TWI495533B - Arc welding method - Google Patents

Description

Arc welding method

The present invention relates to an arc welding method using a pin pulse welding method.

Figure 9 shows an example of a conventional welding system. The welding system 91 in the figure is welded using a so-called stitch pulse welding method. The stitch pulse welding method is a welding method in which the heat influence applied to the base material can be easily suppressed by controlling heating and cooling at the time of welding. Compared with the conventional thin plate welding, it is considered that the use of the stitch pulse welding method can improve the appearance of the welding and also reduce the amount of the welding bead (for example, refer to Patent Document 1).

The robot 9M performs automatic arc welding on the base material 9W, and is composed of an upper arm 93, a lower arm 94, a wrist portion 95, and a servo motor (not shown) for driving the rotation of these mechanisms.

The arc welding lance 9T is attached to the front end of the wrist portion 95 of the manipulator 9M, and is used to guide the welding position of the welding wire 97 wound around the reel 96 to the base material 9W. The welding power source 9WP supplies a welding voltage between the arc welding torch 9T and the base material 9W. When the base material 9W is welded, the welding wire 97 is projected to the length required for the front end of the arc welding spray gun 9T to be welded.

The coil strip 92 is attached to the arc welding torch 9T and is used to guide the inner welding wire 97.

The teaching pendant 9TP as an operating device is a so-called movable operating panel for setting the operation of the robot 9M, the conditions required for the pulse welding of the stitches, and the like.

The robot control device 9RC is for the robot 9M to perform welding operation control, and includes a main control unit, an operation control unit, a servo driver, and the like (all not shown). Then, based on the work program instructed by the operator through the programmer 9TP, the servo driver outputs an operation control signal to each of the servo motors of the robot 9M to rotate the plurality of axes of the robot 9M. Since the robot control device 9RC recognizes the current position by the output of an encoder (not shown) provided in the servo motor of the robot 9M, the tip end position of the arc welding gun 9T can be controlled. Then, stitch welding is performed while welding, moving, and cooling are performed on the welded portion.

Fig. 10 is a view for explaining the state when the stitch pulse welding is performed. The welding wire 97 protrudes from the front end of the arc welding lance 9T. The shielding gas G is continuously blown out by the arc welding lance 9T at a constant flow rate from the start of welding to the end of welding. The following describes each state of the stitch pulse welding.

Figure 10(a) shows the situation when the arc is generated. According to the set welding current and the welding voltage, an arc a is generated between the tip end of the welding wire 97 and the base material 9W, the welding wire 97 and the base material 9W are melted, and the molten pool Y is formed on the base material 9W. The arc a is stopped after the indicated welding time.

Figure 10(b) shows the situation after the arc has stopped. After the arc is stopped, the state after the welding is maintained until the set cooling time elapses. In other words, in the state in which the manipulator 9M and the arc welding lance 9T are stopped in the same state as that at the time of welding, the arc welding lance 9T discharges only the shielding gas G, and the molten pool Y is substantially cooled and solidified by the shielding gas G.

Figure 10(c) shows the movement of the arc welding torch 9T to the next welding position. After the cooling time, the arc welding lance 9T is moved in the welding progress direction to an arc restart point of a predetermined positional pitch Mp. The moving speed at this time is the set moving speed. The moving pitch Mp is a distance at which the welding wire 97 is adjusted to the outer position of the melt mark Y' after the molten pool Y is solidified as shown in Fig. 10(c).

Fig. 10(d) shows the case where the arc a is regenerated at the arc restart point. The front end of the weld mark Y' forms a new molten pool and is welded. In the stitch pulse welding system 91, an arc generating state and a moving state are alternately performed in this manner. Welding beads are then formed such that the weld marks (squamous) overlap.

Figure 11 is a diagram showing the welding beads formed after welding. As shown in Fig. 11, the weld mark Sc is formed at the first arc start point P1, and the weld mark Sc is formed similarly at the restart point P2 of the welding travel direction Dr pitch Mp. The weld mark Sc is also sequentially formed after the arc start point P3. As a result of the welding marks Sc (square) overlapping each other, the scaly welding beads B are formed.

In the above method, as shown in Fig. 10(b), Fig. 10(c) and the like, the step of generating the arc a after the arc a is stopped is repeated. Recurrence of the arc a causes a problem that the appearance of the solder bead B deteriorates due to splashing. Therefore, as shown in Fig. 12, a welding method in which the arc a is not stopped and the arc a is not generated is proposed (for example, see Patent Document 2).

As shown in Fig. 12(b) and Fig. 12(c), this method is different from the case of Fig. 10(b) and Fig. 10(c), and the arc a is not stopped when the molten pool Y is cooled. The state in which the arc a is generated is maintained. Since it is not necessary to generate the arc a again, it is possible to suppress the occurrence of splashing. In this case, a conventional technique is, for example, using an alternating current pulse current during soldering, and using a weak direct current during cooling and moving.

Even with such a stitch soldering method, it is sometimes necessary to perform pit processing in order to prevent defects in the solder terminal portion. The pit processing refers to, for example, a welding process using a welding current and a welding voltage which are weaker than usual in order to make the molten pool Y less likely to cause a depression. Performing this pit treatment can prevent the solder terminal portion from being thinned, and the solder terminal portion is less likely to be defective.

In this arc welding method, it is possible to indicate an arbitrary position as a welding end predetermined position by, for example, the braider 9TP. The above-described pit processing will be performed at the predetermined position where the welding is ended. However, the predetermined position at which the welding ends is sometimes caused by the arc welding lance 9T to be welded without overlapping with the stop position. That is to say, it is possible that the welding lance 9T is moved to a predetermined position at the end of the welding from the stop position to the next stop position of the pitch Mp. At this time, when the pit processing is performed at the predetermined position at the end of the welding, a fish scale having a different pitch from the previous weld mark Sc is formed, and the appearance of the welded bead B is deteriorated.

[Patent Document 1] JP-A-6-55268

[Patent Document 2] Japanese Patent Publication No. 11-267839

The present invention has been conceived in light of the above circumstances, and an object thereof is to provide an arc welding method which can form a more beautiful drop bead.

An arc welding method provided by the present invention repeats the first step and the second step, wherein the first step stops the welding lance at one of a plurality of stop positions at each of the indicated moving pitches, in the base material An arc is generated between the consumable electrode held by the welding lance described above to perform droplet transfer. In the second step, while an arc is generated between the base material and the consumable electrode, the molten pool formed in the base material is cooled, and the welding lance is moved by the moving pitch to the next stop. Location. When the distance from the indicated welding end to the predetermined position is within the above-described stop position within the above-described moving pitch, the welding is stopped after the last first step.

In a preferred embodiment of the present invention, in the welding traveling direction, the welding is ended at the stop position closer to the welding start position than the indicated predetermined end position of the welding.

In a preferred embodiment of the present invention, the first step other than the last first step is performed by flowing an arc welding current between the base material and the consumable electrode. The last first step of the above is performed by flowing the arc welding current between the base material and the consumable electrode.

In still another preferred embodiment of the present invention, the first step other than the last first step is performed by flowing an arc welding current between the base material and the consumable electrode. The first step of the last step is performed by a pit processing current having a flow absolute value smaller than the arc welding current between the base material and the consumable electrode.

In still another preferred embodiment of the present invention, the first step other than the last first step is performed by flowing an arc welding current between the base material and the consumable electrode. The first step of the last step is performed by flowing the arc welding current and then flowing a pit processing current having an absolute value smaller than the arc welding current between the base material and the consumable electrode.

In a preferred embodiment of the present invention, the method further includes the step of moving the welding lance at a speed faster than the moving speed in the second step after performing the last first step of the welding.

In the arc welding method of the present invention, even if the predetermined position at which the welding is completed does not coincide with the stop position of the plural number, the welding is stopped at the stop position at which the last first step is performed. Therefore, in the case where the pit processing is performed before the end of the welding, the pit processing is performed at the above-described stop position. Therefore, according to the arc welding method of the present invention, since the weld marks formed in the welding end portion, such as the pit processing, do not disturb the interval of the previously formed scaly beads, a more beautiful welding bead can be formed.

Other features and advantages of the present invention will be understood by reference to the drawings and the appended claims.

Embodiments of the present invention will be specifically described below with reference to the drawings.

Fig. 1 is a view showing an example of a welding system composition suitable for use in the arc welding method of the present invention. The welding system A shown in Fig. 1 includes a welding robot 1, a robot control device 2, and a welding power source device 3. The welding robot 1 automatically performs, for example, arc welding on the base material W. The welding robot 1 includes a base 11, a plurality of arms 12, a plurality of motors 13, a welding lance 14, a welding wire feeding device 16, and a coil bead 19.

The base 11 is fixed to an appropriate place such as a floor. Each arm 12 is coupled to the base 11 through a shaft.

The welding lance 14 is provided at the front end of the wrist portion 12a at the foremost end of the welding robot 1. The welding lance 14 guides, for example, a welding wire 15 having a diameter of about 1 mm as a consumable electrode to a predetermined position in the vicinity of the base material W. The welding lance 14 is provided with a shielding gas nozzle (not shown) for supplying a shielding gas such as Ar. The motor 13 is disposed at both ends or one end of the arm 12 (a part of the drawing is omitted). The motor 13 is rotationally driven by the robot control device 2. The movement of the plurality of arms 12 is controlled by the rotational drive to allow the welding lance 14 to move freely up, down, left, and right.

The motor 13 is provided with an encoder (not shown). The output of the encoder is given to the robot control unit 2. Through this output value, the robot control device 2 can recognize the current position of the welding lance 14.

The welding wire feeding device 16 is provided on the upper portion of the welding robot 1. The welding wire feed device 16 is for feeding the welding wire 15 to the welding lance 14. The welding wire feeding device 16 is provided with a feed motor 161, a reel (not shown), and a welding wire urging device (not shown). The welding wire pushing device feeds the motor 161 as a driving source, and feeds the welding wire 15 wound around the reel to the welding lance 14.

The coil strip 19 is connected at one end to the welding wire feed device 16 and at the other end to the welding torch 14. The coil strip 19 is formed into a tubular shape, and the welding wire 15 is inserted inside. The coil strip 19 guides the welding wire 15 sent from the welding wire feeding device 16 to the welding lance 14. The supplied welding wire protrudes from the welding lance 14 to function as a consumable electrode.

Fig. 2 shows the internal structure of the welding system A shown in Fig. 1.

The robot control device 2 shown in Figs. 1 and 2 is for controlling the operation of the welding robot 1. As shown in FIG. 2, the robot control device 2 includes an operation control circuit 21, a interface circuit 22, a calculation unit 23, and a programmer TP.

The operation control circuit 21 has a microcomputer and a memory (not shown). An operating program in which various settings of the welding robot 1 are set is stored in the memory. The motion control circuit 21 sets a robot movement speed VR which will be described later. The motion control circuit 21 gives the welding robot 1 operation control signal Mc based on the above-described work program, coordinate information from the encoder, and the robot movement speed VR. By the operation control signal Mc, the respective motors 13 are rotationally driven to move the welding lance 14 to a predetermined welding start position of the base material W, and to move in the inner surface direction of the base material W.

The programmer TP is connected to the motion control circuit 21 and the calculation unit 23. The programmer TP is used to allow the user to set various actions.

The set value input by the user at the programmer TP is transmitted from the programmer TP to the calculation section 23. The calculation unit 23 calculates the set value and sends the calculation result to the operation control circuit 21.

The interface circuit 22 is for transmitting and receiving various signals with the welding power source device 3. The operation control circuit 21 sends a current setting signal Is, an output start signal On, and a feed speed setting signal Ws to the interface circuit 22.

The welding power source device 3 applies a welding power source Vw between the welding wire 15 and the base material W for flowing the welding current Iw and simultaneously feeding it to the welding wire 15. As shown in FIG. 2, the welding power source device 3 includes an output control circuit 31, a current detecting circuit 32, a feed control circuit 34, a interface circuit 35, and a voltage detecting circuit 36.

The interface circuit 35 is for transmitting and receiving various signals with the robot control device 2. Specifically, the interface circuit 22 sends the current setting signal Is, the output start signal On, and the feed speed setting signal Ws to the interface circuit 35.

The output control circuit 31 has an inverter control circuit composed of a plurality of transistor elements. The output control circuit 31 performs high-speed response to an externally input commercial power source (for example, three-phase 200V) through the inverter control circuit to perform precise welding current waveform control.

The output control circuit 31 has an output end connected to the welding lance 14 and the other end connected to the base material W. The output control circuit 31 applies a welding voltage Vw between the welding wire 15 and the base material W through the contact wafer provided at the tip end 14 of the welding torch, and causes the welding current Iw to flow. Thereby, an arc a is generated between the tip end of the welding wire 15 and the welding base material W. The heat welding wire 15 and the base material W are thermally fused by the arc. Then, the welded base material W is welded.

The operation control circuit 21 sends the current setting signal Is and the output start signal On to the output control circuit 31 through the interface circuits 35 and 22.

The current detecting circuit 32 is for detecting the welding current Iw flowing to the welding wire 15. The current detecting circuit 32 outputs the current detecting signal Id corresponding to the welding current Iw to the output control circuit 31 and the operation control circuit 21.

The voltage detecting circuit 36 is for detecting the welding voltage Vw which is the output terminal voltage of the output control circuit 31. The voltage detecting circuit 36 outputs a voltage detection signal Vd corresponding to the welding voltage Vw to the output control circuit 31.

The feed control circuit 34 outputs a feed control signal Fc for feeding the welding wire 15 to the feed motor 161. The feed control signal Fc is a signal indicating the feed speed Fw of the welding wire 15. The output start signal On and the feed speed setting signal Ws from the operation control circuit 21 are transmitted to the feed control circuit 34 through the interface circuits 35 and 22.

Next, an arc welding method using the welding system A will be described. The general method of stitch pulse welding will be described below. Hereinafter, the arc welding method of Embodiment 1 of the present invention will be specifically described.

First, a general stitch pulse welding method will be described using FIG. Fig. 3(a) shows a state of change of the robot movement speed VR; Fig. 3(b) shows a state of change of the welding voltage Vw; and Fig. 3(c) shows a state of change of the feed speed Fv of the welding wire 15; 3(d) shows the state of change of the time average of the absolute value of the welding current Iw. The robot movement speed VR is a moving speed of the welding lance 14 along a predetermined welding traveling direction (corresponding to the welding traveling direction Dr shown in FIG. 11) in the inner surface direction of the base material W.

First, in general, the transition start welding process is performed by the input of the welding start signal St (refer to FIG. 2) from the programmer. In the welding start processing, the operation control circuit 21 outputs an output start signal On to the output control circuit 31 and to the control circuit 34. The output control circuit 31 applies a welding voltage Vw between the welding wire 15 and the base material W. Thereby, the arc a is lit. Then, as shown in Fig. 3, the welding is repeated by repeating the unit welding period Tα including the droplet transfer period T1 and the arc duration T2. In the solder droplet transfer period T1, the welding voltage Vw1 is applied and the solder droplets are transferred by the flow of the welding current Iw1 to form a molten pool. On the other hand, in the arc duration T2, the welding voltage Vw2 is applied and the welding droplets are hardly transferred by the flow of the welding current Iw2, and the arc a is maintained to move the welding lance 14. The following is a detailed description.

(1) T1 during solder droplet transfer (time point t1 to t2)

In the solder droplet transfer period T1, the processing for forming the molten pool Y shown in Figs. 10(a) and 12(a) is described in the description of the prior art. The first step of the present invention is the step performed during the solder droplet transfer period T1. In the solder droplet transfer period T1, as shown in Fig. 3(a), the robot movement speed VR is set to zero. Therefore, the welding lance 14 is stopped with respect to the base material W. As shown in the third graph (b), in the welding voltage Vw, the time average value of the absolute value is the welding voltage Vw1 of the voltage value vw1. As shown in Fig. 3(c), the feed speed Fv of the welding wire 15 is the feed speed fv1. As shown in the third figure (d), the pulse current Iw1 flows in the welding current Iw. The pulse current Iw1 oscillates, for example, at a maximum value of the current value iw1. T1 is a constant voltage control during solder droplet transfer. In the constant voltage control, when the welding conditions of the material, the diameter of the welding wire 15, the protruding length of the welding wire 15, and the polarity of the electrode are determined, the welding current Iw is fixed according to the feeding speed Fv of the welding wire 15. That is, the pulse current Iw1 is set by the feed speed setting signal Ws. The pulse current Iw1 is an example of the arc welding current of the present invention.

(2) Arc duration T2 (time point t2 to t3)

In the arc duration T2 shown in Fig. 3, while the arc a is continued, the processing of the cooling bath Y shown in Figs. 12(b) and 12(c) in the description of the prior art is performed. The second step of the present invention is the step performed during this arc duration T2.

As shown in the third figure (a), the robot movement speed VR is set to V2 at the start of the arc duration period T2, that is, at the time point t2. Thereby, the welding lance 14 starts moving along a predetermined welding traveling direction (Dr). At this time, the distance at which the welding lance 14 is moved is the moving pitch Mp. The pitch Mp of this movement is the value specified by the user through the programmer TP. As shown in the third graph (b), in the welding voltage Vw, the time average value of the absolute value is the welding voltage Vw2 of the voltage value vw2. The arc duration T2 is different from the solder droplet transfer period T1 and is constant current control. In terms of the welding current Iw, the time average value of the absolute value flows through the fixed welding current Iw2 of the current value iw2. The current value iw2 is a minimum value at which the solder droplet is difficult to transfer. The welding current Iw2 flows in a state where the welding wire 15 is an anode and the base material W is a cathode, that is, a so-called positive polarity current. The welding wire 15 is fed toward the base material W at a feed speed fv2 that is smaller than the feed speed fv1.

Thereafter, the solder droplet transfer period T1 is restarted from the time point t3. The unit welding period Tα including the droplet transfer period T1 and the arc duration T2 is repeated as described above. The welding lance 14 does not move during the droplet transfer period T1, and only moves the pitch Mp during the arc duration T2, so the unit welding period Tα has only the movement of the pitch Mp. That is, the welding lance 14 is sequentially stopped at a plurality of stop positions each of which is a moving pitch Mp along a predetermined welding traveling direction (Dr). At each stop position, the pulse current Iw1 flows during the droplet transfer period T1 to perform a soldering operation.

General stitch pulse welding is performed as described above. Next, a better end method of the stitch pulse welding will be specifically described.

When the welding is in progress or before the start of welding, the user instructs the welding end predetermined position Ps through the programmer TP (refer to Fig. 5). The motion control circuit 21 performs the following welding end processing based on the welding end predetermined position Ps.

When the welding end predetermined position Ps is instructed, the robot control device 2 performs control according to Fig. 4. First, the arc is formed in the above-described steps (S1), and the droplet transfer period T1 (S2) is started. Next, a step (S3) of confirming that the droplet transfer period T1 has elapsed is performed, for example, after the indicated time, the processing proceeds to the calculation step (S4). In the calculation step (S4), the distance D between the current position of the welding lance 14 and the welding end predetermined position Ps is calculated.

Next, the step of comparing the distance D with the moving pitch Mp is performed (S5). When the distance D is smaller than the moving pitch Mp, the welding current Iw, the welding voltage Vw, and the feed speed Fv are set to 0 to stop the arc a and end the welding before moving the welding lance 14. After the end of the welding, the welding lance 14 has been moved at a speed faster than the moving speed V2, for example, to another position where welding is to be started. When the distance D is larger than the movement pitch Mp, the arc duration T2 is started (S6), and the welding lance 14 pitch Mp is moved (S7). Then, the solder droplet transfer period T1 is started.

Use Figure 5 to explain the condition at the end of welding. Fig. 5(a) shows the state of change of the robot movement speed VR. Fig. 5(b) shows a state of change of the feed speed Fv of the welding wire 15. Fig. 5(c) shows a state of change in the time average value of the absolute value of the welding current Iw. In Fig. 5, the plurality of stop positions P(n), P(n-1), P(n-2), and the welding end scheduled position Ps which are arranged along the welding traveling direction Dr are further indicated. The stop position P(n) shown in Fig. 5 is located forward of the welding end predetermined position Ps in the welding traveling direction Dr, and is located at a position where the distance D from the welding end predetermined position Ps is smaller than the moving pitch Mp.

When the welding is performed in the step shown in FIG. 4, the welding lance 14 performs the calculation step (S4) after the droplet transfer period T1 at the stop position P(n), and the calculated distance is a value smaller than the movement pitch Mp. Therefore, the welding is ended in a state where the welding lance 14 is stopped at the stop position P(n). Therefore, the actual welding end position is the stop position P(n). The final step in the present invention is the step of the solder droplet transfer period T1 at the stop position P(n).

With this welding end method, even if the welding end position Ps does not overlap with the plurality of stop positions arranged every the movement pitch Mp, the actual welding end position is one of the plurality of stop positions arranged every the movement pitch Mp. Therefore, there is no possibility that the weld mark pitch is lost at the end of the welding. Therefore, according to the welding method of the present embodiment, a more beautiful drop bead can be formed.

According to the present embodiment, the arc a is stopped at the stop position P(n) before the welding end predetermined position Ps, and the welding lance 14 can be removed from the stop position P(n) at a speed faster than the moving speed V2. Therefore, at the stop position P(n), the welding lance 14 can be moved to the next welding start position in a shorter time than when the welding lance 14 is moved by the welding droplet transfer period T1 to the arc duration T2. Therefore, according to the welding method of the present embodiment, the welding time is expected to be shortened, and the welding work can be performed more efficiently.

Other embodiments of the invention are described below. In the drawings, the same or similar elements as those of the above-described embodiment will be denoted by the same reference numerals as those of the above-described embodiment, and the description will be omitted as appropriate.

In the arc welding method according to the second embodiment of the present invention, when the welding end predetermined position Ps is instructed, the robot control device 2 performs control in accordance with the flow shown in Fig. 6. The arc welding method shown in Fig. 6 is performed by the welding system A in the same manner as the arc welding method shown in Fig. 4 .

First, the welding starts and the arc a is generated (S11), and the distance D between the current position of the welding lance 14 and the end predetermined position Ps is calculated (S12). Next, the distance D and the moving pitch Mp are compared (S13). In the step (S13), there are two cases in which the distance D is equal to or greater than the moving pitch Mp and smaller than the moving pitch Mp.

When the distance D is equal to or larger than the moving pitch Mp (S13=NO), the solder droplet transfer period T1 is started (S14), and after the indicated time, the solder droplet transfer period T1 is ended (S15). Thereafter, the arc duration T2 is started (S16), and the arc duration M2 is ended after the welding lance 14 is moved by the pitch Mp (S17 = YES). Then the step is started again (S12).

When the distance D is smaller than the movement pitch Mp (S13 = YES), it is divided into whether or not the pit processing is performed (S18). Whether or not the pit processing is performed is preset by the programmer TP before starting, for example.

When the pit processing is not performed, the solder droplet transfer period T1 is started (S19), and the solder droplet transfer period TT is ended after the indicated time (S20 = YES). Thereafter, the welding current Iw, the welding voltage Vw, and the feed speed Fv are set to 0 to stop the arc a, and the welding is ended.

When the pit processing is to be performed, it is further divided into whether or not the solder droplet transfer period T1 is performed (S21). Here, whether or not the solder droplet transfer period T1 is performed is set in advance by the programmer TP, for example, before starting. In the case where the droplet transfer period T1 is performed, the droplet transfer period T1 is started (S22), and after the indicated time, the droplet transfer period T1 is ended (S23=YES). Thereafter, the pit processing is performed (S24). In the case where the solder droplet transfer period T1 is not performed, the pit processing is directly performed (S24). After the pit processing (S24), the welding current Iw, the welding voltage Vw, and the feed speed Fv are set to 0 to stop the arc a, and the welding is ended.

When the welding is completed after the weld pit process is not performed in the solder droplet transfer period T1, the pit processing is performed at the stop position P(n) as shown in Fig. 7 . The pit processing performed in the present embodiment is, for example, a process in which a pulse current having a maximum value smaller than the current value iw1 flows during the indicated pit processing period Tc. This pulse current is an example of the pit processing current of the present invention. The welding is carried out in accordance with the procedure of Fig. 6, and the pit processing is performed at the stop position P(n). At this time, the last step of the present invention is the pit processing at the stop position P(n). This direct pit processing during the solder droplet transfer period T1 can be employed, for example, when circumferentially soldering the tube. When the weld mark in the circumferential welding is surrounded, the weld pit treatment can be directly performed during the solder droplet transfer period T1, and the height of the weld mark can be made uniform.

When the welding process is performed after the welding droplet transfer period T1 and the welding is completed, as shown in Fig. 8, after the welding droplet transfer period T1 is performed at the stop position P(n), the pit processing is performed. At this time, the last step of the present invention is the solder droplet transfer period T1 step and the pit processing at the stop position P(n).

According to such an arc welding method, the pit processing can be performed as needed, so that the defects of the solder terminal portion can be prevented. Since the pit processing is performed at the stop position P(n), the pit treatment prevents the pitch of the weld marks from being disordered. Therefore, even when the pit processing is performed, a more beautiful drop can be formed even at the welding end position.

In the present embodiment, whether or not the pit processing is performed can be freely selected, but it is also possible to perform the pit processing in a fixed manner. In the solder droplet transfer period, after the T1 is performed, or during the solder droplet transfer, the T1 is directly selected for the pit treatment, and it can be fixed in one of the conditions.

The pulse current Iw1 and the pulse current processed by the pit can be either a DC pulse current or an AC pulse current.

The scope of the invention is not limited to the embodiments described above. The specific composition of each part of the welding system used in the present invention can be freely changed in various designs, and the details of the arc welding method of the present invention can be appropriately changed. For example, in the above embodiment, the welding is stopped at the stop position P(n) before the welding end predetermined position Ps in the welding traveling direction Dr. However, when the base material W has a sufficient length in advance, it is not limited thereto, and the actual welding end position can be further advanced in the welding traveling direction Dr than the welding end predetermined position Ps. That is, the welding can be stopped at the stop position P(n+1) of the distance stop position P(n) pitch Mp shown in FIG. 5, FIG. 7, and FIG.

In the above embodiment, an example of the arc welding current and the pit processing current is represented by a pulse current, and the pulse may be direct current or alternating current. However, the arc welding current and the pit processing current of the present invention are not limited to the pulse current, and may be a current without a pulse.

A. . . Welding system

1. . . Welding manipulator

11. . . Base

12. . . Arm

12a. . . Wrist

13. . . motor

14. . . Welding spray gun

15. . . Welding wire (consumption electrode)

16. . . Welding wire feeding device

161. . . Give the motor

2. . . Robot control device

twenty one. . . Motion control circuit

twenty two. . . Interface circuit

twenty three. . . Computing department

3. . . Welding power supply unit

31. . . Output control circuit

32. . . Current detection circuit

34. . . Give control circuit

35. . . Interface circuit

36. . . Voltage detection circuit

D. . . distance

Fc. . . Send control signal

Fv. . . Send speed

Fv1, fv2. . . Send speed

Is. . . Current setting signal

Iw, Iw1, Iw2. . . Welding current

Iw1, iw2. . . Current value

Mc. . . Motion control signal

Mp. . . Moving pitch

On. . . Output start signal

P(n), P(n-1), P(n-2). . . Stop position

Ps. . . Welding end scheduled position

St. . . Welding start signal

T1. . . Solder droplet transfer period

T2. . . During the duration of the arc

Tc. . . During pit processing

TP. . . Compiler

Tα. . . Unit welding period

VR. . . Robot movement speed

Vw, Vw1, Vw2. . . Welding voltage

Vw1, vw2. . . Voltage value

W. . . Base metal

Ws. . . Send speed setting signal

Fig. 1 is a view showing an example of a welding system composition suitable for use in the arc welding method of the present invention.

Figure 2 shows the internal structure of the welding system shown in Figure 1.

Figs. 3(a) to 3(d) show changes in the welding condition values of the welding system shown in Fig. 1.

Fig. 4 is a flow chart showing the first embodiment of the arc welding method of the present invention.

Figs. 5(a) to 5(c) show the state of change of the welding condition value at the end of welding in the arc welding method shown in Fig. 4.

Fig. 6 is a flow chart showing the second embodiment of the arc welding method of the present invention.

7(a) to 7(c) show the state of change of the welding condition value at the end of welding in the case where the arc welding method shown in Fig. 6 is performed in the pit processing.

Figs. 8(a) to 8(c) show the state of change of the welding condition value at the end of welding in the case where the arc welding method shown in Fig. 6 performs the pit processing after the general AC pulse output.

Fig. 9 is a view showing an example of a conventional welding system composition.

Figures 10(a) through 10(d) illustrate the state in which the pin pulse welding is performed.

Figure 11 is a diagram showing the welding beads formed after welding.

Figures 12(a) through 12(d) illustrate the state in which the pin pulse welding is performed.

Dr. . . Welding direction

Fv. . . Send speed

Fv1, fv2. . . Send speed

Iw, Iw1, Iw2. . . Welding current

Iw1, iw2. . . Current value

Mp. . . Moving pitch

P(n), P(n-1), P(n-2), P(n+1). . . Stop position

Ps. . . Welding end scheduled position

T1. . . Solder droplet transfer period

T2. . . During the duration of the arc

Tα. . . Unit welding period

V2. . . Moving speed

VR. . . Robot movement speed

Claims (8)

An arc welding method, repeating the first step and the second step, wherein the first step stops the welding lance at one of a plurality of stop positions at each of the indicated moving pitches, in the base material and the welding torch An arc is generated between the held consumable electrodes to perform droplet transfer, and the second step is to cool the molten pool formed in the base material while generating an arc between the base material and the consumable electrode, and The welding lance moves the movement pitch to the next stop position, and when the distance from the indicated welding end predetermined position is within the stop position within the movement interval, after the last step That is to say, the welding is stopped. The arc welding method according to claim 1, wherein the first step other than the last step of the last step is a flow arc welding current between the base material and the consumable electrode. The first step of the last step is performed by flowing the arc welding current between the base material and the consumable electrode. The arc welding method according to claim 1, wherein the first step other than the last step of the last step is a flow arc welding current between the base material and the consumable electrode. To perform, the last step 1 of the above is by the absolute value of the flow ratio The pit processing current having a small arc welding current is performed between the base material and the consumable electrode. The arc welding method according to claim 1, wherein the first step other than the last step of the last step is a flow arc welding current between the base material and the consumable electrode. The first step of the last step is to flow between the base material and the consumable electrode by flowing the arc welding current and then flowing a solder pit having an absolute value smaller than the arc welding current. get on. The arc welding method according to claim 1, further comprising: moving the welding at a speed faster than the moving speed in the second step after performing the last first step of the welding. The steps of the spray gun. The arc welding method of claim 2, further comprising: moving the welding at a speed faster than the moving speed in the second step after performing the last first step of the welding. The steps of the spray gun. The arc welding method of claim 3, further comprising: moving the welding at a speed faster than the moving speed in the second step after performing the last first step of the welding. The steps of the spray gun. The arc welding method of claim 4, further comprising: moving the welding at a speed faster than the moving speed in the second step after performing the last first step of the welding. The steps of the spray gun.