JP4700267B2 - Automatic welding method - Google Patents

Description

The present invention relates to a method for performing automatic welding by controlling a robot having a welding torch attached to an arm tip via a torch holder.

In general, welding work in a factory is performed by automatic welding using a welding robot. That is, a welding torch is attached to the tip of the arm of the welding robot via a torch holder or a shock sensor. On the other hand, a temporarily welded work is mounted on a positioner, and the robot and the positioner are controlled by a program of the NC device. The welding is performed along a predetermined welding line by moving the workpiece and reversing the workpiece by the positioner.
As shown in FIG. 4, a general welding robot includes a turn 2 around a vertical axis of the base 1, a vertical swing 4 of the first arm 3, a vertical swing 6 of the second arm 5, a second The arm tip 7 has six control axes of rotation 8 about the arm axis, tilting 10 of the wrist 9 and rotation 11 of the wrist, and these control axes are controlled by the NC device 12. The welding torch 13 is fixed to a wrist flange (portion to which a welding torch is attached) 14 via a mounting plate 15, a shock sensor 16 and a torch holder 17. The shock sensor 16 absorbs the impact when the welding torch collides with a workpiece and outputs an emergency signal to the NC device to stop the robot and the positioner urgently.

  There are a plurality of types of welding torches 13 such as those having different lengths and those that are bent in the shape of a dog and having different angles at the tip of the torch, and these can be used properly depending on the welding site. In terms of length, long torches may not be able to weld near the welding robot, and short torches may not be able to weld deep due to interference between the workpiece and torch holder. is there. The same applies to the angle of the torch. Depending on the location, the tip of the torch cannot be oriented in the optimum direction due to interference between the workpiece and the torch holder. Therefore, when changing the length or angle of the torch, a device for removing and replacing the torch at the neck portion 13a and a device for replacing the tool (the entire torch unit including the holder) are provided.

  However, the former has an electrical contact at the attachment / detachment part at the tip of the torch, and a sealing material is provided. However, if dust adheres to the contact, it will ignite due to energization resistance and the sealing material will frequently be damaged. There is a disadvantage that management is troublesome. On the other hand, because the latter is connected to multiple tools installed in the tool magazine, there will be no problems such as poor contact of electrical contacts. Is disadvantageous in that the range of movement of the torch is limited by being pulled, and the price is also expensive.

Therefore, in general, a single torch selected according to the workpiece is attached to the robot for automatic welding, and the parts that cannot be automatically welded due to interference with the holder are manually welded later. Currently.
JP-A-7-284927

  However, the method of manually welding parts that cannot be automatically welded later requires not only a skilled welder, but also in the case of multiple build-ups such as large welded structures, There is a problem that the structure of the steel becomes discontinuous and the welding quality decreases. On the other hand, the method of exchanging torches and tools has the above-mentioned problems, and since the torch and tools are frequently exchanged during welding, the welding efficiency is lowered, and troubles at the time of exchanging easily occur. There is a problem.

  Accordingly, the present invention provides a technical means that provides the same versatility as if a single torch was replaced by replacing the torch with a wide variety of welding locations that could not be achieved with a single welding torch. It is an object to provide a technical means that enables continuous automatic welding without changing tools and tools.

The welding torch is generally attached to an attachment portion called a wrist flange provided at the arm tip of the welding robot via a torch holder having a shock sensor. The present invention, wherein the Tochihoru da, i.e. between the welding torch (the same. In the mounting portion. Hereinafter and claims of the welding torch or torch holder for a welding robot) wrist flange of the welding robot, the welding torch relative to the wrist flange The above problem is solved by interposing a conversion device that changes the position or posture in a stepwise manner based on an operation signal from an NC device that controls the welding robot .

Chi words, the wrist flange 14 of the welding robot, a detachable mounting plate 15 to the flange, preferably the shock sensor 16, based on the operation signal from the NC device for controlling the welding robot position or orientation of the torch through the torch holder that includes a converter for converting stepwise Te, it mounts the welding torch 13. The first recommended converter is the telescopic device 23 that moves the torch back and forth in the longitudinal direction, and the second recommended device is a tilt that swings the torch around an axis orthogonal to the longitudinal direction. Device 26.

In the automatic welding method according to the first aspect of the present invention, the welding torch 13 is attached to the wrist flange of the welding robot whose position and direction of the wrist flange 14 are controlled by the NC device 12 via the torch holder having the above structure. When the NC device receives a torch replacement command from the machining program 34, the NC device converts the command into an operation signal of the conversion device and outputs it, and the operation position at each stage of the conversion device. The corresponding tool data is registered, the operation of the conversion device is controlled by the NC device, and when the NC device operates the conversion device, the tool data registered corresponding to the position after the operation It is an automatic welding method characterized by controlling a robot using a robot.

The signal conversion unit 39 is a program that, when a torch replacement command is issued from the machining program 34, converts the torch replacement command into an operation signal of the conversion devices 23 and 26 provided in the torch holder and outputs the operation signal.

  When using a torch holder provided with a plurality of conversion devices, such as when using a torch holder provided with both the telescopic device 23 and the tilting device 26, tool data corresponding to each combination of operating positions of each conversion device. Is registered in the NC device 12, and when the NC device performs an operation of a certain conversion device, the robot is controlled using tool data corresponding to the set of operation positions of each conversion device after the operation.

According to the automatic welding method of claim 1 of the present application, by operating the expansion / contraction device 23 or the tilting device 26 to expand / contract or tilt the torch, the torch having a different length or a torch having a different tip angle is exchanged. The same effect as can be realized. Accordingly, by appropriately operating the expansion / contraction device 23 and the tilting device 26 according to the welding site, it is necessary to tilt the torch tip deeply in a near or deep location near the robot or narrowly with one type of torch. It is possible to weld a wide range of welding sites such as locations without changing the torch.

Further, according to the invention of the present application , it is possible to perform automatic welding by the method of the present invention using an existing machining program including a torch replacement command, and when the welding torch is expanded or contracted, the expansion and contraction is performed. The tool data of the NC device 12 is converted according to the position and tilting position, and even if the torch is expanded or tilted during the welding, it is not necessary to change the welding program. It is possible to perform continuous automatic welding of workpieces having various shapes of welding sites without changing the torch and without changing the torch.

It is sufficient that the telescopic device 23 and the tilting device 26 can change the telescopic position and the tilting position in two steps or several steps. On-off control may be used when changing to two stages, but servo control is convenient when changing to three or more stages. Even in the case of servo control, the conversion of the operation position is stepwise, and if the tool data for each step is registered, the welding method of the present invention is possible.

The automatic welding method of the present invention does not increase the control axis of the robot or attach a plurality of torches to the robot, but the torch holder attached to and detached from the robot has a function of changing the position or posture of the torch. Depending on the performance of the welding robot and the type of welded structure, such as a torch holder that can only extend and retract and a torch holder that can both extend and tilt, it can be implemented using the existing robot as it is. It is possible to use different holders, and it is possible to add economically necessary functions by exchanging the torch holder and adding a control program for the NC device.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a mounting structure of a welding torch 13, and 14 is a wrist flange of a welding robot. The wrist flange 14 is provided at the tip of a wrist 9 provided on the wrist tilt portion 20 so as to be rotatable about an axis. The welding torch 13 is a long torch having a long shaft length, and is attached to the wrist flange 14 via a mounting plate 15, a shock sensor 16, a fixed bracket 21, a swinging bracket 22, a telescopic cylinder 23 and a torch clamper 24.

  The mounting plate 15 can be attached to and detached from the wrist flange 14 with a screw (not shown). The shock sensor 16 is mounted with the rod 16a fixed to the mounting plate 15, and a fixing bracket 21 is fixed to the body 16b. The swing bracket 22 is pivotally supported on the fixed bracket 21 by a pin 25. Between the intermediate position of the swing bracket 22 and the fixed bracket 21, a tilt cylinder 26 is installed with a trunnion structure at both ends. The tilt cylinder 26 is a servo cylinder. The telescopic cylinder 23 is fixedly attached to the swing bracket 22, and a torch clamper 24 is fixed to the tip of the telescopic rod 23a. The telescopic cylinder 23 is a servo cylinder with a built-in detent of the rod 23a, and is controlled so as to take only two positions, an extended position and a retracted position. The welding torch 13 is mounted with its neck portion sandwiched by a torch clamper 24. The welding torch 13 can be replaced with another torch by opening the clamper 24.

  In FIG. 1, the retracted position of the welding torch 13 is indicated by a solid line, and the tip of the torch is indicated by imaginary lines 27 and 28 in the figure by extending the telescopic cylinder 23 and extending and retracting the tilting cylinder 26. Elongate or tilt.

  FIG. 2 is a control block diagram of the NC device. The robot control unit 30 and the positioner control unit 31 are the same as those provided in the conventional NC device, and process the robot 32 (see FIG. 4) and the positioner 33, respectively. Control is performed according to a command from the program 34. The telescopic part 35 and the tilting part 36 control the telescopic cylinder 23 and the tilting cylinder 26 of the torch holder, respectively. The tool data selection unit 37 selects a registered data set in association with each combination of position signals of the expansion / contraction unit 35 and the tilting unit 36 from a plurality of registered tool data sets, and the robot control unit 30 The output value is shifted.

  As shown in FIG. 3, the tool data 38 is data indicating the positional relationship between the wrist flange 14 and the torch tip 13b, and the distances (bias amounts) of the torch tip 13b with respect to the center of the wrist flange 14 in the X, Y, and Z directions. The angle α of the nozzle tip with respect to the rotation center axis of the wrist flange 14 is registered as a set of data. In the torch mounting structure of the present invention, X, Y for each of combinations (six types of combinations) when the telescopic cylinder 23 is extended and retracted, and when the tilting cylinder 26 is changed in, for example, three stages. , Z and α are registered as a set.

  When a torch replacement command is issued from the machining program 34, the signal conversion unit 39 converts the torch replacement command into an extension or contraction signal of the expansion / contraction cylinder 23 and a tilt angle of the tilt cylinder 26, and the expansion / contraction unit and tilt unit 35, 36 is a program to be output to 36. If the signal conversion unit 39 having such a function is provided, automatic welding can be performed by the method of the present invention using an existing machining program including a torch replacement command. In the example of FIG. 1, since servo cylinders are used as the telescopic cylinder 23 and the tilting cylinder 26, signals from the telescopic unit 35 and the tilting unit 36 of the NC device are sent to these cylinders 23 and 26 via the servo amplifiers 40 and 41, respectively. It is shown just in case that it is given. A similar servo amplifier is naturally inserted in the control circuit of the robot 32 and the positioner 33, but is omitted in the figure because it has a conventional structure.

  In the above apparatus, when the machining program for the workpiece in the NC device 12 is registered and the workpiece is automatically welded, when the exchange of the welding torch is instructed from the machining program, the expansion and contraction is performed according to the content of the command. The part 35 and the tilting part 36 extend and retract the telescopic cylinder 23 as appropriate, and extend and contract the tilting cylinder 26 so as to have any one of the angles set in three stages. As a result, the torch length and angle are converted so that welding of a welded part that could not have been done without torch conversion is possible.

  Along with this conversion, the tool data selection unit selects the converted tool data and shifts the output of the robot control unit 30 so that the tip of the welding torch after expansion / contraction or tilting becomes a predetermined welded portion. The position of the wrist flange 14 is controlled on the robot side so as to face with an appropriate torch gap, torch position and posture. Then, by operating or returning the telescopic cylinder 23 and the tilting cylinder 26 as necessary during welding, the welding parts having various restrictive conditions are continuously automatically welded.

  When overlaying multiple layers, the necessary torch posture conversion is performed for each layer of overlay, so it is possible to maintain good continuity in welding quality at the site where the torch posture is converted. is there. In addition, although the said Example described what provided the expansion device and tilting device of the welding torch as the best form, in the actual automatic welding, the situation where the tilting of the torch is necessary requires the expansion and contraction of the torch. Since the rate of occurrence is small compared to the situation, if the situation where tilting is not necessary, the structure shown in FIGS. 1 and 2 removes the part related to the tilting of the torch. It is possible to implement the invention at a lower cost.

Side view showing torch mounting structure NC unit control block diagram Illustration of tool data Schematic side view showing the control axis of a general welding robot

Explanation of symbols

13 Welding torch
14 Wrist flange
15 Mounting plate
16 Shock sensor
23 Telescopic cylinder
24 Torch clamper
26 Tilt cylinder

Claims (3)

The position and orientation of the welding torch with respect to the wrist flange on the wrist flange of the welding robot whose position and direction of the wrist flange (14) are controlled by the NC device (12) are stepwise based on the operation signal from the NC device. The welding torch (13) is mounted via a conversion device (23, 26) for converting into a torch holder having a holder (24) for holding the welding torch (13),
When receiving a torch exchange command from the machining program (34), the NC device converts the command into an operation signal of the conversion device and outputs the converted signal, and each stage of the conversion device. Register tool data corresponding to the operating position,
Controls the operation of the converter in the NC device, when the NC device is operated the conversion device to control the robot by using the tool data registered in correspondence to the position after the operation An automatic welding method, wherein automatic welding is performed without exchanging the torch using a machining program including a torch exchange command .
The automatic welding method according to claim 1, wherein the conversion device is an expansion / contraction device (23) for moving the holding tool (24) holding the welding torch (13) forward and backward in the longitudinal direction of the welding torch . The conversion device intersects at right angles to the longitudinal direction of the welding torch held by the holding tool and the telescopic device (23) for moving the holding tool (24) holding the welding torch (13) forward and backward in the longitudinal direction of the welding torch. The automatic welding method according to claim 1 , wherein the tilting device (26) swings the holder around an axis to be rotated .

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