JPS6216744B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic welding device for automatically and continuously performing multilayer welding on a weld line of a saddle-shaped groove.

Many welding devices of this type have been provided in the past, and the device disclosed in Japanese Patent Application Laid-open No. 1983-1959, which was previously proposed by the applicant, is one example, and this device is shown in Fig. 4. As illustrated in
A welding torch 6' is fixed to the base 4 for multi-layer welding of the saddle-shaped groove weld line formed at the joint when the nozzle 2 made of a small diameter circular pipe is orthogonally connected to the shell made of a large diameter circular pipe. R rotating around the central axis of '
axis, a Z-axis that is perpendicular to the R-axis and performs linear operation in the vertical direction parallel to the central axis, an A main shaft system that gives the welding torch 6' the four degrees of freedom of the S axis that swings in the plane, the V axis that moves linearly in the axial direction of the welding torch 6', and the X and Z axes that are parallel to the plane and The welding torch 6' is provided with a correction axis system that provides the welding torch 6' with two degrees of freedom of the H axis that moves linearly in a direction orthogonal to the V axis, and has a fairly complicated structure requiring a total of six degrees of freedom.

Then, the position of the welding torch 6' with respect to the welding line is determined.
After teaching the four axes of the spindle system R, Z, X, and S using the PTP (point to point) method, attach a welding line tracing sensor to the tip of the welding torch 6' and trace the welding line once. In the meantime, the position of the welding torch 6' is taught to follow both VH axes of the correction axis system, and then automatic welding is performed by a closed loop control system.

By the way, controlling six degrees of freedom in this way complicates the structure and operation of the control device, requires PTP teaching work, and requires tracing, so the disadvantage of troublesome handling cannot be avoided. It's something that doesn't exist.

The present invention has been made in response to the fact that the conventional device as described above has a complicated structure and is troublesome to handle. An important objective is to reduce the number of control axes by providing a total of four degrees of freedom, thereby facilitating control and simplifying handling.

However, in order to achieve such an object, the present invention
In particular, the main axis system is formed by three degrees of freedom: the R axis, the Z axis, and the A welding torch and a detector holder are attached to the F axis, and a Z axis is attached to the detector holder.
The extension direction of the central axis of a fixed base as a device axis, in which a pair of scanning detectors are arranged with each detection axis aligned with the axis of the nozzle by pivoting a detector holding axis that moves linearly in the vertical direction parallel to the axis. The nozzle is fixed perpendicularly to the detector holding shaft with the welding torch oriented symmetrically on both sides with the welding torch in between, and the side surface of the nozzle is detected by a pair of tracing detectors. The welding torch is configured to control the position and orientation of the welding torch, while the height is controlled by calculation control, regeneration of the Z-axis memory value, control by a height detector, or constant current control of the arc current in the welding torch. It is characterized by the fact that the number of control axes can be four axes, and
This eliminates the need for PTP teaching and tracing using a copy detector.

A narrow gap thick nozzle neck welding apparatus as a specific embodiment of the apparatus of the present invention having such characteristics will be described in detail below with reference to the accompanying drawings.

FIG. 1 schematically shows an automatic welding device, such as a copy welding machine, in which a nozzle 2 made of a small-diameter circular pipe is orthogonally connected to a shell 1 made of a thick-walled large-diameter circular pipe. , a saddle-shaped welding line 3 formed by the joint between the nozzles 2 is subjected to multilayer welding using a rectangular welding torch 6.

A fixed base 4, which is a member forming the base of the welding machine, is fitted onto and fixed to the upper part of the nozzle 2.

In this case, it goes without saying that the shell 1 and the nozzle 2 are temporarily welded to be integrated so that they do not move.

In addition, the fixed base 4 is equipped with a servo motor 11, which will be described later.
A motor shaft 5 is fixed, a horizontal mount 14 is provided passing through the motor shaft 5, and a servo motor 11, a rotary generator 12, an encoder 13, and a speed reducer (not shown) are mounted on the horizontal mount 14. When the servo motor 11 is driven, the horizontal frame 14 is rotated around the motor shaft 5.

The horizontal mount 14 rotates within a horizontal plane by a predetermined angle in response to a control command, and this motor shaft 5 is referred to as an R-axis.

Reference numeral 15 denotes a fixed arm that is fixed to the pivoting tip of the horizontal frame 14 and extends horizontally.As a result of rotation within a horizontal plane about the motor shaft 5, the tip of the fixed arm 15 is welded. It begins to revolve above line 3, that is, around nozzle 2.

16 and 17 are an upper plate and a lower plate provided above and below to sandwich the tip of the fixed arm 15,
By connecting each other with guide shafts 18 and 19 formed by penetrating the fixed arm 15 so as to be slidable in the vertical direction, the distance between the two plates 16 and 17 is constant.
Both plates 16 and 17 are integrally movable in the vertical direction relative to the fixed arm 15, that is, in a direction parallel to the nozzle 2.

Reference numeral 20 denotes a screw shaft, which is disposed between the upper plate 16 and the lower plate 17 and parallel to the guide shafts 18 and 19, and is screwed into a screw hole provided in the fixed arm 15 so that both After both ends are supported by bearings (not shown) provided on the plates 16 and 17, the upper end is attached to the upper plate 1.
It is connected to the output shaft of a reducer 21 attached to 6.

The input shaft of the reducer 21 is connected to the output shaft of a servo motor 22, which has a rotary generator 23 directly connected to the same shaft. Therefore, when the servo motor 22 is rotated forward or reverse, the screw shaft 20 rotates in the same direction. As a result of forward and backward rotation and screwing forward and backward through the screw hole of the fixed arm 15, the upper plate 16 and the lower plate 17 move in the vertical direction.

The maximum amount of vertical movement of both plates 16 and 17 must be greater than the required amount of movement of the welding torch 6 in the height direction, and the
The length of the screw shaft 20 is set so that there is a margin corresponding to this amount of movement.
Z that moves 0 linearly in the vertical direction parallel to nozzle 2
It is called the axis.

A bearing block 24 is fixed to the lower plate 17, and a guide shaft 25,
26 and a screw shaft 27 are inserted through the fixing arm 15 while keeping parallel to the fixed arm 15.

The guide shafts 25 and 26 are slidably inserted into the bearing block 24, and their ends are fixed to the support member 28, while the screw shaft 27 is screwed into a screw hole provided in the bearing block 24, and is used for deceleration. One end is connected to the output shaft of the machine 31, and the other end is supported by a bearing portion of the support member 28.

The input shaft of the speed reducer 31 is connected to a servo motor 29 equipped with a rotary generator 30, and when the motor 29 is rotated in the forward and reverse directions, the screw shaft 27 is also rotated in the forward and reverse directions to rotate the screw of the bearing block 24. As a result of screwing forward and backward through the hole, the support member 28 moves in a horizontal direction parallel to the fixed arm 15 and orthogonal to the Z-axis.

This screw shaft 27 is called the X axis, and the
The welding torch 6 is operated by three axes: axis, Z axis, and R axis.
It is formed into a spindle system for moving the.

Therefore, the support member 28 is attached to the welding torch 6
and the copying detectors 7A, 7B, and fixes the reducer 39 so that its output shaft faces vertically downward, and also connects the servo motor 32 having the rotary generator 33 to the reducer 39. It is directly connected.

The Z-axis 20 is connected to the output shaft of the reducer 39.
The F-axis 8 is directly connected to the F-axis 8, which is vertically installed parallel to the
It is made to swing about a line parallel to the axis 20.

This F-axis 8 is formed independently in a correction axis system.

The welding torch 6 is attached to the F-axis 8 in a hanging state, and a detector holding part 9 is also attached, and the detector holding shaft 10 is slidably fitted into the vertical shaft hole provided in the detector holding part 9. At least, the holding shaft 10 can be moved up and down in a direction parallel to the Z-axis 20.

Reference numerals 7A and 7B denote a pair of scanning detectors, which are pivoted at the lower end of the detector holding shaft 10 so as to be perpendicular to the holding shaft and arranged symmetrically on both sides of the welding torch 6. It supports me.

The pair of tracing detectors 7A and 7B thus arranged are as follows:
A correction signal is sent to the servo motor 32 so that both detectors 7A and 7B come into contact with the skirt portion at the lower side of the nozzle 2 and reach a neutral state at the same time. The welding location can be detected and the direction of the welding torch 6 can be controlled while using the side surface of the nozzle 2 as a detection target for the processed welding line 3.

In FIG. 1, 34 is a welding wire reel, and 35 is a welding wire feeding device, which is attached to the support member 28 and feeds the welding wire concentrically with the F axis 8. It is set up to provide.

Further, 36 is a height detector for determining the height of the welding torch 6, 37 is a Z-axis potentiometer, 3
8 indicates X-axis potentiometers.

The welding operation of the copy welding machine having the above configuration will now be described with reference to FIG. 1 and FIG. 2 showing the control system.

The welding machine is lifted by a crane or the like, placed on the flange surface of the nozzle 2 which is the work to be welded, and fixed with bolts.

Next, automatic-manual mode selectors 40, 40...
is switched to the manual side, the welding torch 6 is manually returned (moved) to the origin of the R axis 5, and this position information is stored in the memory 41 as the origin.

As for the R-axis 5, position detection is performed by the encoder 13 in an increased amount, so it is necessary to determine the absolute origin when the power is turned on.

In order to calculate the saddle-shaped weld line 3 forming a mutual curve, operate the digital switch on the operation panel interface 42 to calculate the diameter of the shell 1 (a value related to the vertical displacement of the welding position) and Information 43 on the diameter of the nozzle 2 (a value related to the radius of rotation at the position where welding is performed with respect to the fixed base 4) is stored in the memory 41, and information 43 on the number of welding passes and the welding speed change position is also stored in the digital switch. The information 43 on the welding speed is stored in the memory 41 by the operation, and the information 43 on the welding speed is similarly stored in the memory 41 by the operation of the variable resistor.

Next, the welding torch 6 is manually moved to the upper part of the welding start position, and the welding torch 6 is lowered to a specified height at a predetermined distance from the welding surface while visually checking the position indicator 44z of the Z-axis 20 on the operation panel surface.

With this position as the welding start point, each information of the encoder of the R axis 5, the potentiometers of the Z axis 20, and the X axis 27 is stored in the memory 41, respectively.

Before starting the actual welding from this state, a test operation is performed by operating the test switch 46 of the remote control box interface 45 and the run switch 46 to determine the direction of rotation, and then the scanning detector 7A, 7B follows the circumferential surface of the nozzle 2 and moves around the welding line 3 once (one rotation around the nozzle 2), then reverses and returns to the welding test start position, that is, the welding start point.

In this case, the fixed center of the welding machine, that is, the nozzle 2
The distance of the welding line 3 and the direction of the welding torch 6 with respect to the central axis of are controlled by the scanning detectors 7A and 7B, while the height control in the Z-axis 20 direction is controlled by (a) calculation control; b) Z-axis 2 that was previously welded
The 0 position can be performed either by reproducing the value stored in the memory or (c) by controlling the detection using the height detector 36. Among the three types of control, especially the calculation control in item (b) is as follows. It is done as follows. As shown in FIGS. 3A and 3B, the radius of rotation of the welding torch 6 is r, the radius of the shell 1 is R, and the central angle between the lowest welding position and the arbitrary position where welding is made with respect to the center of the nozzle 2. When the horizontal projection is θ, the height (△Z) based on the highest welding position is expressed as △Z=R−√ ² − ^{2 2} , so control with the value based on the above formula is performed. Just go.

After this test run is completed, the actual welding begins, by operating the welding switch on the remote control box interface 45 and operating the run switch.
6. After determining the rotational direction, the welding shield gas is discharged from the tip of the welding torch 6 while the circumferential surface of the nozzle 2 is detected by the scanning detectors 7A and 7B, and the welding torch 6 is operated for welding while being rotated.

It goes without saying that the Z-axis 20 is controlled by one of the three methods described in the test run, and in this case, the welding torch 6 is reversed by a certain amount, then rotated in the specified direction, and welding is started. Welding is started at the point (the arc is started while the welding torch 6 is moving).

In addition to the three Z-axis controls mentioned above, it is known that there is a proportional relationship between the welding arc current and the protrusion length, so the Z-axis is controlled to keep the arc current constant. Also suitable is a current control method.

During welding, the Z-axis position is sequentially stored in the memory 41. When welding is interrupted, R, X, Z
The positions of each axis are stored in the memory 41 as return position information up to the welding interruption point and used when welding is restarted.

Once the number of welding passes is completed or interrupted, crater processing and afterflow are performed and the equipment stops.

Since the shell 1 is thick, welding must be done in multiple layers, and in the case of height control, it is necessary to take into account the thickness of the welded bead.

Therefore, in calculation control A, the diameter of shell 1 changes by the thickness of the welded bead, so it is necessary to set the radius R each time, but automatic welding is possible by partial control. be.

On the other hand, if the memory value is replayed, the Z-axis memory value is the position from the previous welding, so the next time weld, the previous bead thickness is added to the memory value and replayed. Just do it.

Furthermore, in the case of using the height detector 36, the Z-axis may be controlled by adding the bead thickness to the signal from the height detector 36 each time welding is performed. That is, the bead thickness may be cumulatively added to the reference value of the signal from the height detector 36, which is set at the beginning.

The configuration and operation of the example of the device of the present invention are as described above, and the effects of the present invention will be described next.

(1) The position of the weld line is determined by a pair of tracing detectors 7A and 7B.
, and only the Z axis, that is, the vertical movement of the welding torch 6, needs to be controlled.
The welding device has the advantage that it is not necessary to precisely align the center with the nozzle center, making it easier to handle.

(2) No PTP teaching is required prior to welding, and handling is easy. In addition, real-time control is possible without the need for troublesome operations such as attaching a sensor in place of a welding torch and performing tracing.

(3) The main axis system has three degrees of freedom in the RX and Z axes, and the correction axis system has one degree of freedom in the F axis, making it possible to perform saddle-shaped three-dimensional welding with a total of four degrees of freedom. , the structure is simpler than the conventional 4 degrees of freedom for the main axis (RXZS) and 2 degrees of freedom for the correction axis (HV), which required a total of 6 degrees of freedom.
It also has the advantage of being easy to control.

As described above, the present invention is an automatic welding device that has excellent practical value and has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of an example of the device of the present invention, FIG. 2 is a control system diagram, and FIGS. 3A and 3B are plan views for explaining one control method for controlling in the height direction. The front view and FIG. 4 are perspective views of a conventional welding device. 1... Shell, 2... Nozzle, 3... Welding line, 4... Fixed base, 5... Motor shaft, 6... Welding torch, 7A,
7B...Copying detector, 8...F axis, 9...Detector holding part, 10...Detector holding shaft.

Claims (1)

[Claims] 1 A welding device that performs multilayer welding of a saddle-shaped groove welding line 3 formed at a joint when a nozzle 2 made of a small diameter circular pipe is orthogonally connected to a shell 1 made of a large diameter circular pipe, and The welding device includes a fixed base 4 for fixing the device to the upper part of the nozzle 2, an R axis for rotating the welding device around the nozzle 2, a Z axis for linear movement in the vertical direction, and a Z axis that is pivoted on the Z axis. It has three degrees of freedom with an X-axis that moves linearly in a direction perpendicular to the Z-axis, and is equipped with a welding torch 6 at the end of the X-axis, with a line parallel to the Z-axis as the central axis, and around the axis. The F-axis 8, which can be swung, is pivotally supported on the X-axis, and
The welding torch 6 and the detector holder 9 are attached to the F-axis 8, and the detector holder 9 is pivotally supported by a detector holder shaft 10 that moves linearly in the vertical direction. , 7B are fixed to the detector holding shaft 10 with their detection axes oriented in the horizontal direction and arranged symmetrically on both sides with the welding torch 6 in between, the pair of scanning detectors The position and orientation of the welding torch 6 is controlled by detecting the side surface of the nozzle 2 at 7A and 7B, while calculation control,
An automatic welding device characterized in that the height is controlled by reproducing a Z-axis memory value, controlling by a height detector, or by constant current control of an arc current in a welding torch 6.