JP5051351B2 - Arc welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arc welding apparatus which can shorten a teaching time and perform tandem arc welding of high quality, and also to provide an arc welding apparatus with high quality and excellent operability. <P>SOLUTION: In the arc welding apparatus, a first electrode 32 and a second electrode 42 of a torch 30 having consumable electrodes of welding wire are arranged in a designated direction to an object 60 to be welded while keeping a designated distance between the electrodes. The first electrode 32 performs welding and the second electrode 42 does welding succeedingly. A robot control unit 2 includes a tool dimension storing section 202 that stores relative positional relation between a tip of the first electrode 32 and that of the second electrode 42 taking a finger tip of the robot 1 as a reference, a locus calculation section 203 that calculates a locus of the robot 1 taking the tip of the first electrode 32 as the control point of the robot 1, and the second electrode position monitoring section 209 that calculates the tip position of the second electrode 42 and monitors a distance from welding start and welding end points to the position of the tip of the second electrode 42. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  According to the present invention, a two-electrode integrated torch or two single-electrode torches are mounted on a teaching reproduction type welding robot, and a first electrode and a second electrode having a welding wire as a consumable electrode are provided in a predetermined direction in the welding line of the workpiece. The present invention relates to an arc welding apparatus arranged with a distance between electrodes.

For the purpose of thick plate welding or the like, a technique called tandem arc welding is disclosed in which arcs are generated simultaneously using two welding power sources and electrodes. FIG. 6 is a diagram illustrating an overall configuration of a conventional tandem arc welding apparatus (see, for example, Patent Document 1). In the prior art, the roles of the two electrodes are not fixed, and the welding conditions can be commanded by setting the roles of the two electrodes as the leading electrode or the trailing electrode in accordance with the welding direction. Even when the welding direction is reversed, tandem arc welding can be performed without mechanically rotating the torch 180 °.
JP 2003-53535 A

In the prior art, as shown in FIG. 7, the leading electrode (second electrode) is moved to the welding start point (Ps) during welding teaching, the position is registered, and then the distance D between the electrodes is moved from there. The row electrode (first electrode) is positioned at the welding start point, and the position is registered.
In addition, when the leading electrode (second electrode) is moved to the welding start point, in addition to performing settings related to welding by the leading electrode (second electrode), the trailing electrode (first electrode) is set to the welding starting point. Since the first electrode is positioned at the first electrode, welding is set by the leading electrode (second electrode) and the trailing electrode (first electrode). Further, the same procedure is necessary for teaching about the welding end point (Pe).
In other words, in the teaching of the welding start point / end point, position registration and welding-related settings are made for each of the two electrodes, so that each time the teaching of the welding start point / end point is changed, two teaching operations are required. In the case of re-teaching due to changes, etc., there is a problem that the operation becomes complicated and takes time.
The present invention has been made in view of such problems, and an object of the present invention is to provide an arc welding apparatus that can reduce the time required for teaching and perform high-quality tandem arc welding.

  In order to solve the above problem, the present invention is configured as follows.

In an arc welding apparatus comprising: a robot; a robot control apparatus that controls the robot; and a two-electrode integrated torch or two single-electrode torch comprising a first electrode and a second electrode for supplying welding power to each electrode .
The first electrode and the second electrode are arranged with a predetermined inter-electrode distance with respect to the member to be welded ,
The robot control device includes a tool size storage unit that stores a relative positional relationship between a tip of the first electrode and a tip of the second electrode ;
A trajectory calculation unit that calculates the trajectory of the robot using the tip of the first electrode as a control point of the robot;
A second electrode position monitoring unit that calculates a tip position of the second electrode and monitors a distance between a welding start point and a welding end point set in advance on the welding target member and the tip position of the second electrode; Prepared,
After the first electrode reaches the welding start point and starts welding, the control point of the robot is moved at the first moving speed until the second electrode reaches the welding start point, The distance between the tip of the second electrode and the welding start point is acquired by the second electrode position monitoring unit, and when the second electrode reaches the welding start point and starts welding, the robot control point is moved to the second position. Move at speed,
In addition, the first moving speed is lower than the second moving speed .

The arc welding device according to claim 2, wherein the robot control device is configured such that, after the first electrode reaches the welding start point and starts welding, the second electrode position monitoring unit and the second electrode tip are connected to the welding. A distance from the start point is acquired, and a time until the second electrode reaches the welding start point is calculated from the distance and the moving speed of the control point of the robot, and the arrival time is a first predetermined time. When inside, a welding start command is sent to the welding power source of the second electrode .

4. The arc welding apparatus according to claim 3, wherein the robot controller sends an arc generation command to a welding power source for the second electrode, and then the second electrode position monitoring unit and the welding start point of the second electrode. When the arc generation confirmation response is not received from the welding power source of the second electrode even if the distance is equal to or greater than a second predetermined distance, the robot is stopped and a welding end command is sent to each welding power source. Is transmitted .

The arc welding device according to claim 4, wherein the robot control device sends an arc generation command to the welding power source for the second electrode and then from the welding power source for the second electrode even after a second predetermined time has elapsed. When there is no arc generation confirmation response, the robot is stopped and a welding end command is sent to each welding power source .

6. The arc welding apparatus according to claim 5 , wherein after the first electrode reaches the welding end point and the welding is finished, the robot control device uses the second electrode position monitoring unit to connect the tip of the second electrode and the welding. A distance from the end point is acquired, and when the distance falls within a second predetermined distance, a welding stop command is sent to the welding power source of the second electrode .

The arc welding apparatus of claim 6, wherein, the pre-Symbol robot controller, after the first electrode has been completed reaching welded to the welding end point, and the second electrode tip by the second electrode position monitoring unit The distance from the welding end point is acquired, and the time until the tip of the second electrode reaches the welding end point is calculated from the distance and the moving speed of the control point of the robot. A welding stop command is sent to the welding power source of the second electrode within a predetermined time .

The arc welding device according to claim 7, wherein after the first electrode reaches the welding end point and ends the welding, the second electrode position monitoring unit sets a distance between the second electrode tip and the welding end point. The control point of the robot is moved at the third movement speed until the second electrode reaches the welding end point, and the third movement speed is smaller than the second movement speed. It is characterized by that.

The arc welding apparatus according to claim 8, wherein after the first electrode reaches the welding end point and ends the welding, the second electrode position monitoring unit sets a distance between the second electrode tip and the welding end point. The time until the second electrode reaches the welding end point is calculated from the distance and the moving speed of the control point of the robot, and until the second electrode reaches the welding end point. The control point of the robot is moved at a third movement speed, and the third movement speed is smaller than the second movement speed .

According to the arc welding apparatus according to claims 1 to 6, since the tool electrode storage part also grasps the second electrode tip position that follows the preceding first electrode tip position, the welding start point / welding end point When teaching a point, it is only necessary to teach the first electrode. Since it is not necessary to teach the second electrode, the teaching work can be simplified, the required time can be shortened, and only the welding start point is taught only for the first electrode. Welding can also be started for the second electrode. Since the welding start command is issued to the welding power source before the second electrode reaches the welding start point, the actual welding start point by the second electrode is not shifted from that by the first electrode, and high quality tandem arc welding is performed. Can be realized. In addition, it is confirmed whether or not the arc is normally generated with respect to the second electrode, and when the arc generation is not confirmed, the welding is stopped, so that inappropriate welding can be prevented. By only teaching the welding end point for only the electrode, welding can be automatically ended for the second electrode when welding is performed. Since the welding end command is issued to the welding power source before the second electrode reaches the welding end point, the actual welding end point by the second electrode is not shifted from that by the first electrode, and high quality tandem arc welding is performed. Can be realized. Furthermore, only the teaching of the welding start point is performed for only the first electrode, and when welding is performed, automatic welding is performed by welding the first electrode alone in the vicinity of the welding start point and by tandem welding using the first electrode and the second electrode. It is possible to change the welding speed to achieve high quality tandem arc welding over the entire welding line.

According to the arc welding apparatus according to claims 7 and 8, tandem welding with the first electrode and the second electrode in the vicinity of the welding end point is performed at the time of performing welding only by teaching the welding end point only for the first electrode. The welding speed can be automatically changed between the time of welding with the second electrode alone, and high-quality tandem arc welding can be realized over the entire welding line.

  That is, according to the present invention, the labor and time required for teaching can be shortened, and the tandem arc welding with high quality can be performed over all the weld lines.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall configuration of the arc welding apparatus of the present invention.
The articulated robot 1 is controlled by a robot control device 2. Usually, a teaching device 3 for an operator to operate the robot 1 is connected to the robot control device 2. The operator presses a key corresponding to each axis (motor of each joint) arranged on the teaching device 3 to move the robot 1 to a desired position and presses a memory key on the teaching device 3. As a result, the current position of the robot is stored in the robot controller 2. In FIG. 1, various keys on the teaching device are not shown.

The robot 1 includes a two-electrode integrated torch 30 at the tip of the hand, and the two-electrode integrated torch 30 includes a first electrode 32 and a second electrode 42. The first electrode 32 and the second electrode 42 are supplied with electric energy for welding from the welding power source 31 and the welding power source 41, respectively, and perform a welding operation on the workpiece 60 that is a material to be welded. Reference numeral 50 denotes a jig for supporting the workpiece 60.
The welding power source 31 controls the wire feeding device 33 based on the welding condition command output from the robot control device 2. By operating the wire feeding device 33, the welding wire stored in the wire storage portion 34 is sent to the first electrode 32.
Similarly, when the wire feeding device 43 controlled by the welding power source 41 operates, the welding wire stored in the wire storage portion 44 is sent to the second electrode 42.
The wire feeding devices 33 and 43 are installed at appropriate locations between the base of the robot 1 and the two-electrode integrated torch 30.
In this embodiment, the two-electrode integrated torch 30 is used, but two single-electrode torches may be provided at the tip of the hand of the robot 1 instead.

Next, FIG. 2 shows a block diagram in the robot controller 2.
The robot control apparatus 2 includes a CPU 200 that controls the robot 1 and the welding power sources 31 and 41. The robot 1 is a teaching reproduction type, and an operator previously stores an operation locus including a welding start position and welding conditions in the form of a work program at the time of teaching. At the time of reproduction, the robot 1 is operated by executing the work program, and the welding power sources 31 and 41 are instructed. The taught work program is stored in the work program storage unit 210.
An operation command to each axis of the robot 1 is performed via the servo command unit 206, and feedback from the robot 1 is received by the feedback receiving unit 207. On the other hand, a command to the welding power source is given by the welding condition output unit 205 and the arc welding input / output unit 208.
The teaching position storage unit 201 stores a specific teaching position of the robot in the work program. This position can be designated by the Cartesian coordinate value of the robot 1 or can be designated by the pulse value or angle of each joint.

The tool dimension storage unit 202 stores the tip position and posture of the first electrode 32 and the tip position and posture of the second electrode 42 with reference to the tip of the hand of the robot 1. The tip position and orientation of the second electrode 42 may be based on that of the first electrode 32.
The trajectory calculation unit 203 generates the position of the robot 1 for each machine clock based on the interpolation method of the motion trajectory of the robot 1 specified by the work program and the moving speed. The machine clock is an internal clock with a certain period, and the CPU 200 performs processing such as position generation and instructions to the robot and welding power source for each clock. The generated command is sent to each axis of the robot 1 via the servo command unit 206 described above. In this embodiment, the tip of the first electrode 32 is used as a control point of the robot 1.
The welding condition storage unit 204 stores specific welding voltage values and welding current values corresponding to the welding conditions by the first electrode 32 and the second electrode 42 specified in the work program.

The process in the case of actually welding is demonstrated using FIG. 2, FIG.
When a work program reproduction is instructed by the operator operating the teaching device 3, the CPU 200 calls the designated work program from the work program storage unit 210. Then, the teaching position specified in the work program is read from the teaching position storage unit 201. Further, the current position of the robot 1 is read from the feedback receiving unit 207, and a locus from the current position to the teaching position is generated by the locus calculating unit 203.
At this time, the tip position and posture of the first electrode 32 are read from the tool dimension storage unit 202 and added to the position and posture of the tip of the tip of the robot 1 hand obtained from the feedback receiving unit 207 to obtain the control point of the robot 1. Generate a trajectory. The position command generated by the locus calculation unit 203 is output to the servo command unit 206, and the robot 1 moves to the teaching position.
Further, the second electrode position monitoring unit 209 reads the tip position and posture of the second electrode 42 from the tool dimension storage unit 202 and adds them to the position and posture of the tip of the tip of the robot 1 hand obtained from the feedback receiving unit 207. The tip position of the two electrodes 42 is obtained. In order to grasp the tip position of the second electrode 42 by calculation, in this embodiment, it is not necessary to register the state in which the second electrode 42 has reached the welding start point during the teaching operation.
The above process is repeated, and the first electrode 32 provided at the tip of the robot 1 moves to the welding start point taught in advance (FIG. 3A).

After confirming from the feedback position of the feedback receiving unit 207 that the first electrode 32 has reached the welding start point, the CPU 200 stores the first electrode 32 stored in the welding condition storage unit 204 according to the welding conditions specified in the work program. The contents of the welding conditions are read out and output to the welding power source 31 through the welding condition output unit 205. At the same time, the welding start is commanded from the arc welding input / output unit 208 to the welding power source 31 (FIG. 3B).
Further, the position of the welding start point is recorded in the second electrode position monitoring unit 209. The robot 1 stops at the welding start point until the arc welding input / output unit 208 receives an arc generation response from the welding power source 31.

When the arc welding input / output unit 208 receives an arc generation response from the welding power source 31, the robot 1 starts moving to the next teaching position. Further, the second electrode position monitoring unit 209 monitors the distance between the tip position of the second electrode 42 calculated as described above and the welding start point, and notifies the CPU 200 of the distance.
The CPU 200 calculates the remaining time until the second electrode 42 reaches the welding start point from the difference between the current moving speed of the control point and the position of the welding start point and the tip position of the second electrode 42.
When this time becomes equal to or shorter than the first predetermined time, the CPU 200 reads out the content of the welding condition by the second electrode 42 specified by the work program from the welding condition storage unit 204 and outputs it to the welding power source 41 through the welding condition output unit 205. At the same time, a welding start command is output to the welding power source 41 via the arc welding input / output unit 208 (FIG. 3C).
Since there is a delay time from the start of welding to the welding power source 41 until the actual arc is generated at the second electrode 42, the welding start command is output before the second electrode 42 reaches the welding start point. It is.
Further, if the distance between the position of the welding start point and the position of the second electrode 42 approaches the first predetermined distance or less without performing the process for calculating the remaining time, the welding power source 41 is welded. A start command may be output.
Thus, by storing the tip positions and postures of the first electrode 32 and the second electrode 42 in the tool dimension storage unit 202, the welding start point is taught for the first electrode. It is possible to automatically determine the arrival of the welding start point of the second electrode 42 and perform welding.

Also, the welding end point is taught only for the first electrode 32 at the welding end point. When the first electrode 32 reaches the welding end point during welding, the welding end command is sent from the arc welding input / output unit 208 to the welding power source 31, and the position of the welding end point is recorded in the second electrode position monitoring unit 209. To do.
The second electrode position monitoring unit 209 determines the distance between the welding end point and the tip position of the second electrode 42, or the remaining time until the second electrode 42 reaches the welding end point as the first predetermined distance, or the first By comparing with the predetermined time, the arrival of the welding end point of the second electrode 42 is automatically determined, a welding end command is output to the welding power source 41, and the welding by the second electrode 42 can be ended.
Thus, it is not necessary to register the state where the second electrode 42 has reached the welding end point during the teaching operation. Since it is not necessary to teach the welding start point / welding end point for the second electrode 42, re-teaching by changing the workpiece can be performed in a short time, and the teaching operation is not complicated.
Furthermore, since the command is output early in consideration of the command to the welding power source and the delay time until actual arc generation / extinction, the tandem welding can be performed in the range intended by the operator, and the welding quality can be improved.

When receiving the arc generation response from the welding power source 41, the robot 1 continues to move (FIG. 3 (d)). However, after the welding start command is sent to the welding power source 41, the arc welding is started. When the output unit 208 does not receive an arc generation response from the welding power source 41, the robot 1 is stopped and a welding end command is output to the welding power sources 31 and 41 via the arc welding input / output unit 208. The same applies to the case where the arc welding input / output unit 208 does not receive an arc generation response from the welding power source 41 even if the tip position of the second electrode 42 is more than the second predetermined distance from the welding start point. In this way, when arc generation cannot be confirmed for the second electrode, welding is stopped, so that incomplete tandem welding can be prevented.
The first and second predetermined times and predetermined distances are set and saved in the parameter storage unit 211 as parameters in advance. Parameter setting and confirmation can be freely performed by key operation of the teaching device 3.

Another embodiment of the present invention will be described below.
FIG. 4 is a diagram for explaining a change in the welding speed of the robot 1 near the welding start point, and FIG. 5 is a diagram for explaining a change in the welding speed of the robot 1 near the welding end point. As in the first embodiment, when the robot 1 performs welding according to the work program, first, in FIG. 4, when the first electrode 32 reaches the welding start point, the welding is started by the first electrode 32 alone.
During the period from the start of welding by the first electrode 32 until the second electrode 42 reaches the welding start point, welding is performed by the first electrode 32 alone, so that two wire penetration amounts can be ensured. It moves at a predetermined welding speed V1 lower than in the case of tandem welding with electrodes (FIG. 4 (a)).

When the second electrode 42 reaches the welding start point following the first electrode 32, the second electrode 42 starts welding. After starting the welding of the second electrode 42, the tandem welding is performed by the two electrodes of the first electrode 32 and the second electrode 42, so that the welding can be performed at a speed faster than V1.
Therefore, the robot 1 moves up to a predetermined welding speed V2 suitable for welding with the two electrodes, and moves (FIG. 4B). Here, it is appropriate that V1 has a speed of about 50% of V2.

Next, FIG. 5 will be described. The robot 1 continues to move at a predetermined welding speed (V2) along the welding line and approaches the welding end point. First, when the first electrode 32 reaches the welding end point, the first electrode 32 finishes the welding (FIG. 5A).
Thereafter, until the second electrode 42 reaches the welding end point, the robot 1 performs welding with the second electrode 42 alone. Therefore, the robot 1 has a predetermined value lower than V2 as in the vicinity of the welding start point. The welding speed (V3) is lowered and moved (FIG. 5 (b)). When the second electrode 42 reaches the welding end point, the second electrode 42 ends the welding. Here, V3 is suitably about 50% of V2 and is usually the same value as V1, but not necessarily the same speed.

By setting the welding speed at the time of independent welding with the first electrode or the second electrode to be smaller than that at the time of tandem welding with the first electrode and the second electrode to ensure the amount of penetration of the wire at the time of independent welding, As compared with the case where welding is performed at a constant welding speed over the entire length of the weld line regardless of tandem welding, a good weld bead with a constant welding amount can be obtained for all the weld lines, and high-quality welding can be performed.
In addition, according to the method described in the first embodiment, it is not necessary to teach the point at which the second electrode 42 has reached the welding start point / welding end point in the teaching work also in this embodiment. Therefore, the welding speeds V1 and V2 do not need to be changed during the teaching operation, and it is not necessary to specifically teach the switching timing, and the tandem welding by the two electrodes of the first electrode 32 and the second electrode 42 is not necessary. Only the speed V2 needs to be specified.
In order to realize the welding speed V1 / V3 at the time of performing welding, if the welding speed V1 / V3 is designated as a ratio with respect to V2 when teaching the welding start point / welding end point, the first embodiment is performed at the time of welding execution. The position of the second electrode is acquired by the method described in, and the welding speed is automatically switched to V1 / V3 in the vicinity of the welding start point / end point.
As another method of specifying the welding speed V1 / V3, a specific welding speed is stored in advance in the parameter melting storage unit 211 or the like, and the storage destination is specified when teaching the welding start point / welding end point. You may do it.

The figure which shows the whole structure of the arc welding apparatus of this invention Block diagram in the robot controller of the present invention The figure explaining the operation | movement in the vicinity of the welding start point of this invention The figure explaining the change of the welding speed near the welding start point of this invention The figure explaining the change of the welding speed near the welding end point of this invention The figure which shows the whole structure of the conventional tandem arc welding apparatus Diagram showing teaching procedure in the prior art

Explanation of symbols

1, 12 Robot 2, 19 Robot control device 3, 20 Teaching device 11, 30 Two-electrode integrated torch 13, 32 First electrode 14, 42 Second electrode 15, 16, 33, 43 Wire feeding device 17, 18, 31, 41 Welding power source 19a Welding power source dedicated port 19b General-purpose contact output unit 19c General-purpose external output port 19d Tandem welding control unit 34, 44 Wire storage unit 50 Jig 60 Work 200 CPU
201 Teaching position storage unit 202 Tool dimension storage unit 203 Trajectory calculation unit 204 Welding condition storage unit 205 Welding condition output unit 206 Servo command unit 207 Feedback receiving unit 208 Arc welding input / output unit 209 Second electrode position monitoring unit 210 Work program storage unit 211 Parameter storage

Claims (8)

In an arc welding apparatus comprising: a robot; a robot control apparatus that controls the robot; and a two-electrode integrated torch or two single-electrode torch comprising a first electrode and a second electrode for supplying welding power to each electrode .
The first electrode and the second electrode are arranged with a predetermined inter-electrode distance with respect to the member to be welded ,
The robot control device includes a tool size storage unit that stores a relative positional relationship between a tip of the first electrode and a tip of the second electrode ;
A trajectory calculation unit that calculates the trajectory of the robot using the tip of the first electrode as a control point of the robot;
A second electrode position monitoring unit that calculates a tip position of the second electrode and monitors a distance between a welding start point and a welding end point set in advance on the welding target member and the tip position of the second electrode; Prepared,
After the first electrode reaches the welding start point and starts welding, the control point of the robot is moved at the first moving speed until the second electrode reaches the welding start point, The distance between the tip of the second electrode and the welding start point is acquired by the second electrode position monitoring unit, and when the second electrode reaches the welding start point and starts welding, the robot control point is moved to the second position. Move at speed,
An arc welding apparatus characterized in that the first moving speed is smaller than the second moving speed. The robot controller, after the first electrode reaches the welding start point and starts welding, acquires a distance between the second electrode tip and the welding start point by the second electrode position monitoring unit, The time until the second electrode reaches the welding start point is calculated from the distance and the moving speed of the control point of the robot, and when the arrival time falls within the first predetermined time, the welding power source of the second electrode The arc welding apparatus according to claim 1, wherein a welding start command is sent to the welding machine . The robot control device, after sending an arc generation command to the welding power source of the second electrode, acquires a distance between the tip of the second electrode and the welding start point by the second electrode position monitoring unit, and the distance is If from the welding power source of the even become a second predetermined distance or more second electrodes is no arcing acknowledgment claims, characterized in that the robot is stopped, it sends the welding end command to the each welding power supply The arc welding apparatus according to 1 . When the robot control device sends an arc generation command to the welding power source of the second electrode and there is no arc generation confirmation response from the welding power source of the second electrode even after a second predetermined time has elapsed, the robot control device The arc welding apparatus according to claim 2 , wherein a welding end command is sent to each welding power source. The robot control device obtains a distance between the tip of the second electrode and the welding end point by the second electrode position monitoring unit after the first electrode reaches the welding end point and ends the welding. The arc welding apparatus according to claim 1 , wherein when the distance falls within a second predetermined distance, a welding stop command is sent to the welding power source of the second electrode. The robot control device obtains a distance between the tip of the second electrode and the welding end point by the second electrode position monitoring unit after the first electrode reaches the welding end point and ends the welding. The time until the tip of the second electrode reaches the welding end point is calculated from the distance and the moving speed of the control point of the robot. When the arrival time is within a second predetermined time, the welding of the second electrode is performed. 3. The arc welding apparatus according to claim 2 , wherein a welding stop command is sent to the power source. After the first electrode reaches the welding end point and finishes welding, the second electrode position monitoring unit acquires a distance between the second electrode tip and the welding end point, and the second electrode Until the end point is reached, the control point of the robot is moved at the third movement speed ,
The arc welding apparatus according to any one of claims 1 to 6, wherein the third moving speed is lower than the second moving speed. After the first electrode reaches the welding end point and finishes welding, the second electrode position monitoring unit acquires a distance between the second electrode tip and the welding end point, and controls the distance and the robot. The time until the second electrode reaches the welding end point is calculated from the moving speed of the point, and the control point of the robot is set to the third time until the second electrode reaches the welding end point. Move at the moving speed ,
The arc welding apparatus according to any one of claims 1 to 6, wherein the third moving speed is lower than the second moving speed.

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