JP2009154206A - Stitch pulse welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stitch pulse welding method that can improve appearance by always materializing a fixed bead width. <P>SOLUTION: In a stitch pulse welding method, an arc is generated, with a welding torch stopped from an arc starting point, on the basis of welding conditions including a welding current, welding voltage and welding time; after the arc is stopped after a lapse of welding time, the welding torch is moved to an arc resuming point which is away by a prescribed moving pitch in a welding advancing direction, with the arc regenerated; while this is repeated, scales of welding trace formed in one arc generation are superimposed to form a weld bead. For a period until the number of scale formations reaches a prescribed initial formation number Un, welding is performed while an initial welding time Ti is reduced stepwise and, after the number of scale formations reaches the initial formation number Un, welding is performed with a normal welding time Tt. Thus, insufficient bead width near the arc starting point can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stitch pulse welding method for performing welding while minimizing the influence of heat on a thin base metal.

  Stitch pulse welding is a welding method that minimizes the heat effect on the base metal by controlling the heat input and cooling during welding. It is a welding method aiming at automation of thin plate welding, and it is said that the welding appearance can be improved and the amount of welding distortion can be reduced as compared with conventional thin plate welding (see, for example, Patent Document 1).

  In Patent Document 1, an arc is generated for a predetermined time in a state where the welding torch is stopped to melt the welding base material, and after the set time has elapsed, the arc is stopped and the welding torch is connected to the outer periphery of the molten portion. Means for moving to the side arc restart point is disclosed. Hereinafter, this prior art will be described.

  FIG. 9 is a view showing a stitch pulse welding apparatus 51 to which a conventional stitch pulse welding method is applied.

  The manipulator M automatically performs arc welding on the workpiece W, and includes an upper arm 53, a lower arm 54, a wrist portion 55, and a plurality of servo motors (not shown) for rotationally driving them. It is configured.

  The arc welding torch T is attached to the tip portion of the upper arm 53 of the manipulator M, and guides the welding wire 57 having a diameter of about 1 mm wound around the wire reel 56 to the welding position where the workpiece W is taught. It is. The welding power source WP supplies a welding voltage between the arc welding torch T and the workpiece W. When welding the workpiece W, the welding wire 57 is protruded from the tip of the arc welding torch T by a desired protrusion length Ew. The length of the protruding length Ew is generally around 15 mm, but the operator adjusts it to the desired length in advance using the teach pendant TP, which will be described later, according to the groove shape of the welding location, welding conditions, etc. Is possible.

  The conduit cable 52 includes a coil liner (not shown) for guiding the welding wire 57 therein, and is connected to the arc welding torch T. Further, the conduit cable 52 supplies the electric power from the welding power source WP and the shield gas from the gas cylinder 58 to the arc welding torch T.

  The teach pendant TP as an operation means is a so-called portable operation panel, and the conditions (welding current, welding voltage, moving speed, moving pitch, welding time, and the conditions necessary for performing the operation of the manipulator M and stitch pulse welding) Cooling time) and the like. Using this teach pendant TP, the worker creates a work program in which the above conditions are set together with the operation of the manipulator M.

  The robot controller RC is for causing the manipulator M to control the welding operation, and includes a main control unit, an operation control unit, a servo driver (all not shown), and the like. Then, based on a work program taught by the operator using the teach pendant TP, an operation control signal is output from the servo driver to each servo motor of the manipulator M, and a plurality of axes of the manipulator M are rotated. Since the robot controller RC recognizes the current position based on an output from an encoder (not shown) provided in the servo motor of the manipulator M, the robot controller RC can control the tip position of the arc welding torch T. In the welded portion, stitch pulse welding is performed while repeating the welding, movement, and cooling described below.

  FIG. 10 is a diagram for explaining a state when stitch pulse welding is performed. The welding wire 57 protrudes from the tip of the arc welding torch T. The shield gas G is always blown from the arc welding torch T at a constant flow rate from the start of welding to the end of welding. Hereinafter, each state at the time of stitch pulse welding will be described.

  FIG. 4A shows a state when an arc is generated. Based on the set welding current and welding voltage, an arc A is generated between the tip of the welding wire 57 and the workpiece W at the arc start point, and the welding wire 57 is melted to form a molten pool Y in the workpiece W. The The arc A is stopped after the set welding time has elapsed since the arc A was generated.

  FIG. 2B shows a state after the arc is stopped. After the arc is stopped, the state after welding is maintained until the set cooling time has elapsed. That is, since the manipulator M and the arc welding torch T are stopped in the same manner as the welding state, only the shielding gas G is blown out from the arc welding torch T. It cools and solidifies.

  FIG. 3C shows a state where the arc welding torch T is moved to the next welding position. After the elapse of the cooling time, the arc welding torch T is moved to an arc restart point that is a position separated by a preset movement pitch Mp in the welding progress direction. The moving speed at this time is the set moving speed. The moving pitch Mp is a distance adjusted so that the welding wire 57 is positioned on the outer peripheral side of the welding mark Y ′ after the molten pool Y is solidified as shown in FIG.

  FIG. 4D shows how the arc A is regenerated at the arc restart point. A weld pool Y "is newly formed at the front end of the welding mark Y ', and welding is performed. Thus, in the stitch pulse welding apparatus 51, the state in which the arc is generated and welding is performed, and the state in which the cooling and movement are performed are alternately repeated. And a welding bead is formed so that the scale which is a welding trace may overlap.

  FIG. 11 is a diagram for explaining a weld bead formed after welding. As shown in the figure, a welding mark Sc is formed at the first arc start point P1, and a similar welding mark Sc is also formed at an arc restart point P2 separated by a moving pitch Mp toward the welding progress direction Dr. . Further welding marks Sc are sequentially formed even after the arc restart point P3. Thus, as a result of forming so that the scale which is a welding trace may overlap, scale-shaped weld bead B is formed.

JP-A-6-55268

  As described above, in stitch pulse welding, welding starts at the arc start point based on the welding current and welding voltage, stops welding after the lapse of the welding time, waits for the cooling time, and sets the arc start point by the shield gas. After cooling, the welding bead B is formed by moving to the arc restart point separated by the moving pitch and repeating the operation of performing welding and cooling similar to the arc start point until the arc end point.

  By the way, in FIG. 11 described above, the welding marks Sc are represented by the same size, but in reality, the temperatures of the base metal and the welding wire are near the arc start point (from the arc start point to several arc restart points ahead). Therefore, welding scar Sc in the vicinity of the arc starting point becomes small due to insufficient melting.

  FIG. 12 is a view for explaining the state of the welding mark Sc near the arc start point. As shown in the figure, for example, between the arc start point P1 and the arc restart point P3, the temperature of the base material and the welding wire does not rise, so the welding mark Sc becomes small. Thereafter, after the arc restart point P4, the temperatures of the base metal and the welding wire are stabilized, so that sufficient penetration can be obtained, and the welding marks Sc have substantially the same size. That is, there is a problem that the width of the weld bead Bs near the arc start point is narrower than the width of the weld bead Bt after stabilization.

  In order to solve the above-mentioned problem, conventionally, a method has been adopted in which the arc temperature is stabilized by increasing the base metal temperature by performing normal arc welding several mm from the arc starting point, and then stitch pulse welding is started. It was. However, in this case, there is a problem that the appearance is not preferable because scales are not formed in a portion where normal arc welding is performed.

  Accordingly, an object of the present invention is to provide a stitch pulse welding method capable of always realizing a constant bead width by gradually changing the welding conditions in a predetermined period from the arc start point and improving the aesthetic appearance. It is said.

In order to achieve the above object, the first invention provides:
Based on welding conditions including welding current value, welding voltage value and welding time, an arc is generated with the welding torch stopped from the arc starting point, and after the welding time has elapsed, the arc is stopped and then the welding torch is welded. While repeatedly regenerating the arc by moving it to the arc restart point separated by a predetermined movement pitch in the direction of travel, the scales, which are welding marks formed by one occurrence of the arc, are overlapped and welded onto the workpiece. In a stitch pulse welding method for forming a bead,
During the period until the number of scales reaches a predetermined initial number, welding is performed under predetermined initial welding conditions including an initial welding current value, an initial welding voltage value, and an initial welding time. After reaching the initial formation number, the stitch pulse welding method is characterized in that welding is performed under predetermined steady welding conditions including a steady welding current value, a steady welding voltage value, and a steady welding time.

  According to a second aspect of the invention, in the stitch pulse welding method according to the first aspect, the initial welding condition is a condition in which at least the initial welding time is shortened stepwise as the number of formations increases. is there.

  According to a third aspect of the invention, the initial welding time is automatically calculated based on the initial welding time at the arc start point, the initial number of formations, and the steady welding time. The stitch pulse welding method described.

  According to a fourth aspect of the invention, in the stitch pulse welding method according to the first aspect of the invention, the initial welding condition is a condition in which the initial welding current value is lowered stepwise as the number of formations increases. It is.

  According to a fifth aspect of the invention, the initial welding current value is automatically calculated based on the initial welding current value at the arc start point, the initial number of formations, and the steady welding current value. This is a stitch pulse welding method described in the invention.

  According to a sixth aspect of the present invention, the initial formation number is automatically input by inputting the steady welding current value and the steady welding voltage value into a welding condition database in which a correspondence relationship between a welding condition reference value and an initial formation number is stored in advance. The stitch pulse welding method according to any one of the first to fifth inventions, wherein the stitch pulse welding method is calculated automatically.

  According to a seventh aspect of the invention, the initial welding condition is a welding condition database in which the steady welding current value and the steady welding voltage value are stored in advance in correspondence with the welding condition reference value and the initial welding condition for each number of formations. The stitch pulse welding method according to any one of the first, second, and fourth inventions, wherein the stitch pulse welding method is automatically calculated by inputting.

  In an eighth aspect of the present invention, the initial number of formations is the scale diameter value at the steady welding current value and the steady welding voltage value, and the relationship between the scale diameter value, the steady welding current value, and the steady welding voltage value in advance. The steady welding current value and the steady welding voltage value are calculated by inputting the stored welding condition database into the stored welding condition database, and the calculated steady welding current value and the steady welding voltage value are used as the steady welding current value and the steady welding voltage value. The stitch pulse welding method according to any one of the first to fifth inventions, wherein the stitch pulse welding method is calculated by inputting a relationship between the first formation number and the number of initial formations into a previously stored welding condition database.

  According to a ninth aspect of the present invention, the initial welding time or initial welding current value at the arc start point is the scale diameter value at the steady welding current value and the steady welding voltage value, the scale diameter value and the steady welding current value, and The stitch pulse welding method according to the third or fifth invention, wherein the stitch pulse welding method is calculated by inputting a relationship with the steady welding voltage value into a previously stored welding condition database.

  According to the first invention, the period until the scale formation number reaches the preset initial formation number is welded under a predetermined initial welding condition, and after the scale formation number reaches the initial formation number, By welding under steady welding conditions, it is possible to prevent the weld bead near the arc start point from becoming smaller. That is, the beauty of the weld bead can be improved.

  According to the second invention, the welding time is shortened step by step as the number of scales formed is increased at the time of initial welding, so that in addition to the effect exhibited by the first invention, welding near the arc start point is performed. The bead can always be a constant width. That is, the appearance of the weld bead can be further improved.

  According to the third aspect of the invention, the initial welding time is automatically calculated based on the initial welding time at the arc start point, the initial number of formations, and the steady welding time. In addition, the setting of initial welding conditions can be simplified.

  According to the fourth aspect of the present invention, the welding current value is lowered step by step as the number of scales is increased during initial welding. In addition to the effect of the first aspect of the invention, in the vicinity of the arc start point. The weld bead can always have a constant width. That is, the appearance of the weld bead can be further improved.

  According to the fifth invention, the initial welding current value is automatically calculated based on the initial welding current value at the arc start point, the initial number of formations, and the steady welding current value. In addition to the effects produced by, the setting of initial welding conditions can be simplified.

  According to the sixth aspect of the present invention, the initial number of formation is automatically set by inputting the steady welding current value and the steady welding voltage value into the welding condition database in which the correspondence relationship between the welding condition reference value and the number of initial formation is stored in advance. To calculate. That is, if the steady welding current value and the steady welding voltage value are set, the initial number of formations is automatically calculated, so that in addition to the effects of the first to fifth inventions, the setting of the initial welding conditions is further simplified. be able to.

  According to the seventh invention, the steady welding current value and the steady welding voltage value are input to the welding condition database in which the correspondence relationship between the welding condition reference value and the initial welding condition for each number of formations is stored in advance. The welding conditions are automatically calculated. That is, if the steady welding current value and the steady welding voltage value are set, the initial welding conditions are automatically calculated. In addition to the effects exhibited by the first, second and fourth inventions, the number of steps for setting the welding conditions is further reduced. can do.

  According to the eighth invention, the desired value of the scale diameter value corresponding to the bead width is input to the welding condition database in which the relationship between the scale diameter value, the steady welding current, and the steady welding voltage is determined in advance. The number of formations is automatically calculated. That is, if only the scale diameter value is set, the initial number of formation is automatically calculated, so that in addition to the effects produced by the first to fifth inventions, it is possible to further reduce the man-hours for setting the welding conditions.

  According to the ninth aspect, by inputting a desired value of the scale diameter value corresponding to the bead width to the welding condition database in which the relationship between the scale diameter value, the steady welding current value, and the steady welding voltage value is determined in advance. The initial welding time or initial welding current value at the arc start point is automatically calculated. That is, if only the scale diameter value is set, the initial welding time and the initial welding current value at the arc start point are automatically calculated, and based on this result, the number of scale formation reaches a predetermined initial number. The initial welding conditions in the period up to are calculated. That is, in addition to the effects exhibited by the third or fifth invention, the number of man-hours for setting welding conditions can be further reduced.

[Embodiment 1]
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the invention will be described based on examples with reference to the drawings.

  FIG. 1 is a block diagram of a stitch pulse welding apparatus 1 to which a stitch pulse welding method according to the present invention is applied. In the figure, the difference from the prior art FIG. 9 is the robot controller RC and the teach pendant TP. In addition, the manipulator M, the welding power source WP, the wire reel 56, the gas cylinder 58, and the like described in FIG. 9 are omitted from illustration. Hereinafter, the robot controller RC and the teach pendant TP constituting the main part of the present invention will be described.

  The robot controller RC is for causing the manipulator M to control the welding operation. The robot controller RC performs the main control unit 3 serving as the center, the welding condition output control unit 13 for controlling the welding, the trajectory calculation of the manipulator M, and the like. An operation control unit 11 that outputs a calculation result to the drive command unit 12 as a drive signal, a drive command unit 12 that outputs a servo control signal for controlling the rotation of each servo motor of the manipulator M, a work program, various parameters, and the like. A hard disk 4 for storage, a RAM 5 as a temporary calculation area, a CPU 6 as a central processing unit, and a servo driver (not shown) are provided, and these are connected via a bus (not shown).

  The teach pendant TP, which is an operation means, includes a display unit 41 that displays various types of information, and a setting unit 42 that sets various types of data such as position data, welding conditions, and operation parameters of the manipulator M. Various data input by the setting unit 42 is input to the main control unit 3 of the robot controller RC.

  The main control unit 3 includes a teaching processing unit 20, a display processing unit 21, and an interpretation execution unit 22. When the initial processing number, initial welding condition, steady welding condition, moving speed, moving pitch, and cooling time, which are stitch pulse welding conditions, are input from the setting unit 42, the teaching processing unit 20 receives the initial forming number Un, the initial welding condition, Ic, steady welding condition Tc, moving speed Sp, moving pitch Mp, and cooling time Cd are stored in the hard disk 4. The display processing unit 21 displays various input data on the display unit 41 of the teach pendant TP as necessary. The interpretation execution unit 22 outputs a command signal to each of the operation control unit 11 and the welding condition output control unit 13 based on the position data stored in the hard disk 4 and the stitch pulse welding conditions.

  Here, the initial formation number Un sets a period for performing the initial welding, and is designated by the number of scales. For example, when three are set, the first three scale forming portions including the arc start point are set as a period for performing the initial welding.

  The initial welding condition Ic is for setting the welding condition of each scale forming part during the initial welding period, and indicates the initial welding current value Ci, the initial welding voltage value Vi, and the initial welding time Ti. As the initial welding condition Ic, a condition value higher than a steady welding condition Tc described later is set based on an operator's experience or experiment. The reason why the condition value higher than the steady welding condition Tc is set is as follows. The scale is determined by a combination of a welding current value, a welding voltage value, and a welding time. For example, the longer the welding time, the larger the scale, and the shorter the welding time, the smaller the scale. As described in the prior art, since the temperature of the base metal and the welding wire does not increase near the arc start point, the scale size is reduced. A current value Ci, an initial welding voltage value Vi and an initial welding time Ti) are set.

  The initial welding condition Ic may be configured to be set for each scale forming portion, or only the initial welding conditions at the arc starting point are set in advance, and the scale forming portions after the arc starting point are set. The welding conditions may be calculated automatically. Below, it demonstrates on the assumption that the latter method is employ | adopted.

  The steady welding condition Tc is for setting a steady welding condition after the scale formation number reaches the initial formation number Un, and includes a welding current value, a welding voltage value, and an original stitch pulse welding. The welding time is shown. Hereinafter, these will be referred to as a steady welding current value Ct, a steady welding voltage Vt, and a steady welding time Tt. The moving speed Sp, the moving pitch Mp, and the cooling time Cd are the same as the conditions described in the related art.

  The welding condition output control unit 13 outputs a welding control signal Wc to the welding power source WP at a predetermined timing. More specifically, a welding control signal Wc for starting welding including the initial welding condition Ic (initial welding current value Ci, initial welding voltage value Vi and initial welding time Ti) is output to the welding power source WP at the arc starting point. To do. From the initial welding condition Ic to the steady welding condition Tc (steady welding current value Ct, steady welding voltage value Vt and steady welding time Tt) until the number of scales is counted and the number of scales reaches the initial number of formations Un. The so-called down slope control is performed in which the welding conditions are lowered and output step by step. After the scale formation number reaches the initial formation number Un, the steady welding condition Tc is output to the welding power source WP to continue the regular stitch pulse welding.

  Hereinafter, the down slope control of the welding condition output control unit 13 will be described in detail.

  FIG. 2 is a flowchart showing a processing flow of the welding condition output control unit 13. Hereinafter, the process from the arc start point to the down-slope control until the scale formation number reaches the set initial formation number Un and the transition to the steady stitch pulse welding will be described. Since the process after the transition to the steady stitch pulse welding is the same as the conventional one, the description is omitted.

  In step S <b> 1, the scale formation number is set to 0 (zero), and the set initial formation number Un and initial welding condition Ic are read from the hard disk 4.

  In step S2, the initial welding condition Ic is output to the welding power source WP.

  In step S3, input of a welding completion signal from the welding power source WP is checked. If welding has not been completed, the process stands by, and if welding has been completed, the process proceeds to step S4.

  In step S4, the scale formation number is incremented by one.

  In step S5, it is confirmed whether or not the scale formation number has reached the initial formation number Un. If not, the process proceeds to step S6. If it has reached, the process proceeds to step S7.

  In step S6, the next welding conditions (next welding current value, next welding voltage value and next welding time at the next arc restart point) are calculated as follows. When the welding conditions in each forming part are set, the conditions are read from the hard disk 4.

  Initial welding current value Ci, initial welding voltage value Vi, initial welding time Ti, steady welding current value Ct, steady welding voltage value Vt, steady welding time Tt, initial formation number Un, scale up to now When the formation number is Uc, the next welding current value Cn, the next welding voltage value Vn, and the next welding time Tn can be easily calculated by the following equations.

Next welding current value Cn = Ci− (Ci−Ct) / Un × Uc
Next welding voltage value Vn = Vi− (Vi−Vt) / Un × Uc
Next welding time Tn = Ti− (Ti−Tt) / Un × Uc

  Then, the process returns to step S2, and the next welding condition is output to the welding power source WP. Thereafter, steps S3 to S6 are repeated until the scale formation number reaches the initial formation number Un.

  In step S7, after the scale formation number reaches the initial formation number Un, the set steady welding condition Tc is read from the hard disk.

  And in step S8, it transfers to regular stitch pulse welding. That is, the stitch pulse welding is continued until the arc end point by outputting the steady welding condition Tc to the welding power source WP.

  In this way, the welding condition output control unit 13 counts the number of scale formations, and the conditions are set in stages from the initial welding condition Ic to the steady welding condition Tc until the scale formation number reaches the set initial formation number Un. After down-slope control is performed to reduce the number of scales, and the number of scale formations reaches the initial number of formations Ic, the steady welding condition Tc is output to the welding power source WP, and steady stitch pulse welding is continued.

  FIG. 3 is a waveform diagram when the welding time is shortened stepwise, for example. In the figure, the initial welding time is set to 1.3 seconds, the steady welding time is set to 1.0 second, and the number of initial formations is set to three. In other words, the transition is made in stages so that the welding time becomes a steady welding time of 1.0 seconds when the number of scale formation is four.

  As described above, during the period until the number of scales reaches the preset initial number of formations, welding is performed under the predetermined initial welding conditions, and after the number of scales reaches the initial number of formations, By welding under steady welding conditions, it is possible to prevent the weld bead near the arc start point from becoming smaller. That is, the beauty of the weld bead can be improved.

  In the present invention, the welding current, the welding voltage, and the welding time are all configured to be able to be down-slope controlled. However, in general, it is desirable to perform either down-slope control of either the welding time or the welding current. . Therefore, in the first embodiment described above, the welding time is shortened stepwise or the welding current is lowered stepwise as the number of scales increases. As a result, in addition to the above effects, the weld bead near the arc start point can always have a constant width. That is, the appearance of the weld bead can be further improved.

  In addition, the initial welding time is automatically calculated based on the initial welding time at the arc start point, the number of initial formations, and the steady welding time, and the initial welding current value is determined as the initial welding current value at the arc starting point and the initial formation. The number is automatically calculated based on the number and the steady welding current value. This can simplify the setting of the initial welding conditions in addition to the above effects.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. In the second embodiment, the steady welding current and the steady welding voltage are input to the welding condition database storing the welding time for each number of scale formations in which the correspondence relationship between the welding condition reference value and the number of initial formations is stored in advance. The initial formation number and initial welding conditions are automatically calculated.

  FIG. 4 shows a stitch pulse welding apparatus according to Embodiment 2 of the present invention. In the figure, the difference from FIG. 1 which is the first embodiment is a welding condition database 24 provided in the hard disk 4 and a welding condition calculation unit 23 provided in the main control unit 3. Hereinafter, the welding condition database 24 and the welding condition calculation unit 23 will be described. Others are the same as those given the same reference numerals in FIG.

  The welding condition database 24 is a database in which the results of stitch pulse welding in an actual welding environment, such as the thickness of the workpiece to be used, the material and diameter value of the welding wire, are accumulated. The welding condition calculation unit 23 receives the steady welding condition Tc (steady welding current value Ct, steady welding voltage value Vt, steady welding time Tt) as an input from the welding condition database 24 and the initial formation number Un and the initial welding condition Ic (initial welding current Ic). The value Ci, the initial welding voltage value Vi, and the initial welding time Ti) are automatically calculated.

  FIG. 5 is a diagram for explaining the concept of the welding condition database 24. The welding condition database 24 has a welding voltage reference value on the ordinate and a welding current reference value on the abscissa, and the number of scales required for initial welding and the period of initial welding under the condition where these intersect. This is a database of welding time required to make the scale diameter value uniform. For example, the data described in the bold line frame in the figure shows the scale formation necessary for initial welding when stitch pulse welding is performed with a welding current value of 90 to 100 A and a welding voltage value of 15 to 17 V. The number (corresponding to the initial formation number Un) is 7, and the welding time for making the scale diameter value uniform during this period is determined according to the scale formation number. Since the welding time is not a direct value but a ratio with respect to a predetermined steady welding time Tt, it is expressed in%.

  Next, the operation will be described. The welding condition calculation unit 23 calculates the initial formation number Un and the initial welding condition Ic from the welding condition database 24 based on the input steady welding condition Tc. Hereinafter, a case where “steady welding current value Ct = 120 A, steady welding voltage value Vt = 16 V, steady welding time Tt = 1.0 second” is input as the steady welding condition Tc will be described as an example.

  First, the initial formation number Un is calculated. Since the steady welding current value Ct = 120 A and the steady welding voltage value Vt = 16 V, the corresponding condition is searched from the welding condition database 24. As a result, since the condition indicated by the dotted frame is applicable, the initial number of formation Un is 5.

  Next, the initial welding time Ti is calculated. The steady welding time Tt is 1.0 second, and the condition indicated by the dotted line frame is that the welding time is 140% for the first piece, 130% for the second piece, 120% for the third piece, and 110% for the fourth piece. %, The fifth is 100%. That is, the initial welding time Ti is 1.0 × 140% = 1.4 seconds for the first scale, 1.0 × 130% = 1.3 seconds for the second scale, and 1.0 × 120 for the third scale. % = 1.2 seconds, the fourth is 1.0 × 110% = 1.1 seconds, and the fifth is 1.0 × 100% = 1.0 seconds. The initial welding current value Ci may be the same value as the steady welding current value Ct, and the initial welding voltage value Vi may be the same value as the steady welding voltage value Vt. The calculated initial formation number Un and initial welding condition Ic are stored in the hard disk 4.

  As in the first embodiment, when performing stitch pulse welding, the welding control signal Wc is output to the welding power source WP based on the calculated initial formation number Un and the initial welding condition Ic. Then, until the number of scales is counted and the number of scales reaches the initial number of formations Un, the welding conditions are reduced step by step from the initial welding condition Ic to the steady welding condition Tc (in this embodiment, only the welding time is output). Is output step by step). After the scale formation number reaches the initial formation number Un, the steady welding condition Tc is output to the welding power source WP to continue the regular stitch pulse welding.

  As described above, in the second embodiment, the initial forming is performed by inputting the steady welding current value and the steady welding voltage value to the welding condition database in which the correspondence relationship between the welding condition reference value and the initial forming number is stored in advance. The number and initial welding conditions are automatically calculated. That is, if the steady welding current value and the steady welding voltage value are set, the initial formation number and the initial welding conditions are automatically calculated, so that the number of steps for setting the welding conditions can be reduced.

[Embodiment 3]
Next, a third embodiment of the present invention will be described. In the third embodiment, by inputting the scale diameter value corresponding to the bead width to the welding condition database in which the relationship between the scale diameter value, the steady welding current value, and the steady welding voltage value is determined in advance, Initial welding conditions and steady welding conditions are automatically calculated.

  FIG. 6 shows a stitch pulse welding apparatus according to Embodiment 3 of the present invention. In the figure, the difference from FIG. 1 which is Embodiment 1 is the scale diameter value Sr stored in the hard disk 4, the welding condition database 24, and the welding condition calculation unit 23 provided in the main control unit 3. These will be described below, and the others are the same as those in the first embodiment, and thus description thereof will be omitted.

  The scale diameter value Sr is the diameter value (corresponding to the bead width) of the scale formed during stitch pulse welding, and is input from the setting unit 42 of the teach pendant TP. The welding condition database 24 is a database in which the relationship with the scale diameter value formed under predetermined welding conditions is associated for each number of scales formed. The welding condition calculation unit 23 automatically calculates the initial formation number Un, the initial welding condition Ic, and the steady welding condition Tc from the welding condition database 24 with the scale diameter value Sr as an input.

  FIG. 7 is a diagram for explaining the concept of the welding condition database 24. The welding condition database 24 provides reference values for the welding current and welding voltage in the actual welding environment, such as the thickness of the workpiece to be used, the material and diameter of the welding wire, and performs stitch pulse welding according to the reference value. This is a database of data accumulated by the method of measuring the scale diameter value for each scale formation number. Hereinafter, each data of the welding condition database 24 in which the measurement results are accumulated will be specifically described.

  The figure (a) shows the diameter value of the scale formed when the stitch pulse welding is performed with the welding time fixed to 0.7 seconds and the welding current value and the welding voltage value changed, for each number of scales formed. This is a database of measurement results. For example, the data described in the bold line frame in FIG. 4A is the scale formed on the first piece under the welding conditions of a welding time of 0.7 seconds, a welding current value of 90 A, and a welding voltage value of 15 V. The diameter value of 1.9 mm is 2 mm, the second is 2.1 mm, and the last 7 is 3.5 mm. The reason why there is no data after the eighth piece is that the diameter value after the eighth piece is stable and becomes 3.5 mm.

  Furthermore, the database also shows the results of measuring the diameter of the scale for each number of scales while increasing the welding time in increments of 0.1 seconds (0.8 seconds, 0.9 seconds, ...) and changing the welding current and welding voltage. It has become. FIG. 5B shows data when the welding time is 1.3 seconds, for example. In FIGS. 4A and 4B, for convenience of explanation, when the welding voltage value is a value other than 15V, the value is omitted without being entered. The hatched lines indicate that no data exists, that is, no data is required because the scale diameter value is stable. Further, Ad1 to Ad10 shown in the figure show data at a stage where the scale diameter value is stabilized under each welding condition. Hereinafter, these data are referred to as stable time data Ad.

  Next, the operation will be described. The welding condition calculation unit 23 calculates the initial formation number Un, the initial welding condition Ic, and the steady welding condition Tc from the welding condition database 24 based on the input scale diameter value Sr. Hereinafter, the case where the input scale diameter value Sr is 3.5 mm will be described as an example.

  First, steady welding conditions Tc and initial formation number Un are calculated. The steady welding condition Tc is a welding condition when the scale diameter value is stabilized. The initial formation number Un is the number of scale formations until the scale diameter value is stabilized.

  In order to calculate the steady welding condition Tc and the initial number of formations Un, data matching the inputted scale diameter value Sr is extracted from the stable time data Ad in each welding condition. If there is no match, the data closest to the input scale diameter value Sr is extracted. Taking the case of the welding condition database 24 shown in FIG. 7 as an example, stable data Ad1 and stable data Ad2 having a scale diameter value of 3.5 mm are selected. The stable data Ad1 includes a welding current value of 90A, a welding voltage value of 15V, and a welding time of 0.7 seconds. This condition is a candidate for the steady welding condition Tc. In addition, the number of scales formed under the above conditions is 7, which is a candidate for the initial number Un. Similarly, the stable time data Ad2 has a welding current value of 100A, a welding voltage value of 15V, and a welding time of 0.7 seconds, and this condition is a candidate for the steady welding condition Tc. Further, the number of scales formed under the above conditions is five, which is a candidate for the initial number of formations Un.

  When there are a plurality of condition candidates, which one to select is displayed on the display unit 41 of the teach pendant TP and the operator selects the calculated steady welding condition Tc and the initial formation number candidate. Of course, if there is only one candidate for the steady welding condition Tc and the initial formation number Un, there is no need for the operator to select it. In this way, the steady welding condition Tc and the initial formation number Un are calculated, and if necessary, are selected by an operator and stored in the hard disk 4.

  Next, the initial welding condition Ic is calculated. The steady welding condition Tc and the initial formation number Un are calculated by the processing up to the above. Below, when the scale diameter value Sr is 3.5 mm, the welding current value 90A, welding voltage value 15V, and welding time 0.7 seconds corresponding to the stable data Ad1 are calculated as the steady welding conditions Tc. A method for calculating the initial welding condition Ic will be described assuming that seven are formed as the initial formation number Un.

  From the data when the number of scales formed under each welding condition is one, data with the scale diameter value Sr matching 3.5 mm is extracted. If there is no match, the data closest to the input scale diameter value Sr is extracted. Taking the welding condition database 24 shown in FIG. 7 as an example, data Bd1 having a scale diameter value of 3.5 mm is selected. Based on the data Bd1 and the stable data Ad1, the initial welding condition Ic is automatically calculated.

  FIG. 8 is a diagram showing an example in which the initial welding condition Ic is automatically calculated. As shown in FIG. 5A, the first welding condition is the same as the data Bd1. The welding conditions for the seventh and eighth scales are the same as the stable data Ad1. The second to sixth scale welding conditions are values in which the welding current values of both the data Bd1 and the stable data Ad1 are equally divided so that the welding current value decreases as the number of scale formation increases ( In the figure, the value indicated by the underlined portion).

  In the above description, the data Bd1 is selected, and based on the data Bd1 and the stable data Ad1, the welding current values of both are equally divided to automatically calculate the initial welding condition Ic. Data Bd2 close to 5 mm may be selected. In this case, as shown in FIG. 5B, the first welding condition is the same as the data Bd2. The welding conditions for the seventh and eighth scales are the same as the stable data Ad1. The second to sixth welding conditions are values in which the welding time of both the data Bd2 and the stable data Ad1 is equally divided, and the welding time is gradually reduced as the number of scales increases. (Value shown by the underlined portion in the figure).

  Then, the calculated initial formation number Un, initial welding condition Ic, and steady welding condition Tc are stored in the hard disk 4. Since the subsequent processing is the same as that of the first embodiment, description thereof is omitted.

  As described above, in the third embodiment, a desired value of the scale diameter value corresponding to the bead width is determined in advance, and the relationship between the scale diameter value, the steady welding current, and the steady welding voltage is determined based on the scale diameter value. The number of initial formations, initial welding conditions, and steady welding conditions are automatically calculated by inputting them into a predetermined welding condition database. That is, in addition to the effect that the welding bead near the arc start point can always be set to a constant width, the number of man-hours for setting welding conditions can be reduced.

1 is a block diagram of a stitch pulse welding apparatus to which a stitch pulse welding method according to the present invention is applied. It is a wave form diagram at the time of shortening only welding time as an example which performs down slope control. It is a flowchart of a welding condition output control part. It is a block diagram of the stitch pulse welding apparatus to which the stitch pulse welding method according to Embodiment 2 is applied. It is a figure which shows an example of the welding condition database which concerns on Embodiment 2. FIG. It is a block diagram of the stitch pulse welding apparatus to which the stitch pulse welding method according to Embodiment 3 is applied. It is a figure which shows an example of the welding condition database which concerns on Embodiment 3. FIG. It is a figure which shows the example which calculated the initial welding conditions automatically. It is the figure which showed the stitch pulse welding apparatus to which the conventional stitch pulse welding method was applied. It is a figure for demonstrating a state when performing stitch pulse welding. It is a figure for demonstrating the weld bead formed after welding construction. It is a figure for demonstrating the mode of the welding trace near arc start point.

Explanation of symbols

1 Stitch pulse welding device 3 Main control unit 4 Hard disk 5 RAM
6 CPU
7 Welding wire 11 Operation control unit 12 Drive command unit 13 Welding condition output control unit 20 Teaching processing unit 21 Display processing unit 22 Interpretation execution unit 23 Welding condition calculation unit
24 Welding condition database 41 Display unit 42 Setting unit 51 Conventional stitch pulse welding device 52 Conduit cable 53 Upper arm 54 Lower arm 55 Wrist 56 Wire reel 57 Welding wire 58 Gas cylinder A Arc Ad Stable data B Weld bead Bd Data Bs Arc Weld bead Bt near start point Weld bead Ci after stabilization Initial welding current value Cd Cooling time Cn Next welding current value Ct Steady welding current value Dr Welding direction Ew Protrusion length G Shielding gas Ic Initial welding condition M Manipulator Mp Movement pitch P1 Arc starting point
P2 to P6 Arc restart point RC Robot controller Sc Welding mark Sp Travel speed Sr Scale diameter T Arc welding torch Tc Steady welding condition Ti Initial welding time Tn Next welding time TP Teach pendant Tt Steady welding time Uc Scale formation number Un Initial Number of formations Vi Initial welding voltage value Vn Next welding voltage value Vt Steady welding voltage value W Work Wc Welding control signal WP Welding power source Y Weld pool Y 'Weld mark Y''Weld mark

Claims (9)

Based on welding conditions including welding current value, welding voltage value and welding time, an arc is generated with the welding torch stopped from the arc starting point, and after the welding time has elapsed, the arc is stopped and then the welding torch is welded. While repeatedly regenerating the arc by moving it to the arc restart point separated by a predetermined movement pitch in the direction of travel, the scales, which are welding marks formed by one occurrence of the arc, are overlapped and welded onto the workpiece. In a stitch pulse welding method for forming a bead,
During the period until the number of scales reaches a predetermined initial number, welding is performed under predetermined initial welding conditions including an initial welding current value, an initial welding voltage value, and an initial welding time. After reaching the initial number of formations, a stitch pulse welding method comprising welding under predetermined steady welding conditions including a steady welding current value, a steady welding voltage value, and a steady welding time.   2. The stitch pulse welding method according to claim 1, wherein the initial welding condition is a condition in which at least the initial welding time is shortened stepwise as the number of formations increases.   The stitch pulse welding method according to claim 2, wherein the initial welding time is automatically calculated based on the initial welding time at the arc start point, the initial number of formations, and the steady welding time.   2. The stitch pulse welding method according to claim 1, wherein the initial welding condition is a condition in which at least the initial welding current value is lowered stepwise as the number of formations increases.   The stitch pulse welding according to claim 4, wherein the initial welding current value is automatically calculated based on an initial welding current value at the arc start point, the initial number of formations, and the steady welding current value. Method.   The initial formation number is automatically calculated by inputting the steady welding current value and the steady welding voltage value into a welding condition database in which a correspondence relationship between a welding condition reference value and an initial formation number is stored in advance. The stitch pulse welding method according to any one of claims 1 to 5, wherein:   The initial welding condition is automatically input by inputting the steady welding current value and the steady welding voltage value into a welding condition database in which a correspondence relationship between a welding condition reference value and the initial welding condition for each number of formations is stored in advance. 5. The stitch pulse welding method according to claim 1, wherein the stitch pulse welding method is calculated as follows.   The initial formation number is a welding condition database in which the relationship between the scale diameter value, the steady welding current value, and the steady welding voltage value is stored in advance as the scale diameter value at the steady welding current value and the steady welding voltage value. The steady welding current value and the steady welding voltage value are input and the calculated steady welding current value and the steady welding voltage value are calculated from the steady welding current value, the steady welding voltage value, and the initial number of formations. The stitch pulse welding method according to any one of claims 1 to 5, wherein the stitch pulse welding method is calculated by inputting the relationship into a previously stored welding condition database.   The initial welding time or initial welding current value at the arc start point is the scale diameter value at the steady welding current value and the steady welding voltage value, the scale diameter value, the steady welding current value, and the steady welding voltage value. The stitch pulse welding method according to claim 1, wherein the relationship is calculated by inputting the relationship into a welding condition database stored in advance.

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