JPH038582A - Welding robot and its use - Google Patents

Abstract

PURPOSE:To send information with high precision to a control part by supporting a main shaft provided with a welding torch on its tip freely rotatably from a traveling carriage and fitting a laser beam sensor to form an optical axis to cross an axis of the main shaft to a shaft supporting part. CONSTITUTION:The self-traveling carriage 2 is provided to the welding robot. The main shaft 4 provided with the welding torch 3 on its tip is then supported freely rotatably from the traveling carriage 2. The laser beam sensor 6 to form the optical axis to cross the axis of the main shaft 4 is fitted to the shaft supporting part 5. The laser beam sensor 6 outputs the voltage in accordance with the distance where spot light is thrown. By this method, the distance from the reference position of a robot main body to a welding groove can be detected by subjecting this to A/D conversion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a robot used for welding a steel structure workpiece and a method of using the robot.

[Prior Art] Welding robots have been put into practical use that attach a welding torch to a self-propelled traveling cart and drive the position three-dimensionally to automatically continue welding.

In conventional self-propelled welding robots, a teaching method such as the so-called PTP (point-to-point) method is often used to determine the welding trajectory (welding line).However, in actual work, the FTP method etc. This method is complicated because it requires teaching one point at a time before the welding line is finalized.
Many welding robots equipped with groove measurement sensors have been proposed.

There are two types of surface light measurement sensors: contact type and non-contact type. Among these, electric contact type sensors are the contact type.

Although it is called a welding wire contact sensor, it has drawbacks such as being applicable only to joints with a curvature larger than a -window and not being able to detect the entire weld line with high precision, which leaves problems to be solved.

Therefore, non-contact type sensors are considered appropriate for solving the problem, and these types include magnetic type and optical type. It could be classified.

Regarding the structure of the welding robot equipped with the non-contact sensor mentioned above, for example, "welding line tracing detection device" (Japanese Patent Application Laid-Open No. 62-101379) and "Optical tracing welding device" (Utility Model Publication No. 64-3588) You can find the official bulletin.

Of the cited conventional techniques, the visible structure itself of the former is shown in FIG.
A and the optical system of the detection device are integrated and attached to a movable support 2a. 1, in which the light sources 6a, 6a are installed so as to intersect at a predetermined angle with respect to the central axis of the torch, and irradiate sheet-shaped laser beams La-La to irradiate areas on the welding line that are in the shadow of each other. ．． A slit beam of t is formed.

In addition, as shown in FIG. 9, in the latter prior art, an optical detector 6b that traces and controls the torch is linked to the front of the welding torch 3b that arc-welds the groove in the welding direction. A structure in which a heat-resistant cloth 101 and a plurality of flexible heat-resistant wires 102 are suspended is intended to protect the optical detector and prevent arc light from penetrating.

[Problems to be Solved by the Invention] Each of the non-contact sensors themselves has advantages and disadvantages, so it is best to select the type that best adapts to the actual conditions, but no matter what type of sensor is installed, the durability of the sensor In practical terms, maintaining this ability directly determines the performance of the welding robot, so it is the most important factor in practical use.

As mentioned above, the sensor is used to perform welding based on the trajectory measured on the groove shape @ car surface, or to guide welding while detecting the immediately preceding groove. Even if it is used for this purpose, it cannot escape from the causal relationship that highly accurate detection cannot be achieved unless it is installed close to the welding torch. Welding involves the most severe conditions in metal processing in a broad sense, and the heat and light that it produces are the greatest obstacles for all precision equipment. As is well known, during welding, spatter scatters and welds to nearby components, and arc light not only disturbs the sensor light emitted from the light source and significantly impedes the detection function, but also its high heat can cause life-threatening optical damage. This is a major cause of early functional decline.

Although it is easy to imagine mounting a sensor coaxially with the welding torch and as far away as possible, in order to compensate for the detection ability that diminishes as the distance increases, the sensor must be extremely large and flexible. This results in a loss of functionality and creates new practical issues.

Next, there are common issues when welding automatically using a welding robot. When welding is done manually by workers, they move the rod themselves and accurately monitor the flow of molten metal and slag through the welding surface, making it easy to check for defects in the weld. It can be said that the weld line is formed while checking. In the case of automatic welding, it would be the same if a skilled welder were to accompany the welding robot along its path while observing it.From the original purpose of automation, this kind of self-check of welding is also the same as that of the welding robot itself. It is most desirable that the

In order to solve some of the problems mentioned above, the present invention provides a new welding robot configuration equipped with a known non-contact sensor, and a novel welding robot configuration that is made possible only by this configuration. The purpose is to provide usage instructions.

[Means for Solving the Problems 1] The welding robot according to the present invention has a main shaft equipped with a welding torch at the tip rotatably supported by a traveling carriage, and has an optical axis intersecting the axis of the main shaft in the supported part. The above problem was solved by installing a laser sensor that forms a .

In addition, a characteristic usage method based on the configuration of this welding robot is to rotate the main shaft so that the optical axis of the laser sensor is directed directly downward, so that the laser spot light is positioned at the start of the groove of the welding line. The spot light oscillates across an area slightly wider than the groove width, electrically captures the groove shape and stores it in the computer, and then rotates the main shaft to direct the welding torch directly below. Weld by tracing the groove with the welding torch guided by the command based on the memory, and when the desired welding is completed, rotate the main shaft again to direct the main shaft of the laser sensor straight down, and weld across the welded part. We have disclosed a procedure for inspecting the presence or absence of defects by running the vehicle while rocking and electrically checking its appearance.

[Operation] FIG. 1 shows both the mechanical structure and the information transmission path of an embodiment of the present invention. 2 to 4 are perspective views showing the operation of this embodiment. The operation will be explained according to these figures.

The welding robot 1 has a self-propelled traveling carriage 2, and a main shaft 4 having a welding torch 3 at its tip is rotatably supported from the carriage by a shaft support 5. A laser sensor 6 is mounted on this shaft support 5 to form a light emission direction (optical axis L) that intersects the axis C of the main shaft 4.

The welding robot first directs the optical axis of the laser sensor 6 directly downward as shown in FIG. 2, and operates the drive mechanism to set the position so that the spot light falls within the welding groove W. Since the laser sensor 6 outputs a voltage according to the distance hit by the spotlight, by A/D converting this, the distance from the reference position of the robot body to the welding groove can be detected.

Next, in order to measure the groove and find the actual welding trajectory, as shown in Figure 5, the spot light is oscillated and travels across a range W that is slightly wider than the groove width. Trace the W shape. At the same time, the computer 7 sequentially outputs a voltage waveform proportional to the distance from the spotlight to the m1 position.
and calculate the relative position from the robot. The groove line is determined by sequentially arranging these relative positions and numerically processing them using the computer 7. Regard this as a weld line,
This trajectory is again set as the trajectory for actually performing welding. Based on the locus numerically processed by the computer, the spindle 4 is rotated and set in the welding direction of the welding torch as shown in FIG. 3, and the welding operation is performed.

Next, when this welding work is completed, the computer 7 automatically rotates the spindle 4 to the same angle as when measuring the groove in order to inspect the welding excess condition, etc. Since the relative position of the robot body and the welding line is sufficiently recognized from the previous operation, it automatically returns to the welding start point and swings the laser sensor 6 along the welding line as shown in Figure 4. At the same time as the movement, the traveling cart 2 is made to travel at a constant speed, and the weld appearance is inspected using the same method as when measuring the groove. FIG. 5 explains this state.

[Embodiment] FIG. 1 is a perspective view showing an embodiment of the present invention. Figure 2 shows the welding robot running for groove measurement.
FIG. 3 is a diagram showing the welding robot in a welding operation. FIG. 4 is a diagram showing a welding robot performing a welding appearance inspection. FIGS. 5 and 6 are diagrams showing the positional relationship between the laser sensor and the object to be welded. FIG. 7 is a flowchart showing a series of operations.

As shown in FIG. 1, the traveling truck 2 travels while a pinion directly connected to a truck driving motor 21 meshes with a rail-shaped rack 22 fixed on a structure to be welded.

The welding torch 3 is tilted forward and backward by rotating the shaft support 5 which is directly connected to the front and rear b23 and is directly connected to the turning motor 24 under computer control.

Figures 2 and 7 show the case of welding by capturing the groove shape of the workpiece.
This will be explained based on the flowchart shown in the figure. First, the tip of the broken line in FIG. 2 is the groove measurement start position, and point A is the groove measurement start point. From this state, the robot starts measuring the groove shape. In this case, with the welding torch tilted, the front-back axis 23, the vertical The shaft 25 is moved and set by rotating a motor 26 for the front and rear axes and a motor for the upper and lower axes, respectively, and turning a ball screw directly connected thereto to convert rotational motion into linear motion.

Next, groove measurement control is started from this state.

That is, the longitudinal shaft 23 is oscillated by setting the value W so that the swing width in the longitudinal direction is equal to or larger than the groove width, and reciprocating the shaft 23 an appropriate number of times.

At the same time, the running bogie on the rail is connected to the bogie drive motor 21.
It is operated by giving commands from PU.

Further, as shown in the perspective view of FIG. 1, the voltage output that matches the unevenness of the groove shape is A/D converted and sequentially and continuously placed in the RAM according to instructions from the CPU.

At this point, the spot light emitted from the laser sensor 6 is
The voltage waveform is converted according to the distance, and the voltage waveform is A/
The D converter 71 converts the analog data into digital data. At a point that is an arbitrary distance away from the starting point A, the trolley drive motor 21 and the front and rear axle motor 26
Since the encoder output is passed through the frequency divider 72, it is expressed as numerical data corresponding to the distance traveled by each axis, and by deducing this, the robot can control the welding. The relative positions of 1 to -chi are found. Arrange this relative position sequentially.12. C
This means that the rays of light can be found by performing numerical processing using the method of least squares in PtJ.

Next, when the traveling carriage 2 moves by a preset distance, the computer 7 gives a stop command to the carriage drive motor 21 and the front and rear shaft motors 26, respectively, thereby completing recognition of the groove shape.

At this point, the welding line is determined by taking out the locus from the RAM according to a command from the CPU, stopping and stopping the locus of the front and rear axes, and checking the straight line. Once the welding line has been determined, the computer 7 gives a command to the /iλ motor 24 for the shaft support so that welding lines 1 to 3 are in the original welding position, as shown in the flowchart of FIG. The computer 7 sends commands to the front and rear axis motor 26, the vertical axis motor 26, and the travel axis motor 21 to rotate the robots 1 and 1 to return the tips of the welding torches 3 to the welding starting point. give. Next, by giving a command to each axial motor to follow the welding line, the d-contact work is started.

The computer 7 is directly connected to the trolley drive motor 21 and the set distance that has been set in advance.
By comparing the distance from the welding start point determined by calculating the pulse distance q, the welding operation is continued if the set distance is not reached. On the other hand, if it is equal to or exceeds the set distance, the computer 7
．． The welding operation is stopped by giving a stop command to 21 and canceling the arc start command to the welding power source.

Next, the robot makes the next movement to perform the visual inspection. For the visual inspection, the shaft support 5 is rotated in the same manner as in the groove measurement, as shown in Figure 4, and the robot l
To return the main body to the welding starting point △, move the front and rear shaft motor 26. A command is given to the vertical axis motor and the traveling axis motor 21 to return to the starting end. In this case, unlike when measuring the groove, the weld line is determined by the operation when measuring the groove, so there is no need for any manual operation. 21. When the robot returns to the starting point, the computer 7 causes the front and rear shaft motor 26 to reciprocate an appropriate number of times to tighten the swing, as in the case of groove measurement.

At this time, the distance from the laser sensor 6 to the welded appearance of the object to be welded is sequentially stored in the RAM according to instructions from the CPU, and the data is sequentially processed to recognize the appearance.

[Effects of the Invention] The present invention allows the above-mentioned laser sensor, which is thermally sensitive and has a high risk of damage or deterioration, to be evacuated away from the welding part during the time when the welding torch is working. During the time when detection is required, it can be brought close to the welding area and send highly accurate information to the control section.

In addition, it is possible to automate the visual inspection after welding, which conventionally required a separate inspection and confirmation by the operator, and if necessary, it opens the way to full automation where the results are provided ablind, making it easier to perform during actual work. The benefits are great. One of the secondary effects is that the entire device is miniaturized and easy to use, making it easy to transport.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of an embodiment of the present invention, FIGS. 2 to 4 are perspective views showing the same operation, and FIGS. 5 and 6 are front cross-sections showing the operation of the laser sensor 1. FIG. 7 is a flowchart explaining the same operation, and FIGS. 8 and 9 are a front view and a perspective view showing separate conventional techniques, respectively. 1... Rohot for welding, 2... Traveling trolley 3... Welding torch, 4... Main shaft, 5
...Axis support 6...Laser sensor, 7.
...Computer C...Main shaft axis, L
...Optical axis, D...Group width W...
・Sensor swing width

Claims (2)

[Claims] (1) In a welding robot that has a self-propelled traveling truck, a main shaft equipped with a welding torch at the tip is rotatably supported from the traveling truck, and an optical axis that intersects the axis of the main shaft is attached to the supported portion. A welding robot characterized by being equipped with a forming laser sensor. (2) The main shaft of the welding robot according to claim 1 is rotated to direct the optical axis of the laser sensor directly below, and the laser spot light is driven to be positioned at the groove start end of the welding line, and the spot light The welding machine swings across an area slightly wider than the groove width, electrically captures the groove shape and stores it in the computer, and then rotates the main shaft to direct the welding torch straight down and store it in the memory. The welding torch traces the groove and welds, guided by the commands based on the command, and when the desired welding is completed, the main shaft is rotated again to direct the optical axis of the laser sensor directly below, and the welding section is oscillated across the welded area. A method of using a welding robot, characterized in that it travels and electrically grasps its appearance to inspect the presence or absence of defects.