JPS6119343B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of copying and welding a welding line in which the welding carriage traveling line and the welding line are entirely or partially non-parallel.

FIG. 1 is a plan view of such a welded part viewed from above, in which a standing plate 2 is erected on a flat plate 1, and a fillet weld line W is formed. Further, a substantially straight rail 3 is laid on the flat plate 1, and the welding cart moves in the direction of arrow T. Therefore, the welding carriage traveling line and the welding line are completely or partially non-parallel. A slide base 8 is fixed to the welding cart 4, and a slide arm 7 to which a welding torch 5 and a copying roller 6 are attached moves forward and backward in a direction A that is substantially perpendicular to the arrow T, thereby adjusting the distance between the welding line W and the rail 3. Since it follows fluctuations, it is possible to perform accurate copy welding.

However, the welding conditions are selected appropriately depending on the type of material to be welded and the situation of the welded part. For example, when welding is performed at a constant speed when viewed from the welding line W, the traveling speed of the welding cart 4 is adjusted accordingly. It is necessary to adjust the welding cart 4 depending on various other factors.
The running speed of can vary. For example, in Fig. 2, the traveling direction T of the welding cart and the welding line W are at an angle θ
If we consider the case where the welding cart intersects at , and the traveling speed of the welding cart is a, in order to follow the welding line W, it is necessary to advance the slide arm 7 in the direction of arrow A at a speed of atan θ. If the traveling speed of the welding cart decreases to b midway through, the above advancement speed should be changed to
If the traveling speed of the welding cart increases to c, the advancing speed of the slide arm must be increased to c tan θ. If you neglect to adjust the slide arm advance speed in this way, in the former case, the tracing speed will be too fast and hunting will occur repeatedly.
In the latter case, the tracing will not catch up and the arc will not reach the welding line W. Therefore, in order to improve the scanning accuracy, it is necessary to change the forward and backward movement speed in the scanning direction (hereinafter referred to as scanning speed) in accordance with the traveling speed of the welding cart.

Furthermore, as shown in Fig. 3, if we consider a situation in which the angle formed by the bogie running direction T and the welding line W changes, for example, θ ₁ , θ ₂ , and θ ₃ , the tracing speeds also become e, respectively.
It is necessary to change f and g, but if the running speed of the bogie is a, then e=a tanθ ₁ , f=a
tanθ ₂ , g=a tanθ ₃ . And θ ₁ →
It goes without saying that when the angle changes to θ ₃ , the advancing speed of the slide arm must be similarly increased. In addition to the above-mentioned problems in improving the scanning accuracy, there are also the following problems in the detector used for scanning.

For example, Figures 4 and 5 are explanatory diagrams of a contact type ON-OFF type detector, and the angle of the weld line is
30 degrees, detector accuracy ±0.25mm, welding speed 60
Consider cm/min (10mm/sec). Note that LS ₁ and LS ₂ are both limit switches, and 9 is a detector unit. Starting with the welding cart at point 0 and the striker 10 in the detector unit 9 in the center, when it moves 0.43mm to the right and reaches point S, the detection roller 6' moves forward by exactly 0.25mm. , Striker 10 reaches limit switch LS ₁ . In response to this signal, the slide arm 7 to which the torch, detector unit 9, etc. are integrally attached moves forward, and when, for example, the copying roller 6 comes into contact with the upright plate 2, the detection roller 6' is pushed back. And Striker 10 separates from Limit Switch LS ₁ .
When turned OFF, a signal to stop the forward movement of the slide arm 7 is output. At this time, due to the inertia of the slide arm, the striker 10 is pushed back to a position approximately halfway between LS ₁ and LS _{2 and} stops. However, during these series of operations, the trolley was 0.43mm
The time required for movement is 43 milliseconds, and it is extremely difficult and practically impossible to start and stop the copying motor within this time. In other words, it is not possible to maintain the accuracy of copying, and the motor has to be started and stopped repeatedly, requiring an extremely large capacity.

On the other hand, there is a method in which, for example, a differential transformer is used as a tracing detector to linearly detect the amount of displacement between the bogie travel line and the weld line. That is, as shown in FIG. 7, this is a method of giving the slide arm a tracing speed proportional to the amount of displacement detected by a differential transformer.
Now, as shown in Fig. 6, the angle θ, the bogie traveling speed a
Considering the scanning at , the scanning speed must remain at a tan θ and the movement must continue. In order to produce this output, the amount of displacement between the bogie running line and the welding line must be x as shown in FIG. Therefore, the tracing accuracy is reduced accordingly.

Furthermore, if the weld line W is curved as shown in Fig. 8, the angle θ changes to a negative value at the inflection point P, but in this case, a differential transformer type detector as shown in Fig. 6 is used. If this happens, as shown in FIG. 7, a response deviation occurs due to the relationship between the displacement position and the scanning speed, so there is a problem that the scanning trajectory shows a delay as shown by the chain line.

The present invention has been made in view of these circumstances, and it is an object of the present invention to provide a copy welding method that always exhibits highly accurate copying regardless of fluctuations in the weld line. Therefore, the present invention detects a copying device and a welding device based on a signal obtained by an angle detector that detects the angle formed by a traveling line of a welding cart and a welding line, and a signal obtained by a welding cart traveling speed detector. A command signal proportional to the moving speed of the head in the direction perpendicular to the traveling line of the welding cart is calculated, and by comparing the above command signal with the signal of the scanning detector for the welding line, the above command signal is converted into the signal of the scanning detector. Corresponding modifications are made and the copying device and welding head are moved. That is, by calculating the moving speed in the direction perpendicular to the bogie running line, the relationship between the bogie running line and the welding line is simulated to be in a parallel state, and the deviation from this is traced and the signal from the detector is used. It is meant to be corrected. For example, when the carriage running line and the welding line are practically parallel, the moving speed in the direction perpendicular to the carriage running line is zero, and it is sufficient to move the welding head etc. only by the signal from the tracing detector. Also, as shown in Figure 2, when the angle is deviated by θ and the bogie running speed is a, the moving speed in the direction perpendicular to the bogie running line is a tanθ, which makes the welding line parallel. , the signal from the scanning detector is further added for correction.

Next, the configuration and effects of the present invention will be explained using copy welding of a bending boom in a hydraulic excavator as an example. Figure 9 shows the case of welding following the welding line W of the hydraulic excavator, and the bogie running direction is Tp (towards the right).
This is reciprocating welding as shown by and Tq (towards the left).
Therefore, when the truck moves in the direction Tp, the welding head etc. first moves forward and follows in the direction of arrow Ap, and after passing the inflection point P, moves backward in the direction of arrow A'p. When the truck returns in the Tq direction, the welding head etc. first moves forward in the direction of the arrow Aq and follows the track, and after passing the inflection point P, moves backward in the direction of the arrow A'q. That is, the traveling direction of the welding head etc. needs to be switched according to the traveling direction of the truck, but such detection and response should be operated in conjunction with a switch such as a push button that indicates the traveling direction of the truck.
Alternatively, it may be carried out by using a relay contact operated by the push button, or by extracting the terminal voltage or current polarity of the bogie traveling motor.

Next, the means for detecting the moving speed of the welding cart in the direction perpendicular to the welding cart running line may be based on any system, but a typical one is a drive motor. Examples include a method using a tachogenerator attached to the motor, a method of extracting it from the armature voltage when using a DC motor, a method of extracting it by comparing it with the set voltage at the standard speed of the bogie or the set voltage of the bogie traveling speed using a double volume. Ru.

Also, the intersection angle between the bogie running line and the welding line necessary to calculate the vertical movement speed can be detected by any means, but for example, a pair of rollers can be distributed like the Yajirobei doll, tilting the support arm by pressing the roller against the weld line;
It is preferable to detect the angle of inclination using a potentiometer, an encoder, or the like.

The above two signals calculate the traveling speed of the bogie in the vertical direction for scanning, but there are no restrictions on the detection means for the scanning detector that should correct this, as mentioned above. Various types of contact-type ON-OFF type detectors and detectors using differential transformers can be used.

FIG. 10 is a flowchart for carrying out the present invention. First, a voltage Vs ₁ proportional to the bogie running speed S ₁ is detected in the running speed detecting section 11, and then the running direction determining section 14 equipped with a direction switching relay contact etc. A determination is made as to whether it is (+) or (-), and the result is input to the arithmetic unit 15. On the other hand, the angle θ between the welding line and the trolley running line is detected in the angle detection section 12, and this signal is also input to the calculation section, where the welding head or the like is detected at a speed proportional to the moving speed _S2 in the vertical direction with respect to the welding trolley. Command voltage
Vs ₂ is calculated.

Vs ₂ = ±Vs ₁・Tanθ The calculation result is input to the adder 16, and the signal voltage V _D from the scanning detector 13 is also input to the adder 16, and the speed command voltage Vs ₂ and the signal voltage Vp are compared. be done. That is, when the scanning detector 13 has gone too far with respect to the angle θ and the moving speed s ₂ , it outputs a signal voltage -V _D in proportion to the amount, and when it has gone insufficiently, it outputs a signal voltage +V _D , The adder 16 corrects the former to slow down the moving speed (Vs ₂ -V _D ), and the latter to increase the moving speed (Vs ₂ +V _D ). In this way, the calculation result is corrected and a speed command is issued to the motor drive 17, so that the copying motor M rotates at a speed according to the command. Note that in an angular range where tan θ increases almost linearly with θ, the moving speed in the direction perpendicular to the bogie running line may be calculated as Vs ₂ +Vs ₁ ·θ. It is also recommended to adjust the signal voltage V _D from the ON-OFF type scanning detector so that it is about ±20 cm/min when θ=0.

The configuration of the present invention, particularly the portion related to modification of calculation results, will be explained in more detail using specific numerical values. Assume the conditions as follows.

Bogie running speed S ₁ : 0 to 100 cm/min Voltage proportional to running speed S ₁ : 0 to 10 V Angle between welding line and bogie running line; θ Speed command voltage Vs ₂ : 0 _to ±10 V Traveling speed: 0 to ±100 cm/min This will be explained with reference to FIG. Current running speed s ₁
When Vs 1 is 50 cm/min, the voltage Vs ₁ detected by the traveling speed detection section 11 is 5V. When the traveling direction determining unit 14 determines (+), +
Outputs 5V. Next, assuming that the angle θ is 10°, θ=10° is input from the angle detector 12 to the calculating section 15, and the following calculations are performed.

tan10゜=0.18 Vs ₂ = ±Vs ₁ tanθ = (+5V) x 0.18 = 0.9 (calculation result) In other words, 0.9V is the voltage value that becomes the speed command signal for movement, and at 10V it moves at a rate of 100cm/min. Therefore, the moving speed of the welding head etc. is 9 cm/min. Logically, it would be sufficient to trace a welding line inclined at an angle θ of 10°, but due to distortion of the workpiece, detection error, etc., a tracing detector 13 is used and correction is made using a tracing signal as described below.

When the correction voltage V _D from the scanning detector 13 is αV, the adder 16 adds the signal resulting from the above calculation and the correction voltage αV.

Vs ₂ +V _D =0.9V+αV Here, if we use a scanning detector that outputs 1V when there is a deviation of 10 mm, it will output 0.1V (=αV) when there is a deviation of 0.1 mm during scanning. That is, Vs ₂ +V _D =
0.9V + 0.1V = 1.0V, and the motor speed is corrected from 9cm/min to 10cm/min by a +0.1mm deviation. On the other hand, if it is shifted towards you by -0.1mm, it will be 0.9V.
+(-0.1V) = 0.8V, from 9cm/min to 8cm/min
Corrected to min.

As described above, copying is performed while the calculation results are corrected.

Since the present invention is configured as described above, it is possible to achieve extremely high tracing accuracy when the bogie running line and the welding line are non-parallel.

[Brief explanation of the drawing]

Figure 1 is a plan view of the welded part, Figures 2 to 7 are explanatory diagrams of the copying method, Figure 8 is a plan view of the welded part, Figure 9 is an explanatory diagram showing the copying method of the hydraulic excavator, and Figure 10 is the flow. It is a diagram. 11... Traveling speed detection unit, 12... Angle detection unit, 13... Copying detector, 15... Calculation unit, 16
...Adder, 17...Motor drive.

Claims (1)

[Claims] 1 A method of welding by copying a welding line that is completely or partially non-parallel to the almost straight welding bogie running line, where the welding bogie moving straight has a welding line that is approximately perpendicular to the bogie running line. The moving copying device and welding head are mounted on a tower, and the copying device and welding head are detected from the signals obtained by the angle detector that detects the angle formed between the bogie running line and the welding line, and the welding bogie running detector, respectively. A command signal proportional to the traveling speed of the bogie in the direction perpendicular to the running line of the dolly is calculated, and by comparing the command signal with the signal of the tracing detector for the welding line, the command signal corresponds to the signal of the tracing detector. A copying welding method characterized by modifying the welding part so that the welding part is moved and moving a copying device and a welding head.