JP2010099690A - Arc welding robot device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arc welding robot device, wherein initial welding conditions are automatically calculated based on instructed regular welding conditions and a distance in a slope section. <P>SOLUTION: In the arc welding robot device, welding conditions are changed in a slope from a starting condition value to an end condition value, during the movement of a welding torch in a slope section S defined by a starting point Ss and an end point Se prescribed on a welding line Ws. The robot is provided with a setting means for setting the starting point Ss position, the end point Se position, and the end point condition value. A distance-modification rate table is preliminarily stored in which correspondence relation is determined between the distance of the staring point Ss and the end point Se (slope distance D) and a modification rate of welding conditions. The starting point condition value is calculated by multiplying the end point condition value by the modification rate which is obtained by inputting the slope distance D in the distance-modification rate table. The starting point condition value is automatically calculated to thereby reduce the number of instruction process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an arc welding robot apparatus that changes welding conditions into a slope shape.

  2. Description of the Related Art Conventionally, there has been known an arc welding robot apparatus that performs slope control for gradually increasing or decreasing welding conditions between two points taught in advance (between a start point and an end point) at the start or end of welding (for example, Patent Document 1). reference). Slope control refers to control for increasing or decreasing the welding condition in a slope shape from the welding condition value determined at the start point to the welding condition value determined at the end point.

  In Patent Document 1, a start point (welding start position) at which slope control is started and an end point (slope end position) at which slope control is ended are taught on one weld line, and the welding torch moves from the welding start position to the slope end position. An arc welding method is disclosed in which welding conditions (welding current value, welding voltage value and welding speed) are changed to a slope shape based on a predetermined welding start condition value and slope end condition value during movement. Hereinafter, the prior art described in Patent Document 1 will be described.

  FIG. 4 is a configuration diagram of a conventional arc welding robot apparatus 51.

  The manipulator M automatically performs arc welding on the workpiece W, and includes an upper arm 53, a lower arm 54, a wrist portion 55, and a plurality of servo motors (not shown) for rotationally driving them. It is configured.

  The welding torch T is attached to the distal end portion of the upper arm 53 of the manipulator M, and guides the welding wire 57 having a diameter of about 1 mm wound around the wire reel 56 to the weld line taught by the workpiece W. is there. The welding power source WP supplies a welding voltage between the welding torch T and the workpiece W.

  The conduit cable 52 includes a coil liner (not shown) for guiding the welding wire 57 therein, and is connected to the welding torch T. Further, the conduit cable 52 supplies the welding torch T with the electric power from the welding power source WP and the shielding gas from the gas cylinder 58.

  The teach pendant TP is used to set the welding conditions (welding current value, welding voltage value, welding speed) and the like necessary for performing the operation of the manipulator M and arc welding as teaching data. A display unit 41 to be displayed and a keyboard 42 for inputting teaching data are provided. Using this teach pendant TP, the operator creates a work program in which the welding conditions are set together with the operation of the manipulator M.

  The robot controller RC is for causing the manipulator M to control the welding operation, and includes a main control unit, an operation control unit, a servo driver (all not shown), and the like. Then, based on the work program taught by the operator using the teach pendant TP, an operation control signal is output from the servo driver to each servo motor of the manipulator M, and the plurality of axes of the manipulator M are rotated. Since the robot controller RC recognizes the current position based on an output from an encoder (not shown) provided in the servo motor of the manipulator M, the robot controller RC can control the tip position of the welding torch T.

  Next, teaching data and operation when slope control is performed will be described.

  FIG. 5 is a diagram for explaining a state in which the welding condition is slope-controlled based on the teaching data. FIG. 5A shows an example in which a start point Ss and an end point Se for performing slope control after starting welding are taught. In FIG. 2A, a welding line Ws of a workpiece W is a work line formed by a welding start position As and a welding end position Ae. A starting point Ss for starting slope control and an end point Se for ending slope control are taught on the weld line Ws. The starting point Ss is the same position as the welding start position As. Hereinafter, a section from the start point Ss to the end point Se is referred to as a slope section, and a section from the end point Se that is the slope end position to the welding end position Ae is referred to as a steady welding section.

  FIG. 5B shows the welding condition Wc taught at the welding start position As. The welding condition Wc is a condition for welding the welding line Ws. As shown in FIG. 5B, a parameter (slope function) for determining whether or not to perform slope control is set to be effective, and as a welding start condition value at the start point Ss, for example, an initial welding current value 150 A, an initial welding voltage value of 17 V, and an initial welding speed of 55 cm / min are taught. Further, as the slope end condition value at the end point Se (that is, the welding condition value in the steady welding section after the slope section ends), the steady welding current value 240A, the steady welding voltage value 19V, and the steady welding speed 60 cm / min are taught. Yes.

  And (c) shows the change of the welding current value in the slope section, (d) shows the change of the welding voltage value in the slope section, (e) shows the change of the welding speed, respectively. Yes. In other words, the welding current value, the welding voltage value, and the welding speed are gradually increased by performing slope control in the slope section based on the teaching data shown in FIGS. Slope control of the welding current value, the welding voltage value, and the welding speed is performed as follows.

  The calculation of the welding current value and the welding voltage value in the slope section is obtained by a predetermined function using the movement distance from the starting point Ss as a variable. Specifically, while the welding torch T moves between the start point Ss and the end point Se, the difference obtained by subtracting the start point condition value at the start point Ss from the end point condition value at the end point Se to the start point condition value at the start point Ss is referred to as the start point. The robot controller RC performs an operation of adding and adding an integral multiple of the value obtained by dividing the movement command between the end points by the interpolation number for each interpolation cycle of the integral multiple, and outputting the welding power source WP for each interpolation cycle. The current value and welding voltage value are changed to a slope.

  Moreover, the calculation of the welding speed in a slope area is performed as follows. While the welding speed at the start point Ss is an initial value of the current speed, while the welding torch T moves between the start point Ss and the end point Se, (1) each distance of the robot from the current position to the end point Se and the current speed for each interpolation cycle The movement command amount to be output to the axis is obtained, the total number of interpolations is obtained, the movement command amount to each axis is outputted for each interpolation cycle, the robot is driven, and (2) the end point Se is welded every set number of interpolations A value obtained by multiplying the difference obtained by subtracting the current speed from the speed by the total number of interpolations and the set number of interpolations is added to the current speed, and the current speed is updated. (3) (1), By repeatedly executing the step (2), the stepwise welding speed at the end point Se is calculated from the welding speed at the start point Ss by the robot controller RC, and the calculation result is output to the servo motor of the manipulator M at every interpolation period. , Melt It has changed the speed on a slope shape.

Japanese Patent Laid-Open No. 10-6005

  As described above, in the prior art, it is necessary to set the welding conditions at both the start point (welding start position) and the end point (slope end position). Specifically, three conditions of initial welding current value, initial welding voltage value and initial welding speed as initial welding conditions at the welding start position, and steady welding current value and steady state as slope end conditions (steady welding conditions) at the slope end position. It was necessary to teach the three conditions of the welding voltage value and the steady welding speed, and there was a problem that the teaching man-hours increased.

  Therefore, the present invention provides an arc welding robot apparatus capable of reducing the teaching man-hour by automatically calculating the initial welding condition based on the taught steady welding condition and the distance of the slope section. Objective.

In order to achieve the above object, the first invention provides:
While the welding torch moves in a section connecting a predetermined welding start position and slope end position on the weld line, at least one of the welding current value, welding voltage value, or welding speed, which is a welding condition, is determined from the welding start condition value. In the arc welding robot device that changes to the slope shape up to the slope end condition value,
Setting means for setting the welding start position, the slope end position, and the slope end condition value;
Storage means for storing a separation distance-change rate table in which a correspondence relationship between a separation distance between the welding start position and the slope end position and a change rate of the welding condition is predetermined;
Calculating means for calculating the welding start condition value by multiplying the slope end condition value by a change rate obtained by inputting a separation distance between the welding start position and the slope end position into the separation distance-change rate table;
An arc welding robot apparatus comprising:

  2nd invention is provided with the determination correction means which corrects the said welding speed to an appropriate value while determining whether the welding speed in the said area exceeds the predetermined threshold value, The said welding speed exceeds the said threshold value When it is determined that the welding speed is used, the welding speed is used as it is, and when it is determined that the welding speed does not exceed the threshold value, the welding speed is set to the same value as the threshold value. The arc welding robot apparatus according to the above.

  A third aspect of the invention is the arc welding robot apparatus according to the first or second aspect of the invention, further comprising a correcting unit for correcting the separation distance-change rate table.

  According to a fourth aspect of the present invention, any one of the first to third aspects is characterized in that the slope end position is a position on the weld line calculated by designating a separation distance from the welding start position in the welding progress direction. This is an arc welding robot apparatus according to the first aspect of the invention.

  According to a fifth aspect of the present invention, in the arc welding according to the fourth aspect, the slope end position is a position calculated by designating a moving time of the welding torch instead of the separation distance. It is a robot device.

  According to the first aspect of the present invention, there is provided the separation distance-change rate table in which the correspondence relationship between the separation distance between the welding start position and the slope end position and the change rate of the welding conditions is provided, and the separation between the welding start position and the slope end position. The welding condition at the welding start position is automatically calculated based on the distance and the slope end condition value (that is, the steady welding condition value) that is the welding condition at the slope end position. That is, since the setting operation of the welding conditions at the welding start position is not required, the teaching man-hour can be reduced. In addition, the above-mentioned separation distance-change rate table has an optimal change rate according to the welding environment such as the type of workpiece, the type of welding wire, the type of shield gas, and the separation distance of the welding start position and the slope end position in advance. This is predetermined by the experiment. Thereby, the optimum welding condition at the welding start position can also be calculated.

  According to the second invention, it is determined whether or not the welding speed in the slope section exceeds a predetermined threshold value. If it is determined that the welding speed exceeds the threshold value, the welding speed is used as it is. When it is determined that the speed does not exceed the threshold, the welding speed is set to the same value (increased) as the threshold. If the welding speed in the slope section is relatively low, the amount of heat input to the workpiece may increase, so that burnout may occur in the slope section. The effect of the first invention is achieved by the second invention. In addition, it is possible to prevent the burn-through from occurring.

  According to the third aspect of the present invention, since the correction means for correcting the separation distance-change rate table is provided, the separation according to the welding construction environment of the user in addition to the effects exhibited by the first or second invention. A distance-change rate table can be provided.

  According to the fourth aspect of the invention, the slope end point position is set based on the distance from the welding start position, so that it is not necessary to manually move the robot when setting the slope end point position. That is, in addition to the effect produced by any one of the first to third inventions, the teaching man-hour can be further reduced.

  According to the fifth invention, in addition to the effect of the fourth invention, the slope end point position can be specified by the moving time of the welding torch instead of the distance from the welding start position. A flexible teaching method according to user needs can be provided.

[Embodiment 1]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on examples with reference to the drawings.

  FIG. 1 is a block diagram of an arc welding robot apparatus 1 showing an embodiment of the present invention. In the figure, the difference from FIG. 4 shown as the prior art is the teach pendant TP and the robot control device RC. Hereinafter, the teach pendant TP and the robot controller RC will be described. Others are the same as those shown in FIG.

  The teach pendant TP is used for inputting the operation data of the manipulator M, teaching data Td necessary for performing arc welding, welding conditions Wc (welding current value, welding voltage value, welding speed), etc., and storing them in the hard disk 4. Is. In this embodiment, the hard disk 4 is modified by correcting setting means for setting a slope start position, a slope end position, and a slope end condition value (steady welding condition) for performing slope control, and a later-described separation distance-change rate table Tb. This corresponds to the correction means stored in.

  Each part of the robot controller RC will be described. The CPU 6 is a central processing unit, and the RAM 5 is a temporary calculation area. The hard disk 4 is a non-volatile memory for storing teaching data Td, which is position data of the manipulator M, welding conditions Wc for determining an output value for the welding power source WP when performing arc welding processing, and the like. In addition to the teaching data Td and the welding condition Wc, the hard disk 4 stores a separation distance-change rate table Tb that defines a correspondence relationship between the welding start position and the slope end position separation distance and the welding condition change rate. In this embodiment, it corresponds to a storage means. The separation distance-change rate table Tb will be described later.

  The main control unit 3 is a control center of the robot controller RC, and includes a teaching processing unit 20, a display processing unit 21, an interpretation executing unit 22, a start condition value calculating unit 25, and a table correcting unit 26. The teaching processing unit 20 stores the teaching data Td, the welding conditions Wc, and the like input from the teach pendant TP in the hard disk 4. The display processing unit 21 displays the teaching data Td, various messages, and the like on the teach pendant TP as necessary. The interpretation execution unit 22 interprets the teaching data Td and outputs various control signals to the welding condition control unit 13 and the operation control unit 11.

  The start condition value calculation unit 25 serving as a calculation means uses the change rate obtained by inputting the separation distance between the welding start position and the slope end position in the above-described separation distance-change rate table Tb, and the welding condition value at the slope end position. By multiplying the slope end condition value, a welding start condition value that is a welding condition value at the welding start position is calculated. The table correction unit 26 corrects the separation distance-change rate table Tb and stores it in the hard disk 4 in response to an instruction input from the teach pendant TP as correction means.

  The welding condition control unit 13 drives the welding power source WP by outputting a welding current control signal and a welding voltage control signal to the welding power source WP at a predetermined cycle.

  The operation control unit 11 outputs a position command signal for moving the manipulator M based on the teaching data Td to the drive command unit 12. The drive command unit 12 outputs a servo control signal for controlling the rotation of each servo motor of the manipulator M based on the position command signal, drives each axis of the manipulator M, and moves the control point of the welding torch T.

  Next, teaching data and welding conditions when performing slope control will be described.

  FIG. 2 is a diagram for explaining a state in which slope control is performed based on teaching data and welding conditions.

  The figure (a) shows a mode that the start point Ss and the end point Se which show the section which performs slope control are set up, and the figure (b) shows welding conditions Wc1 set up at welding start position As. Yes. Moreover, the figure (c)-(e) has shown the mode when slope control is performed in the slope area S based on the teaching data and welding conditions shown to the figure (a) and (b), FIG. 4C shows a change in welding current value, FIG. 4D shows a change in welding voltage value, and FIG. 5E shows a change in welding speed.

  In FIG. 2A, a welding line Ws of a workpiece W is a work line formed by a welding start position As and a welding end position Ae. The start point Ss is a position where slope control is started, and is the same position as the welding start position As. The end point Se is a slope end position where the slope control is ended.

  In FIG. 4B, a welding condition Wc1 is a condition for welding the welding line Ws. As shown in FIG. 5B, a parameter (slope control) for determining whether or not to perform slope control is set to be effective. Further, a parameter (slope distance D) for determining the position of the end point Se is set to 25 mm. In this case, the end point Se is automatically determined at a position on the weld line Ws separated from the welding start position As (start point Ss) by 25 mm in the welding progress direction. The end point Se is set as a distance from the welding start position As. Instead, the moving time of the welding torch T is set, and the position calculated based on this moving time is set as the end point. Se may also be used.

  Further, as the slope end condition value at the end point Se (that is, the welding condition in the steady welding section after the end of the slope section), the steady welding current value 240A, the steady welding voltage value 19.0V, and the steady welding speed 60 cm / min are set. ing. As welding start condition values at the starting point Ss, an initial welding current value 150A, an initial welding voltage value 17V, and an initial welding speed of 45 cm / min are automatically calculated by a method described later.

  Hereinafter, a method for calculating the welding start condition value at the start point Ss will be described.

  FIG. 3 is a diagram illustrating an example of the separation distance-change rate table Tb. As shown in the figure, in the separation distance-change rate table Tb, a correspondence relationship between the separation distance between the welding start position and the slope end position (corresponding to the slope distance D) and the change rate of the welding condition value is determined in advance. ing.

  The start condition value calculation unit 25 inputs the set slope distance D to the separation distance-change rate table Tb, and the change rate obtained as a result is a slope end condition that is a welding condition value at the end point Se (slope end position). By multiplying the value, a welding start condition value that is a welding condition value at the welding start position As is calculated. Specifically, for example, when the welding condition Wc1 shown in FIG. 2B is taught, since the slope distance D is 25 mm, the change rate of the welding current value is 70 from the separation distance-change rate table Tb. %, 75% as the change rate of the welding voltage value, and 75% as the change rate of the welding speed. These change rates are multiplied by the slope end condition values. As a result, an initial welding current value of 150 A, an initial welding voltage value of 17 V, and an initial welding speed of 45 cm / min are calculated.

  By the way, the separation distance-change rate table Tb is a table in which several points are stored for the separation distance and the change rate of the welding conditions. Since these are internally developed as approximate curves, for example, the slope distance D is 22 Even if an intermediate value such as 0.5 mm is input, the change rate can be obtained based on the approximate curve.

  It should be noted that the welding start condition value at the welding start position As depends on the welding environment such as the type of the workpiece W, the type of the welding wire, the type of the shielding gas, and the like, and is also optimal depending on the separation distance. The value changes. For this reason, the optimum correspondence relationship is determined in advance by a prior experiment for the separation distance in the separation distance-change rate table Tb and the change rate of the welding condition value corresponding thereto.

  As described above, a separation distance-change rate table in which the correspondence between the separation distance between the welding start position and the slope end position and the change rate of the welding conditions is provided in advance, the separation distance between the welding start position and the slope end position, The welding condition at the welding start position is automatically calculated based on the slope end condition value (that is, the steady welding condition value) that is the welding condition at the slope end position. That is, since the setting operation of the welding conditions at the welding start position is not required, the teaching man-hour can be reduced. The separation distance-change rate table has an optimum change rate according to the welding construction environment such as the type of workpiece, the type of welding wire, the type of shield gas, and the separation distance of the welding start position and the slope end position. It is predetermined by a prior experiment. Thereby, the optimum welding condition at the welding start position can also be calculated.

  Further, it is desirable that the separation distance-change rate table Tb can be corrected from the teach pendant TP. That is, by providing the correction means for correcting the separation distance-change rate table Tb, in addition to the above effects, a separation distance-change rate table according to the user's welding construction environment can be provided.

  In addition, since the slope end point position is set according to the separation distance from the welding start position, it is not necessary to move the robot by manual operation when setting the slope end point position. That is, in addition to the effects described above, the teaching man-hour can be reduced.

  In addition to specifying the end point of the slope section by the moving time of the welding torch instead of specifying the separation distance from the welding start position, in addition to the above effects, a flexible teaching method according to user needs Can be provided.

  By the way, if slope control is performed even though the steady welding speed is set to a relatively low state, welding is performed at a welding speed lower than the steady welding speed, so that the amount of heat input to the workpiece increases and melting occurs. Drops may occur.

  In order to prevent this burn-through, the operation control unit 11 determines whether or not the welding speed in the slope section S exceeds a predetermined threshold (for example, 20 cm / min), and sets the welding speed to an appropriate value. You may make it correct. That is, when it is determined that the welding speed calculated for each interpolation period during the slope control exceeds the threshold value, the manipulator M is driven and controlled at the calculated welding speed. Conversely, when it is determined that the calculated welding speed does not exceed the threshold value, the welding speed is corrected to the same value as the threshold value, and the manipulator M is driven and controlled. Specifically, when the calculated welding speed is 30 cm / min, the threshold value (20 cm / min) is exceeded, so it is determined that no burnout occurs and the manipulator M is driven and controlled at 30 cm / min. The drive control signal is output to the drive command unit 12. When the calculated welding speed is 15 cm / min, it is determined that there is a possibility that burnout may occur because the threshold (20 cm / min) is not exceeded, and the threshold is 20 cm / min instead of 15 cm / min. A drive control signal for driving and controlling the manipulator M is output to the drive command unit 12. As a result, it is possible to prevent melt-down.

1 is a block diagram of an arc welding robot apparatus showing an embodiment of the present invention. It is a figure for demonstrating a mode that slope control is based on teaching data and welding conditions. It is a figure which shows an example of a separation distance-change rate table. It is a block diagram of the conventional arc welding robot apparatus. It is a figure for demonstrating the conventional slope control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Arc welding robot apparatus 3 Main control part 4 Hard disk 11 Operation control part 12 Drive command part 13 Welding condition control part 20 Teaching process part 21 Display process part 22 Interpretation execution part 25 Start condition value calculation part 26 Table correction part 41 Display part 42 Keyboard 51 Arc welding robot device 52 Conduit cable 53 Upper arm 54 Lower arm 55 Wrist 56 Wire reel 57 Welding wire 58 Gas cylinder Ae Welding end position As Welding start position M Manipulator RC Robot controller Se End point (slope end position)
Ss start point (welding start position)
T welding torch Tb separation distance-change rate table Td teaching data TP teach pendant W work Wc welding condition Wc1 welding condition WP welding power source

Claims (5)

While the welding torch moves in a section connecting a predetermined welding start position and slope end position on the weld line, at least one of the welding current value, welding voltage value, or welding speed, which is a welding condition, is determined from the welding start condition value. In the arc welding robot device that changes to the slope shape up to the slope end condition value,
Setting means for setting the welding start position, the slope end position, and the slope end condition value;
Storage means for storing a separation distance-change rate table in which a correspondence relationship between a separation distance between the welding start position and the slope end position and a change rate of the welding condition is predetermined;
Calculating means for calculating the welding start condition value by multiplying the slope end condition value by a change rate obtained by inputting a separation distance between the welding start position and the slope end position into the separation distance-change rate table;
An arc welding robot apparatus comprising:   When determining whether or not the welding speed in the section exceeds a predetermined threshold, and including determination correction means for correcting the welding speed to an appropriate value, and determining that the welding speed exceeds the threshold The arc welding robot apparatus according to claim 1, wherein the welding speed is used as it is, and when it is determined that the welding speed does not exceed the threshold value, the welding speed is set to the same value as the threshold value.   The arc welding robot apparatus according to claim 1, further comprising a correcting means for correcting the separation distance-change rate table.   The said slope end position is a position on the said welding line calculated by designating the separation distance from the said welding start position to a welding advancing direction, The any one of Claims 1-3 characterized by the above-mentioned. Arc welding robot device.   The arc welding robot apparatus according to claim 4, wherein the slope end position is a position calculated by designating a moving time of the welding torch instead of the separation distance.

Images