JP4510475B2 - Automatic welding method - Google Patents

Description

This invention relates to a method for automatic welding by controlling the robot equipped with a welding torch, to a welding method which enables converting the angle of the torch tip in accordance with the welding site.

  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 arm tip of the welding robot via a torch holder equipped with a shock sensor, while the temporarily welded work is mounted on a positioner, and the robot and the positioner are controlled by a program of the NC device. Welding is performed along a predetermined welding line by moving the welding torch and reversing the workpiece by the positioner.

  As shown in FIG. 5, a general welding robot has a swing A around the vertical axis of the base 1, a vertical swing B of the first arm 2, a vertical swing C of the second arm 3, a second The arm has four control axes of rotation D around the arm axis of the tip 4 of the arm, tilting E of the wrist 5 and rotation F of the wrist, and these control axes are controlled by the NC device 12. The welding torch 13 is fixed to a mounting plate 15 of a wrist flange (a portion to which a welding torch is attached) 14 via a torch holder 17 having a shock sensor 16. 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 ones having different lengths and ones that are bent into a square shape in the middle and differing in the angle of the tip of the torch. For example, when welding a groove-like part or narrow part, if the torch interferes with the edge of the groove or an adjacent member and welding cannot be performed, replace the tip with a torch that is bent in a square shape to avoid interference. . Depending on the direction of the groove, it may be necessary to replace the torch bent in the opposite direction. The same applies to the length of the torch. When welding the bottom of the deep groove portion, a long torch must be used. In view of this, there are provided devices for exchanging the tip of the torch by removing the tip of the torch at the neck portion 13a when changing the length of the torch or the angle of the tip of the torch and devices for exchanging the tool (the entire torch unit including the holder).

In addition, for the purpose of reducing the interference between welding cables, air piping, etc., workpieces and jigs, a structure that provides a flexible device with a mechanism that bends left and right or back and forth, and wire winding that can bend the torch body Patent Documents 2 and 3 disclose the torch formed by the above.
JP-A-7-284927 JP-A-5-309586 Japanese Patent No. 2701370

  However, the method of exchanging the tip of the torch has an electrical contact at the neck portion 13a to be attached and detached, and a sealing material is provided. There is a drawback that maintenance management is troublesome, such as frequent damage. On the other hand, in the method of replacing the entire unit including the holder, since the electric cable is connected to each of the plurality of tools mounted on the tool magazine, problems such as poor contact of the electric contacts do not occur. There are drawbacks such as the cable becoming tangled by changing the tool, the cable being pulled and the range of movement of the torch being limited, and the price is also expensive.

  Furthermore, in the conventional method of exchanging torches and tools, there is a problem that the torch and tools are frequently exchanged during welding, so that the welding efficiency is lowered and troubles are easily caused during the exchange.

  Therefore, the present invention provides a technical means for imparting the same versatility as if a single torch was replaced by replacing a torch. The object is to obtain technical means that enables continuous automatic welding without changing torches 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. In the present invention, between the welding torch and the torch holder, and instrumentation through the tilting device that converts the angle of the torch head relative to the torch holder.

That is, in the automatic welding method according to the invention of the present gun according to claim 1, an elongated support rod 18 which is supported the support portion 24a of the proximal end by welding robot, in the longitudinal direction perpendicular axis 19 around the tip of the support rod to the welding torch 13 which is rotatably mounted, it is provided a tilting device 26 for tilting the welding torch in the axial direction.

  The support rod 18 is mounted on the torch holder 24 with its longitudinal direction being the same as the longitudinal direction of a conventional welding torch. The direction of the rotating shaft at the tip of the torch is a direction in which the axial direction becomes the moving direction of the welding torch. By operating the tilting device 26, the torch tip 13b attached to the tip of the support rod 18 can be tilted by a predetermined angle around the axis 19 in the moving direction of the welding torch. This inclination angle is set by a movement amount set in the tilting device 26 and a stopper that defines the movement amount.

By operating the tilting device 26 in the tilting direction or the return direction, the torch tip 13b is converted into a bent shape or a straight direction with respect to the support rod 18, so that the position of the torch tip 13b with respect to the torch holder 24 is changed. Displace. Therefore, it is necessary to correct the deviation of the torch tip 13b from the predetermined weld line with the operation of the tilting device. The automatic welding method of the present application is a method of performing automatic welding by correcting the deviation on the NC device side.

That is, in the automatic welding method according to the first aspect of the present invention, the torch tip 13b is moved close to and away from the wrist flange of the welding robot that controls the position and direction of the wrist flange 14 by the NC device 12. A welding torch 13 is mounted via a torch holder 24 provided with a telescopic device 23 and a swing bracket 29 provided with a tilting device 26 for converting the angle of the welding torch 13, and a torch exchange command of a machining program of the NC device the converted the tilting angle signal expansion signal and the inclination movement device of the telescopic device, controls the operation of the telescopic device and tilting device in the NC device, the NC device tool data corresponding to each operating position When the NC device operates at least one of the telescopic device and the tilting device, it corresponds to the position and posture after the operation. It is characterized in that to control the robot by using the recorded set of tools data.

  By operating the tilting device 26, the welding torch 13 attached to the tip of the support rod 18 rotates by a predetermined angle around the axis 19 in the moving direction of the torch. Therefore, even if the welding torch is not replaced, the same effect can be obtained as when the torch is changed from a straight torch to a torch that is bent like a letter, or vice versa. Without interchanging the torch, it is possible to avoid interference between the welding torch and the workpiece or jig being welded.

Further, according to the automatic welding method of claim 1 of the present application, the extension of the expansion / contraction device 23 provides the same effect as replacing the torch with a long torch, and welding the bottom of the deep groove-like portion without replacing the torch. It can be performed.

  Accordingly, by appropriately operating the expansion / contraction device 23 and the tilting device 26 according to the welding site, the one near the front of the welding robot, the deeper portion, or the narrower torch tip must be inclined deeply with one type of torch. It is possible to perform welding of a wide range of welding parts such as a place that must be performed without exchanging the torch.

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

The present invention, or increase the control shaft of the robot, instead of mounting a plurality of torches on the robot, the torch mounting portion at an angle conversion function of the torch tip, extension of the telescopic device torch changing command of a machining program or Since it is converted into a contraction signal and a tilt angle of the tilting device and output to the telescopic unit and tilting unit, it can be implemented using the existing machining program including the torch replacement command and the existing robot and torch holder as they are. .

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing an example of a mounting structure of a welding torch used in the method of the present invention . FIG. 1 is a side view and FIG. 2 is a front view. The moving direction of the welding torch (the direction of the welding line) is a direction perpendicular to the paper surface of FIG. In the drawing, the wrist flange of the welding robot indicated by reference numeral 14 is provided at the tip of the wrist 5 provided to be rotatable around the central axis of the tilt portion 20.

1 and 2, the mounting plate 15 is detachably fixed to the wrist flange 14 with screws or the like (not shown). Shock sensor 16, the has a body 16b is fixedly attached to the mounting plate 15 is fixed to a fixing bracket 21 of the cylinder 23 to the rod 16a is telescopic device. A support tool (torch holder) 24 for supporting the support rod 18 is attached to the slider 23a of the cylinder. The welding torch 13 having a short length is attached to the tip of the support rod so as to be rotatable around the pin 19. Reference numeral 26 denotes a cylinder for tilting the welding torch.

The support 24 includes a reverse L-shaped portion (support portion) 24a in a front view shown in FIG. 2, and a bottom plate 24b positioned on the back side in FIG. 2 of the reverse L-shaped portion . The proximal end of the support rod 18 is fixed to the outer surface 24c of the vertical member in the inverted L-shaped portion of the support 24, and the lateral member 24d in the inverted L-shaped portion of the support 24 has a torch. A through hole 27 for guiding the cable 25 is provided. A pin 19 whose axial direction is the direction of movement of the torch is rotatably mounted on the front end side of the support rod 18 by a bearing 28. A torch fixture 29 is integrally formed at one end of the pin 19, and a crank 51 having a crankpin 50 at the tip is fixed to the other end. A three-position cylinder 26 serving as a tilting cylinder is mounted on the base end side of the support rod 18 so as to be swingable around a mounting pin 52 parallel to the pin 19, and a screw at the tip of the rod 26a is connected to the crank pin. 50 is screwed into a base end of a crank rod 53 having a tip connected to 50, and is fixed by a lock nut 54 so that the length can be adjusted. The welding torch 13 is fixed to the torch fixing tool 29.

  As shown by an imaginary line in FIG. The tilt angle can be adjusted by adjusting the screwing amount of the connecting portion between the rod 26a of the three-position cylinder and the crank rod 53. By using the three-position cylinder 26 as a drive source for the tilting device, the angle of the torch tip 13b can be changed in three steps, that is, the straight direction S and the tilting directions L and R to both sides as shown in FIG. it can.

  The support rod 18 is in a position deviated from the support tool (torch holder) 24 in a front view, and the center of the welding torch 13 and the center of the support tool 24 coincide.

  FIG. 3 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 the machining program for the robot 32 (see the figure) and the positioner 33, respectively. Control is performed in accordance with a command from 34. The telescopic part 35 and the tilting part 36 control the telescopic cylinder 23 and the tilting cylinder 26, 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. 4, the tool data 38 is data indicating the positional relationship between the wrist flange 14 and the torch tip 13b, and 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 torch 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 three stages, for example. , 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 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. Thereby, the length of the torch and the angle of the tip of the torch are converted so that welding of a welded part that could not be performed without torch replacement 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 and automatically welded. When overlaying multiple layers, the necessary torch posture conversion is performed for each layer, so it is possible to maintain good continuity of welding quality at the part where the torch posture is converted. is there.

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

Explanation of symbols

12 NC unit
13 Welding torch
13b Torch tip
14 Wrist flange
15 Mounting plate
18 Supporting cage
23 Telescopic device
24 Support
24a L-shaped part
26 Tilt cylinder
29 Torch fixture

Claims (1)

A torch holder provided with an expansion / contraction device (23) for bringing the tip of the torch (13b) close to and away from the wrist flange of the welding robot that controls the position and direction of the wrist flange (14) with the NC device (12) (24) and a swinging bracket (29) provided with a tilting device (26) for converting the angle of the welding torch (13), the welding torch (13) is mounted, and the machining program of the NC device the torch changing command to convert the tilting angle signal expansion signal and the inclination movement device of the telescopic device, controls the operation of the telescopic device and tilting device in the NC device, the tool data corresponding to each operating position registered in the NC device, when the NC device is operated at least one of the telescopic device and the tilting device, and controls the robot by using the tool data registered in correspondence with the position and orientation after the operation , Replace the torch An automatic welding method characterized in that automatic welding is enabled by the processing program including a torch replacement command without any change .

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