JP2007216240A - Welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding method capable of reliably preventing a backing strip from falling off or melting off. <P>SOLUTION: An end face of a backing strip 3 is abutted on an end face of a first member to be welded (a diaphragm 1), an upper side of the backing strip 3 is abutted on a lower side of a second member to be welded (a beam flange) 2, and a groove is arc-welded. In this condition, the welding condition is set so that the smaller contact length decreases the amount of a weld metal more according to the contact length which is the dimension in the vertical direction of an overlapping area of the end face of the backing strip 3 on the end face of the diaphragm 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a welding method suitable for joint welding of architectural steel frames.

  In joint welding of architectural steel frames, the Building Standards Act was revised in 2000, resulting in restrictions on the assembly shape. This new standard requires that the flange must not be displaced with respect to the diaphragm. For this reason, the thickness of the diaphragm and the flange may be the same. However, in consideration of assembly errors and generation of welding distortion, the diaphragm 1 is welded when the diaphragm 1 and the beam flange 2 are welded together as shown in FIG. Assembling is generally performed so that the total thickness of the beam flange 2 is within the range of the end face of the plate in the thickness direction. That is, the thickness of the beam flange 2 is always smaller than the thickness of the diaphragm. For this reason, the side surface of the backing metal 3 disposed at the lower portion of the groove formed by the end surfaces of the diaphragm 1 and the beam flange 2 comes into contact with the end surface of the diaphragm 1.

  The contact length in the thickness direction between the side surface of the backing metal 3 and the end surface of the diaphragm 1 is said to be “the backing metal is applied”, and it is between the upper surface of the diaphragm 1 and the upper surface of the beam flange 2. The difference in height is said to be “difference”. In other words, the value obtained by subtracting the thickness of the beam flange 2 from the thickness of the diaphragm 1 is the sum of “the amount of buckling” and “difference”. Therefore, in joint welding, depending on the arrangement mode of the diaphragm 1 and the beam flange 2, the “difference” is large and the “backing buckle” is small, whereas the “difference” is small, There is a case where “the cost of money” is large. For this reason, when the amount of “backing metal” is small, there is a tendency that the backing metal 3 does not touch the end face of the diaphragm 1, that is, the case where the backing metal 3 does not touch the end face of the diaphragm 1. There is a problem in that the side face of the metal 3 is detached from the end face of the diaphragm 1 and the back metal 3 falls off (melts).

  In particular, in automatic welding by an arc welding robot (see Patent Document 1), since the welding condition is generated or selected according to the root gap regardless of the degree of application of the backing metal 3 to the diaphragm 1, it is necessary to In the case where the thickness is shallow, there is a problem that the backing money frequently falls out (melts).

JP-A-5-329644

  As described above, in order to meet the new standard in joint welding of architectural steel frames, the degree to which the backing metal is applied to the diaphragm has been a problem, but conventional arc welding methods, particularly automatic welding by welding robots In this case, it is impossible to reliably prevent the falling off (melting) of the backing metal when the hook is shallow.

  For this reason, conventionally, in order to perform welding with a welding robot, in order to compensate for the thickness of the backing metal, it is necessary for an operator to perform repair welding (the repair welding portion 4) before welding by the robot. There is a problem that the time is increased and the cost is increased.

  The present invention has been made in view of such a problem, and is such that the end surface of the backing metal overlaps the end surface of one welded material and the upper surface of the backing metal overlaps the lower surface of the other welded material. It is an object of the present invention to provide a welding method capable of reliably preventing the backing metal from falling off and melting even in the new standard joint welding of the tip shape.

  In the welding method according to the present invention, the end surface of the backing metal is brought into contact with the end surface of the first welded material at the groove portion, and the upper surface of the backing metal is applied to the lower surface of the second welded material. In the welding method in which the groove portion is arc-welded in contact with each other, the end face of the backing metal is the vertical dimension of the region overlapping the end face of the first workpiece to be welded. Welding conditions are set such that the smaller the amount, the smaller the amount of deposited metal.

  This welding method is applied to, for example, an automatic welding method using a welding robot, and the applied amount is set in a welding program by an input operation or a sensing operation.

  Further, when the applied amount is small, for example, the welding current is controlled to be low by reducing the welding current.

  Then, when a portion between 5 and 30 mm from the end of the weld line is a welding start end and a welding end, and a portion between them is a main welding portion, when the applied amount is 6 mm or less, the welding current of the welding start end is It is preferably 5 to 20 A higher than the welding current of the main welding.

  In addition, when a portion of 5 to 30 mm from the end of the weld line is a welding start end and a welding end, and a portion between them is a main welding portion, when the applied amount is 6 mm or less, the welding current of the welding end is set. It is preferably 5 to 20 A lower than the welding current of the main welding.

  According to the present invention, when the amount of backing metal applied is small, for example, the welding current is reduced or the welding speed is increased so that the energy applied to the welded portion is reduced, Since the welding conditions are adjusted according to the amount applied, the backing metal does not fall out or melt even when the amount applied is small.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a welding method according to an embodiment of the present invention. FIG. 2 is a schematic view showing a butt weld portion of a joint, and FIG. 3 is a perspective view showing an installation form of the backing metal shown in FIG. As shown in FIG. 2, the column pillar is a structure in which the beam flange 2 having a low thickness and a small plate thickness is abutted against the diaphragm 1, and the SRC is similarly used for the diaphragm 1 having a large plate thickness. The beam flange 2 having a small plate thickness is abutted against each other.

  And, for example, as shown in FIG. 3, the plate thickness of the diaphragm 1 as the first material to be welded is set to the second thickness in order to meet the new standard of joint welding while taking assembly errors and welding distortion into consideration. It is designed to be larger than the plate thickness of the beam flange 2 as a material to be welded, and a part of the end face of the backing metal 3 is in contact with the side surface of the diaphragm 1, and the diaphragm is in this part of the region. The backing metal 3 is arranged so that the side surface of 1 and the end surface of the backing metal 3 overlap, and a part of the surface of the backing metal 3 is in contact with the lower surface of the beam flange 2. In this case, the plate thickness of the diaphragm 1 is t1, the plate thickness of the beam flange 2 is t2, and the amount of the vertical area of the contact area between the end face of the backing metal 3 and the end face of the diaphragm 1 is x. The height difference between the upper surface of the diaphragm 1 and the upper surface of the beam flange 2 is defined as a discrepancy amount y. At this time, t1 = t2 + x + y.

  And the groove | channel shown in FIG. 1 is welded with an automatic arc welding robot. FIG. 5 is a control block diagram of the automatic welding apparatus. A feeding motor control device 15 of the welding power source 14 controls the wire feeding of the wire feeding device 12 with respect to the device section 10 such as the welding torch 11, the wire feeding device 12 and the welding robot body 13. The sensing voltage application device 16 supplies a sensing voltage to the welding robot body 13. In addition, the control device 17 (robot controller) includes a calculation device 18, an external control device 19, and a storage device 20, and controls the welding power source 14 and the device unit 10. A signal for controlling the control device 17 is input from the personal computer (hereinafter referred to as a personal computer) 21 to the control device 17. The personal computer 21 includes a dimension data input interface, executes data generation calculation processing and data transmission / reception processing, and transmits and receives signals to the control device 17.

  Next, an embodiment of the present invention using the above-described automatic arc welding robot will be described. First, as shown in FIG. 4, a joint in which the backing metal 3 is temporarily fixed to the welded portion between the diaphragm 1 and the beam flange 2 by welding is disposed at a position near the welding robot body 13.

  Then, the workpiece dimensions are input from the personal computer 21. The workpiece dimensions are the joint position, the plate thickness of the diaphragm 1, the plate thickness of the beam flange 2, the flange width, and the like. Thereafter, the personal computer 21 starts generating sensing data and transmits the obtained sensing data to the control device 17. In the control device 17, the welding torch 11, the wire feeding device 12, and the welding robot body 13 are subjected to sensing operations, the joint positions are corrected, the flange width is corrected, the route gap is sensed, and the discrepancy amount is further increased. Sense y. As a method for detecting a groove route gap by the arc welding robot, there is a method described in Patent Document 1 described above. Specifically, a detection start position of a predetermined depth with respect to a set groove depth from the surface of at least one weld joint forming member is obtained, and both groove surfaces in the groove width direction are determined at the detection start position. Detecting the groove root gap based on the detected position data of both the groove surfaces, the difference between the set groove depth and the detection start position, and the preset angle of the groove surface. is there.

  As shown in FIG. 4, the discrepancy amount y can be calculated from the difference between the surface positions of the surface of the diaphragm 1 and the surface of the beam flange 2 sensed.

  After executing the sensing operation, the control device 17 transmits the sensing data to the personal computer 21, and the personal computer 21 calculates the route gap, the difference amount y and the amount x of the backing money 3 from each sensing data. Since the plate thickness t1 of the diaphragm 1 and the plate thickness t2 of the beam flange 2 are input to the personal computer 21, the amount x can be calculated as x = t1−t2−y from the measurement result of the discrepancy amount y. it can. The software set in the personal computer 21 calculates a welding condition for the first pass from a prepared welding condition database based on the amount x of the backing metal. The welding condition determined by the amount x of backing metal is the welding condition at the reference gap. Note that this welding condition is held as data for several points (amounts) as shown in Table 1 below. If the amount is a value between these points, Can be calculated by linear interpolation. The welding conditions include a welding current, an arc voltage, a welding speed, a welding wire feed amount, and the like. Then, for the welding condition at the reference gap, a welding speed at which the throat thickness at the actual route gap is equal to the throat thickness at the reference gap is calculated. The personal computer 21 also generates an operation locus based on sensing.

  Thereafter, the personal computer 21 transmits the operation trajectory and the welding conditions to the control device 17, and the control device 17 controls the apparatus 10 and the welding power source 14 to start welding based on the operation trajectory and the welding conditions.

  As a method for calculating welding conditions based on the amount of backing metal from the welding condition database, for example, as shown in Table 1 below, welding condition data depending on the amount of backing metal is registered in the database. As described above, the welding conditions are extracted from Table 1 based on the amount obtained by the sensing operation.

  FIG. 6 is a diagram in which the welding current and welding speed in Table 1 are plotted against the amount of backing metal applied. From the database shown in Table 1 and FIG. 6, for the welding conditions in the reference route gap extracted based on the amount of backing metal, the throat thickness of the reference gap from the wire feed amount and welding efficiency with respect to the current value, etc. The welding speed at an actual gap having the same throat thickness is obtained, and this is set as a working welding speed.

  FIG. 8 is a perspective view schematically showing the shape of the weld metal supplied to the groove. S1 and S2 indicate the groove cross-sectional area of the weld metal. The reference route gap obtained from Table 1 is G1, and the actual gap is G2. Moreover, the welding speed calculated | required from Table 1 is v1, and the welding speed calculated based on this is v2. The throat thickness is h for any weld metal. In the present embodiment, when the reference gap G1 obtained from Table 1 and the actual gap G2 are different, the welding speed obtained from Table 1 is changed so that the throat thickness h is the same. That is, v2 is calculated so that S1 × v1 = S2 × v2, and v2 is set as an actual welding speed.

  As described above, in the welding method according to the embodiment of the present invention, as shown in Table 1 and FIG. 6, the welding conditions such as the welding current and the welding speed are determined according to the amount x of the backing metal 3. As an example, when the applied amount x of the backing metal 3 is reduced without keeping the throat thickness constant, the welding current (wire feed speed) is reduced according to FIG. 6 and Table 1, Even if the welding current is reduced, the corresponding welding speed is not reduced. For this reason, the amount of deposited metal per unit weld length decreases due to a decrease in welding current. In this way, the welding conditions are set, and the groove between the diaphragm 1 and the beam flange 2 is first layer welded. When welding the same groove (the same root gap and throat thickness and the same weld metal volume is required), when the protruding length of the welding wire fed from the current-carrying tip is constant, The welding current can be expressed as a function of the wire feed rate, and the wire feed rate increases as the welding current increases. Accordingly, when the volume is a precondition, the relationship between the welding current and the welding speed is as shown by (2) in FIG. On the other hand, in the present invention, when the amount of the backing metal is reduced, and when the amount of the backing becomes shallower, it becomes easier for the burnout to occur, as shown by ◆ in FIG. 7, compared with the case where the volume is constant. Thus, welding is performed under conditions where the welding speed is increased and the volume of the deposited metal is reduced. That is, in the present invention, the welding current is reduced when the amount of the backing metal is reduced and melting is likely to occur. At this time, the welding speed required to keep the volume of the deposited metal constant. The degree of decrease in welding speed is small. Therefore, the amount of deposited metal is reduced. In Table 1, when the applied amount is small, the welding speed is reduced. This is due to the following reason. In automatic welding, the wire protrusion length is usually constant, and at this time, the wire feed amount is expressed as a function of the welding current. For example, when the wire diameter is 1.2 mm and the wire protrusion length is 25 mm, there is some variation, but when the welding current is 200 A, the wire feed amount is about 8 m / min, when 250 A, about 10 m / min, 300 A In this case, it is about 13 m / min. The welding amount (g / cm) is calculated as wire feed amount (g / min) / welding speed (cm / min) × welding efficiency (%). Accordingly, if the welding speed alone is viewed, the welding amount increases if the welding speed is slow, but the welding current value is reduced when the applied amount is small as in this embodiment, and therefore the wire feed speed. In this case, the welding amount may decrease even if the welding speed decreases. In this embodiment, when the applied amount is small, the welding amount is reduced by reducing the welding current even if the welding speed is reduced.

  Thereby, when the applied amount of the backing metal 3 is small, the amount of the deposited metal is reduced, and the backing metal 3 is prevented from being melted down. Further, when the welding current is reduced, energy is generally reduced, so that the penetration tends to become shallow. However, when the backing metal is shallow, it can be said that it is in a state of being easily melted because the heat capacity is originally small. In addition, when the welding speed is increased with respect to the welding current (the amount of weld metal is reduced), it is difficult for molten metal to flow into the portion where the arc is present. For this reason, the arc tends to directly hit the backing metal, the groove surface, and the standing plate (diaphragm side surface), and easily melts. For these reasons, the necessary penetration can be obtained even if the welding current is reduced.

  As described above, in the present invention, the welding conditions are controlled in accordance with the applied amount x so that the amount of deposited metal is reduced when the applied amount x is small. Show. In this case, it is preferable that the welding start and end portions are different from the welding conditions of the main welding.

  The welding start end portion and the welding end portion refer to portions of 5 to 30 mm from the end of the weld line. And the part between these welding start-end parts and welding termination | terminus parts is a main welding part. In this case, when the applied amount is 6 mm or less, it is preferable to make the welding current at the welding start end portion 5 to 20 A higher than the welding current of the main welding. In the first layer welding, this always corresponds to the first pass of the joint, but the welding start end portion is a portion where an arc is first generated (heat is applied) to the joint, and the base material temperature is low. For this reason, in spite of being hard to melt down, it is hard to obtain melt. Therefore, the welding start end is set to a higher welding current than the steady portion.

  Further, when the applied amount is 6 mm or less, it is preferable that the welding current at the welding end portion is 5 to 20 A lower than the welding current of the main welding. In this case, contrary to the case of the welding start end, the temperature of the base material is increased by welding of the steady portion. In addition, since the heat hardly escapes from the end portion, the end portion is easily melted down, and the penetration is large. Accordingly, the welding current is set lower for the welding end portion than for the steady portion.

  As shown in Table 1, when the route gap is not fixed as 3 mm, for example, and the route gap is also included as a variable, as shown in Table 2 and FIG. The welding current and welding speed can be determined. The range in which the welding speed and welding current change is indicated by hatching.

  In the embodiment described above, the amount to be applied is obtained by the sensing operation. However, the present invention is not limited to this, and the worker may manually input the amount x of the backing money to the personal computer 21.

It is a schematic diagram of a groove part showing a welding method according to an embodiment of the present invention. It is a schematic diagram which shows the example of the butt-welding part of a joint. It is a perspective view which shows an example of the place where the backing metal is installed in the groove | channel between a diaphragm and a beam flange, and forms the groove | channel shown in FIG. It is a figure which shows the method of calculating | requiring the discrepancy amount y by sensing. It is a block diagram which shows the control method of an automatic welding apparatus. It is a graph which shows the relationship between amount of backing money, and the setting value of welding current and welding speed. It is a graph which compares and shows the welding method with constant volume of a deposit metal, and the method of changing a welding speed according to the amount of backing metal of this invention. It is a perspective view which shows typically the shape of the weld metal supplied to the groove. It is a graph which shows the relationship between application | coating of backing metal, welding current, and welding voltage. It is a schematic diagram which shows a repair welding part in the conventional welding method.

Explanation of symbols

1: Diaphragm 2: Beam flange 3: Back metal 4: Repair weld

Claims (5)

At the groove portion, the end surface of the backing metal is brought into contact with the end surface of the first workpiece, the upper surface of the backing metal is brought into contact with the lower surface of the second workpiece, and the groove portion In the welding method for arc welding, in accordance with the amount of application that is the vertical dimension of the region where the end surface of the backing metal overlaps the end surface of the first material to be welded, the smaller the amount applied, the amount of deposited metal Welding method characterized by setting welding conditions so that there is less. The welding method according to claim 1, wherein the welding method is applied to an automatic welding method using a welding robot, and the applied amount is set in a welding program by an input operation or a sensing operation. 3. The welding method according to claim 1, wherein when the applied amount is small, the welding current amount is reduced by reducing the welding current. 4. When the welding distance is 6 mm or less, the welding current at the welding start end is set to the main welding when the portion between 5 and 30 mm from the end of the weld line is set as the welding start end and the welding end and the portion between them is the main welding. The welding method according to any one of claims 1 to 3, wherein the welding current is higher by 5 to 20A than the welding current. A portion between 5 and 30 mm from the end portion of the weld line is used as a welding start end portion and a welding end portion, and a portion between them is a main welding portion. When the applied amount is 6 mm or less, the welding current of the welding end portion is subjected to main welding. 5. The welding method according to claim 1, wherein the welding current is 5 to 20 A lower than the welding current.

Images