JP2009034685A - Automatic welding method and automatic welding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the labor required for preparing a teaching program for measurement. <P>SOLUTION: A teaching program Pr2 for measurement allows the operation associated with a weaving action for measuring a groove sectional shape of a welding workpiece to be executed by a welding robot 2, and prepared based on a teaching program Pr1 for welding. A groove sectional shape generation unit 11 executes the measurement of the groove sectional shape by a laser displacement meter 17 by the reproduction of the teaching program Pr2 for measurement. A gap width calculation unit 12 calculates the gap widths D<SB>k</SB>at a plurality of parts from the groove sectional shape. A welding condition selection unit 13 selects the optimum welding condition based on the gap widths D<SB>k</SB>. A robot controller 4 changes the welding condition including the target position of a welding torch regulated by the teaching program for welding based on the optimum welding condition, and allows the welding action to be executed by the welding robot 2 based on the welding condition after the change. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an automatic welding method and apparatus for measuring a groove cross-sectional shape of a welding workpiece and performing welding by changing welding conditions based on the measurement result.

  There is known an automatic welding method and apparatus for measuring a groove cross-sectional shape of a welding workpiece and performing welding by changing welding conditions based on the measurement result (see, for example, Patent Document 1). This type of automatic welding method is generally as follows. First, a distance meter such as a laser displacement meter is attached near the welding torch at the tip of the welding robot. In the measurement of the groove cross-sectional shape, the cross-sectional shape is acquired by scanning the distance meter in the direction orthogonal to the weld line by the welding robot before the main welding. Next, the gap width of the groove is calculated from the measured groove cross-sectional shape. Subsequently, based on the calculated gap width, the welding torch target position, weaving operation parameters (eg, sine wave, triangular wave operation method, amplitude, frequency, etc.), welding current, welding voltage and other welding conditions are changed and optimized. Turn into. Thereafter, the welding robot performs welding based on the optimized welding conditions.

  What is a teaching program (measurement teaching program) for causing a welding robot to execute an operation for measuring a groove cross-sectional shape? What is a teaching program (welding teaching program) for causing a welding robot to perform an actual welding operation? Created separately.

  In order to calculate the gap width at one location from the measurement result of the groove cross-sectional shape, at least two teaching points, that is, a measurement teaching one point on the left side (point A) and one point on the right side (point B) It is necessary to register a teaching program, measure the distance from point A to point B by reproducing the measuring teaching program and operating the welding robot. When the gap width changes in one weld line, it is necessary to calculate the gap widths at a plurality of locations in order to finely change the welding conditions based on the gap width. However, if the weld line is long, the gap width at more points must be measured, and the teaching points increase. The increase in teaching points increases the labor required when an operator who operates the automatic welding apparatus creates a teaching program for measurement. In particular, an increase in teaching points only for gap width calculation that is not directly related to actual welding is painful for an operator who creates a teaching program.

JP 2001-334366 A

  An object of the present invention is to reduce the labor required for creating a teaching program for measurement for measuring a groove cross-sectional shape used for gap width calculation in an automatic welding method and apparatus.

  A first aspect of the present invention is an automatic welding method for welding a workpiece by operating an automatic welder by reproducing a welding teaching program, wherein the distance is measured near a welding torch at the tip of the automatic welder. Based on the welding teaching program, a measuring teaching program for causing the automatic welding machine to perform an operation accompanied by a weaving operation for measuring a groove cross-sectional shape of the welding workpiece is arranged, The automatic welding machine is operated by replaying the measurement teaching program, the groove cross-sectional shape is measured by the distance meter, a groove gap width is calculated from the measured groove cross-sectional shape, and the calculated The optimum welding conditions are selected based on the gap width, and the welding torch defined by at least the welding teaching program is selected based on the selected optimum welding conditions. Change the welding conditions including the target position, and executes the welding by operating the automatic welding machine on the basis of the welding condition of the changed provides an automated welding process.

  According to a second aspect of the present invention, an automatic welding machine in which a distance meter for measuring a distance is arranged in the vicinity of the welding torch at the tip, a welding teaching program are stored, the welding teaching program is reproduced, and the automatic welding is performed. A welding control unit for operating a machine to perform welding of the welding workpiece, and an operation accompanied by a weaving operation for measuring the groove cross-sectional shape of the welding workpiece created based on the welding teaching program. A groove cross-section shape generating unit that stores a measurement teaching program to be executed by a welding machine, and operates the automatic welding machine by reproducing the measurement teaching program to measure a groove cross-section shape by the distance meter A gap width calculation unit that calculates gap widths at a plurality of locations from the groove cross-sectional shape obtained by the groove cross-sectional shape generation unit, and a gap calculated by the gap width calculation unit. A welding condition selection unit that selects an optimum welding condition based on a welding width, and the welding control unit is defined by at least the welding teaching program based on the optimum welding condition selected by the welding condition selection unit. An automatic welding apparatus is provided that changes a welding condition including a target position of the welded torch and causes an automatic welding machine to perform a welding operation based on the changed welding condition.

  The welding teaching program preferably prescribes a welding operation accompanied by a weaving operation.

  According to the present invention, a measurement teaching program for measuring the groove cross-sectional shape used for gap width calculation is created based on the welding teaching program. Therefore, it is possible to easily create a measurement teaching program for calculating gap widths at a large number of locations, and the labor of an operator required for creating the measurement teaching program can be greatly reduced. In particular, when the welding teaching program defines a welding operation accompanied by a weaving operation, the measurement teaching program can be easily created by effectively utilizing the welding teaching program.

  Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  An automatic welding apparatus 1 according to an embodiment of the present invention shown in FIG. 1 operates a 6-axis vertical articulated welding robot (automatic welding machine) 2 to weld welding workpieces 3A and 3B. In addition, a robot controller (welding control unit) 4 and a signal processing device 5 are provided. The signal processing device 5 includes a groove cross-section shape generation unit 11, a gap width calculation unit 12, and a welding condition selection unit 13. Further, the automatic welding apparatus 1 includes an input device 14 for an operator to access the robot controller 4 and the signal processing device 5 to input a command for creating a program and the like, and the robot controller 4 and the signal processing device. 5 is provided with a display device 15 for displaying the information in 5 to the operator.

  A welding torch 16 is attached to the tip of the welding robot 2, and a sensor head 18 of a laser displacement meter (distance meter) 17 is attached in the vicinity of the welding torch 16. The sensor head 18 includes a light emitting element that projects laser spot light onto the surfaces of the welding workpieces 3A and 3B, and a light receiving element such as a CCD that receives irregularly reflected light from the surfaces of the welding workpieces 3A and 3B. The sensor amplifier unit 19 of the laser displacement meter 17 detects the laser peak position (maximum value) on the light receiving element, and calculates the distance from the sensor head 18 (the sensor irradiation position is set to 0 by calculation based on the triangulation method). 18) is calculated. Further, the sensor amplifier unit 19 outputs a power value having a positive correlation with the calculated distance to the groove cross-sectional shape generation unit 11 of the signal processing device 5 as distance information.

  The robot controller 4 stores a welding teaching program Pr1 for operating the welding robot 2 to execute welding of the welding workpieces 3A and 3B. The welding teaching program Pr1 defines at least the target position (teaching point) of the welding torch 16 when executing the welding operation. The welding torch 16 moves on a desired weld line by sequentially moving the target position. When the welding operation is accompanied by a weaving operation, the welding teaching program Pr1 defines a weaving operation parameter. The robot controller 4 also stores other welding conditions that are not defined by the welding teaching program Pr1, such as welding current and welding voltage.

  Referring to FIG. 2, the weaving operation is an operation of vibrating the welding torch 16 to the left and right with respect to the welding line in order to obtain a wide bead overlay when welding the groove portions of the welding workpieces 3A and 3B. It is. In FIG. 2, the advancing direction of the tip of the welding robot 2 (welding torch 16) is set to the X axis, the amplitude direction is set to the Y axis, and the direction perpendicular to the welding workpieces 3A and 3B is set to the Z axis (described later). The coordinate axes are similarly set for 3 and FIG. Usually, the weaving operation vibrates the welding torch 16 with a sine wave having a frequency of about 1 to 8 Hz and an amplitude of several mm. Normally, as the creation of the welding teaching program Pr1, that is, the teaching of the welding operation for the welding robot 2, the welding start position and the welding end position are stored in the robot controller 4. Then, when executing a wobbling operation, an operating method such as a sine wave and a triangular wave, an amplitude, a frequency, and the like are set as a wobbling operation parameter and stored in the robot controller 4.

  The groove cross-sectional shape generation unit 11 stores a measurement teaching program Pr2. The measurement teaching program Pr2 is for causing the welding robot 2 to perform an operation accompanied by a weaving operation for measuring the groove cross-sectional shape of the welding workpieces 3A and 3B. The groove cross-sectional shape generation unit 11 reproduces the measurement teaching program Pr2 and operates the welding robot 2 via the robot controller 4 to measure the groove cross-sectional shape by the laser displacement meter 17.

The gap width calculation unit 12 calculates a plurality of gap widths D _k (see FIGS. 3 and 4) from the groove cross-sectional shape obtained by the groove cross-sectional shape generation unit 11. The welding condition selection unit 13 selects the optimum welding condition based on the gap width _Dk calculated by the gap width calculation unit 12. Further, the robot controller 4 changes the welding conditions including at least the target position of the welding torch 16 defined by the welding teaching program Pr1 based on the optimum welding conditions selected by the welding condition selection unit 13, and after the change Based on the welding conditions, the welding robot 2 is caused to execute a welding operation.

A method of creating the measurement teaching program Pr2 for measuring the groove cross-sectional shape used for the calculation of the gap width _Dk will be described. First, when the welding teaching program Pr1 defines a welding operation involving a weaving operation, the teaching points on the weld line defined by the welding teaching program Pr1 are used as they are in the measurement teaching program Pr2, and the weaving is performed. The amplitude of the operating parameters is set sufficiently larger than the maximum value of the assumed gap width _Dk . By setting in this way, the data of the groove cross-sectional shape from the welding start point to the welding end point can be obtained reliably, and the gap width can be calculated at many points from the welding start point to the welding end point. is there. On the other hand, if the welding teaching program Pr1 does not define a welding operation that involves a weaving operation, the teaching points on the weld line defined by the welding teaching program Pr1 are used as they are in the measurement teaching program Pr2, and Wibbing operation parameters (for example, operation methods such as sine wave and triangular wave, amplitude frequency, etc.) are set. The measurement teaching program Pr2 created as described above is stored in the groove cross-sectional shape generation unit 11.

  The welding teaching program Pr1 shown in FIG. 5 performs welding from “position 1” to “position 2” while performing a weaving operation. To correct this welding teaching program Pr1 and create a measurement program Pr2, delete "welding current" and "welding voltage", change "welding start" to "measurement start", and "weld end" "Is just changed to" end of measurement ". The welding teaching program Pr1 shown in FIG. 6 is used for welding from “position 1” to “position 2” without performing a weaving operation. In order to modify the welding teaching program Pr1 and create the measurement program Pr2, “welding current” and “welding voltage” are deleted, “welding start” is changed to “measurement start”, and “wibbing operation” is performed. Is simply changed from “None” to “Yes” and the wobbling condition (amplitude: 5 mm, shape: sine wave) is set.

Thus, the measurement teaching program Pr2 is not based on a separate program created independently of the welding teaching program Pr1, but based on the welding teaching program Pr1. Therefore, the measurement teaching program Pr2 for calculating the gap widths _Dk at many locations can be easily created, and the labor of the operator required for creating the measurement teaching program Pr2 can be greatly reduced. In particular, when the welding teaching program Pr1 prescribes a welding operation accompanied by a weaving operation, the measurement teaching program Pr2 can be easily created by effectively utilizing the welding teaching program.

  Hereinafter, the groove cross-sectional shape generation unit 11, the gap width calculation unit 12, and the welding condition selection unit 13 will be further described.

  When the groove sectional shape generation unit 11 reproduces the measurement teaching program Pr2 and drives the welding robot 2, distance information (voltage value) is sometimes transmitted from the sensor amplifier unit 19 of the laser displacement meter 17 to the groove sectional shape generation unit 11. Input every moment. The groove cross-sectional shape generation unit 11 calculates the distance from the sensor head 18 to the groove surface that is the object by performing AD conversion and numerical conversion on the power value input from the sensor head 18. Further, the tip position information (x, y, z) of the welding robot 2 is input from the robot controller 4 to the groove section shape generation unit 11 every moment. The groove cross-sectional shape generation unit 11 creates a distance data group (three-dimensional point sequence) representing the groove cross-sectional shape from the distance from the sensor head 18 to the groove surface and the tip position information of the welding robot 2.

A distance data group created by the groove cross-section shape generation unit is input to the gap width calculation unit 12. The gap width calculation unit 12 analyzes the input distance data group and calculates the gap width _Dk . As shown in FIG. 3, the calculation of the gap width D _k will be described by taking as an example a case where a butt joint is used and the weaving operation at the time of groove cross-sectional shape measurement is a sine wave. The distance data representing the butt joint shape is an XY point sequence. Since the Z-axis value changes abruptly before and after the gap end point, by evaluating the lack of a continuous point sequence, two end points L _k (x _k , y _k ), R _k (x _k , y _k ) ( k = 1, 2,..., n) can be calculated. If the distance between L _k and R _k is D ′ _k , the gap width D _k needs to be corrected. As an example of the correction method, an approximation method will be described below. Now, when the sine wave of the weaving operation is the weaving frequency f and the vibration width A and the tip of the welding robot 2 is moving at the operation speed v, the deviation angle θ between the distance D ′ _k and the actual gap width D _k is It is represented by the following formula (1).

Further, the actual gap width _Dk can be calculated by the following equation (2).

As described above, a plurality of gap widths D (D ₁ , D ₂ ,..., D _k ,... D _n ) are obtained for one weld line.

As shown in FIG. 4, when the wobbling operation is a triangle instead of a sine wave, the shift angle θ can be calculated accurately, so that the gap width _Dk can be calculated with higher accuracy.

A plurality of gap widths D (D ₁ , D ₂ ,..., D _k ,... D _n ) are input to the welding condition selection unit 13 from the gap width calculation unit 12 for one welding. The welding condition selection unit 13 calculates an average gap value D _mean for each fixed section of the weld line from the input gap width D (D ₁ , D ₂ ,..., D _k ,... D _n ). The welding condition selection unit 13 stores in advance optimum welding conditions for the average gap value D _{mean in} the form of a table, for example, and selects the optimum welding conditions for the calculated average gap value D _mean . As described above, the selected optimum welding condition is output to the robot controller 4 and used for changing the welding condition.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, a storage unit for storing the welding teaching program Pr1 and the measurement teaching program Pr2 is provided in the signal processing device 5, and the robot controller 4 and the groove cross-sectional shape generating unit 11 store the teaching program as needed from the storage unit. A reading configuration may be adopted. Further, in FIG. 1, for easy understanding, the groove sectional shape generation unit 11, the gap width calculation unit 12, and the welding condition selection unit 13 are illustrated as separate units, but two or more of these are illustrated. A configuration in which one unit executes the above functions may be adopted.

The block diagram which shows the automatic welding apparatus concerning embodiment of this invention. The schematic diagram for demonstrating welding accompanied by a whibbing operation | movement. The schematic diagram which shows measurement of groove cross-sectional shape (when a wobbling operation is a sine wave). The schematic diagram which shows measurement of groove cross-sectional shape (when a wobbling operation | movement is a triangular wave). The schematic diagram which shows an example of preparation of the teaching program for a measurement. The schematic diagram which shows another example of preparation of the teaching program for a measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic welding apparatus 2 Welding robot 3A, 3B Welding workpiece 4 Robot controller 5 Signal processing apparatus 11 Groove cross-section shape generation part 12 Gap width calculation part 13 Welding condition selection part 14 Input device 15 Display apparatus 16 Welding torch 17 Laser displacement meter 18 Sensor head 19 Sensor amplifier unit Pr1 Welding teaching program Pr2 Measurement teaching program

Claims (4)

An automatic welding method for welding a workpiece by operating an automatic welding machine by replaying a welding teaching program,
Place a distance meter to measure the distance near the welding torch at the tip of the automatic welder,
Creating a measurement teaching program for causing the automatic welding machine to execute an operation accompanied by a weaving operation for measuring a groove cross-sectional shape of the welding workpiece based on the welding teaching program;
Measure the groove cross-sectional shape with the distance meter by operating the automatic welder by playing the measurement teaching program,
Calculate the gap width of the groove from the measured groove cross-sectional shape,
Select the optimum welding conditions based on the calculated gap width,
Based on the selected optimum welding condition, at least a welding condition including a target position of the welding torch specified by the welding teaching program is changed,
Welding is performed by operating the automatic welder based on the welding conditions after the change,
Automatic welding method.   The automatic welding method according to claim 1, wherein the welding teaching program defines a welding operation accompanied by a weaving operation. An automatic welding machine in which a distance meter for measuring the distance is disposed near the tip of the welding torch;
A welding control unit that stores a teaching program for welding, reproduces the teaching program for welding, operates the automatic welding machine, and executes welding of the welding workpiece;
A measurement teaching program for causing the automatic welding machine to execute an operation accompanied by a weaving operation for measuring the groove cross-sectional shape of the welding workpiece, created based on the welding teaching program, is stored. A groove cross-sectional shape generating unit that operates the automatic welding machine by playing back the teaching program for executing the measurement of the groove cross-sectional shape by the distance meter;
A gap width calculation unit for calculating a gap width at a plurality of locations from the groove cross-sectional shape obtained by the groove cross-sectional shape generation unit;
A welding condition selection unit that selects an optimum welding condition based on the gap width calculated by the gap width calculation unit,
The welding control unit changes a welding condition including at least a target position of the welding torch specified by the welding teaching program based on the optimum welding condition selected by the welding condition selection unit, and An automatic welding device that causes an automatic welder to perform a welding operation based on welding conditions.   The automatic welding apparatus according to claim 3, wherein the welding teaching program defines a welding operation accompanied by a weaving operation.

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