JP5795198B2 - Arc welding method - Google Patents

Description

  The present invention relates to an arc welding method for performing arc welding by setting welding conditions based on a measurement result of a geometric amount related to a welded joint.

  Conventionally, as such an arc welding method, when a member such as aluminum is arc-welded while switching the polarity of the welding voltage, an arc welding method in which the polarity ratio is changed in accordance with the gap between the members to be welded. It is known (see, for example, Patent Document 1).

  In this arc welding method, welding conditions other than the polarity ratio, that is, welding current, welding voltage, welding speed, weaving frequency, weaving amplitude, and target position offset amount are also changed according to the gap of the lap joint. .

  Conventionally, in arc welding with a circular or arc-shaped weaving operation, the weaving angle, which is the angle formed by the weaving surface and the welding direction, is equal to the advance angle of the welding torch or 0 °. A weaving angle of 0 ° means that the weaving surface and the welding direction are parallel.

JP 2002-316265 A

  However, according to the arc welding method of Patent Document 1, when the gap of the lap joint varies, welding is performed while changing the welding conditions such as the polarity ratio in accordance with the variation. The bead has a non-uniform appearance and deteriorates in appearance.

  Also, when performing arc welding with the weaving operation as described above, if the welded joint is a joint, the gap in the direction along the base material surface in the joint, that is, the width of the groove is narrow. A sufficient amount of penetration cannot be obtained, and good welding strength cannot be obtained. In addition, a squeeze joint is a structure in which a step portion is provided on one base material in a lap joint so that both base materials are located on substantially the same plane.

  An object of the present invention is to provide an arc welding method capable of obtaining a weld bead having a uniform appearance regardless of a change in geometric amount in a welded joint in view of the problems of the prior art.

The arc welding method of the present invention includes a measurement step of measuring a geometric amount of a welded joint for each measurement point at a plurality of measurement points within a predetermined range along a weld line on the workpiece, and a geometric amount by the measurement step. Based on the measurement results, a setting step for setting welding conditions so that the appearance of the weld bead by arc welding over the predetermined range is uniform, and arc welding over the predetermined range according to the welding conditions set in the setting step A welding step to be performed , wherein the weld joint is a joint, and in the measurement step, an interval in a direction parallel to the surface of the workpiece with respect to the joint is measured, and in the setting step, the measurement is performed. The weaving width corresponding to the maximum value of the distance between the joint joints measured in the process is set as a common weaving width over the predetermined range .

  According to the present invention, the geometric amount of the welded joint is measured at each measurement point within a predetermined range, and the welding conditions are set based on the measurement result so that the appearance of the weld bead is uniform over the predetermined range. Therefore, even when the interval between weld joints fluctuates within a predetermined range, a weld bead having a uniform appearance can be obtained.

Further , since arc welding is performed with a common weaving width over a predetermined range, the appearance of the weld bead formed by arc welding can be made uniform in terms of the width of the weld bead.

Further, another arc welding method of the present invention includes a measuring step of measuring a geometric amount of a welded joint for each measuring point with respect to a plurality of measuring points within a predetermined range along the weld line on the workpiece, and the measuring step A setting step for setting welding conditions so that the appearance of the weld bead by arc welding over the predetermined range is uniform based on the measurement result of the geometric amount by the method, and the predetermined range according to the welding conditions set in the setting step A welding step of performing arc welding over the welding joint , the weld joint is a joint, and in the measurement step, the spacing in the direction parallel to the surface of the workpiece with respect to the joint is measured, and the setting step in the as spacing Segiri joint measured by the measuring step is greater welding position smaller weaving angle, to set the weaving different angles depending on the welding position And butterflies.

  According to this, since the heat input to the workpiece is small at the welding position where the gap of the gap joint is large, and the heat input is large at the welding position where the gap is small, a sufficient amount of penetration can be obtained at the welding position where the gap is small. In addition, it is possible to eliminate the inconvenience associated with the conventional weaving operation in which melt-off is likely to occur at welding positions having a large interval. Therefore, uniform appearance can be achieved without degrading the welding strength.

It is a block diagram which shows the structure of the welding robot system which concerns on one Embodiment of this invention. It is a flowchart which shows the process performed by the control part of the system of FIG. It is a perspective view which cuts out and shows a part of workpiece | work in the system of FIG. It is sectional drawing which cut | disconnects and shows the part of FIG. 3 by the surface perpendicular | vertical to a welding line. It is a perspective view which shows a mode that the geometric amount of the workpiece joint in the system of FIG. 1 is measured. 2 is a graph illustrating the relationship between a maximum value of a gap G1 measured in the system of FIG. 1 and a setting value of a weaving amplitude φ corresponding to the maximum value. It is a figure which illustrates the locus of weaving in the system of FIG. It is a graph which illustrates the relationship between the measured value of groove cross-sectional area S measured in the system of FIG. 1, and the setting value of the welding current corresponding to this. It is a graph which shows the relationship between the measured value of the gaps G1 and G2 of the welded joint in the system of FIG. 1, and the setting value of EN ratio set based on this. It is a graph which shows the relationship between the measured value of the gap G1 of the weld joint in the system of FIG. 1, and the welding target position y set based on this. It is a graph which shows the relationship between the measured value of the gap G1 of the weld joint in the system of FIG. 1, and the setting value of the weaving angle (theta) set based on this.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a welding robot system according to an embodiment of the present invention. In this system, a workpiece 1 made of an aluminum member is welded by MIG welding.

  As shown in FIG. 1, this system includes a control unit 2 that controls each part of the system, an operation unit 3 that gives instructions to the control unit 2, and a geometric amount of a welded joint of the workpiece 1. A laser sensor 4, a welding torch 5 for welding the workpiece 1, a welding power source 6 for supplying a welding current to the welding torch 5 and the workpiece 1, and a wire supply unit 7 for supplying a welding wire to the welding torch 5; A gas supply unit 8 that supplies a shielding gas to the welding torch 5, and a manipulator 9 that holds and moves the workpiece 1, the laser sensor 4, and the welding torch 5.

  The manipulator 9 is composed of two robot bodies. One robot body holds and positions the workpiece 1 directly or via a jig. Further, the laser sensor 4 and the welding torch 5 are operated by the other robot body. That is, the control unit 2 controls the two robot bodies and performs a welding operation in cooperation with each other.

  FIG. 2 is a flowchart showing a part of the welding process executed by the control unit 2. In this welding process, one of the welding ranges on the workpiece 1 (hereinafter, referred to as “external appearance unified range”) that is predetermined as a range in which the appearance of the weld beads formed by welding should be made uniform and uniform should be described. MIG welding is performed so that the weld bead has a uniform appearance. Examples of the uniform appearance range include a welding range related to one welding line, a welding range covering a plurality of designated welding lines, and a welding range covering all the welding lines on the workpiece 1.

  In the welding process of FIG. 2, the control unit 2 first performs a “geometric amount measurement process” in the measurement process of step S <b> 1. In this process, the geometric amount is measured over the uniform appearance range on the workpiece 1. Next, based on the measurement result, a “welding condition setting process” for setting a welding condition for performing welding over the uniform appearance range is performed in the setting step of step S2. Then, in the welding process of step S3, “MIG welding processing” is performed in which joining along the weld line is performed by MIG welding, which is a type of arc welding, over the uniform appearance range in accordance with the set welding conditions.

  Hereinafter, each process of said step S1-S3 is demonstrated in detail.

(1) Measurement process In the geometric amount measurement process in step S1, the workpiece 1 is held by one robot body constituting the manipulator 9, and the laser sensor 4 fixed to the welding torch 5 by the other robot body, A geometric quantity is measured.

  FIG. 3 is a perspective view showing a part of the work 1 whose geometric amount is measured. As shown in FIG. 3, the workpiece 1 includes a workpiece portion 11 and a workpiece portion 12 whose end portions are welded to each other. The geometric quantity is measured along the weld line along the mutually adjacent ends of the work parts 11 and 12. For example, a motorcycle frame corresponds to the work 1. In the following description, a right-handed XYZ coordinate system in which the welding direction is the positive direction of the X axis and the Y axis is parallel to the surface of the workpiece 1 is used.

  FIG. 4 is a cross-sectional view showing the portion of FIG. 3 cut along a plane (YZ plane) perpendicular to the weld line. As shown in FIG. 4, the end portion of the work portion 11 is adjacent to the overlap portion 11 a and the overlap portion 11 a that borders the end portion with a predetermined width from the end parallel to the X axis. 11 and an inclined portion 11b that forms a step reaching the main portion.

  It faces the surface of the overlapping portion 11a so that the back surface of the end portion of the work portion 12 overlaps with a predetermined gap. Thus, a groove 15 having a substantially V-shaped groove shape is formed between the inclined portion 11b and the end portion of the work portion 12. That is, the welded joint between the work parts 11 and 12 is a claw joint 13. Therefore, in the vicinity of the barbed joint 13, the front and back surfaces of the work parts 11 and 12 are located on substantially one plane.

  A gap G1 is formed as a distance in the Y-axis direction between a line where the surface of the overlapping portion 11a intersects the surface of the oblique portion 11b and the edge of the back surface of the work portion 12. Further, a gap G2 is formed as a distance in the Z-axis direction between the back surface of the end portion of the work portion 12 and the surface of the overlapping portion 11a. In step S1, the cross-sectional areas of the gap G1, the gap G2, and the groove 15 are measured as geometric quantities.

  FIG. 5 shows how these geometric quantities are measured. As shown in FIG. 5A, the geometric amount is measured by the laser sensor 4 fixed to the welding torch 5 to each teaching point Pi (i =..., N−1, n, n + 1,. ) In the direction opposite to the welding direction (the negative direction of the X axis). Each teaching point Pi is set in advance by teaching along the weld line 14 as shown in FIG.

(2) Setting process In the welding condition setting process of step S2, as a welding condition for the uniform appearance range, a weaving amplitude (weaving width) φ common to the entire range of the uniform appearance range and other teaching points are set. Welding conditions are set.

  In setting the weaving amplitude φ, the value of the weaving amplitude φ corresponding to the maximum value of the gap G1 at each teaching point measured in step S1 is set. This set value is set as a common welding condition over the uniform appearance range. This set value is determined based on the correspondence between a predetermined maximum value of the gap G1 and the set value of the weaving amplitude φ.

  FIG. 6 illustrates the relationship between the maximum value of the gap G1 and the set value of the weaving amplitude φ. In the case of this example, as shown in FIG. 6, the maximum value of the gap G1 in the uniform appearance range and the set value of the weaving amplitude φ corresponding thereto are substantially proportional. Such a relationship is defined by a table or function stored in the control unit 2. In accordance with such a relationship, a common weaving amplitude φ in the uniform appearance range is set based on the measurement result in step S1.

  When setting other welding conditions for each teaching point, for example, a welding current, an EN ratio, a welding target position y (FIG. 4), and a weaving angle θ are set as other welding conditions. The set value is determined based on a correspondence relationship between a predetermined geometric amount measurement value and the set value. Such correspondence is defined by a table or function stored in the control unit 2.

  For example, the setting of the welding current for each teaching point is performed based on the measurement result of the cross-sectional area of the groove 15 at the teaching point. The setting of the EN ratio for each teaching point is performed based on the measurement results of the gaps G1 and G2 at the teaching point. The setting of the welding target position y and the weaving angle θ for each teaching point is performed based on the measurement result of the gap G1 at the teaching point.

  FIG. 7 illustrates the weaving trajectory drawn by the welding wire during welding. For example, as shown in FIG. 7A, the tip of the welding wire fed out from the welding torch 5 moves so as to draw a circular locus 16 in a plane perpendicular to the ZX plane. However, since the welding torch 5 moves in the welding direction (the positive direction of the X axis) with respect to the workpiece 1, a spiral trajectory along the welding direction is drawn. In this case, the weaving amplitude φ corresponds to the diameter of the locus 16.

  When the surface on which the locus 16 exists is a weaving surface, the weaving surface forms an acute angle θ with respect to the XY plane as shown in FIG. 7B. However, the counterclockwise direction toward the negative direction of the Y axis is the positive direction of the angle θ. This angle θ is the weaving angle θ. The locus 16 includes a half locus section 16A on the opposite side to the welding direction and a half locus section 16B on the welding direction side.

  FIG. 8 illustrates the relationship between the measured value of the groove cross-sectional area S, which is the cross-sectional area of the groove 15 (FIG. 4), and the set value of the welding current set based on the measured value. The relationship between the measured value of the groove cross-sectional area S and the set value of the welding current differs between when the welding torch 5 moves along the locus section 16A and when it moves along the locus section 16B. The graph curve 19A in FIG. 8 shows the relationship between the measured value of the groove cross-sectional area S in the locus section 16A and the set value of the welding current, and the graph curve 19B shows the same relationship in the locus section 16B.

  As shown in FIG. 8, in any of the trajectory sections 16A and 16B, the welding current is set to a larger value as the groove sectional area S is larger. As a result, an appropriate amount of weld metal corresponding to the groove sectional area S can be applied to the groove 15.

  For the same measured value of the groove sectional area S, the welding current in the locus section 16B is set to a larger value than the locus section 16A. Thereby, in the locus | trajectory area 16B, the welding heat input (heat amount) to the workpiece | work 1 can be made larger than the welding heat input in the locus | trajectory area 16A, and favorable penetration can be obtained.

  FIG. 9 shows the relationship between the measured values of the gaps G1 and G2 and the set value of the EN ratio set based on the measured values. FIG. 9A shows the relationship between the measured value of the gap G1 and the set value of the EN ratio in the locus section 16A for each case where the gap G2 is 1 mm, 2 mm, 3 mm, and 4 mm. FIG. 9B shows the relationship between the measured value of the gap G1 and the set value of the EN ratio in the trajectory section 16B for each case where the gap G2 is 1 mm, 2 mm, 3 mm, and 4 mm.

  In the present embodiment, an AC pulse is used as the welding current, and different EN ratios are applied to each of the trajectory section 16A and the trajectory section 16B. The EN ratio is when the welding wire (electrode) side has a negative polarity (EN polarity) with respect to the total amount of current (electricity) flowing between the welding wire of the welding torch 5 and the work 1 in one cycle of the AC pulse. This is the ratio of the amount of current flowing.

  That is, assuming that the current amount in the case of EN polarity is Ien and the current amount in the case where the welding wire (electrode) side is positive polarity (EP polarity) is Iep, EN ratio = (Ien / (Ien + Iep)) × 100 (% ) The higher the EN ratio is, the easier it is to obtain a surplus, and the lower the EN ratio, the deeper the penetration can be obtained.

  As shown in FIG. 9, in the locus section 16A, by increasing the EN ratio as a whole, the amount of melting of the welding wire is increased to secure surplus, and the heat input to the work 1 is reduced. Therefore, the solidification boundary of the molten pool is made clear. In the trajectory section 16B, by reducing the EN ratio as a whole, the heat input to the workpiece 1 is increased to ensure good penetration.

  Further, as shown in FIG. 9A, the EN ratio in the locus section 16A is linearly increased as the gap G1 is larger and the gap G2 is larger, so that the surplus is made uniform. Further, as shown in FIG. 9B, the EN ratio in the trajectory section 16B is increased with a gentle gradient in the range up to 1 mm in the gap G1 to obtain good penetration, and in the range of 1 mm or more. In order to prevent meltdown, it is increased with a steep slope.

  FIG. 10 shows the relationship between the measured value of the gap G1 and the welding target position set based on the measured value. The welding target position is represented by a distance y in the Y-axis direction from the edge of the back surface of the work part 12 as shown in FIG. As the set value of the welding target position y, a larger value is adopted as the measured value of the gap G1 is larger as shown in FIG. This prevents undercuts and poor fusion.

  FIG. 11 shows the relationship between the measured value of the gap G1 and the set value of the weaving angle θ (FIG. 7B) set based on the measured value. As shown in FIG. 11, the smaller the gap G1, the larger the weaving angle θ is set. When the gap G1 is small, the arc energy hardly reaches the workpiece 1 and the penetration amount is extremely reduced. Therefore, the weaving angle θ is increased, the arc energy easily reaches the workpiece 1 and the penetration amount is increased. It is necessary.

  On the contrary, the smaller the gap G1, the smaller the weaving angle θ is set. If the gap G1 is large, the arc energy easily reaches the workpiece 1 and the amount of penetration increases, so the weaving angle θ is reduced, the arc heat is kept away from the workpiece 1, and the heat input to the workpiece 1 is reduced, This is because it is necessary to prevent the occurrence of poor welding due to melting.

(3) Welding process In the MIG welding process in step S3, MIG welding is performed over the uniform appearance range according to the welding conditions set in step S2. At the start of welding, the welding torch 5 and the laser sensor 4 are located at the position when the measurement in step S1 is completed, that is, the welding start position in the uniform appearance range. Welding can be started along the welding direction (the positive direction of the X axis). When the welding is completed, the welding process in FIG. 2 ends.

  According to the present embodiment, the geometric amount such as the gap G1 is measured over the uniform appearance range, and the weaving corresponding to the maximum value of the gap G1 is performed as a common welding condition over the uniform appearance range based on the measurement result. Since the value of the amplitude φ is set, it is possible to make the appearance uniform by unifying the width of the weld bead over the uniform appearance range.

  Further, as shown in FIG. 9, since the EN ratio in the trajectory sections 16A and 16B is set according to the measurement results of the gaps G1 and G2, in the trajectory section 16A, a surplus is ensured and a clear molten pool is obtained. The solidification boundary is formed, and in the locus section 16B, it is possible to ensure good penetration and prevent melting.

  Accordingly, a scaly shape due to surplus build-up can be surely formed in the trajectory section 16A without deteriorating the welding strength over the uniform appearance range, which can contribute to the uniform appearance of the weld bead. Therefore, combined with the effect of unifying the weld bead width described above, a weld bead is formed in which the surplus is constant and the solidification boundary such as TIG (TIG) welding is clear regardless of the variation of the gaps G1 and G2. In addition, the uniform appearance can be further improved.

  In addition, since a different weaving angle is set according to the welding position so that the welding position with a larger gap G1 has a smaller weaving angle θ, the amount of heat input to the workpiece 1 is reduced at the welding position with a larger gap G1. The amount of heat input can be increased at the welding position where the gap G1 is small.

  As a result, it is possible to eliminate the conventional inconvenience that a sufficient amount of penetration cannot be obtained at a welding position where the gap G1 is small, and melting-down easily occurs at a welding position where the gap G1 is large. Further, even when the weaving amplitude φ is unified, it is possible to prevent the welding strength from deteriorating. Therefore, it can contribute to the uniform appearance of the weld bead over the uniform appearance range.

  The present invention is not limited to the above embodiment. For example, in the above description, the case of performing MIG welding as arc welding has been described. However, the present invention is not limited to MIG welding, but other arc welding, for example, MAG (mag) welding used for an iron-based base material, or carbon dioxide arc welding. The present invention can also be applied to.

  In the above description, the case where the welded joint is a barbed joint has been described. However, the present invention can also be applied to other welded joints such as a lap joint. In that case, the gap in the overlapping portion of the lap joint is measured over the uniform appearance range, and the welding conditions are set based on the measurement result so that the appearance of the weld bead is uniform.

DESCRIPTION OF SYMBOLS 1 ... Work, Pn-1, Pn, Pn-1 ... Teaching point (measurement point), 13 ... Claw joint, S1 ... Measurement process, S2 ... Setting process, S3 ... Welding process.

Claims (2)

For a plurality of measurement points within a predetermined range along the weld line on the workpiece, a measurement process for measuring the geometric amount of the weld joint for each measurement point;
Based on the measurement result of the geometric amount by the measurement step, a setting step for setting welding conditions so that the appearance of the weld bead by arc welding over the predetermined range is uniform;
In accordance with the welding conditions set in the setting step, a welding step for performing arc welding over the predetermined range ,
The welded joint is a clam joint,
In the measurement step, the distance in the direction parallel to the surface of the workpiece about the interference joint is measured,
In the setting step, the weaving width corresponding to the maximum value of the gap joint distance measured in the measurement step is set as a common weaving width over the predetermined range . For a plurality of measurement points within a predetermined range along the weld line on the workpiece, a measurement process for measuring the geometric amount of the weld joint for each measurement point;
Based on the measurement result of the geometric amount by the measurement step, a setting step for setting welding conditions so that the appearance of the weld bead by arc welding over the predetermined range is uniform;
In accordance with the welding conditions set in the setting step, a welding step for performing arc welding over the predetermined range,
The welded joint is a clam joint,
In the measurement step, the distance in the direction parallel to the surface of the workpiece about the interference joint is measured,
In the setting step, an arc welding method is characterized in that a different weaving angle is set according to a welding position so that a welding position having a larger gap between the gap joints measured in the measurement step has a smaller weaving angle .

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