JP2863298B2 - Welding robot controller - Google Patents

Description

The present invention relates to an automatic welding apparatus using a teaching / playback type robot, and particularly to a case where a thick plate-shaped member is welded to an H-section steel. The present invention relates to a welding robot control device suitable for welding a work having a groove having a step parallel shape.

[Conventional technology]

As an example of a workpiece to which an automatic welding apparatus using a robot is applied, as shown in FIG. 2, a strip-shaped member 2 is welded to a concave opening end of an H-section steel 1 while maintaining the illustrated positional relationship. In such a work, a groove 3 serving as a welding line is formed between the inner surface 1 'of the opening end of the concave portion of the H-section steel 1 and the side surface 2' of the strip-shaped member 2. become. In FIG. 2, (a) is a view from the top, (b) is a view from the end, and (c) is a view from the side.

Here, regarding the groove 3, since the inner surface 1 'and the side surface 2' are substantially parallel and are stepped,
Here, such a groove is referred to as a "step parallel groove".

By the way, when welding a workpiece having such a step parallel groove to a robot, the accuracy of the workpiece is good, and if the groove width is always kept constant along the welding line, it is always constant. Since the welding conditions described above were sufficient, welding could be easily performed using the conventional technique.

However, in the case of a work with a variable groove width, if welding is performed with the welding conditions kept constant,
There is a problem in terms of maintenance of welding quality and welding work, and welding operation may not be performed depending on a robot used.

Therefore, the following prior art is known as an apparatus that enables welding by a robot even for such a work in which the groove width is changed. In other words, in this conventional technique, a linear approach sensor is used as an external device, which detects the groove width of the work and converts it to an analog value.
This is A / D converted by an analog module, and a digital value is arithmetically processed to obtain distance data, which is input to a robot to set welding conditions and perform welding.

[Problems to be solved by the invention]

 The prior art has the following problems.

Since the groove width is detected by an external device and converted into an input signal of the robot, no consideration is given to the detected tact, and there is a problem that the tact time of the entire system increases.

No consideration is given to the relationship between the set position of the work and the position of the robot (robot coordinate system), and the direction vector of the groove width must always match one of the axes of the robot coordinate system. There is a problem in that high accuracy is required for installation of the device, and the operation becomes extremely difficult.

Since the groove width is uniquely set for one welding line, no consideration is given to changes in groove width, and appropriate welding conditions are used for welding lines with an irregular groove width. There was a problem that cannot be selected.

When determining welding conditions, selection is made by input signals, so no consideration is given to the resolution of groove width detection, and it is not possible to select fine-grained welding conditions corresponding to changes in groove width. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the related art, and to detect a groove width sufficiently quickly and accurately with respect to a work having a stepped parallel groove in which the groove width is not constant. It is an object of the present invention to provide a welding robot control device capable of easily selecting appropriate welding conditions.

[Means for solving the problem]

The above object is achieved by using a teaching / playback type robot equipped with a work position detection sensor, using an H-shaped steel and a strip-shaped member as a work, and forming an inner surface of the recessed opening end of the H-shaped steel of the work and a strip. With a groove between the side of the shaped member,
In a welding robot controller configured to perform automatic arc welding, at the time of teaching, the robot is sequentially moved to a plurality of work position detection start points that are set in advance, and the sensor is used to detect the end of the concave opening of the H-shaped steel. Means for detecting the outer surface position and the side surface position of the strip-shaped member at each detection start point, detection results of the outer surface position and each side position by the sensor, and a preset recess opening of the H-section steel A means for calculating the width of the groove for each detection start point based on the thickness of the end, and an outer surface position of the concave opening end of the H-section steel, wherein each of the detection start points is an index data I portion. Means for sequentially creating a groove width detection vector table in which stored results of the detection of the above and the side surface position of the strip-shaped member are set as data J and the calculation results of the groove width are set as data A. Only, during playback, the position of the robot is controlled based on the groove width detection vector table is achieved as welding conditions are selected.

According to this embodiment, first, in one embodiment, a robot performs sensing (position detection) on two surfaces of a work forming a groove, and performs a sensing start point position and a sensing end position, respectively. A total of four kinds of position data of the point position are taken into the robot. Here, the timing for taking in the position data is obtained from the command of the robot. The sensing start point position becomes the teaching position data of the robot, while the sensing end point position becomes the position data when the tip of the torch of the robot comes into contact with the surface of the corresponding work. Next, based on the sensing end point position data for each surface of the captured position data, a deviation vector including a groove width component (a groove width vector) and the sensing position data for one surface are used to open the deviation vector. The groove width vector is calculated by calculating a groove direction vector as a direction vector for extracting a tip component, and projecting the groove width vector onto the groove direction vector.

In another embodiment, the above-described groove width detection is performed a plurality of times along the target welding line, and each time the obtained groove width is stored, these stored groove widths are stored. The calculated width values are averaged and stored in a groove width register inside the robot as a groove width value of the welding line.

Further, in one embodiment, a comparison command is provided in the groove width register, and the comparison command refers to a welding condition table corresponding to the groove width, and determines welding conditions such as welding current, voltage, and welding speed. A selection is made.

[Action]

The groove width detecting means can calculate the groove width in the robot coordinate system regardless of the position of the target work at any position with respect to the robot position. can do.

In addition, as a result, even when the groove width is not kept constant, appropriate welding conditions can always be set, and automatic welding by the robot can be performed with high accuracy.

〔Example〕

Hereinafter, the welding robot control device according to the present invention,
This will be described in detail with reference to the illustrated embodiment.

First, FIG. 3 shows a hardware configuration of a robot system to which one embodiment of the present invention is applied.
10 is a robot, 11 is a torch for welding, 12 is a welding wire,
14 is a work table on which the work 1 is placed, 16 is a wire feeder,
18 is a reel stand, 20 is a robot controller, 22 is a welding machine, 23 is a teaching device (PBC), 24 is an operation panel (PGU), and 25 is a gas cylinder. Note that the robot system having such a configuration is very general, and a general description of the operation is also omitted.

FIG. 4 shows a sensor mechanism for detecting a sensing end point, which will be described later. A power source 30 is provided between the welding wire 12 of the torch 11 and the worktable 14, and the robot 10 moves to make the welding wire 12 work. When it comes into contact with the section steel 1, a closed circuit is formed, the work contact signal is turned on, and the timing for obtaining the sensing end point at the time of sensing the groove width by the robot can be taken.

FIG. 5 shows the software configuration of the robot controller 20. In the figure, reference numeral 201 denotes a man-machine control unit, which controls a man-machine interface such as start / stop of the robot 10 and welds a workpiece. It is responsible for teaching teach commands including operations,
As a result, the teach commands in the auxiliary storage device 202 are loaded into the storage device of the robot.

A utility 203 sets various auxiliary data and stores the auxiliary data in an internal storage device. In addition, as the auxiliary data, the thickness data S ₁ of the H-section steel 1 serving as a work is used.
(FIG. 2 (b)) and the number n of times of sensing.

204 is an operation control system, which operates the robot in accordance with a command value issued from the interprinter system of 205,
On the other hand, the interprinter system 205 fetches the current value of the robot via the operation control system 204. Further, the interprinter system 205 loads the teaching data from the auxiliary storage device 202 in response to the activation request from the man-machine control unit 201, and sequentially analyzes and executes the teaching commands for each command. Thus, the operation according to the embodiment of the present invention described below is obtained.

FIG. 6 shows an example of the teaching command flow at this time.
According to the above-described embodiment, the work shown in FIG. 2 is welded by a robot. This flow is sequentially analyzed and executed by the interprinter system 205.

FIG. 7 shows the software configuration of the interprinter system 205 at this time. Hereinafter, the operation of this embodiment will be described.

In FIG. 7, reference numeral 71 denotes an instruction fetch processing unit, which fetches the teaching commands shown in FIG. 6 one by one and transfers them to an instruction determination processing unit 72. Therefore, the instruction determination processing unit 72 determines the passed teaching command, and activates the processing units 80, 90, 110, and 120 corresponding to the type.

First, when the sense start process 80 of FIG. 7 is started by the sense start command of FIG. 6, as shown in FIG.
First, the sense start point Is stored in the I section of the groove width detection vector data table group (process 81), and the point data is passed to the operation control system 204 to execute the interpolation operation (process 82).

Next, when the sense end process 90 shown in FIG. 7 is started by the sense end command shown in FIG. 6, the process shown in FIG. 9 is started. And sense end point To calculate the traveling direction vector of the robot (Process 9
1) Based on this, an interpolation command is given to the motion control system 204 (process 92), and the process is performed while operating the robot in that direction.
At 93, the above-mentioned work contact signal is monitored via the I / O control unit 206, and waits until it is turned on. Then, when this signal is turned on, the robot is stopped (step 94), and subsequently, the current position of the robot at this time is read from the operation control system 204 (step 95). Is stored in the J portion of the groove width detection vector data table group (process 96).

The above processing is repeatedly started as shown in FIG. 6 as a groove width detection sensing operation, thereby setting a groove width detection vector data table.

The groove width detection vector data table has a structure as shown in FIG. 10, and is prepared for the number of times of sensing n (set by the utility 203).

By the way, one sensing count here means
As shown in FIG. 1, two operations of a sensing operation on the outer surface of the H-shaped steel 1 constituting the stepped parallel groove and a sensing operation on the side surface 2 ′ of the strip-shaped member 2 are defined as one set. Each time this one sensing operation is completed, the groove width Δ is calculated by the following formula using the data of the groove width detection vector data table of FIG.
Is calculated and set in the A portion of the groove width detection vector data table (process 97).

First, the groove width vector Is calculated by the following equation.

Here, the suffixes ₁ and ₂ of each symbol are the sense of the groove width forming surface.
No., and the suffix _SE indicates the end point of the sense.

Next, the groove width vector Size of Is Next, a groove width direction vector for projecting the groove width vector Is always calculated on the basis of the sense for the first surface, and is calculated by the following equation.

here, And

Therefore, the groove width vector Groove width direction vector The projection component ΔV is calculated by the following equation.

Where cosθ is the groove width vector And the groove width direction vector B make an angle,
It is obtained by the following equation.

_{cosθ = · = (Δx 2 ·} Δx 1 + Δy 2 · Δy 1 + Δz 2 · Δz 1) ......
(5) Next, the groove width average calculation process 110 shown in FIG. 7 is started by the groove width calculation command shown in FIG. 6, and the processing shown in FIG. 11 is executed. Groove width average And find it in the groove width storage register. Store in the department.

Here, n: sensing the number of times S _1: a plate thickness of the H-shaped steel.

Thereafter, the welding condition selection command of FIG. 6 starts the welding condition process 120 of FIG. 7, and the process of FIG. 12 is executed to select the welding condition. In this embodiment, the groove is set. Width average The welding condition is selected by searching the welding condition table according to.

In FIG. 12, four types of numerical values T _{1 to} T ₄ are set for the groove width T, and the relationship between them is as follows.

T ₁ <T ₂ <T ₃ <T ₄ Finally, the process proceeds to the welding operation command in FIG. 6, and the welding operation by the robot 10 is executed according to the welding condition selected in the welding condition selection processing 120.

Therefore, according to this embodiment, the following excellent effects can be obtained.

Since the positional relationship between the two surfaces forming the groove width is vectorized and the sense direction vector is used as a reference for projecting the above vector, the groove can be easily formed in the robot's coordinate system regardless of how the work is placed. The width component can be detected.

Since the groove width is detected a plurality of times and the average thereof is taken, the groove width can be easily obtained even for a welding line having a non-constant groove width, and the sheet thickness is also taken into consideration.
Good welding can be obtained by easily coping with parallel grooves in steps such as H-section steel.

Since the welding conditions are automatically set according to the groove width, a welding robot control system capable of flexibly responding to the groove width can be easily constructed.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, the width of a groove | channel of the workpiece | work which has a step gap parallel groove which is not constant is obtained sufficiently quickly and with sufficient accuracy, and automatic welding by a robot always under appropriate welding conditions. Can be easily obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a detecting operation by an embodiment of a welding robot control device according to the present invention, FIG. 2 is an explanatory view of a work having a step parallel groove to which the present invention is applied, and FIG. FIG. 4 is a diagram illustrating a sensor mechanism, FIG. 5 is a diagram illustrating a software configuration, FIG. 6 is a diagram illustrating a teaching command, and FIG. 7 is a diagram illustrating a teaching command. FIG. 8 is a flowchart of the sensing start distance, FIG. 9 is a flowchart of the sensing end process, FIG. 10 is an explanatory diagram of the groove width detection vector table, and FIG. 11 is an average calculation of the groove width. FIG. 12 is a flowchart of a welding condition selection process. DESCRIPTION OF SYMBOLS 1 ... H-shaped steel, 2 ... Strip-shaped member, 3 ... Step parallel groove, 10 ... Robot, 11 ... Welding torch, 12 ... Welding wire, 14 ... Workbench, 16 ... Wire Feeding device, 18 Reel stand, 20 Robot control device, 22 Welding machine, 23 Teaching device (PBC), 24 Operation panel (PG
U), 25 ... gas cylinder.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Takabuchi 7-1-1, Higashi Narashino, Narashino City, Chiba Prefecture Inside Hitachi Keiyo Engineering Co., Ltd. (72) Inventor Kazuyuki Ichimura 7-1-1, Higashi Narashino, Narashino City, Chiba Prefecture No. Hitachi Keiyo Engineering Co., Ltd. (56) References JP-A-1-83375 (JP, A) JP-A-63-126678 (JP, A) JP-A-59-82172 (JP, A) JP-A-59-82172 147777 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B23K 9/095, 9/12

Claims (2)

(57) [Claims] An H-shaped steel and a strip-shaped member are used as a work using a teaching / playback type robot equipped with a work position detection sensor. In a welding robot controller configured to perform automatic arc welding with a groove between the side surfaces of the plate-shaped member, during teaching, the robot is sequentially moved to a plurality of work position detection start points set in advance, and Means for detecting the outer surface position of the opening end of the concave portion of the H-shaped steel and the side surface position of the strip-shaped member at each detection start point by a sensor; Means for calculating the width of the groove for each detection start point based on a preset thickness of the recess opening end of the H-section steel; and setting each detection start point as an index data I section. ,Up A groove in which the detection result of the outer surface position of the opening end of the concave portion of the H-section steel and the detection result of the side surface position of the strip-shaped member are stored as data J, and the calculation result of the groove width is stored as data A. Means for sequentially creating a width detection vector table, wherein during playback, the position of the robot is controlled based on the groove width detection vector table, and welding conditions are selected. Welding robot controller. 2. The invention according to claim 1, wherein the selection of the welding condition is performed by selecting one of a plurality of welding conditions set and stored in advance corresponding to each of a plurality of different groove widths.
A welding robot control device characterized by being configured to be processed by selecting a kind.