JPS6235862B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copy welding device that allows the torch angle to be changed using simple control means.

Most conventional welding devices that perform automatic profile welding are of the type where the sensor follows the groove of the weld line and precedes the welding torch, regardless of whether it is a contact or non-contact method. It was done.

In this type of sensor-advanced type, the phase shift that occurs between the torch and the sensor complicates the control circuit because it requires a memory function, and when the sensors are placed close together, the thermal effect caused by the arc increases the complexity of the control circuit. There were practical problems such as damage to the sensor.

Furthermore, the sensor-advance type cannot perform welding processes that repeatedly move forward and backward, and the welding work is restricted to one direction. Complex procedures such as reversing are required, and considering the special case where the target welding line is continuous and endless, repeating welding in one direction may cause twisting of the electrical wiring or welding wire. Therefore, the relative positions of the welding torch and the sensor must be reversed, which makes the operation troublesome and the device complicated.

In addition, when we list the welding conditions for general welding, it goes without saying that current, voltage, and speed are the three elements, but there are other factors that affect welding performance, such as the torch angle. When welding is performed using a robot, an important practical problem is how to change the torch angle, that is, the advancing angle and the receding angle, using a simple mechanism and control means.

However, with conventional devices of this kind, changing the torch angle can cause the arc point to deviate or the relative position to the scanning sensor to change, so a correction command is given at the same time as the torch angle is changed. This necessitates the use of other means such as the following, which not only complicates the mechanism and control device, resulting in high costs, but also makes handling operations extremely troublesome.

The present invention was achieved as a result of various studies aimed at addressing and improving the current situation as described above, and consists of a two-dimensional or three-dimensional curve formed in the circumferential direction of a cylindrical surface, particularly a cylindrical surface. In the case of a specific welding operation in which welding follows a welding line, the F-axis tracing sensor that is moved around the column surface is separated from the arc point of the welding torch, and is synchronously moved with no relation to the arc point. Not only can the position of the weld line be detected accurately, but also the torch angle can be easily changed without any deviation of the arc point by giving a simple rotational motion command. The present invention has led to the provision of a novel copy welding apparatus, and its specific contents will be described in detail below with reference to the accompanying drawings.

The workpiece 1, which is the object to be welded by the welding device, is
A weld line that is a two-dimensional or three-dimensional curve formed around the cylindrical surface of a steel pipe with a cylindrical surface.
The welding line 1 is welded by the welding device.

The illustrated workpiece 1 includes a main pipe 2 as a member 2 constituting the workpiece 1 which has a large diameter cylindrical surface and is arranged horizontally, and a main pipe 2 as a member 2 constituting the workpiece 1 which has a large diameter cylindrical surface and is arranged vertically and has a small diameter cylindrical surface compared to the main pipe 2. It is an interrelated body formed by joining a short diameter branch pipe 3 as a column body 3 in a penetrating relationship in which both pipe axes are orthogonal to each other, and the weld line l at the joint part is:
In the illustrated example, since the main pipe 2 is arranged horizontally and the branch pipes 3 are arranged vertically, it is clear that the bird's-eye view shape is a three-dimensional curve formed on the periphery of a perfect circle saddle shape. .

In addition, the welding line l forming the above three-dimensional curve has the following two axes in the horizontal direction among its three-axis components:
By tracking the pipe wall portion of the branch pipe 3 with a sensor, the welding can be performed indirectly at a position distant from the welding line 1, so that various known switches such as a proximity switch can be applied.

Although not shown, the welding device that performs arc welding on the welding line 1 has a Z-axis that is parallel to the generatrix of the cylindrical surface of the branch pipe 3 and has a vertical degree of freedom in FIG. An arm 4 having degrees of freedom in three axes, the X and Y axes having degrees of freedom in the front-rear direction and left-right direction on the orthogonal planes shown in FIG.
is provided in the main body, and an F-axis 5 parallel to the Z-axis is rotatably supported at the tip of the arm 4 so as to be rotatable about its own axis.

That is, the axial structure of the welding device has three directions: a Z-axis in the vertical direction parallel to the generatrix of the branch pipe 3, a Y-axis in the direction toward and away from the arc 1, and an X-axis perpendicular to the Y and Z axes. In addition to the shaft, it comprises a rotatable F-shaft 5 held parallel to the Z-axis, and the structure is such that the F-shaft 5 can rotate above the pipe wall of the branch pipe 3.

The F-axis 5 is connected to a drive shaft 9 via a gear train 8, and a sensor mounting shaft 10 vertically installed in parallel with the F-axis 5 at an appropriate distance is directly connected and integrated with the F-axis 5. A torch mounting shaft 11 is vertically installed in parallel with an appropriate distance from the worm wheel 13 and the worm 1 is rotatably supported around the F axis 5 as a central axis.
The F-axis 5 is
It is connected to

A copying sensor 7 is attached to the sensor mounting shaft 10.
Further, welding torches 6 are attached to the torch attachment shafts 11, respectively.

Note that the above-mentioned shafts 10 and 11 rotate once for each revolution around the F-axis 5, and therefore the welding torch 6 and the copying sensor 7 are always directed toward the workpiece 1 side. I am doing what I get.

The welding torch 6 and the copying sensor 7 are supported by the respective shafts 11 and 10 so that the welding axis and the detection neutral line can be maintained in relative positions with respect to the extension line of the F-axis 5, respectively. There is.

Note that the welding axis refers to the welding direction in which the welding torch 6 is directed toward the workpiece, and is shown as a line w in FIGS. 1 and 5. On the other hand, the detection neutral line This refers to the tracing direction with the axis 10 that supports the sensor 7 as a base point, and as will be clear from the structural description described later, a pair of tactile pieces 17 _L are used to detect two points. , 17 _R and the center of the sensor mounting shaft 10 that swingably supports both tactile pieces 17 _L and 17 _R is the detection neutral line. , shown as line n in FIGS. 2 and 3.

In the figure, 16 is a Z-axis sensor, whose tactile part is brought into contact with the pipe wall of the main tube 2 in the workpiece 1, and the vertical level of the tactile part is converted into an electrical signal level by a potentiometer PoT. , by moving the Z axis up and down by a drive source (not shown),
It is formed so that the upper and lower levels of the weld line 1 can be indirectly detected.

In the welding device configured as above, the arc point height of the welding torch 6 can be determined by the Z-axis potentiometer PoT, and the X-axis potentiometer, Y-axis potentiometer, and F-axis potentiometer By combining three electrical displacements of potentiometers (none of which are shown), the relative position of the welding torch 6 with respect to the workpiece 1 can be determined, and furthermore, the position of the welding torch 6 relative to the workpiece 1 can be determined.
By issuing correction commands for the X-axis, Y-axis, and F-axis 5, the welding torch 6 can be directed at a predetermined target angle with respect to the welding line l.

Note that the torch angle of the welding torch 6, that is, the forward angle,
The sweepback angle is set to a desired value using the rotation transmission mechanism 12 in FIG.

That is, in this rotation transmission mechanism 12, the worm wheel 13 is fitted onto the F-shaft 5, and the worm 14, which is engaged with the foil 13, is rotatably supported on the torch attachment shaft 11. When the worm 14 is rotated, the worm 1
4 rolls on the teeth around the worm wheel 13, and as a result, the torch attachment shaft 11 rotates around the F-axis 5.

In this way, the torch angle can be adjusted to the desired value, but
At a neutral angle where neither the advancing angle nor the receding angle exists, the welding axis of the welding torch 6 and the detected neutral line of the copying sensor 7 are included in one vertical plane.

Therefore, the scanning sensor 7 is connected to the X, Y and F axes 5.
As mentioned above, it issues a correction command for workpiece 1 (on the wall of branch pipe 3).
1 for confirming the position by direct contact
A pair of tactile pieces 17 _L , 17 _R and the tactile pieces 17 _L , 1
A dual detection device consisting of a pair of sensor parts 18 _L and 18 _R for converting the relative position of 7 _R as an electrical signal, and a pair of connecting members 19 _L and 19 _R for bridging these two members. It consists of 5 different units: a neutral state indicating a predetermined position, an overshoot correction, an overreturn correction, a clockwise direction correction, and a counterclockwise direction correction.
emit a seed signal.

A specific structural example of this tracing sensor 7 is shown in FIG. 2, and a pair of tactile pieces 17 _L and 17 _R can come into contact with a cylindrical surface (branch pipe 3) near the weld line l. , and the detection neutral line formed between them is provided so that it coincides with the welding axis of the welding torch 6, while the pair of sensor parts _18L and _18R are located at a position where they are not affected by welding heat. , are provided on the opposite side of the tactile pieces 17 _L and 17 _R with respect to the mounting shaft 10.

Next, the pair of connecting members 19 _L and 19 _R are formed by integrally connecting a hanging rod 19a and a horizontal plate 19b, respectively, and the intermediate part of the horizontal plate 19b is rotatably engaged with the mounting shaft 10. , can be rotated within an appropriate angle in the horizontal direction about the mounting shaft 10.

And the rod 1 in these connecting members 19 _L and 19 _R
The tactile pieces 17 _L and 17 _R are attached to the lower end of the horizontal plate 9a so as to be adjustable in and out, while the sensor parts 18 _L and 18 _R are attached to the end of the horizontal plate 19b.

Each of the sensor parts 18 _L and 18 _R is connected to a horizontal plate 19
a dog 20 that protrudes from and can be adjusted in and out of b;
An operating unit consisting of a micro switch 21 that is provided on a bearing portion that rotatably supports the mounting shaft 10 so as to be able to come into contact with and separate from the dog 20 is connected to a reference line passing through the mounting shaft 10, that is, the welding axis of the welding torch 6. Tactile piece 17
They are arranged in a line-symmetrical pair with reference to lines that match the neutral lines of _L and _17R , respectively.

The connecting members 19 _L and 19 _R each have horizontal plates 1
9b is drawn by the spring 34 toward the bearing portion to which one of the microswitches 21 is fixed, and in the free state, the dog 20 is attached to this microswitch 21.
At the same time, the pair of tactile pieces 17 _L and 17 _R can be held close to each other.

The tracing sensor 7 configured as described above operates as follows and generates various signals.

In FIG. 3, if the pair of tactile pieces 17 _L and 17 _R are in contact with the workpiece 1 and their positions are appropriate, the micro switches 21-L ₁ , 21-L ₂ , 21
-R ₁ and 21-R ₂ are both off and in a neutral state where they do not emit any signals, and if the positions are not appropriate and are too close or too fast, the on/off state of each micro switch will be different, and the As shown in Figure 4, it is possible to emit signals with a total of 10 combinations.

For example, if the copying sensor 7 goes too far, that is, comes too close to the workpiece 1, the micro switch 21- _R1 and the micro switch 21- _L2 will send an on signal (〇 ) is emitted.

In addition, when the relative position of the copying sensor 7 with respect to the workpiece 1 is in an unbalanced state, when the tactile piece _17L is closer than the tactile piece _17R ,
Three types of signals are output as shown in the columns ○H, ○H, and ○G in Figure 4, indicating that correction is required clockwise, that is, clockwise in the diagram, and conversely, the tactile piece _17R When the two are approaching each other, it is indicated that correction is required counterclockwise, that is, counterclockwise on the diagram, as shown in the columns ○, ○, and ○ in Figure 4.

In this way, apart from the standby ○A state, the neutral state ○B, over-return correction (preceding instruction) ○C, over-travel correction (backward instruction) ○D, clockwise rotation direction correction ○H~○G, counterclockwise rotation direction Five types of correction signals from ○chi to ○nu can be emitted from the copying sensor 7, and when it returns too far or goes too far, appropriate correction outputs are given to the X and Y axes, and
For clockwise direction correction and counterclockwise rotation direction correction, it is sufficient to take measures such as giving correction outputs to the X-axis and Y-axis while giving a rotation correction output to the F-axis 5.

The basic operating mode of the scanning sensor 7 has been clarified through the above explanation, but the scanning sensor 7 is designed so that the sensor section 18, which requires careful handling as a central functional section, is separated so that it is not affected by welding heat. Since the sensor is located at a fixed position, the response accuracy does not change over time and provides stable function over a long period of time.

Thus, the copying sensor 7 has a pair of tactile sections 17,
A rotation correction command is given to the F-axis 5 so that the detected neutral line when 17 contacts two points close to each other on the surface of the column surface coincides with the normal line to the column surface, and therefore the welding torch 6 The arc point advances in the welding direction with respect to the detection point of the tracing sensor 7, does not lag, maintains a synchronous relationship, and does not deviate, and the torch angle is held constant.
Tracing control for correctly orienting the welding torch 6 to the welding line l is smoothly performed.

In the example described above, the independent rotary motion of the F-axis 5 is performed manually, but it is of course also possible to perform this using a drive source such as a motor or cylinder. Therefore, various means such as remote control or automatic operation in which the torch angle is programmed in advance in cooperation with automatic welding can be employed.

Note that the above-mentioned example includes a mechanism for adjusting the aiming angle of the welding torch 6 in addition to a mechanism for adjusting the torch angle, that is, the angle at which the welding axis is directed.

This adjustment mechanism is shown in Figure 5 and Figure 6.
An example is shown in which a torch swinging device 22 is provided at the tip of the torch mounting shaft 11, and the device 2
Reference numeral 2 consists of an arcuate guide member 23 connected to the tip of the shaft 11, and a torch fixing member 24 slidably engaged with the guide member 23.

The guide member 23 has grooves 25, 25 on both the inner and outer arc surfaces.
The torch fixing member 24 has pulleys 27, 27, 27 rotatably attached to the main body of the torch fixing member 24, and an arc-shaped elongated hole 26 is bored in the center thereof.
5, 25, and a threaded rod 28 inserted into the center of the main body is inserted into the elongated hole 26 and screwed into the square nut 30.
formed to be able to slide along the guide member 24;
This movement range is defined by the length of the elongated hole 26.

The torch swinging device 22 having the above structure is constructed by rotating the threaded rod 28 inserted into the torch fixing member 24 clockwise to tighten the threaded engagement with the square nut 30. The torch fixing member 24 can be slid relative to the guide member 23 by fixing the torch fixing member 23 and loosening the guide member 23.

On the other hand, a knob 29 and a pinion 31 are fitted onto a support shaft 33 that supports one pulley 27, and the pinion 31 meshes with an arc-shaped rack 32 formed on the outer arc surface of the guide member 23. Hey, knob 2
By rotating the pinion 9, the pinion 31 rolls on the rack 32, so that the torch fixing member 24 can be slid to a desired position.

Further, since the shaft 100 is eccentric at the position of the torch fixing member and the pulley 27, the spacing between the guide member 23 and the pulley 27 can be adjusted by rotating the shaft 100.

The welding torch 6 is connected via this torch swinging device 22.
By attaching the welding torch 6 to the torch mounting shaft 11, the welding torch 6 can be swung within a plane including the axis, with the welding torch 6 centered around a point P, which is located a short distance, for example, 30 mm, from the arc point on the torch side on the extension of the axis. can be done.

Note that this swing range can be set as appropriate, but normally if it can be within a range of ±10° on both sides of the neutral line, the aiming angle in cases such as multi-layer welding can be adjusted with sufficient margin. I can do it.

By providing the torch swinging device 22 in this way, the welding torch 6 can change the aiming direction on the support side at hand, and therefore, the position of the arc point can be deviated by a wide range by changing the aiming angle. No problems at all,
Furthermore, since the welding torch 6 is made to swing two-dimensionally, changing the aiming angle is simple and easy, and is completely independent of the movement of the arm following the welding line l. Since the aiming angle can be changed at will, the control circuit can be simplified and accurate positioning can be achieved in the case of automatic control.

In particular, since the center of swing of the welding torch 6 is not at the arc point but slightly shifted toward the torch side, in the case of multi-layer overlay welding, the swing operation can be performed without changing the repeating trajectory of the arm. The arc point can be easily moved, and the position of the arc point will not be biased in the far or near direction with respect to the welding line l.
Therefore, reliable multilayer overlay welding can be performed.

Although the torch swinging device 22 has been exemplified as a manual method in which the knob 29 is operated, it is also possible to connect a drive source such as a motor to the shaft 33 and perform remote control or automatic control using a predetermined program. Needless to say.

The device of the present invention has the configuration and operation described above, and is composed of a columnar body 3 and a member 2 that intersects the columnar body 3 and its generatrix, and is formed on the outer peripheral surface of the columnar body 3 by the crossing. A copy welding device for copy welding a welding object 1 using a two-dimensional or three-dimensional curve as a welding line l, which includes three axes that are orthogonal to each other, including a Z axis that is parallel to the generatrix of the column 3. An F-axis 5 parallel to the Z-axis is provided at the tip of the arm 4, which has a degree of freedom, and is rotatable about its own axis. The welding torch 6 is mounted on the torch mounting shaft 11 so that it can rotate around the F-axis 5, and the welding torch 6 is oriented to a fixed position on the extension line of the F-axis 5, and A sensor mounting shaft 10 parallel to the extension line of the F-axis 5
is directly connected and integrated with the F axis 5, and is supported so as to be swingable so as to maintain an equal distance on both sides of the detection neutral line n, and is given elasticity in the direction of approaching the detection neutral line n. 1 to contact two points on the outer peripheral surface of 3
Pair of tactile pieces 17 _L , 17 _R and their corresponding 1
Copying sensor 7 consisting of a pair of sensor parts 18 _L and 18 _R
is attached to the sensor mounting shaft 10 so that the detection neutral line n extends between a position on an extension of the F-axis 5 that is away from the fixed position where the welding axis w is directed, and the sensor mounting shaft 10. , the copying sensor 7 is set to 1
At least one of the pair of tactile pieces 17 _L and 17 _R is connected to the column 3
There are 5 different types: a neutral state in which contact is made with the outer circumferential surface of the device and coincides with the detected neutral line n depending on the state of contact, over-travel correction, over-return correction, clockwise rotation direction correction, and counterclockwise rotation direction correction. Further, the arm 4 is configured to be able to transmit signals such as
Giving a correction output to two axes perpendicular to the Z axis of
The present invention is characterized in that a control means is provided for maintaining the scanning sensor 7 in a neutral state in which the detection neutral line n is normal to the outer circumferential surface of the columnar body 3. Therefore, the torch angle can be changed with a simple mechanism of rotating the torch mounting shaft portion around the F-axis 5.

Therefore, a simplified and robust mechanism with a small number of parts is required, resulting in low cost.

Moreover, since the torch angle can be adjusted independently from the F-axis copying sensor 7 and other axis sensors, the torch angle can be changed at any time even when each sensor is in copying operation, using a simple control device. This has the advantage of allowing reliable angle determination.

Furthermore, even if the torch angle is changed, the arc point will not deviate, so there is no need to make corrections each time, and it is noteworthy that the automatic control method can be reliably and easily executed compared to the conventional complex structure. As described above, the present invention is a copy welding device that exhibits various excellent effects.

[Brief explanation of the drawing]

Each figure shows an embodiment of the device of the present invention, in which Figure 1 is a skeletal diagram schematically showing the structure, Figure 2 is a perspective view of the F-axis scanning sensor section, and Figures 3 and 4 are the second figure. Schematic diagram and operating characteristic table of the tracing sensor, Figures 5 and 6 are a front view of the welding torch support part and A
- It is a sectional view along the A line. 1... object to be welded, 2... member, 3... column,
4...Arm, 5...F axis, 6...Welding torch,
7...Copying sensor, 10...Sensor mounting shaft, 1
1... Torch mounting shaft, 17 _L , 17 _R ... Tactile piece, 18 _L , 18 _R ... Sensor part, l... Welding line,
n...Detection neutral line, w...Welding axis line.

Claims (1)

[Claims] 1 Consists of a column 3 and a member 2 that intersects the column 3 and its generatrix, and a two-dimensional or three-dimensional curve formed on the outer circumferential surface of the column 3 by the intersection is defined as a weld line l. This is a copy welding device that copies and welds a welding object 1, and includes a Z-axis and a Z-axis at the tip of an arm 4 having degrees of freedom in three axes that are orthogonal to each other, including a Z-axis that is parallel to the generatrix of the columnar body 3. While the parallel F-axis 5 is provided so as to be rotatable around its own axis,
A torch mounting shaft 11 parallel to the extension line of the F-axis 5 is provided to be rotatable around the F-axis 5, and the welding torch 6 is attached so that the welding axis w in the welding direction is F.
The torch is attached to the torch mounting shaft 11 so as to be oriented at a fixed position on the extension line of the shaft 5, and the F shaft 5 is
The sensor mounting shaft 10 parallel to the extension line is directly connected and integrated with the F axis 5 to maintain an equal distance on both sides of the detection neutral line n and to provide elasticity in the direction approaching the detection neutral line n. A pair of tactile pieces 17 _L and 17 R that are supported in a swingable manner and come into contact with two points on the outer circumferential surface of the column 3 and a pair of sensor parts 18 L and 18 _R that correspond to the tactile pieces 17 _L and 17 _R. The scanning sensor 7 is mounted on the sensor mounting shaft 10 such that the detection neutral line n extends between the sensor mounting shaft 10 and a position away from the fixed position where the welding axis w is directed on the extension line of the F-axis 5. At least one of the pair of tactile pieces 17 _L and 17 _R is in contact with the outer peripheral surface of the column 3, and depending on the state of contact, the scanning sensor 7 is attached to the detection neutral line n. It is configured to be capable of transmitting five different types of signals: a matched neutral state, overshoot correction, overreturn correction, clockwise rotation direction correction, and counterclockwise rotation direction correction; The Z of the arm 4 is adjusted by the excessive return correction signal.
A correction output is given to the two axes orthogonal to the axis, and a rotation correction output is given to the F-axis 5 in response to clockwise direction correction and counterclockwise rotation direction correction signals, so that the scanning sensor 7 is detected when the detection neutral line n is a column. A copy welding device characterized by being provided with a control means for maintaining the body 3 in a neutral state that is normal to the outer circumferential surface of the body 3.