Welding method and control device

Abstract

To provide an automatic welding method which performs excellent welding.SOLUTION: A welding method is an automatic welding method to weld by an automatic welding machine, and includes a forward movement step in which welding is performed while moving a torch forward along a welding line by a predetermined first distance at a predetermined first voltage and a predetermined first speed, and then welding is performed while stopping the torch for a predetermined first time; and a backward movement step in which after stopping the torch for a predetermined first time, welding is performed while moving the torch backward along the welding line by a predetermined second distance at a predetermined second voltage and predetermined second speed, and then the torch is stopped for a predetermined second time. The welding of the welding line is performed by alternately repeating the forward movement step and backward movement step from a start point to an end point of the welding line.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a welding method and control device. [Background technology]

[0002] When welding copper fins to a dissimilar base material such as carbon steel, the high thermal conductivity of copper makes it difficult for the copper side to melt, and there are spatial restrictions due to the angle of the fin, which can easily lead to the following inconveniences. For example, in terms of quality, the melting phenomenon is unstable, making it easy for insufficient fusion to occur at the joint (root) between the fin and the base material. Also, when trying to improve this by using high heat input construction, overlap occurs. In terms of cost, the amount of welded welding material increases, and copper welding material, which has a high unit price, is consumed in large quantities, resulting in high costs. In terms of labor, unstable melting increases the lead time due to the need to correct the wire target position, which is an error factor.

[0003] Patent Document 1 discloses a method for welding heat-transfer copper fins to the body of a steel cask, in which the ratio Ia / Ib of the current Ia supplied for TIG welding and the current Ib supplied for MIG welding is output within a predetermined range, and mutually repelling TIG arcs and MIG arcs are generated at the welding start position of the fillet joint by the magnetic force of repulsion generated by the preceding TIG current Ia and the following MIG current Ib, and a single molten pool is formed by the repelling TIG arc and MIG arc, and a welding method is performed by composite welding using the TIG arc, MIG arc, and this single molten pool. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-11845 A Summary of the Invention [Problem to be solved by the invention]

[0005] When welding high thermal conductivity materials such as copper, there is a need for a method to perform a good weld without poor fusion or overlap when performing the weld with a single weld rather than a composite weld.

[0006] The present disclosure provides a welding method and a control device that can solve the above problems. [Means for solving the problem]

[0007] The welding method according to the present disclosure is a welding method for performing welding using an automatic welding machine, and includes an advancing step of performing welding while advancing a torch along a weld line a predetermined first distance at a predetermined first voltage and a predetermined first speed, and then stopping the torch for a predetermined first period of time, and a reversing step of performing welding while advancing the torch along the weld line a predetermined second distance at a predetermined second voltage and a predetermined second speed, after stopping the torch for the first period of time, and then stopping the torch for a predetermined second period of time, and the weld line is welded by alternately repeating the advancing step and the reversing step from a start point to an end point of the weld line.

[0008] The control device according to the present disclosure is a control device for an automatic welding machine, and includes a control unit that alternately repeats from a start point of the weld line to an end point of the weld line a forward step of welding by advancing the torch along the weld line a predetermined first distance at a predetermined first voltage and a predetermined first speed, and then stopping the torch for a predetermined first period of time to perform welding, and a backward step of, after stopping the torch for the first period of time, advancing the torch backward along the weld line a predetermined second distance at a predetermined second voltage and a predetermined second speed to perform welding, and then stopping the torch for a predetermined second period of time, to weld the weld line. Effect of the Invention

[0009] According to the welding method and control device disclosed herein, it is possible to prevent insufficient melting and overlap when welding materials with high thermal conductivity such as copper, and also to reduce costs by reducing the consumption of welding materials and to suppress increases in lead time. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing an outline of an automatic welding robot according to an embodiment; [Diagram 2] FIG. 1 is a diagram showing an example of a welding target according to an embodiment; [Diagram 3] 1A and 1B are diagrams illustrating problems with welding by conventional methods and ideal welding. [Figure 4] 11A and 11B are diagrams illustrating control of temporary attachment according to the embodiment. [Diagram 5] FIG. 4 is a diagram for explaining control of main welding according to the embodiment. [Figure 6] 2 is a flowchart showing an example of an automatic welding method according to an embodiment. [Figure 7] FIG. 2 illustrates an example of a hardware configuration of a control device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Embodiment> Hereinafter, the automatic welding method of the present disclosure will be described with reference to FIGS. (composition) FIG. 1 is a block diagram showing an outline of an automatic welding robot according to an embodiment. The automatic welding robot 100 includes a welding device 10 and a control device 20. The welding device 10 includes a manipulator, a torch, an actuator for driving these, a welding machine, etc., and operates according to instructions from a control device 20 to perform welding. The control device 20 controls the operation of the welding device 10. The control device 20 includes a setting receiving unit 21 and a control unit 22. The setting reception unit 21 receives and stores settings for the operation of the welding device 10 and the welding conditions. The welding condition settings include the welding current, voltage, welding speed, wire feed amount, etc. The setting reception unit 21 also receives settings for the welding line. Control unit 22 operates welding device 10 in accordance with the settings received by setting reception unit 21 .

[0012] 2 shows an example of a welding target according to the embodiment. The welding target is, for example, a main body 1, which is the body of a cask, which is a container used to store spent fuel, and a heat transfer fin 2 attached to the main body 1. The main body 1 is made of carbon steel, and the heat transfer fin 2 is made of copper. As shown in the figure, welding is performed so that the acute angle between the heat transfer fin 2 and the main body 1 is, for example, 60°. In this case, a torch 11 provided in a welding device 10 is placed between the main body 1 and the heat transfer fin 2 as shown in the figure, and MIG (Metal Insert Gas) welding is performed while moving the torch 11 from the front side to the back side of the paper, but copper has a high thermal conductivity, so the heat transfer fin 2 side is difficult to melt, and poor fusion is likely to occur at the root 3 where the main body 1 and the heat transfer fin 2 are joined.

[0013] The phenomenon that is likely to occur in the welding of the main body 1 and the heat transfer fin 2 is shown in the "conventional" column in the upper part of Figure 3. Conventionally, welding was performed by setting a large current and a low welding speed to meet the design conditions of the throat thickness. However, when MIG welding is performed under these welding conditions, the molten pool is likely to form first (the molten pool is likely to form a mass of molten metal on the forward direction side of the actual welding position, and this mass impedes the welding of the root part 3 and becomes a part of the fusion defect in the root part 3). In addition, the deposition amount of the welding material increases, and the lead time increases due to the correction of the wire target position 4 (Figure 2). In contrast, the ideal welding is shown in the "ideal" column in the lower part of Figure 3. In the ideal welding, the molten pool is not formed first, the deposition amount of the welding material is small, fusion defect does not occur in the root part 3, and a bead with good wettability is obtained. Good wettability is, for example, a state in which the weld surface becomes concave. In this embodiment, in order to realize the ideal welding shown in the lower part of FIG. 3, tack welding and main welding are performed in the following manner.

[0014] (Temporary attachment) In tack welding, welding is performed under welding conditions that satisfy the following requirements (A) and (B). (A) A "throat thickness" strong enough not to break during real welding is required. (B) A smaller leg length is desirable because real welding is performed on top of the tack welded part. In this embodiment, the current, voltage, wire feed amount, and welding speed during tack welding are adjusted to reduce insufficient fusion of the main body 1 and the heat transfer fin 2, thereby satisfying the requirements (A) and (B). FIG. 4 shows an outline of conventional tack welding and ideal tack welding. In this embodiment, in order to perform ideal tack welding, the current, voltage, and wire feed amount are reduced compared to conventional methods, and the welding speed is increased compared to conventional methods to perform MIG welding along the weld line. The current and wire feed amount are reduced and the welding speed is increased to improve the leading of the molten pool. The voltage is reduced to improve the concentration of the arc and ensure penetration at the root portion 3. By adjusting the welding conditions and performing tack welding in this manner, the leg length can be reduced while ensuring the actual throat thickness required for tack welding, and a good bead appearance can be obtained.

[0015] (Main welding) In the actual welding, the torch 11 is moved back and forth over the tack welded part, advancing little by little along the weld line (i.e., repeating forward and backward movements) to perform MIG welding from the start point of the weld line to the end point. This welding method is called front-back weaving. The details of front-back weaving are shown in Figure 5. As shown in the figure, front-back weaving is performed in the following steps. (Step 1) Welding is performed while advancing the torch 11 by 16 mm under conditions of a voltage of 28 V and a welding speed of 256 mm / sec. After advancing 16 mm, the torch is stopped on the spot for 0.7 sec and welding is performed under the same conditions. (Step 2) Next, welding is performed while retracting the torch 11 by 8 mm under conditions of a voltage of 33 (V) and a welding speed of 42 (mm / sec). After retracting 8 (mm), the torch is stopped in place for 2.0 (sec) and welding is performed under the same conditions. (Step 3) Along the weld line, weld while moving forward as in step 1, then weld while moving backward as in step 2. Repeat this process until welding is complete from the starting point to the end point. In both steps 1 and 2, the current is set to 350 (A) and the wire feed rate is set to 11.9 (m / min), for example.

[0016] In the forward process, low voltage and high speed welding is used to prevent the weld pool from leading, promote melting of the root 3, and improve overlap. In the backward process, high voltage and low speed welding is used to increase the leg length and ensure the actual throat thickness. In addition, a bead with good wettability is realized with a concave surface.

[0017] (operation) Next, the operation of the automatic welding robot 100 of this embodiment will be described. FIG. 6 is a flowchart showing an example of an automatic welding method according to an embodiment. First, the user sets the operation of the automatic welding robot 100 by teaching or the like (step S11). For example, it is assumed that the design requirement is that the actual throat thickness of the welded portion between the main body trunk 1 and the heat transfer fin 2 be 8 (mm) or more. In this case, in the temporary joint, conditions are selected that can realize a sufficient actual throat thickness and a smaller leg length, and welding conditions are set that can satisfy the conditions. For example, if the actual throat thickness is 6.4 (mm) and the leg length is 9.7 to 14.4 (mm) in the temporary joint in the conventional method, for example, an actual throat thickness of 7.8 (mm) and a leg length of 8.2 to 11.1 (mm) are selected as the conditions to be satisfied in the temporary joint of this embodiment. If the conventional welding conditions for tack welding are current 380 (A), wire feed 12.7 (m / min), voltage 34 (V), and welding speed 160 (mm / min), the welding conditions for tack welding in this embodiment are set to current 350 (A), wire feed 11.9 (m / min), voltage 30 (V), and welding speed 200 (mm / min), so that the current, voltage, and speed are lower than those of the conventional welding. In addition, if the conventional welding conditions for main welding are current 450 (A), wire feed 14.3 (m / min), voltage 37 (V), and welding speed 120 (mm / min), so that the design requirement of the actual throat thickness being 8 (mm) or more is satisfied, the welding conditions for main welding in this embodiment are set, for example, as exemplified in (Step 1) to (Step 3) above. In addition, the user sets the trajectory (welding line) for moving the torch 11. The setting reception unit 21 receives the welding conditions for tack welding and main welding, and the settings of the welding line, and stores this information.

[0018] Next, the user instructs the control device 20 to perform tack welding. The control unit 22 receives this instruction and controls the welding device 10 according to the tack welding settings made in step S11 to perform tack welding (step S12). By performing MIG welding at a lower voltage and higher speed than in the past, a sufficient throat thickness and a smaller leg length are achieved.

[0019] Next, the user instructs the control device 20 to perform main welding. The control unit 22 receives this instruction and controls the welding device 10 according to the settings for main welding set in step S11 to perform main welding (step S13). By repeating the process of moving forward while welding under low-voltage and high-speed welding conditions and then moving backward while welding under high-voltage and low-speed welding conditions, back and forth weaving, poor fusion at the root 3 is eliminated and a bead with good wettability is achieved.

[0020] (effect) When it is difficult to melt during welding, it is often the case that the heat input is increased by increasing the current and decreasing the welding speed. However, this method is not applicable to materials with high thermal conductivity such as copper, and poor fusion and overlap occur. In contrast, the front-back weaving of this embodiment can prevent poor fusion and overlap at the root 3 that occur on the acute angle side when welding a material with high thermal conductivity such as copper and a different material at an angle. In addition, it is possible to reduce costs by reducing the amount of deposition, and to reduce lead time by increasing the welding speed. In addition, by performing front-back weaving using an automatic welding robot instead of by hand, it is possible to perform front-back weaving with high accuracy and achieve the desired welding.

[0021] The values ​​of the current, wire feed, voltage, welding speed, throat thickness, leg length, etc. exemplified in the above embodiment are merely examples and are not limited to the above. In addition, as an example in which front-rear weaving is suitable, a case where front-rear weaving is applied to welding on the acute angle side when welding a member with high thermal conductivity and a dissimilar material at an angle has been described, but front-rear weaving may also be applied to welding on the obtuse angle side. In addition, front-rear weaving may also be applied to welding members with high thermal conductivity together, not limited to combinations of a member with high thermal conductivity and a dissimilar material.

[0022] FIG. 7 is a diagram illustrating an example of a hardware configuration of the control device 20 according to the embodiment. The computer 900 includes a CPU 901 , a main memory device 902 , an auxiliary memory device 903 , an input / output interface 904 , and a communication interface 905 . The above-mentioned control device 20 is implemented in a computer 900. The above-mentioned functions are stored in the auxiliary storage device 903 in the form of a program. The CPU 901 reads the program from the auxiliary storage device 903, loads it in the main storage device 902, and executes the above-mentioned processing in accordance with the program. The CPU 901 also reserves a storage area in the main storage device 902 in accordance with the program. The CPU 901 also reserves a storage area in the auxiliary storage device 903 for storing data being processed in accordance with the program.

[0023] In addition, a program for realizing all or part of the functions of the control device 20 may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to perform processing by each functional unit. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. In addition, if a WWW system is used, the term "computer system" also includes a homepage providing environment (or display environment). In addition, the term "computer-readable recording medium" refers to a portable medium such as a CD, DVD, or USB, and a storage device such as a hard disk built into a computer system. In addition, if the program is distributed to the computer 900 through a communication line, the computer 900 that receives the program may expand the program in the main storage device 902 and execute the above processing. In addition, the above program may be for realizing part of the above-mentioned functions, and may further be capable of realizing the above-mentioned functions in combination with a program already recorded in the computer system.

[0024] As described above, several embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and gist of the invention.

[0025] <Additional Notes> The welding method and control device described in the embodiment can be understood, for example, as follows.

[0026] (1) An automatic welding method according to a first aspect is an automatic welding method for performing welding using an automatic welding machine, comprising the steps of setting as welding conditions the voltage, speed and distance for advancing a torch, a time for stopping the torch after advancing it, the voltage, speed and distance for reversing the torch after the time for stopping the torch, and the time for stopping the torch after reversing it, and repeatedly performing the forward movement and the reverse movement, and performing automatic welding based on the welding conditions. This prevents poor fusion and overlapping, and also reduces the consumption of welding materials, resulting in cost savings and reduced lead time.

[0027] (2) A second aspect of an automatic welding method is the automatic welding method of (1), wherein the first voltage is lower than the second voltage, the first speed is faster than the second speed, and the first distance is longer than the second distance. This prevents poor fusion and overlapping, and also reduces the consumption of welding materials, resulting in cost savings and reduced lead time.

[0028] (3) An automatic welding method according to a third aspect is the automatic welding method of (1) to (2), in which the automatic welding method is performed between a specified first member having a high thermal conductivity and prone to incomplete fusion, and a second member. This makes it possible to prevent insufficient fusion or overlap on the first member side.

[0029] (4) A welding method according to a fourth aspect is the welding method according to any one of (1) to (3), wherein the automatic welding is performed on a region where an acute angle is formed between the first member and the second member. This makes it possible to prevent insufficient fusion or overlap at the root.

[0030] (5) A control device according to a fifth aspect is a control device for an automatic welding machine, and has a control unit that alternately repeats from a start point of the weld line to an end point of the weld line a forward movement step of welding while advancing a torch along the weld line a predetermined first distance at a predetermined first voltage and a predetermined first speed, and then stopping the torch for a predetermined first period of time to perform welding, and a backward movement step of, after stopping the torch for the first period of time, advancing the torch backward along the weld line a predetermined second distance at a predetermined second voltage and a predetermined second speed to perform welding, and then stopping the torch for a predetermined second period of time, to weld the weld line. [Explanation of symbols]

[0031] 1...Main body 2. Heat transfer fin 3. Root section 4. Wire target position 10. Welding equipment 20. Control device 21. Settings reception section 22 Control section 100 Automatic welding robot 900...Computer 901··CPU 902...Main memory 903...Auxiliary storage device 904 Input / Output Interface 905 Communication Interface

Claims

1. A welding method for performing welding using an automatic welding machine, an advancing step of advancing a torch along the weld line a first predetermined distance at a first predetermined voltage and a first predetermined speed, and then stopping the torch for a first predetermined time to perform welding; a retracting step of, after stopping the torch for the first time, performing welding while retracting the torch along the weld line by a predetermined second distance at a predetermined second voltage and a predetermined second speed, and then stopping the torch for the predetermined second time; having The forward movement step and the backward movement step are alternately repeated from the start point to the end point of the weld line to weld the weld line. Welding method.

2. the first voltage is lower than the second voltage, the first speed is higher than the second speed, and the first distance is longer than the second distance; The welding method according to claim 1.

3. The welding is performed between a first member having a high thermal conductivity and prone to incomplete fusion, and a second member. The welding method according to claim 1 or 2.

4. The welding is performed on a region where an acute angle is formed between the first member and the second member. The welding method according to claim 3.

5. A control device for an automatic welding machine, a control unit that performs welding of the weld line by alternately repeating from a start point of the weld line to an end point of the weld line a forward step of performing welding while forwarding the torch along the weld line by a predetermined first distance at a predetermined first voltage and a predetermined first speed, and then stopping the torch for a predetermined first period of time, and a backward step of performing welding while backwarding the torch along the weld line by a predetermined second distance at a predetermined second voltage and a predetermined second speed, after stopping the torch for the first period of time, and then stopping the torch for a predetermined second period of time; A control device having the above configuration.

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