensing control automatically, position data (hereinafter referred to as “target position data”) in the welding target workpiece Wp is acquired.

  Next, as a fourth step, the robot control device 20 is set to the teaching point correction mode, and new teaching point data (first one) is set based on the reference position data of the reference workpiece Ws and the target position data of the welding workpiece Wp. Data obtained by correcting the teaching point data acquired in the process) is calculated. In the welding mode, a welding operation is actually performed based on the new teaching point data.

  Hereinafter, each process is explained in full detail. First, in the first step, the reference workpiece Ws is installed on a welding work table or the like, and the welding torch 14 is traced along the actual welding locus by manual operation or input of operation from the operation device 27 by the welding robot 10. As shown in FIG. 4, a plurality of welding teaching points P1 to P5 are taken into the robot control device 20 as teaching point data. The teaching point data is temporarily stored in the memory unit 22.

Next, in the second step, pre-sensing control is performed using the same reference workpiece Ws from which the teaching point data has been acquired. Specifically, as shown in FIG. 5, the control unit 21 of the robot control device 20 determines whether or not the position data of the operation start point A and the direction indication point B has already been acquired (S1). This determination may be made in the target position data input mode or in the case where the lots are different even for the workpiece W having the same shape, for example, the teaching point data may be re-acquired and the reference position data re-acquired accordingly. When re-acquiring the reference position data even in the data input mode, since the position data of the operation start point A and the direction indication point B have already been acquired in the pre-sensing control and do not need to be acquired again, the operation start point A and the direction indication It is determined whether or not the position data of the point B needs to be acquired.

  If the position data of the operation start point A and the direction indication point B has not been acquired yet (S1: NO), the position data of the operation start point A and the direction indication point B is subsequently controlled by the control unit 21 of the robot controller 20. Is determined by the operator or the like using the operation device 27 (S2). On the other hand, if the position data of the operation start point A and the direction indication point B have already been acquired (S1: YES), the process of step S2 is skipped.

Here, the direction indicating point B is a point indicating the operation direction of the welding torch 14 located at the operation start point A. Usually, for example, an arbitrary point between the operation start point A and the reference workpiece Ws by an operator or the like. Set to a point in space. The direction instruction point B, if located in the space between the operation starting point A and the reference work Ws, may be set to any position on that space. That is, it is only necessary that the point is located inside the outline of the reference workpiece W s when the reference workpiece W s is viewed from the operation start point A. Further, the direction indicating point B may be set at a position on the space exceeding the reference workpiece Ws.

  An operator or the like manually moves the welding torch 14 so that the tip of the welding torch 14 is positioned at the operation start point A, and performs a setting to set the position of the welding torch 14 at the operation start point A as the operation start point A. . Subsequently, the operator or the like manually moves the welding torch 14 so that the tip of the welding torch 14 is positioned at the direction indicating point B, and the position of the welding torch 14 at the direction indicating point B should be the direction indicating point B. Set up.

  Thereby, the control part 21 discriminate | determines that the position data of the operation | movement start point A and the direction indication point B were input (S2: YES), and is acquiring the position data of the welding torch 14 in each position. The position data from 24 is stored in the memory unit 22.

  As the operation start point A, a retreat point of the welding torch 14 recognized in advance by the robot controller 20 (a predetermined point at which the welding torch 14 is retreated when the welding operation is not performed) is adopted. You may make it do.

  Next, the control unit 21 determines whether or not an operation for obtaining position data (position data at a point C shown in FIG. 4) is input by an operator or the like (S3). When the operator or the like presses the operation button of the operating device 27 for acquiring the reference position data, the control unit 21 determines that an operation for acquiring the reference position data is input by the operator or the like (S3: YES), the search program stored in advance in the memory unit 22 is read and executed. Here, the search program is a program including a process of moving the welding torch 14 in order to acquire reference position data for correcting the positional deviation.

  When this search program is executed, the moving speed of the welding torch 14 (search speed), detection logic (whether the work W is not present is detected or the work W is present is detected). Whether or not a non-existing state is detected), a non-detection distance (maximum distance for detecting the workpiece W), and the like may be set. Note that the moving speed of the welding torch 14 may be changed to an appropriate speed.

  Specifically, the control unit 21 temporarily moves the welding torch 14 to the operation start point A (S4), and moves the welding torch 14 so that the tip of the welding torch 14 faces the direction indicating point B (S5). . The control unit 21 moves the welding torch 14 until the tip of the welding torch 14 contacts the reference workpiece Ws. If the welding torch 14 does not contact the reference workpiece Ws before reaching the direction indication point B, the welding torch 14 is moved beyond the direction indication point B on the extension line toward the reference workpiece Ws.

  Next, the control unit 21 determines whether or not the welding torch 14 contacts the surface of the reference workpiece Ws (S6). This is based on the control signal from the welding power source device 30, and the contact detection unit 26 detects that the welding torch 14 and the reference workpiece Ws are in contact at the point C shown in FIG. 4, and the contact detection unit 26 controls the control unit 21. Is determined by sending a signal to that effect. When it is determined that the welding torch 14 has contacted the surface of the reference workpiece Ws (S6: YES), the control unit 21 stops the movement of the welding torch 14 (S7). Then, position data is acquired in the current position monitoring unit 24 (S8).

Next, the control unit 21 determines whether or not it is the reference position data input mode (S9), and if it is the reference position data input mode (S9: YES), the memory unit 22 uses the acquired position data as reference position data. Are stored in the storage area of the reference position data (S10). When the reference position data is re-acquired, the newly acquired reference position data is overwritten on the reference position data already stored in the memory unit 22. On the other hand, if it is not the reference position data input mode, that is, if it is the target position data input mode (S9: NO), the acquired position data is stored as the target position data in the storage area of the target position data in the memory unit 22 ( S 11).

  Next, in the third step, instead of the reference workpiece Ws, the welding target workpiece Wp to be welded is placed on a welding work table or the like, the target position data input mode is set, and pre-sensing control is performed on the welding target workpiece Wp. Is done. The reference workpiece Ws may be actually welded by moving the welding torch 14 along the welded portion based on the teaching data after the end of the second step.

  When the workpiece Wp to be welded is set on the welding work table or the like by the operator and the target position data input mode is set, the control unit 21 performs the same control as the pre-sensing control shown in the flowchart of FIG. That is, the control unit 21 determines whether or not the position data of the operation start point A and the direction indication point B has been acquired (S1). In the target position data input mode, since the position data of the operation start point A and the direction indication point B have already been acquired in the process of acquiring the reference position data in the reference position data input mode, step S1 is always YES, The control unit 21 skips step 2 and proceeds to step S3.

  In step S3, it is determined whether or not an operation for obtaining position data (position data at a point C shown in FIG. 4) has been input by an operator or the like, and an operation for obtaining the reference position data by the worker or the like. When the button is pressed (S3: YES), the control unit 21 reads the search program and the position data of the operation start point A and the direction indication point B stored in advance in the memory unit 22.

  Then, the welding torch 14 is moved to the operation start point A (S4), and the welding torch 14 is moved from the operation start point A toward the direction indicating point B until the tip of the welding torch 14 comes into contact with the workpiece Wp to be welded ( S5).

  Next, it is determined whether or not the welding torch 14 is in contact with the surface of the workpiece Wp to be welded (S6), and when the welding torch 14 is in contact with the workpiece Wp to be welded beyond the direction indicating point B (S6: YES). Then, the movement of the welding torch 14 is stopped (S7). Then, position data is acquired in the current position monitoring unit 24 (S8).

Next, the control unit 21 determines whether or not it is the reference position data input mode (S9), and if it is the reference position data input mode (S9: YES), the memory unit 22 uses the acquired position data as reference position data. Are stored in the storage area of the reference position data (S10). On the other hand, if it is not the reference position data input mode, that is, if it is the target position data input mode (S9: NO), the acquired position data is stored as the target position data in the storage area of the target position data in the memory unit 22 ( S 11). Since this time is the target position data input mode, the acquired position data is stored as target position data in the storage area of the target position data in the memory unit 22.

  Next, in the fourth step, as shown in FIG. 6, the target position data of the workpiece Wp to be welded acquired in the third step is compared with the reference position data of the reference workpiece Ws acquired in the second step. (Specifically, the difference data between the rotational position data at the reference position of each drive motor 13 and the rotational position data at the target position) is obtained as a positional deviation amount (S12). Then, the teaching point data obtained by teaching in the first step is corrected with the positional deviation amount data, and the actual welding operation is performed (S13).

  More specifically, as shown in FIG. 7, when the positions of the reference position data (see point C) of the reference work Ws and the target position data (see point C ') of the workpiece Wp to be welded are different, The difference ΔC is calculated. Then, the teaching point data of the reference workpiece Ws acquired in the first step is read out, and the difference ΔC is added to the read teaching point data to calculate new teaching point data. And when welding with respect to the workpiece | work Wp to be welded, welding is performed based on new teaching point data. In the new teaching point data, since the amount of positional deviation is corrected, welding can be performed at an accurate position.

Thus, in the above-described control process, when the position deviation of the workpiece W is detected in advance before welding, if the operation start point A and the direction indication point B are set in advance, the position deviation is detected by pre-sensing control. Therefore, it is possible to easily and reliably acquire reference position data and target position data. Therefore, conventionally, in order it has been performed by an input by the manual or operating equipment position data indicative of the position deviation for each work W, together with very takes a long time, have to generate a troublesome work for the operator or the like However, the above configuration can solve these problems. For example, the time required for pre-sensing is expected to be about ½ of the time required for the conventional configuration, and pre-sensing is performed for the entire time (including the time required for pre-sensing) for teaching the welding trajectory. Since the time required for is estimated to be about 1/3 to 1/2, it is estimated that about 25% of the time is reduced as a whole.

  In particular, according to the robot control apparatus 20 according to the present embodiment, the reference position data is acquired for re-reading the reference position data when the workpiece W has the same shape and different lots, or for another workpiece W having a similar shape. At this time, if the reference position data acquisition process is performed for the previous workpiece W, the data of the movement path of the welding torch 14 based on the operation start point A and the direction indication point B acquired in the acquisition process is used. In this case, the operation of teaching the operation start point A and the direction indication point B is not necessary, and the reference position data can be acquired quickly.

In the welding robot 10, when the welding torch 14 is stopped, it slightly coasts due to inertia. For this reason, when the contact point between the welding torch 14 and the workpiece W is detected, the welding robot 10 (welding torch 14) runs coasting and an original accurate position is not detected, but an error occurs. Even when teaching, the welding robot 10 (welding torch 14) coasts, and the error is cancelled. Therefore, an accurate contact point can be detected for the welded portion.

  In the above description, the case where the target position data at one contact point (see point C in FIG. 4) is acquired with respect to the workpiece W in the pre-sensing control has been described. Instead, as shown in FIG. Further, correction data at a plurality of contact points C1, C2,... May be acquired. In this case, operation start points A1, A2,... And direction indication points B1, B2,. Thereby, the positional accuracy in the welding part of the workpiece | work W can be raised.

  In the pre-sensing control described above, only the one-dimensional direction has been described. Alternatively, two-dimensional or three-dimensional directions may be combined. In this way, when there are a plurality of deviation directions, the target position data can be acquired with higher accuracy. For example, as shown in FIG. 9, target position data at a plurality of contact points C1, C2,... May be acquired in the X direction, the Y direction, and the Z direction.

  Of course, the scope of the present invention is not limited to the embodiment described above. For example, in the above-described embodiment, the pre-sensing control based on the method of acquiring the reference position data and the target position data by bringing the welding torch 14 into direct contact with the workpiece W has been described, but instead of this, light (for example, laser light) The target position data is acquired after detecting that the welding torch 14 and the workpiece W have reached a predetermined positional relationship using a non-contact type sensor using magnetism, capacitance, or the like. Also good. That is, a method of directly contacting the tip of the position detection sensor with the workpiece W (a method of detecting a position where the distance from the tip of the position detection sensor to the workpiece W is “0”) may be used. A method of detecting a position where the distance between the workpiece and the workpiece W is a predetermined distance may be used.

It is a block diagram which shows the control system containing the control apparatus of the welding robot which concerns on this invention. It is a block diagram which shows the structure of a robot control apparatus and its peripheral device. It is a figure for demonstrating the work procedure of pre-sensing control. It is a figure for demonstrating the operation start point with respect to a workpiece | work, a direction indication point, and a contact point. It is a flowchart for demonstrating the effect | action of this invention. It is a flowchart for demonstrating the effect | action of this invention. It is a figure for demonstrating the deviation | shift amount of a contact point. It is a figure for demonstrating the operation start point with respect to a workpiece | work, a direction indication point, and a contact point. It is a figure for demonstrating the operation start point with respect to a workpiece | work, a direction indication point, and a contact point.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Welding robot 14 Welding torch 20 Robot control apparatus 21 Control part 22 Memory part 23 Servo drive part 24 Current position monitoring part 25 Welding control part 26 Contact detection part 27 Operating device 30 Welding power supply device A Operation start point B Direction indication point C Contact Point W Work

Claims (5)

Using a welding robot equipped with a welding torch attached to the tip of the arm and a workpiece position detecting means for detecting the positional relationship of the workpiece placed on the welding worktable with respect to the welding torch, the welding torch is sequentially installed on the welding worktable. A workpiece welding method for performing welding while moving the welding torch along a welding portion of the workpiece for each of a plurality of workpieces to be performed,
A reference work as a reference for the plurality of works is set on the welding work table, and the welding torch is moved along the welding location of the reference work to teach a plurality of movement position data indicating a movement locus during welding. A first step of teaching as point data;
An operation start point for specifying a movement line for moving the welding torch toward the reference workpiece with respect to the reference workpiece installed on the welding work table, and between the operation start point and the reference workpiece. A second step of setting position information of direction indicating points indicating a moving direction of the welding torch for each of a plurality of moving lines;
The welding torch is moved on a plurality of movement lines specified by the operation start point and the direction indicating point set in the second step, and the welding detected on the movement lines by the workpiece position detecting means. When the positional relationship of the reference workpiece with respect to the torch becomes a predetermined positional relationship, a third step of acquiring positional information of the reference workpiece based on the positional relationship at that time,
When each of the plurality of workpieces is installed as a workpiece to be welded on the welding workbench, the welding torch is specified by the operation start point and the direction indication point set in the second step. When the positional relationship of the workpiece to be welded with respect to the welding torch detected by the workpiece position detecting means on each movement line is the predetermined positional relationship, the welding is performed based on the positional relationship at that time. A fourth step of acquiring position information of the target workpiece,
Position information acquired on the same movement line between the plurality of position information of the workpiece to be welded acquired in the fourth step and the plurality of position information of the reference workpiece acquired in the third step. A fifth step of comparing and calculating the difference between the two and correcting the teaching point data taught in the first step based on the difference;
A sixth step of performing welding on the workpiece to be welded while moving the welding torch by the welding robot based on the teaching point data corrected in the fifth step;
A method for welding workpieces using a welding robot characterized by comprising: 2. The welding robot according to claim 1 , wherein the operation start point is a retraction point that is set in advance to retract the welding torch from a movement locus during the welding when a welding operation is not performed . Work welding method. The predetermined positional relationship between the reference workpiece and the workpiece to be welded with respect to the welding torch is a positional relationship in which the welding torch contacts the reference workpiece and the workpiece to be welded.
The workpiece position detecting means, wherein the welding torch is detected that conducts in contact with the surface of the workpiece, a moving position detecting means for detecting the movement position of the welding torch at that time, to claim 1 or 2 A work welding method using the welding robot described above . Wherein the reference workpiece and the predetermined positional relationship of the welded workpiece for welding torch, the distance between the welding torch and the surface of said workpiece is to a predetermined distance,
The workpiece position detecting means, wherein the distance from the welding torch to the surface of the workpiece is detected by the light sensor, a movement position detector for detecting the movement position of the welding torch at that time, according to claim 1 or 2 Machining method for workpieces using a welding robot . 5. The work welding method using a welding robot according to claim 1 , wherein the plurality of movement lines set in the second step are parallel to each other .

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