JP2806733B2 - Multi-pass welding method for fillet joints - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-pass welding method for fillet joints by arc welding, and more particularly to a multi-pass welding method suitable for automatic multi-pass welding.

[0002]

2. Description of the Related Art Conventionally, in the field of welding technology for mass-produced products such as automobile parts, stamped parts, and machine parts, automation and rationalization of welding have been widely spread and expanded by promoting automation and rationalization of production. . On the other hand, in the field of welding technology that handles small-volume products such as large structures,
Automation of production and improvement of work environment are delayed, and there are problems of young people leaving the manufacturing industry, shortage of skilled technicians, aging, and shortage of human resources.
There is a strong demand for improving the work environment.

[0003] Unlike single-pass welding of thin plates, it is necessary to perform multi-pass multi-pass welding of thick plate structures. For example, when performing automatic multi-pass welding with an automatic welding device such as an arc welding robot. It is necessary to teach the welding conditions and the position of the welding torch (the target position of the tip of the welding wire) to the automatic welding apparatus in advance for each welding pass. As a conventional teaching method, a skilled welding operator teaches and sets a welding torch position and a welding condition of a next pass and a corresponding welding pass by judging a situation of a welding bead of a previous pass for each welding pass. .

However, in the above-mentioned conventional teaching method,
Since the welding operator must teach each welding pass by hand, not only beginners need difficult construction techniques, but also require a lot of time to teach,
There was a drawback that welding could not be performed continuously, and work efficiency could not be improved. Conventionally, there have been attempts to solve this drawback, and several methods have been proposed for automatically determining the welding torch position and welding conditions.

[0005] For example, as described in Japanese Patent Publication No. 63-65425, for automatic multi-pass welding of a fillet joint, the geometrical shape of the groove cross section and the welding current and welding speed in layer units. Is input, the arc voltage is calculated based on the input information, and then the welding is performed. At the same time, the welding amount of each layer, the bead height and width of the welding pass, the number of passes, and the like are calculated. The welding torch position of the next layer and the next pass is determined and automatically determined and moved, and the calculation and movement of the welding torch position are repeatedly performed until a predetermined total lamination height is reached, thereby performing multi-layer welding. ing.

[0006] Further, the welding method described in Japanese Patent Publication No. 4-29473 discloses a multi-layer welding of a grooved joint.
After calculating the welding cross-sectional area and the amount of wire welding per pass to calculate the number of passes required for welding, select an approximate set pass number from the set pass numbers set in advance corresponding to the number of weld layers. The expected welding cross-sectional area is obtained by dividing the side corresponding to the groove of the expected welding cross-section by the number of welding layers and the set number of passes, and at each intersection, a horizontal line and a parallel line are extended from each division point, respectively. Is the welding torch position for each pass.

[0007]

In order to automatically determine the teaching and setting of the welding torch position and the welding conditions for each welding pass without relying on a skilled welding operator, a predetermined welding joint is required. An algorithm and an arithmetic expression for multi-layer welding that can automatically calculate the welding torch position and welding conditions are indispensable.

In the multi-pass fillet welding method for fillet joints described in Japanese Patent Publication No. 63-65425, the amount of wire welded, the bead height and width of the welding pass,
The welding torch position of the next layer and the next pass is calculated according to the calculation such as the number of passes and the calculation result, and is automatically determined and moved. For this reason, it is difficult not only to formulate a construction plan before performing multi-layer welding, but also to consider in advance the location of the welding torch for each lamination and each pass. Had not been.

FIG. 1 shows a conventional welding operation of a fillet joint.
This will be described with reference to FIGS. FIG. 17 is an explanatory diagram showing a conventional multi-pass welding of a fillet joint, and FIG. 18 is an explanatory diagram showing another conventional multi-pass welding of a fillet joint. In these figures, 1 indicates a lower plate, 2 indicates an upper plate, and 3 indicates a welding pass sequence. In the multi-pass fillet welding of a fillet joint shown in the embodiment of Japanese Patent Publication No. 63-65425, as shown in FIG. 17, the welding paths are arranged in a horizontal direction from the lower side and sequentially stacked on the upper side. Welding is performed in the order of the numbers. However, in an actual welding site, as shown in FIG. 18, generally, a method of sequentially stacking and laminating welding paths in an oblique direction in which a lower plate 1 and an upper plate 2 are alternately welded has been adopted. The number of multi-pass welding by the lamination method as shown in FIG. 17 is extremely small.

On the other hand, in the horizontal groove welding method described in Japanese Patent Publication No. 4-29473, an algorithm for multi-layer welding required for determining a welding torch position for each welding pass with respect to a predetermined welding joint, and the like. The arithmetic expression is not disclosed at all and is unknown. For example, the welding torch position of each pass is divided by the number of layers of welding and the set number of passes, and the horizontal line and the parallel line are extended from the respective dividing points to the respective intersections. It is not clear whether it is determined using a formula or an arithmetic expression. In addition, since the estimated welding cross-sectional area is obtained by selecting an approximate set number of passes from the set number of passes set in advance corresponding to the number of welding layers, the welding break required for welding the actual groove Unlike the area, no consideration has been given to the fact that the welded cross-sectional area to be welded becomes larger or smaller than the steady area, and particularly tends to adversely affect the welding result of the final layer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to make it possible for even a novice to operate without relying on a skilled welding operator, and to provide a first layer to a final layer. The optimum welding line and welding torch position for each pass and the optimum welding conditions can be automatically calculated and determined, and the welding from the first layer to the last layer required for the welding leg length to satisfy the prescribed weld metal The method is to provide a multi-layer fillet welding method for a fillet joint which can accurately and sequentially perform the welding.

[0012]

In order to achieve the above object, a multi-layer fillet welding method for a fillet joint according to the present invention comprises automatic welding capable of performing arc welding of an arbitrary joint shape according to predetermined teaching data. In a method for performing a multi-pass welding of a fillet joint using a device, an operation processing device for controlling the automatic welding device and performing an automatic calculation process of a multi-pass welding path plan is provided, and the multi-pass welding by the operation processing device is provided. In the automatic calculation of the plan, at least the joint shape of the weld, the length of the welding leg to satisfy the predetermined weld metal, the gap of the joint, the same welding current and the shift amount of the welding torch from the first layer to the last layer are used as initial conditions. Based on this input value, the welding voltage, wire melting speed, total welding cross-sectional area required to satisfy the welding leg length and the number of welding layers, the number of welding passes from the first layer to the last layer Welding speed and welding cross-sectional area per pass unit, bead height and width of first layer welding, total bead height and width associated with lamination welding, etc. are calculated, and each welding pass from the first layer to the last layer is calculated based on this calculation result. Each pass coordinate and the position coordinates of the welding torch are calculated, and a series of these calculation results are displayed. By the automatic calculation, the optimal calculation for each welding pass from the first layer to the last layer required for multi-layer welding is performed. Path plan data composed of welding conditions, path coordinates and position coordinates of the welding torch is created. Necessary teaching data for fillet joints to be subjected to multi-layer welding are the welding line and welding torch position of the first layer. Is input to the automatic welding device as an initial condition and then transmitted to the arithmetic processing device, and from the first layer to the last layer based on the teaching data and the created path plan data. After automatically create a teaching path plan data for teaching to determine the optimum welding line and the welding torch position coordinates and the optimum welding conditions for each pass in the processing unit, transmitted to the automatic welding apparatus,
Each welding pass from the first layer to the last layer is sequentially executed based on the teaching path plan data.

In this case, of the welding conditions required for performing the automatic calculation processing, the welding voltage is calculated as a function of the input welding current and a predetermined wire protrusion length between the tip and the base material, In addition, the welding voltage obtained by the calculation can be corrected by additional input of an increase / decrease value desired by the operator.
It is calculated as a function of the wire protrusion length between the base material and the increase / decrease value of the additionally input welding voltage.
Calculated as a function of the input welding leg length and gap, the number of layers of welding that can be calculated from this welding leg length, and the wire melting speed, and within the range of welding speeds that can form a normal welding beat for the calculated welding speed The upper limit and the lower limit are set so that the welding speed related to the number of laminations can be increased or decreased within this range.The total number of welding passes is calculated based on the welding speed used when calculating and determining the welding speed. As a function of the number of laminations, the total weld cross section is a function of the weld leg length and the gap, the weld cross section per weld pass unit is a function of the calculated wire melting rate and welding rate, and The bead height and width are calculated as a function of the welding cross-sectional area per unit and the gap.
The cumulative bead height and width of the lamination welding are a function of the lamination number from the first layer to the last layer and the welding cross-sectional area per unit. It is calculated as a function of bead height and width, respectively.

Further, the path coordinates for each welding pass from the first layer to the last layer are calculated as a function of the relationship between the paths to be welded, the number of laminations and the number of steps, the total number of lamination weldings, and the bead height and width per unit. Further, the position coordinates of each welding torch are calculated as a function of the path coordinates of each welding path determined by the above calculation and the shift amount of the input welding torch, and when performing the first layer welding, the path coordinates and the shift amount are calculated. It is represented as a function of the gap and is automatically calculated. Further, the set range of the shift amount (S) of the welding torch with respect to the pass coordinates for each welding pass is set so that 0 <S ≦ 4.

In displaying the calculation results, the optimum welding conditions, path coordinates, and position coordinates of the welding torch for each welding pass from the first layer to the last layer required for the multi-layer welding obtained by the automatic calculation are represented by CRT. In addition to being displayed on the screen, the displayed result can be edited, such as changed, corrected, or added, by the judgment of the operator.

[0016]

As described above, it is necessary to perform control of an automatic welding apparatus and automatic calculation processing of a multi-pass welding path plan.
For example, an arithmetic processing unit such as a personal computer with built-in software is provided, and a predetermined fillet joint is subjected to multi-pass welding based on a small amount of input information necessary for each calculation from the first layer to the last layer. The arithmetic processing unit automatically calculates and determines the optimal welding line, welding torch position coordinates, and welding conditions for each welding path up to and determines and teaching. This makes it possible for even a beginner to easily draft a construction plan before performing multi-layer welding without relying on a skilled welding operator.

The formula for calculating the welding voltage required for performing the automatic calculation process is expressed as a function of the input welding current and a predetermined wire protrusion length between the tip and the base material.
In addition, by adopting a method in which the welding voltage obtained by the calculation can be corrected by an additional input of an increase / decrease value desired by the operator, a welding voltage suitable for the value of the welding current and the wire protrusion length can be calculated, and Based on the empirical judgment of each welding operator, it is possible to take in the desire to slightly increase or decrease the value of the welding voltage, which makes it easier to use.

Further, by making the arithmetic expression of the wire melting rate a function of the welding current, the wire protrusion length between the tip and the base material, and the increase / decrease value of the additionally input welding voltage,
It is possible to always properly calculate the wire melting speed that changes not only with the change in the welding current but also with the increase or decrease in the wire protrusion length and the welding voltage.

The arithmetic expression for the welding speed, which is an important factor when performing welding, is expressed as a function of the input welding leg length and gap, the number of welded layers that can be calculated from the welding leg length and the wire melting speed, and An upper limit value and a lower limit value are provided so as to be within a range of a welding speed at which a normal welding beat can be formed with respect to the calculated welding speed, and a welding speed related to the number of laminations can be increased or decreased within this range. . By doing so, it is possible to eliminate the undercut and poorly penetrated weld bead that are likely to occur on the high-speed side and the overlapped weld bead that is likely to occur on the low-speed side, and a normal weld bead is always obtained. Not only that, even if the welding speed related to the number of laminations is increased or decreased within an appropriate range, it is possible to correctly secure a welding leg length that satisfies a predetermined weld metal.

Since the equation for calculating the total number of welding passes required for multi-pass welding can be expressed as a function of the number of laminations determined from the input welding leg length, it is possible to accurately satisfy the welding metal required for a given welding leg length. it can. In addition, by using the equation for the bead height and width of the first layer welding as a function of the welding cross-sectional area per unit and the gap, the bead height and width of the first layer welding taking into account the effect of the gap can be correctly obtained. it can.

Further, the arithmetic expression of the path coordinates for each welding pass from the first layer to the last layer is a relation between the path to be sequentially welded, the number of laminations and the number of steps, the cumulative number of lamination welding, and the function of the bead height and width per unit. The equation for calculating the position coordinates of the welding torch was a function of the path coordinates of each welding path obtained by the above calculation and the shift amount of the input welding torch. This not only enables a lamination method in which the lower and upper plates are alternately welded in a direction in which the lower plate and the upper plate are alternately welded, as is widely used in actual welding sites, but also enables the lamination method from the first layer to the final layer. The welding torch position for each welding pass required for multi-pass welding can be accurately and automatically calculated and determined.

Further, by setting the shift range (S) of the welding torch to a range of 0 <S ≦ 4, it is possible to prevent the occurrence of a phenomenon that the welding leg lengths in the lower plate direction and the upper plate direction tend to be non-uniform. Becomes possible.

The results of the multipass welding path plan data obtained by the automatic calculation are displayed on the CRT screen and can be edited, so that the operability and usability are good and the contents of the multipass welding are verified in advance. It becomes possible.

From the automatically created path plan data and the initially input teaching data of the first layer, the optimum welding line and welding torch position coordinates and the optimum welding conditions for each welding pass required for multi-layer welding. Is determined by the arithmetic processing unit and automatically transmitted to the automatic welding apparatus. Based on the transmitted teaching path plan data, each welding pass of the multi-pass welding is sequentially executed. It has become. This eliminates the need for the welding operator to teach the welding torch position for each welding pass, which required a great deal of time in the past, and not only can improve the welding efficiency by shortening the time, but also from the first layer to the last layer. Uniform and good results of multi-pass welding can be obtained without causing defects in each welding.

[0025]

FIG. 1 to FIG. 17 show an embodiment of the present invention.
This will be described with reference to FIG. First, FIG. 1 is a flowchart showing an algorithm of a multi-pass welding method according to one embodiment of the present invention, and prepares path plan data necessary for multi-pass welding of a fillet joint having a welding leg length to satisfy a predetermined weld metal. This is a procedure for performing the above. FIG. 2 is a system diagram showing the configuration of the multi-pass welding system according to one embodiment of the present invention.

After inputting the initial conditions, the welding voltage, the number of laminations and the number of passes, the wire melting speed, the amount of wire welded per pass, the welding speed, the total welded cross-sectional area are set in accordance with the flowchart shown in FIG. , Welding cross-sectional area per pass, bead width, height and total bead width and height of welding pass, welding pass coordinates, welding position coordinates, correction path, detection path, etc. A series of calculations are performed. Further, the result of the calculation (also referred to as an operation) is displayed on a CRT screen, and its contents can be edited (changed, corrected, added, etc.) as necessary.

FIG. 2 shows an apparatus configuration for realizing the multi-layer welding method. In FIG. 2, 6 is an automatic arithmetic processing unit,
7 is a welding robot control unit, and the automatic arithmetic processing unit 6 is
A series of software necessary for controlling the welding robot controller 7 and performing automatic calculation processing of the multi-pass welding path plan is incorporated. Reference numeral 8 denotes a teaching box for teaching and inputting an arbitrary welding line and welding position to the welding robot control device 7. Reference numeral 11 denotes a welding robot main body, on which a welding torch 14 is mounted on the wrist, and which is connected to the welding robot control device 7 together with the welding machine 9. Then, the welding work 13 installed on the welding work table 12 is welded.

The automatic arithmetic processing unit 6 automatically determines and teaches the optimum welding conditions, path coordinates, position coordinates of the welding torch and the like for each welding pass necessary for multi-pass welding, and automatically creates a multi-pass welding pass plan. At the same time, communication control is performed with a welding robot control device 7 that controls the welding robot main body 11 for performing automatic welding.

Reference numeral 15 denotes a visual sensor head capable of detecting a welding position, which is connected to the automatic processing unit 6 via a sensor controller 16 and a sensor image processing unit 17. The sensor image processing device 17 that can automatically process the detection information from the visual sensor head 15 detects and recognizes the welding position for each welding pass according to a command from the automatic calculation processing device 6, and automatically calculates the detection information. The data is transmitted to the processing device 6. Then, after performing the correction calculation of the welding position deviation according to the transmitted detection information,
It has a function of transmitting the correction information to the welding robot control device 7 and instructing to perform the correction control of the welding position deviation.

As described above, the present apparatus has no sensor,
Since it has the selection function of presence, for example, when there is no sensor, multilayer overlay welding can be performed reliably and appropriately in accordance with the multilayer overlay welding path plan automatically created by the automatic processing unit 6. When a sensor is used, the information of the multi-pass welding pass plan and the automatic arithmetic processing unit 6 are used.
The multi-pass welding can be performed while appropriately correcting and controlling the welding position based on the detection information transmitted from the sensor. The software related to the multi-pass welding algorithm shown in FIG. 1 is built in the automatic arithmetic processing unit 6, and the contents will be described with reference to the drawings.

FIG. 3 is an explanatory view of the shape and input conditions of the fillet joint according to the present embodiment, FIG. 4 is an explanatory view showing a welding torch position in the present embodiment, and FIG. FIG. 6 is a characteristic diagram showing the relationship between voltages, FIG. 6 is a flowchart of an appropriate welding voltage calculation process in one embodiment of the present invention,
FIG. 7 is a characteristic diagram of an appropriate wire melting rate, FIG. 8 is an explanatory diagram showing a bead shape of initial layer welding, FIG. 9 is a lamination pattern diagram of multilayer multi-pass welding, and FIG. It is an arithmetic processing flowchart of lamination welding bead height and width in an example.

First, initial conditions necessary for a series of calculations are input to the automatic calculation processing device 6. For example, welded workpieces as shown in FIG. 3, i.e. against the fillet joint between the upper plate 2 of the lower plate 1 and the plate thickness T ₂ of the thickness T _1, corresponding fillet among several joint shape After selecting a joint, an arbitrary set welding leg length L required for multi-layer welding, a gap G generated at the joint between the lower plate 1 and the upper plate 2, and a welding current identical from the first layer to the last layer Ia and FIGS. 4 (a) and 4 (b)
(C) welding torch 5 (target position Q _{1 of} wire tip)
ＱQ ₃ ) is input.

Here, the input range of the welding leg length L is set from a minimum of 5 mm at which a thin plate can be welded in one pass to a maximum of 100 mm at which a thick plate can be welded in multiple passes. FIG.
The input range is set to 0 <S ≦ 4 mm for the shift amount S of the welding torch shown in FIG. The reason for this is, for example,
According to the results of an experiment in which multi-layer welding was performed at a welding torch angle θ of 45 ° ± 5 °, when S = 0, molten metal was transferred to the upper plate 2 by the action of wire droplet transfer and arc force.
, And the length of the welding leg in the upper plate 2 direction is likely to be larger than that in the lower plate 1 direction. On the other hand, S> 4 mm
In this case, on the contrary, the force of gravity for flowing the molten metal in the direction of the lower plate 1 is larger than the force for pushing the molten metal in the direction of the upper plate 2, so that the problem that the welding leg length in the direction of the lower plate is increased. Because. It has been found that the range in which welding results with vertically uniform welding leg lengths can be obtained is 0 <S ≦ 4 mm.

Therefore, here, the standard value of the shift amount S of the welding torch is set to about 1 mm, and the shift amount S can be variably set within the above range. In addition, the wire protrusion length lc related to the wire melting rate (see FIG. 5)
The standard value is set to about 25 mm, and the setting can be changed within a range of 15 to 35 mm that can be generally used for welding.

Hereinafter, these calculation methods will be described. FIG. 5 shows the welding current Ia (A) on the horizontal axis and the welding voltage Ea (V) on the vertical axis.
The relationship between the welding current and the appropriate welding voltage is shown by changing the welding current to 5, 30 mm. The appropriate welding voltage Ea required to perform the welding is determined by the welding current Ia as shown in the embodiment of FIG.
a is not only proportional to a, but also
c, the welding current Ia as shown in equation (1).
And the wire protrusion length (wire distance between the power supply tip and the base material) lc.

[0036]

Ea = k ₁ · Ia + k ₂ · lc (1) where k ₁ and k ₂ are constants that vary depending on the wire diameter and the type of shielding gas used, and are solid wires having a wire diameter of 1.2 mm. In the example where MAG gas was used as the shielding gas, k ₁ = 0.08 and k ₂ = 0.4.

In setting the welding voltage, as shown in FIG. 6, the welding voltage Ea calculated in the above (1) can be corrected by inputting the increase / decrease value ΔE desired by the operator. . Therefore, the equation for calculating the corrected welding voltage E is as shown in equation (2).

E = Ea + ΔE (2) By doing so, a welding voltage suitable for the values of the welding current Ia and the wire protrusion length lc can be calculated, and the value of the welding voltage E can be slightly increased or It is possible to cope with the demands of the welding operator who wants to lower the temperature and changes in the wire material and the shield gas component, thereby improving usability.

In order to satisfy a predetermined welding leg length L by multi-pass welding, it is necessary to determine the number of laminations and the number of passes. For example, in the case of lamination as shown in FIGS. 18 and 19, the relationship between the welding leg length L and the number of laminations Ns is represented by the following equation (3), and the relationship between the number of laminations Ns and the number of passes Np is (4) )).

[Number 3] Ns = L / C ₁ (however, and rounded to the nearest yen) (3)

Equation 4] Np = Ns (Ns + 1) / 2 ...... (4) where, C ₁ is stacked bead height of the weld, a constant relating to the width, of about 5-9. Therefore, when welding is performed with the number of laminations Ns and the number of passes Np obtained from the equations (3) and (4), a predetermined welding leg length L is satisfied.

FIG. 7 shows the welding current Ia (A) on the horizontal axis and the wire melting speed Ws (m / min) on the vertical axis, and changes the wire projection length lc to 20, 25, and 30 mm to change the welding current. The relationship with the appropriate wire melting rate is shown. FIG. 7 is an example showing the characteristics of the wire melting speed Ws when welding is performed using a solid wire having a wire diameter of 1.2 mm under the condition that the relationship (1) between the welding voltage and the welding current is satisfied. In the figure, the increase / decrease value of the welding voltage (ΔE = E−Ea)
Is also changed by ± 2 V. The wire melting speed Ws increases substantially in proportion to the welding current Ia and the wire protrusion length lc, and increases as the welding voltage becomes lower than the standard, and is expressed by the following equation (5).

[0040]

Ws = [k ₃ lc + k ₄ −k ₅ (E−Ea)] Ia− (k ₆ lc + k ₇ ) (5) The constants at this time are k ₃ = 0.0016 and k ₄ = 0. .0
_{012, k 5 = 0.008, k} 6 = 0.16, k 7 = 0.
It was 2. In a small current region where the welding current is less than 150 A, the wire melting speed Ws tends to decrease in a curve and deviate from the above equation (5). Therefore, the welding current region to which the expression (5) can be applied is 150 A or more.
In the present multi-layer welding method, a high current region of 200 A or more is used in order to stabilize the welding arc and increase the welding of the wire.

As described above, by using the function shown in the equation (5), not only the change in the welding current Ia but also the increase or decrease in the wire protrusion length lc and the welding voltage (ΔE = E−Ea) are always appropriate. It is possible to calculate the wire melting speed Ws. As described above, the wire melting speed Ws (m / mi)
When n) is obtained, the wire welding amount Wv (mm ³ / min) per welding pass unit can be obtained from the following equation (6).

[6] _{^{Wv = 10 3 πd 2 WsC 2}} /4 ...... (6) where the wire diameter d is used, C ₂ is a constant that indicates the deposition efficiency of the wire, when using a MAG gas shielding gas It is about 0.94 to 0.98, and in the case of carbon dioxide gas, it is about 0.90 to 0.94.

Similarly to the welding voltage, the welding speed V is one of the welding conditions necessary for performing the welding, and is represented by the wire welding amount Wv per welding pass unit of the above formula (6) and the formula (4). There is a relationship that is proportional to the number of laminations Ns related to the number of passes and inversely proportional to the length L and gap G of the welding leg to be filled with the molten metal, and is expressed by the following equation (7).

(Equation 7)

According to the results of the welding experiment, the welding speed was about V
On the high-speed side, which is too high as> 550 mm / min, an undercut or insufficient penetration of a weld bead tends to occur, and on the low-speed side, where the welding speed is as low as about V <150 mm / min, an overlap welding bead tends to occur. It has been found that the welding speed in an appropriate range in which a good weld bead having no welding defects can be formed is 150 ≦ V ≦ 550 mm / min.

For this reason, as shown in the flow chart of FIG. 1, in the present multi-layer welding method, the welding speed that always falls within the proper range (150 ≦ V ≦ 550 mm / min) is calculated using the equation (7). And a function of increasing or decreasing the welding speed within the proper range. That is, when the calculated welding speed is V <150 and when it is desired to increase the welding speed within an appropriate range, the number of laminations related to the welding speed is set to Ns = Ns + 1 (lamination number increment processing).
The appropriate welding speed is recalculated and found again. Conversely,
When the calculated welding speed is V> 550 and it is desired to reduce the welding speed within an appropriate range, the proper welding speed is recalculated to Ns = Ns-1 (the number-of-laminations decrementing process).

By changing the lamination number Ns related to the welding speed as described above, it is possible to increase or decrease the welding speed within an appropriate range. Therefore, even if the welding speed is increased or decreased according to the demands of the individual workers, not only a good weld bead can be obtained at all times, but also a welding leg length that satisfies a predetermined weld metal can be accurately secured.

The welding cross-sectional area Sn per welding pass unit is represented by the following equation (8): wire welding amount W per welding pass unit.
v and the welding speed V. Further, the total welding cross-sectional area A required for the welding leg length is equivalent to the welding leg length L and the cross-sectional area of the gap G of the joint portion to satisfy the welding metal, as shown in the equation (9), the wire welding amount Wv and the number of passes. Is expressed as a function of the number of laminations Ns and the welding speed V.

## EQU8 ## Sn = Wv / V (8)

A = (L ² + 2G ² ) / 2 = Wv · Ns (Ns + 1) / 2V (9)

When a fillet joint in consideration of the presence or absence of the gap G is subjected to one-pass welding or multi-pass welding, the weld bead height bh ₁ and bead width bw ₁ of the first layer are, as shown in FIG. Depending on the welding cross-sectional area Sn, bh
If ₁ ≒ bw _1, represented as (10) below.

(Equation 10)

FIG. 9 shows a lamination pattern diagram assuming, for example, three-layer six-pass multi-pass welding. The total bead width Lwi and the total bead height Lhi at the time of lamination are represented by the number of laminations (Ns = 3) (i = 1)
3) and the welding cross-sectional area Sn per welding pass unit, so that it is expressed as in equations (11) and (12).
Further, the total bead width Lwi and the total bead height Lhi
Is obtained, the bead width bwi per unit for each lamination unit
And the bead height bhi are obtained from the equations (13) and (14). Although an example of three layers is shown here, the same concept can be used regardless of the number of layers, and these calculations can be easily performed by, for example, a flowchart shown in FIG.

[0049]

[Equation 11]

Lhi = i (i + 1) · Sn / Lwi (12)

Bwi = Lwi−Lw (i−1) (13)

Bwi = Sn / (Lwi−Lw (i−1)) (14) where i is an integer number indicating the order of performing the multi-layer welding of the number Ns of layers, and varies from 1 to Ns. C ₃ is approximately constant in accordance with excess prime the root pass bead 1.0-1.2, also, C ₄
Is a constant related to the ratio of the length of the weld leg in the vertical direction to the horizontal direction,
0.05 to 0.2.

Based on the calculated results such as the bead height and width per unit, the accumulated bead height and width per unit, and the like, welding pass coordinates and welding position coordinates necessary for performing multi-pass welding are obtained. The method for obtaining the value will be described with reference to FIGS. FIG. 11 is an explanatory diagram showing a relationship between a welding pattern and welding path coordinates according to an embodiment of the present invention. FIG. 12 is a diagram showing a relationship between welding path coordinates and welding position coordinates obtained by shifting a welding torch according to an embodiment of the present invention. FIG. 13 is an explanatory diagram showing the relationship, FIG. 13 is a flowchart of a calculation process of welding path coordinates and welding position coordinates in one embodiment of the present invention,
FIG. 14 is an explanatory diagram showing the shape of the fillet joint and the teaching position of the welding line route, and FIG. 15 is an explanatory diagram showing the teaching position of the welding line route in the present embodiment.

FIG. 11 shows that the number of layers Ns = 5 (the number of paths Np = 1).
5 shows an example of a lamination pattern and welding pass coordinates when performing multi-layer welding of 5). i is a lamination number (i = 1 to 5) classified according to lamination, m is a stage number (m = 1 to 5) classified according to the Xj-axis direction, and numerals 1 to 15 are divided according to welding paths. Path number (j =
1~15), P ₁ ~P ₁₅ shows a welding path coordinate Pj (Xj, Yj) corresponding to the path number. From this figure,
The pass number j of the welding where i = m is 1, 3, 6, 10, 1
5 and the total bead height Lh (i-1) of the (i-1) th layer
Only in the direction in contact with the Yj axis (the direction of the vertical plate of the fillet joint), and does not change in the Xj axis direction (Xj = 0). When j = 1, Xj = 0 and Yj = 0.

On the other hand, the path number j excluding these numbers
Is expressed as a function of the lamination number i and the number of steps m as shown in the following equation (15). The welding path coordinates Pj (Xj, Yj) at this path number j are calculated as shown in the equation (16). It can be represented by a function of the i-th cumulative bead width Lwi, the bead width bwi per pass, the number of steps of (m-1), and the bead height bhi.

When j = i (i−1) / 2 + m and i ≧ m (15)

(Equation 16)

The welding position coordinates Qj (Xnj,
Ynj) is the welding path coordinate Pj obtained as described above.
The shift amount S of the welding torch with respect to (Xj, Yj) (FIG. 4)
Shift) (see reference). In the welding of the first layer (j = 1), it is necessary to consider the gap G generated at the joint part in particular, so that it is expressed as shown in equation (17). Also, the welding position coordinates Qj (X) of the pass numbers (j = 3, 6, 10, 15) that satisfy the relationship of j> 1, m = i
(nj, Ynj) is desirable to shift the welding torch in the vertical and horizontal directions as shown in FIG.
It is expressed as shown in the equation, and further, the above (15) (1)
6) The welding position coordinates Qj (Xn
(j, Ynj) is expressed as in equation (19).

Although an example of five layers is shown here, the same idea can be obtained even if the number of layers increases, and these calculations can be easily performed by, for example, a flowchart shown in FIG. . In addition, the welding position coordinate Qj which is the welding torch position (the target position of the wire tip) is
By shifting the welding torch in the range of 0 <S ≦ 4 from the welding path coordinates Pj, it is possible to prevent the occurrence of a phenomenon in which the lengths of the welding legs in the lower plate direction and the upper plate direction are likely to be non-uniform, and a good welding result is obtained. Is obtained.

(A) When j = 1

Equation 17] Xnj = Xj + S-G, Ynj = Yj ...... (17) (b) j> 1, when m = i (Note, C ₅ is a constant of about 0.5 to 1.0)

Equation 18] Xnj = Xj + S, Ynj = Yj-C 5 S ...... (18) (c) (a) (b) in all other

Xnj = Xn + S, Ynj = Yj (19)

By calculating the welding pass coordinates and the welding position coordinates in this manner, the welding from the first layer to the last layer can be performed regardless of the presence or absence of a gap and for multi-layer welding with an arbitrary set welding leg length. In this way, an appropriate welding torch position for each welding pass required for the welding can be quickly and accurately determined.

When welding is performed without using a sensor, the correction path and the detection path need not be calculated. However, when welding is performed using a sensor, which welding path is detected and which welding path is corrected. Information on whether to do so is required. For example, when the visual sensor head is installed in front of the welding torch with respect to the traveling direction of the welding to detect and correct the welding position, the welding path is detected and the same path is corrected (preceding detection method). become. Therefore, the detection path Kp
j and the correction path Hpj are welding pass numbers (j = 1 to
Np) is represented by the equation (20) because it has a relationship that coincides with the welding path coordinates Pj (Xj, Yj) corresponding to (Np).

On the other hand, when the visual sensor head is installed behind the welding torch to detect and correct the welding position, the welding path is detected and the next path is corrected (rear detection). Therefore, the 0th pass (j =
It is necessary to add a detection path for detecting 0) and calculate a correction path for correcting the next path after detection. Therefore, the path number j is j = 0 to Np, and the detection path and the correction path are represented by the equations (21) and (22).

[0059]

Kpj = Hpj = [j, Pj (Xj, Yj)] (20) Here, j = 1 to Np in advance detection.

Kpj = [j, Pj + 1 (Xj + 1, Yj + 1)] (21)

Hpj = [j, Pj (Xj, Yj)] (22) However, j = 0 to Np in the subsequent detection.

The detection of the welding position by the sensor and the correction control of the positional deviation can be automatically performed by the commands of the detection path and the correction path thus obtained. These series of calculation results are displayed on the CRT screen, and the contents can be edited, such as correction, change, addition, etc., at the discretion of the operator. Through such a process, from the first layer to the final layer, appropriate welding conditions for each welding pass, and path plan data necessary for multi-layer welding, such as path coordinates and position coordinates of a welding torch, are created and stored.

On the other hand, in order to perform welding of a workpiece to be welded having an arbitrary welding length, it is necessary to previously teach a welding robot a welding torch position, a welding line, or a welding path to be a reference. As input of the teaching data, for example, FIG.
(A) As shown in (b), R ₁ ,
A total of four points including three points R ₂ and R ₃ and R ₄ on the end point side are taught and input from the teaching box. With these four teaching points, the joint shape, the welding length, and the straight welding line can be recognized. If the welding line at this time is a straight line as shown in FIG.
Only the above teaching input is required. However, when the welding line as shown in FIG. 14B is a large curve, it is necessary to input a teaching point for teaching the welding path of this curve.

Therefore, in the case of a welding line having a curve and a large bend, for example, as shown in FIGS. 15A and 15B, the teaching points W ₁ , W ₁ ,.
n is added as needed to input teaching. By performing the teaching input in this manner, it is possible to recognize a welding line and a welding position of an arbitrary shape. In the case where welding is performed with the use of a sensor, if the welding position and the weld line can be bent within a detectable range, the teaching input as shown in FIGS. 15A and 15B is not required. It is possible to perform correction scanning control of the displacement of the welding line by sensing with the visual sensor. FIGS. 15 (a) and 15 (b) show a bent welding line exceeding the detection range of the sensor.
Needless to say, the teaching input shown in FIG.

FIG. 16 is a block diagram of the main software incorporated in the automatic arithmetic processing device for performing the above arithmetic processing.
This will be described with reference to FIG. FIG. 16 is a block diagram showing a configuration of software built in an automatic arithmetic processing device for performing multi-pass welding of a fillet joint according to an embodiment of the present invention, a path of arithmetic processing, and the like. In FIG. 16, reference numeral 20 denotes a communication interface for performing communication between the welding robot control device 7 and the sensor image processing device 17 and the automatic arithmetic processing device 6, and reference numeral 21 denotes a signal transmitted from the teaching box 8 and the welding robot control device 7. This is the teaching input data that has been input.

Reference numeral 22 denotes a process for performing detailed processing of the first-layer welding line path, workpiece coordinates, welding robot coordinates, and the like for welding of an arbitrary-shaped welding line based on the teaching input data 21, and performing workpiece teaching data. 23 is a work coordinate calculation processing program for creating 23; 24 is a communication parameter for determining communication handling; 25 is a sensor image processing device 1
7, sensor detection data transmitted as needed,
Reference numeral 26 denotes a sensor and robot coordinate conversion parameter that determines the handling of coordinate conversion between the sensor and the robot.

Reference numeral 27 denotes a man-machine interface, and reference numeral 28 denotes multi-pass welding in which the optimum welding conditions, pass coordinates, and position coordinates of the welding torch for each pass necessary for multi-pass welding are calculated to create pass plan data 29. The plan calculation processing program 30 is a welding and coordinate teaching calculation program.
The path plan data 29 and the work teaching data 23
The arithmetic processing for determining and teaching the optimum welding conditions, welding line path, welding torch position coordinates, robot position coordinates, and the like necessary for welding for each welding pass from the first layer to the last layer based on the sensor detection data 25 and the sensor detection data 25. Then, the teaching path plan data 31 is created.

The teaching path plan data 31 automatically created in this manner is stored in the welding execution management program 32.
Is sequentially transmitted to the welding robot control device 7 through the command, and under the instruction and management by the welding execution management program 32, the welding for each pass from the first layer to the last layer indicated in the teaching path plan data 31 is performed. Are executed sequentially in an appropriate manner. Reference numeral 33 denotes a keyboard connected to the man-machine interface 27, and reference numeral 34 denotes a CRT.

As described above, by using the automatic arithmetic processing unit 6 incorporating a series of software necessary for the automatic arithmetic processing of the multipass welding path plan and the communication control of the welding robot control device 7 and the sensor image processing device 17, Not only is it possible to easily draft a construction plan for multi-layer welding, but also it is possible to reduce the time for teaching by a welding operator and to improve the efficiency of welding.

By using the multi-pass welding method of this embodiment, even a beginner can easily draft a construction plan before performing multi-pass welding. In addition, the optimum welding line and welding torch position and the optimum welding conditions for each pass from the first layer to the last layer are automatically calculated and determined by the teaching path plan data 31 created by the automatic calculation, and the welding is sequentially performed. Therefore, there is an effect that the time for teaching by the welding operator can be reduced and the efficiency of welding can be improved.

Further, according to the present embodiment, the result automatically calculated before the execution of welding is displayed on the CRT screen, and the result can be changed or corrected by the judgment of the operator. Therefore, the operability and usability are good, and the construction contents of the multi-layer welding can be verified. Furthermore, since appropriate teaching path plan data is created so as to satisfy a predetermined welding leg length, a good welding result can be obtained from the first layer to the last layer without causing a defect in each welding, and the welding quality can be improved. Security,
There is also an effect that management can be easily performed.

FIG. 19 is a photograph of a weld cross-section metallographic structure showing the results of multi-layer welding of a fillet joint according to one embodiment of the present invention. It shows the welding cross section when welding is performed. The welding conditions were welding current I = 275 A, welding speed V
= 270 mm / min, welding voltage E = 32 V constant. As can be seen from the welding cross-sectional view, the welding leg length is a predetermined value of about 41 mm, and welding is performed satisfactorily for each pass, and a sound welding result is obtained.

[0071]

As described in detail above, according to the present invention, even a beginner can easily operate without relying on a skilled welding worker, and can perform optimal welding for each pass from the first layer to the last layer. In addition to automatically calculating and determining the line and welding torch position and the optimum welding conditions, it is possible to accurately and sequentially execute welding from the first layer to the last layer necessary for the welding leg length to satisfy the prescribed weld metal. It is possible to provide a possible multi-pass welding method for a fillet joint.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an algorithm of a multi-pass welding method according to an embodiment of the present invention.

FIG. 2 is a system diagram illustrating a configuration of a multi-pass welding system according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a shape and an input condition of a fillet joint according to the present embodiment.

FIG. 4 is an explanatory view showing a welding torch position in the embodiment.

FIG. 5 is a characteristic diagram showing a relationship between a welding current and an appropriate welding voltage.

FIG. 6 is a flowchart of a calculation process of an appropriate welding voltage in one embodiment of the present invention.

FIG. 7 is a characteristic diagram of an appropriate wire melting speed.

FIG. 8 is an explanatory view showing a bead shape of first layer welding.

FIG. 9 is a diagram showing a multilayer pattern of multilayer multi-pass welding.

FIG. 10 is a flowchart of a process for calculating the height and width of the laminated weld bead according to one embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a relationship between a welding pattern and welding pass coordinates in one embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a relationship between welding path coordinates and welding position coordinates obtained by shifting a welding torch in one embodiment of the present invention.

FIG. 13 is a flowchart of a calculation process of welding path coordinates and welding position coordinates in one embodiment of the present invention.

FIG. 14 is an explanatory diagram showing a shape of a fillet joint and a teaching position of a welding line path.

FIG. 15 is an explanatory diagram showing a teaching position of a welding line path in the embodiment.

FIG. 16 is a block diagram showing a configuration of software built in an automatic arithmetic processing device for performing multi-pass welding of a fillet joint according to an embodiment of the present invention, a path of arithmetic processing, and the like.

FIG. 17 is an explanatory view showing a conventional multi-pass welding of a fillet joint.

FIG. 18 is an explanatory view showing another conventional multi-pass welding of a fillet joint.

FIG. 19 is a photograph of a weld cross-sectional metal structure showing a result of multi-pass welding of a fillet joint according to one example of the present invention.

[Explanation of symbols]

3 Welding pass train 4 Welding torch 5 Welding torch 6 Automatic processing unit 7 Welding robot control unit 8 Teaching box 9 Welding machine 11 Welding robot body 14 Welding torch 15 Visual sensor head 17 Sensor image processing unit L Weld leg length G Gap S shift the amount I the welding current i stacking number j weld path number m weld pass number number P ₁ to P ₁₅ weld pass coordinates Q ₁ to Q ₁₅ welding position coordinates 21 teaching input data 22 work coordinate computing programs 23 work teaching data 26 sensors and Robot coordinate conversion parameters 28 Multi-pass welding plan calculation processing program 29 Path plan data 30 Welding and coordinate teaching calculation program 31 Teaching path plan data 32 Welding execution management program 33 Keyboard 34 CRT

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Nobuo Shibata 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. In-house (72) Inventor Hideo Higashida 7-1-1 Higashi-Narashino, Narashino-shi, Chiba Hitachi Keiyo Engineering Co., Ltd. (56) References JP-A-2-70384 (JP, A) JP-A-60-99484 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23K 9/095 B23K 9 / 127 509

Claims (5)

(57) [Claims] 1. A method for performing multi-pass welding of a fillet joint using an automatic welding device capable of performing arc welding of an arbitrary joint shape according to predetermined teaching data, comprising: controlling the automatic welding device and a multi-pass welding pass plan. In the automatic calculation of the multi-pass welding path plan by the arithmetic processing device, at least the joint shape of welding, the length of a welding leg to satisfy a predetermined weld metal, Enter the same welding current and shift amount of the welding torch as the initial conditions from the gap, the first layer to the last layer, and based on these input values, based on these input values, the total welding break required to satisfy the welding voltage, wire melting speed, and welding leg length Area and number of layers of welding,
The number of welding passes from the first layer to the last layer, welding speed and welding cross-sectional area per pass unit, bead height and width of first layer welding, total bead height and width due to lamination welding, etc. are calculated respectively, and From the first layer to the last layer, the path coordinates of each welding pass and the position coordinates of the welding torch are calculated from the first layer to the last layer, and a series of these calculation results is displayed. Creates path plan data consisting of optimal welding conditions, path coordinates and welding torch position coordinates for each welding pass from the first to the last layer, and as necessary teaching data for fillet joints to be subjected to multi-layer welding. After inputting the welding line and welding torch position of the first layer as initial conditions to the automatic welding device, the automatic transmission device transmits the teaching data and the created path plan to the arithmetic processing device. With the data, the teaching processing unit automatically determines teaching path plan data for determining and teaching the optimum welding line and welding torch position coordinates and the optimum welding conditions for each pass from the first layer to the last layer. A multi-pass fillet welding method for a fillet joint, wherein the method is transmitted to the automatic welding apparatus, and sequentially executes each welding pass from the first layer to the last layer based on the teaching path plan data. 2. A welding voltage among welding conditions required for performing an automatic calculation process is calculated as a function of an input welding current and a predetermined wire protrusion length between a tip and a base material, and The welding voltage obtained by the calculation can be corrected by additional input of an increase / decrease value desired by the operator. The wire melting speed is obtained by additionally inputting the welding current and the wire protrusion length between the tip and the base material. The welding speed is calculated as a function of the increase / decrease value of the welding voltage, and the welding speed is calculated as a function of the input welding leg length and gap, the number of layers of welding that can be calculated from the welding leg length, and the wire melting speed, and is calculated. The upper and lower limits are set so that the welding speed is within the range of the welding speed at which a normal welding beat can be formed.
Within this range, the welding speed related to the number of laminations can be increased or decreased, and the total number of welding passes is a function of the number of laminations used in the calculation and determination of the welding speed. The welding cross-sectional area per welding pass unit is a function of the calculated wire melting speed and welding speed, and the bead height and width of the first layer weld are the calculated welding unit per unit. As a function of cross-sectional area and gap, the cumulative bead height and width of the lamination weld is a function of the lamination number from the first layer to the last layer and the weld cross-section per unit. 2. The multi-pass fillet welding method for a fillet joint according to claim 1, wherein the calculation is performed as a function of the lamination number and the total bead height and width obtained by the calculation. 3. The path coordinates for each welding pass from the first layer to the last layer are calculated as a function of the relationship between the path to be sequentially welded, the number of layers and the number of steps, the total number of layer welding, and the bead height and width per unit. Further, the position coordinates of the welding torch are calculated as a function of the path coordinates of each welding pass obtained by the above calculation and the shift amount of the input welding torch. 2. The method according to claim 1, wherein the calculation is performed as a function of the coordinate, the shift amount, and the gap. 4. The fillet joint according to claim 1, wherein the setting range of the shift amount (S) of the welding torch with respect to the path coordinates for each welding pass is 0 <S ≦ 4. Multi-layer welding method. 5. In displaying the calculation result, the optimum welding conditions and path coordinates for each welding pass from the first layer to the last layer required for the multi-pass welding obtained by the calculation, the path coordinates, and the position coordinates of the welding torch are displayed. 2. The multi-layer fillet of a fillet joint according to claim 1, wherein the information is displayed on a CRT screen, and the displayed result can be edited, such as change, correction, addition, etc., by the judgment of an operator. Welding method.