JPS625708B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention improves work efficiency by providing a profile sensor and a Z-axis sensor at separate positions that do not interfere with welding work, and eliminates the phase shift between the welding torch and both sensors. By making accurate and easy profile welding possible, and by providing a simple teaching function that eliminates the need for complicated calculations, position control can be easily performed by simply teaching two points at the beginning of the work. The purpose is to provide a profile welding device suitable for practical use.

When configuring a header by inserting a branch pipe on a cylindrical surface, such as a nozzle side, orthogonally to a cylindrical surface with a larger radius of curvature, such as a main pipe on the shell side, Conventional methods for welding a three-dimensional saddle-shaped weld line formed by intersecting lines include the following types.

(b) When a person specifies the diameter and center position of the main pipe and branch pipes, the intersection point of the two pipes is given by a mathematical formula related to the mutuality curve, so the trajectory can be calculated based on calculations by a microcomputer. The method of determining the trajectory and driving the welding robot along the trajectory.

(b) After aligning the rotation center of the robot torch with the upper center of the branch pipe, first align the weld line with the groove detector and memorize the trajectory.

During actual welding, the groove detector is removed, a welding torch is attached to this part, and welding is performed in regeneration mode.

(c) Using the teaching method, each point of the welding trajectory (at approximately 10 mm intervals) is memorized in order and the trajectory is taught to the robot. Then, during playback, welding is performed by interpolating between each point with a straight line or circular arc.

However, although each of the above-mentioned conventional devices is called a robot, it does not have a tactile function, so the work to be welded must be set in a fixed position on a surface plate, etc., and the accuracy of this positioning is the welding accuracy. Therefore, in addition to the welding robot, there was a drawback that the surrounding related equipment became expensive.

In addition, the device shown in item (a) requires a sophisticated and high-cost device because the calculation procedure of the microcomputer requires complicated formulas, and moreover, the device needs to be sophisticated and expensive every time the diameters of the main pipe and branch pipes change. Calculations must be performed and handling is troublesome, and the device shown in item (b) must be operated with a groove detector each time the diameter of the main pipe or branch pipe changes. The same problem occurs when the relative positions of the welding robot and the welding robot change, making it difficult to handle the welding robot.

Next, the method shown in item (c) requires time and effort for teaching, requires a teaching function with a large storage capacity, and has a negative impact on work efficiency and productivity.

As described above, each conventional welding robot has many defects, and what they all have in common is that they require complicated teaching and calculations.
The drawback was that it could not be called an ideal robot that could replace human work, and therefore it felt far from being a practical machine.

In response to these circumstances, the present invention aims to provide a new welding device capable of eliminating the defects of conventional devices, and in particular, it is an object of the present invention to provide a new welding device that is capable of eliminating the defects of conventional devices. By providing it in conjunction with the welding torch, it is possible to indirectly detect welding lines that form intersecting lines at predetermined positions on cylindrical surfaces such as short-axis cylindrical surfaces and cylindrical surfaces with large curvatures such as long-axis cylindrical surfaces. The welding equipment can be roughly positioned, eliminating the need for any effort or investment for positioning.
The present invention is characterized by being able to provide a tracing welding device that is more human-like.

In addition, the present invention is equipped with a teaching function, which is typical of a profile welding robot, but this teaching function is extremely simple. Before actual welding, it is possible to check the Z-axis level of the welding torch at two specific positions and the Z-axis level of the Z-axis sensor. Another feature is that once the level is taught, the proportional constant between the welding torch and the Z-axis sensor can be easily set without any troublesome calculations.

Hereinafter, specific embodiments of the device of the present invention will be described in detail with reference to the accompanying drawings.

First, a workpiece 1 to be welded has a main pipe 2 having a long diameter cylindrical surface and a branch pipe 3 having a short diameter cylindrical surface having a smaller diameter than the main pipe 2, as shown in FIG. It is an interdigital body inserted into the main pipe 2 so that the axes of both pipes are orthogonal to each other, and the weld line l at the joint part is in the case where the main pipe 2 is horizontal in the illustrated example.
Since the branch pipes 3 are arranged vertically, the bird's-eye view shape is a three-dimensional intersecting line formed on the periphery of a perfectly circular saddle shape.

The welding line l forming this three-dimensional curve is separated from the welding line l by tracking the pipe wall portion of the branch pipe 3 with an appropriate sensor for two horizontal axes among its three axis components. It is possible to detect the position indirectly.

The structure of the welding device that performs arc welding on the welding line 1 is, as shown in the basic diagram skeleton form in FIG. The X-axis is pivoted at the upper end of the Z-axis and has degrees of freedom in the left and right horizontal directions (left-right direction with respect to the position of the workpiece 1), and the X-axis is pivoted on the Y-axis and is The Y-axis has a degree of freedom in the direction of approach and departure from the position of It has four axes, including a rotating axis F that performs revolving operation, and the Z axis and reference axis V are both parallel to the generatrix (line parallel to the pipe axis on the pipe surface) of the branch pipe 3 that is fixed upright. The branch pipe 3 is held so that the rotation axis F can rotate on the outside of the branch pipe 3.

A welding torch 6 is pivotally attached to the tip of the rotating shaft F so as to be swingable in a vertical plane.

The vertical dimension of the Z axis is adjusted by a drive source, for example, the electric motor 7, and the vertical displacement at this time is
The length is measured as electrical displacement by the potentiometer 8.

The horizontal dimension of the X-axis is adjusted by a drive source such as an electric motor 9, and the horizontal displacement at this time is measured as an electrical displacement by an X potentiometer 10.

Further, the longitudinal dimension of the Y axis is adjusted by an electric motor 11, and the longitudinal displacement at this time is measured as an electrical displacement by a Y potentiometer 12.

The rotational axis F is rotated by an electric motor 13, and the rotational displacement at this time is measured by the F potentiometer 14 as an electrical displacement corresponding to a clockwise rotation angle with respect to the Y-axis.

Note that the rotating shaft F is integrally connected to the reference shaft V via the horizontal arm 15, and rotates once on its axis for every revolution, so that the welding torch 6 attached to the end of the rotating shaft F and the The X, Y, and F profiling sensor 17 attached to the rotation axis F with its neutral line aligned with the vertical plane including the pointing line of the torch 6 can always be directed toward the workpiece 1 side. .

Next, the welding torch 6 is swingably attached to the end of the rotating shaft F so that the tip can always be oriented on the extension of the reference axis V.

The welding device configured as described above can determine the height and aiming angle of the welding torch 6 based on the electrical displacement of the Z potentiometer 8 provided on the Z axis, and the
Welding to the workpiece 1 is performed by combining the three electrical displacements of the X potentiometer 10 provided on the axis, the Y potentiometer 12 provided on the Y axis, and the F potentiometer 14 provided on the F axis. It is possible to determine the relative position of the torch 6, and correction commands for the Z-axis, X-axis, and Y-axis are issued from the Z-axis sensor 5 provided in relation to the F-axis and the profile sensor 17, The welding torch 6 can be directed at a predetermined aiming angle with respect to the welding line l.

Note that the weld line 1 has a circular shape on a horizontal plane, and extends diagonally upward with the groove portion where overlay welding is performed.

The above-mentioned welding device is provided with a Z-axis sensor 5, a tracing sensor 17, and a speed command device 21 as displacement detectors. The welding torch 6 is oriented in the same direction as the torch 6, and is fixed to the rotation axis F so that its neutral state point correctly matches the extension of the reference axis V.
It is placed near the top of.

The profiling sensor 17 is capable of emitting five different signals: a neutral state indicating a predetermined position, an overshoot correction, an overreturn correction, a clockwise direction correction, and a counterclockwise direction correction.

On the other hand, the speed command device 21 has a known sine/cosine potentiometer as a component, and detects the rotation angle of the reference axis V in the clockwise direction with respect to the longitudinal axis Y. Both the corresponding sine output e _s and cosine output e _c can be output simultaneously, and the reference axis V
It is established in connection with.

As an example of the profile sensor 17 is shown in FIG. 2, the basic structure is an on-off switch, and includes a switch 18A consisting of an actuating piece 20A, a contact part 19A, an actuating piece 20B, and a contact part 19.
For example, the switch 18B consisting of
A, 20B are connected via bullets so that they are attracted to each other, and are arranged in a line symmetrical manner, and if the actuating pieces 20A, 20B abut against the object and their positions are appropriate. Both contact portions 19A and 19B are in a neutral state in which they do not emit any signals at all, and the open and closed states of the contact portions 19A and 19B are variously different due to incorrect positions and being too close or too far apart. The third signal is the combination of species.
It is possible to emit it as shown in the figure.

In Figures 2 and 3, profile sensor 1
7 is too close to the workpiece 1, for example, the contact portion 19 is
At A, the contact 19AR and the movable contact piece are closed (indicated by a circle symbol), and at the contact part 19B, the contact 19BR and the movable contact piece are closed o.

In addition, when the relative positions of the actuating pieces 20A and 20B with respect to the workpiece 1 are in an unbalanced state, and when the actuating piece 20B is closer to the actuating piece 20A than the actuating piece 20A, the positions shown in FIG. Three types of signals are output as shown in the columns F and ○G, indicating that clockwise correction is necessary, and conversely, when the actuating piece 20A is closer, , ○ri, ○nu Indicates that counterclockwise correction is required as shown in each column.

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 to ○G, counter-clockwise rotation direction The tracing sensor 17 can emit five types of signals from correction ○chi to ○nu.

On the other hand, the speed command device 21, as shown in FIG.
It is a circular sine/cosine potentiometer, and the card on which the winding is wound is made proportional to the sine waveform.
A resistor is wound linearly around this, and two sliding pieces 22A and 22B with phase angles shifted by 90 degrees are rotated together about a reference axis V to come into sliding contact with the resistor.

Then, by applying a potential to a portion that has shifted 90 degrees clockwise from the direction of the longitudinal axis Y as a base line, and a partial potential that has shifted 270 degrees, an output _{e c} corresponding to cos θ is generated from the preceding sliding contact piece 22B. However, the following sliding contact piece 22A outputs e _s according to sin θ.
are respectively taken out, and the polarity of both signals at that time is the fourth
In the first quadrant of the figure, cos θ→, sin θ
→, and in the second quadrant cos θ→, sin
θ→, cos θ→, sin θ→ in the third quadrant
, in the fourth quadrant, the polarity is converted to cos θ→ and sin θ→, respectively.

As is clear from this principle, the speed command device 2
1, a sine component output e _s and a cosine component output e _c are simultaneously taken out in accordance with the rotation angle of the reference axis V, and moreover, they are taken out in four combinations of polarities.

Next, the Z-axis sensor 5 is a Z-axis sensor attached to the rotation axis F, and is provided so as to be movable in parallel to the rotation axis F under a constant downward elastic force. There is. When this sensor 5 is installed, it is arranged in such a way that it satisfies the following conditions.

That is, as shown in FIGS. 5A and 5B, the pointing line of the Z-axis sensor 5 is parallel to a plane parallel to the Z-axis that includes the normal line at the arc point A to which the welding torch 6 is directed on the welding line L. The line formed at the intersection with the surface of the tube 2 should always intersect, and the intersection point B
and the horizontal line segment between arc point A on welding line l (=
δ) is always maintained at a constant length.To further aid understanding, we will add an explanation to this point: δ) should always be kept at a constant length. so that the Z-axis sensor 5 can always detect the intersection point B between a plane parallel to the Z-axis and a similar-looking line l' that is concentric with the welding line l and appears on the main pipe 2. It is to do so.

In order to satisfy such conditions, for example, the pointing line of the Z-axis sensor 5 should be directed vertically downward, and the Z-axis sensor 5 should be aligned so that the welding torch 6 is included in the oscillating plane.
This can be easily done by arranging it on the rotation axis F.

Next, the operating mode of the above-mentioned welding device will be explained. This device uses a command from a profiling sensor 17 that detects the surface position of the branch pipe 3 to move the welding torch 6 so that the arc point A on its axis is on the surface of the branch pipe 3. The Z-axis sensor 5 detects a predetermined intersection B on the intersecting line l' and moves in the vertical direction along the Z-axis. Give instructions.

In this way, the welding torch 6 follows the welding line 1 and performs welding.

In this case, the contact position of the Z-axis sensor 5 is the welding line l.
The vertical displacement of this position does not exactly match the vertical displacement of the weld line l.

That is, as is clear from what is shown in FIGS. 5A to 5C, there is a concentric circle relationship with a constant distance δ between the welding line l and the contact point locus l' of the Z-axis sensor 5 in FIG. On the other hand, when compared on the vertical plane including the normal line passing through arc point A, the difference in the Z-axis direction is zero (minimum) at the top surface of the main tube 2 as shown in the diagram, but the difference in the Z-axis direction is perpendicular to this top surface. The maximum level difference is in the Z-axis direction on the vertical plane in the direction of
The level difference value increases and decreases line-symmetrically.

It can also be seen that the change in the Z-axis sensor 5 increases as the welding line l changes in the Z-axis direction.

This change in height can be calculated using equations (a) and (b) below (see Figure 5).

Z _W = R−√ ² − ^{2 2} ………(a) Z _D = R−√ ₂ −(+) ^{2 2} ………(b) However, R=D/2, γ=d/2, arbitrary Find the ratio K of both heights at the angle θ of becomes.

If this _K is defined as a proportionality constant, then the height Z _W of the weld line _l is calculated from equation ( _c ) as The height at a point can be determined indirectly.

Although such calculations can be performed quickly by employing co-computers, they are still time consuming and costly.

Therefore, the present invention is characterized in that it can calculate the proportionality constant K, which requires such complicated calculations, easily and within an extremely small error range, making it suitable as a practical device.This will be described in detail below. do.

As is clear from the skeleton diagram in FIG. 1, the displacement _Sz of the Z-axis sensor 5 naturally changes as the Z-axis moves up and down, but this is only because mechanical feedback is provided.

That is, if the Z-axis sensor 5 is moved down, the command causes the Z-axis to move up or down by a value multiplied by a constant K, but due to this up/down movement, the Z-axis sensor 5 moves relatively downward or downward. This is an upward motion.

Here, when the Z-axis descends to Z _W MAX (the maximum value) along the welding line l, since the Z-axis sensor 5 is located at the tip, the actual displacement of the sensor 5 Z _S
becomes Z _S =Z _D −Z _W. If the ratio of Z _W and Z _S is K _A = Z _W / Z _S (e), and the constant K _A is the amplifier gain of the Z-axis control system, then mechanical feedback exists as described above. From this, the control system shown in Figure 7 is obtained, and the output Z is Therefore, Z operates Z _W /Z _D times as much as S _Z .

Therefore, if the amplifier is operated with an amplifier gain of K _A =Z _W /Z _S , the actual movement will be K = Z _W /Z _D times as originally planned, and since it will be as intended, K _A can be found. Thus, the Z-axis control of the welding torch 6 can be easily performed.

By the way, as shown in equation (c) above, the proportionality constant K is a function of the sine with respect to the angle θ, so it is natural that K will change if the angle θ changes. The diameter of branch pipe 3 for 2 is
In addition to changing 10mm increments in the range of 160 to 260mm, Z
As shown by the maximum error △max when measuring the length of the axis sensor 5 at a horizontal distance of 45 mm, K is
When replacing _A = Z _W /Z _S , the error class when controlling using the welding line l and constant K _A is 10 ^-2
This constant value of K _A is used in the present invention because it is a small value that does not pose a practical problem.

Therefore, the present invention aims to obtain the above-mentioned constant K _A accurately with a simple and inexpensive mechanism. (located directly below the point), then start teaching mode. First, the welding robot is automatically moved forward on the Y axis and then centered on the rotating axis F, while only the lowering of the Z axis can be manually operated, and the welding robot is stopped at the facing position.

Then, a person lowers the welding torch 6 while watching the tip thereof until the welding position, that is, the arc point A coincides with the welding line l.

When this torch setting (lowering of the Z-axis) is completed, the Z-axis and the respective positions Zo and So of the Z-axis sensor 5 at that time are stored in the storage means of the microcomputer.

Note that since the Z-axis sensor 5 is always given a downward force, it is automatically set to the intersection B position.

Next, give a start command to the welding robot and start at 90
゜Stop after rotating.

The position of the welding robot at this time is welding torch 6.
This corresponds to a state in which the Z-axis sensor 5 is aligned near the top surface of the main tube 2, that is, a state in which the displacement difference between Z _W and Z _D is minimum (MIN).

However, during this rotation, the Z-axis is adjusted so that no displacement occurs in the Z-axis sensor 5.

That is, since the displacement difference between the welding torch 6 and the Z-axis sensor 5 changes between the MAX position and the MIN position, the Z-axis sensor 5 that has been taught the Z _MAX welding point
It is necessary to raise the Z-axis so that the positional amount remains constant.

In this case, if the position (displacement) of the Z-axis sensor 5 is small, the welding torch 6 may come into contact with the workpiece, and conversely, if the position (displacement) of the Z-axis sensor 5 is large, the
The Z-axis must be adjusted to avoid such problems because the distance may exceed the effective length measurement range.

As a result, the arc point A of the welding torch 6 is located above the welding line 1 at a position rotated by 90 degrees.

Therefore, in the same manner as the previous operation, the Z-axis is lowered to align the arc point A with the welding line 1, and the Z-axis and the respective positions Z ₉₀ and S ₉₀ of the Z-axis sensor 5 at that time are similarly memorized.

Thereafter, the welding robot is returned to its original starting point by a signal indicating that the memorization has ended.

The teaching mode ends with the above steps, so if we calculate the constant K _A from this series of operations, we get (H)
From the formula, K _A =Z _W /Z _S = |Z ₀ −Z ₉₀ |/|S ₀ −S _9
0 |......(g) Here, Z _S becomes Z _S −S _90. As explained above, if the Z axis moves, the Z axis sensor 5 also moves, so as a result, Z Therefore, _S is required.

In order to calculate the above equation (g), it is sufficient to perform two subtractions and one division using the arithmetic means in the Z-axis control system, making it simple.

In addition, to find the K _A value, find K = Z _W /Z _D at θ = 90° in equations (A) to (C), This is simpler than calculating inside a computer from the respective diameters D and d of the main pipe 2 and branch pipe 3.

Therefore, Fig. 6 shows the case where the diameter of the branch pipe 3 is changed in 10 mm increments in the range of 160 to 260 mm with respect to the main pipe 2 with a diameter of 1000 mm, and the length is measured with the Z-axis sensor 5 at a horizontal distance of 45 mm. , where △max is an approximation obtained by multiplying the true height by a constant φ when the horizontal projection movement θ is changed up to 90° with the top generatrix of the main tube 2 as a reference. The value in parentheses after the △max value indicates the maximum error △θ
According to this, the horizontal plane projection movement angle is maximum at around 45°, but the error class is small at about 10 ^-2 .

Therefore, the above-mentioned constant K is the ratio of the maximum difference between the welding line l with respect to the Z-axis and the maximum difference with respect to the Z-axis of the contact point locus detected by the Z-axis sensor 5, that is, K≒
If Zd max/Z'd max, then Z-axis sensor 5
Although the value in the Z-axis direction detected by the value does not completely match the value in the axial direction of the weld line l, it is clear that this does not pose any practical problem.

In addition, in the table of FIG. 6, d is the diameter of the branch pipe 3 (m/
m), d' is the diameter (m/m) of the contact point locus on the horizontal projection plane of the profile sensor 5, and Zdmax is the welding line l
The maximum difference (m/m) with respect to the Z-axis of
m), φ indicates the ratio of Zd′max to Zdmax, and Δmax indicates the maximum deviation value, respectively.

In addition, although the embodiment described above has been explained in the case where both the pipes 2 and 3 are circular pipes, the present invention is not necessarily limited to circular pipes, but can be similarly applied to elliptical pipes and oblong pipes. be.

As clarified from the above explanation, the device of the present invention determines the positional relationship between the welding torch 6 and the Z-axis sensor 5 with the arc point A coincident with the weld line l formed in the interpenetrating part. At A, a plane parallel to the Z-axis that includes a line normal to the welding line l, and a similar plane appearing on the column surface (main pipe) 2 concentric with the welding line l and having a large radius of curvature. The welding torch 6 and the Z-axis sensor 5 are set so that the position of the intersection B with the curve l' can be detected by the Z-axis sensor 5, and the welding torch 6 and the Z-axis sensor 5 are set between the arc point A and the intersection B. The minimum height Z MIN and maximum height _MAX of the arc point A can be determined by tracing the actual location at or near the position where the level difference in the Z-axis direction is the minimum and at or near the position where the level difference in the Z- _{axis direction} is the maximum.
Storage means for storing the minimum height S _MIN and maximum height S _MAX of the intersection B, and based on the stored information of the storage means, Z _MIN −Z _MAX =Z _W and S _MIN −S _MAX =
arithmetic means for performing each difference of Z _S and division of K _A =Z _W /Z _S ; and providing an output of a value obtained by multiplying the displacement of the Z axis sensor 5 by the constant K _A to the Z axis drive source. Since the Z-axis control system is equipped with an output means, profile welding is possible by first teaching the two points that indicate the maximum height change, and is therefore less troublesome. This eliminates the need for extensive calculations, reduces the number of parts, and provides an extremely inexpensive product.

Moreover, the constant K _A can be easily and automatically determined without knowing the diameters of both cylindrical surfaces 2 and 3, so even those without advanced knowledge can easily operate it, making it practical for use in the field. It has excellent advantages as a device.

Furthermore, since all operations are possible through tracing motion using a tracing sensor, there is no need to be concerned about the positioning accuracy of the workpiece, and high-precision welding is possible even though peripheral equipment is inexpensive. The present invention has various excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic structural diagram of an example of the device of the present invention, and FIG.
Figure 1 is a schematic diagram of the profiling sensor in the device shown in Figure 1, Figure 3 is a table of operating characteristics, and Figure 4 is a diagram of the profile sensor in the device shown in Figure 1.
Figure 5 is an explanatory diagram of the principle of output characteristics of the speed command device in the device shown in Fig. 5. A, B, and C are plan views and front views showing the relationship between the weld line and the Z-axis sensor detection point locus on the workpiece according to the device of the present invention. Figure 6 is an explanatory diagram numerically showing the relationship between the weld line and the Z-axis sensor detection point locus, and Figure 7 is a schematic block diagram of the Z-axis control system according to the device of the present invention. be. 1... Workpiece, 2... Long diameter cylindrical surface, 3... Short diameter cylindrical surface, 5... Z-axis sensor, 6... Welding torch.

Claims (1)

[Claims] 1 Cylindrical surface 3 has a larger radius of curvature than that of cylindrical surface 2
This is a device that welds by tracing a three-dimensional welding line l that is inserted perpendicularly to the cylindrical surface 3 and is formed with a mutually intersecting line at the joint, and the Z
At the tip of the arm, which has three-dimensional degrees of freedom including the axis,
A rotation axis F that rotates while maintaining equidistant parallelism around a reference axis V that passes through the tip and is parallel to the Z axis.
A welding torch 6 and a profiling sensor 17 for detecting the surface position of the columnar surface 3 are attached to this rotation axis F, and the welding torch 6 is moved in accordance with a command from the profiling sensor 17. While the arc point A on the axis is movable concentrically around the columnar surface 3 in a state where it coincides with the surface portion of the columnar surface 3, the arc point A of the welding torch 6 is aligned with the normal line to the welding line l. It is possible to detect the position of the intersection point B between a plane parallel to the Z-axis and the intersecting line l' that is concentric with the welding line l and appears on the cylindrical surface 2 with a large radius of curvature. The position of the Z-axis is controlled by the Z-axis sensor 5 provided to maintain the relative position with the welding torch 6, and the welding torch 6 and the Z-axis sensor 5
The arc point can be determined by tracing the actual position at or near the position where the level difference in the Z-axis direction is the minimum between the arc point A and the intersection B, and at or near the position where the level difference is the maximum. storage means for storing the minimum height Z _MIN and maximum height Z _MAX of point A and the minimum height S _MIN and maximum height S _MAX of intersection B; and Z _MIN based on the stored information of the storage means.
−Z _MAX = Z _W and S _MIN −S _MAX = Z _S and division K _A =Z _W /Z _S ;
A profile welding apparatus characterized in that a Z-axis control system is equipped with an output means for providing an output of a value obtained by multiplying the displacement of the axis sensor 5 by the constant K _A to the Z-axis drive source.