DESCRIPTION
WELDING CONDITION DETERMINING METHOD, AND WELDING
DEVICE
TECHNICAL FIELD
The present invention relates to a method to determine welding
conditions suitable for an object to be welded (base material) in
consumable electrode arc welding in which an arc is created between
an electrode wire and the object. The invention also relates to a
welding device which can determine the welding conditions.
BACKGROUND ART
In conventional arc welding, welding operators set welding
conditions such as welding current, welding voltage, and welding speed
to the welding device according to their knowledge and experience.
Then, the operators repeatedly change welding conditions while
verifying the welding results, and finally find the optimum welding
conditions.
There are well-known welding machines including an encoder
which is generally called a jog dial, and a light emitting diode (LED)
display device with which allow operators to set welding conditions
(see, for example, Patent Literature 1).
Expert operators may set welding conditions in a comparatively
short time according to their knowledge and experience.
Inexperienced operators who are growing in number these days,
however, often spend a lot of time and waste a lot of objects before

setting optimum welding conditions.
Citation List
Patent Literature
Patent Literature 1: Design registration No. 1274142
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for
determining welding conditions and a welding device which can easily
calculate welding conditions.
To solve the above-described problems, a method of the present
invention to determine welding conditions includes the following steps:
a first step of receiving object-to-be-welded information, which is
information about an object to be welded; a second step of receiving
welding method information, which is information about an arc
welding method; a third step of determining a quantity of arc heat,
which is a quantity of heat of an arc created between an electrode wire
and an object to be welded based on the object-to-be-welded
information and the welding method information; a fourth step of
determining a recommended value for a wire feed speed, a
recommended value for a leg length, a recommended value for a
welding speed, a recommended value for a welding current, and a
recommended value for a welding voltage based on the
object-to-be-welded information, the welding method information, and
the quantity of arc heat; a feed speed calculation step of, if at least one
of the leg length and the welding speed which are displayed as welding
conditions after the fourth step is changed to a value different from the

recommended values determined in the fourth step, calculating the
wire feed speed from the after-change value, based on a formula for
calculating the wire feed speed, which is in proportion to a square of
the leg length and also in proportion to the welding speed; a current
value calculation step of calculating the welding current from the wire
feed speed calculated in the feed speed calculation step based either on
a formula for calculating the welding current, which increases with an
increase in the wire feed speed or on a table showing a relation
between the wire feed speed and the welding current; and a voltage
value calculation step of calculating the welding voltage from the
welding current calculated in the current value calculation step. The
welding current calculated in the current value calculation step and
the welding voltage calculated in the voltage value calculation step are
determined to be a new recommended value for the welding current
and a new recommended value for the welding voltage, respectively.
This method can determine and display the recommended
values for the welding conditions which are suitable for the
information about the object to be welded and the information about
the welding method set by the operator. The welding conditions
include a welding current, a welding voltage, a wire feed speed, a
welding speed, and a leg length. Furthermore, if the operator changes
the recommended value for a welding condition to a new value, the
method can determine new recommended values for the other welding
conditions compatible with the new value and display the new
recommended values.
This reduces the operator's time and effort to determine the
welding conditions, thereby reducing the operator's burden to set

welding conditions. This also reduces the amount of objects wasted
until the definitive welding conditions are determined.
Another method of the present invention to determine welding
conditions includes the following steps: a first step of receiving
object-to-be-welded information, which is information about an object
to be welded; a second step of receiving welding method information,
which is information about an arc welding method; a third step of
determining a quantity of arc heat, which is a quantity of heat of an arc
created between an electrode wire and an object to be welded based on
the object-to-be-welded information and the welding method
information; a fourth step of determining a recommended value for a
wire feed speed, a recommended value for a leg length, a recommended
value for a welding speed, a recommended value for a welding current,
and a recommended value for a welding voltage based on the
object-to-be-welded information, the welding method information, and
the quantity of arc heat; a current value/voltage value calculation step
of calculating the welding current and the welding voltage from an
integrated value based on a relational expression or table showing a
relation between the welding current and the welding voltage if the
welding speed displayed as a welding condition after the fourth step is
changed to a value different from the recommended value for the
welding speed, the integrated value being calculated from the
already-determined quantity of arc heat and the displayed
after-change value of the welding speed based on a formula for
calculating the quantity of arc heat, which is in proportion to the
welding current and the welding voltage and is in inverse proportion to
the welding speed. When the displayed welding speed is changed, the

welding current and the welding voltage calculated in the current
value/voltage value calculation step are determined to be a new
recommended value for welding current and a new recommended value
for the welding voltage, respectively.
This method can determine and display the recommended
values for the welding conditions which are suitable for the
information about the object to be welded and the information about
the welding method set by the operator. The welding conditions
include a welding current, a welding voltage, a wire feed speed, a
welding speed, and a leg length. Furthermore, if the operator changes
the recommended value for a welding condition to a new value, the
method can determine new recommended values for the other welding
conditions compatible with the new value and display the new
recommended values.
This reduces the operator's time and effort to determine the
welding conditions, thereby reducing the operator's burden to set
welding conditions. This also reduces the amount of objects wasted
until the definitive welding conditions are determined.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 shows a schematic configuration of a welding device
according to a first exemplary embodiment of the present invention.
Fig. 2 shows an example of an object to be welded in the first
exemplary embodiment.
Fig. 3 is a flowchart showing a procedure to determine
recommended values for welding conditions in the first exemplary
embodiment.

Fig. 4 shows the relation between board thickness and the
quantity of arc heat required for welding in the first exemplary
embodiment.
Fig. 5 shows an example of a display screen of a setting device
in the first exemplary embodiment.
Fig. 6 shows the relation between board thickness and the
quantity of arc heat required for welding, and the acceptable range of
the quantity of arc heat in the first exemplary embodiment.
Fig. 7 shows the relation between the board thicknesses of
different joints and the quantity of arc heat required for welding in the
first exemplary embodiment.
Fig. 8 is a flowchart showing a procedure to determine
recommended values for welding conditions in a second exemplary
embodiment of the present invention.
Fig. 9 shows the relation between the product of welding
current I x welding voltage V and wire feed speed WF in the second
exemplary embodiment.
Fig. 10 is a flowchart showing another procedure to determine
the recommended values for the welding conditions in the second
exemplary embodiment.
Fig. 11 shows the relation between board thickness and welding
speed in the second exemplary embodiment.
Fig. 12A is a first flowchart showing a procedure to determine
recommended values for welding conditions in a third exemplary
embodiment of the present invention.
Fig. 12B is a second flowchart showing the procedure to
determine the recommended values for the welding conditions in the

third exemplary embodiment.
Fig. 13A is a first flowchart showing a procedure to determine
other recommended values for the welding conditions in the third
exemplary embodiment.
Fig. 13B is a second flowchart showing a procedure to determine
the other recommended values for the welding conditions in the third
exemplary embodiment.
DESCRIPTION OF EMBODIMENTS
FIRST EXEMPLARY EMBODIMENT
Fig. 1 shows a schematic configuration of a welding device
according to a first exemplary embodiment of the present invention.
As shown in Fig. 1, the welding device of the present first
exemplary embodiment, which is an arc welding device, includes
manipulator 3, robot controller 4 for controlling the operation of
manipulator 3, and setting device 5. Manipulator 3 moves welding
torch 2, which holds electrode wire 1. Setting device 5 performs
communications with robot controller 4 so as to set information to
robot controller 4.
Robot controller 4 includes welding power supply 7, control unit
8, calculation unit 9, and storage unit 10. Welding power supply 7
supplies electric power to wire 1 so that welding is applied to object 6
to be welded. Control unit 8 controls the operations of manipulator 3
and welding power supply 7. Calculation unit 9 performs calculations
for welding conditions. Storage unit 10 stores an operational program
with which control unit 8 controls the operation of manipulator 3,
mathematical formulas and tables that calculation unit 9 uses for

calculation, and calculation results. Welding power supply 7, which is
disposed in robot controller 4 as shown in Fig. 1, may alternatively be
disposed outside robot controller 4.
As will be described later, setting device 5 includes
object-to-be-welded information input unit 11 and welding method
information input unit 12. Object-to-be-welded information input
unit 11 receives information about object 6. Welding method
information input unit 12 receives information about the welding
method. Setting device 5 further includes leg length setting unit 13,
welding speed setting unit 14, and display unit 15. Leg length setting
unit 13 sets or changes the leg length when object 6 is welded.
Welding speed setting unit 14 sets or changes the welding speed.
Display unit 15 displays various information items.
The following is a description of a method to determine welding
conditions according to the present first exemplary embodiment.
Fig. 2 shows an example of object 6 to be welded in the first
exemplary embodiment. Fig. 3 is a flowchart showing a procedure to
determine recommended values for the welding conditions in the first
exemplary embodiment.
As shown in Fig. 2, a T joint consisting of upper board 16 and
lower board 17 is going to be welded.
The present first exemplary embodiment first describes a
method to determine recommended values for a welding speed v, a
welding current I, a welding voltage V, a wire feed speed WF, and a leg
length S in response to the object-to-be-welded information and
welding method information which are entered by the operator through
setting device 5 to the welding device. These recommended values are

displayed on display unit 15 of setting device 5 so as to be provided as
welding condition information to the operator. The present first
exemplary embodiment next describes a method to determine new
recommended values for the welding speed v, the welding current I, the
welding voltage V, and the wire feed speed WF when the operator
changes the displayed recommended value for the leg length to a new
value. The new recommended values are displayed on display unit 15
so as to be provided as the welding conditions to the operator.
The following is a description of the method to determine the
recommended values for the welding current and the other welding
conditions when the operator enters the object-to-be-welded
information and the welding method information to the welding device.
In a first step Si in Fig. 3, the operator enters
object-to-be-welded information about object 6 to the welding device
through object-to-be-welded information input unit 11 of setting device
5. The object-to-be-welded information set in the first step SI
includes the materials and thicknesses of upper and lower boards 16
and 17, and the joint shape of object 6.
In a second step S2 in Fig. 3, the operator enters welding
method information, which is the information about the arc welding
method, to the welding device through welding method information
input unit 12 of setting device 5. The welding information entered in
the second step S2 includes the following items: the use or non-use of
pulse welding, indicating whether or not pulse welding is used in the
arc welding, the pulse mode type, the shielding gas type, the extended
length of the welding wire, the method for controlling the wire feed,
the material of wire 1, and the diameter of wire 1.

The following is a description of determining a recommended
value vr for the welding speed, a recommended value WFr for the wire
feed speed, a recommended value Ir for the welding current, a
recommended value Vr for the welding voltage, and a recommended
value Sr for the leg length.
The recommended value vr for the welding speed is calculated
as follows.
A plurality of pieces of information about the welding speed v,
which are associated with the object-to-be-welded information and the
welding method information are previously stored in the form of
calculation formulas or tables in storage unit 10.
Calculation unit 9 selects one piece of information about the
welding speed v as the recommended value vr for the welding speed
from storage unit 10 based on the object-to-be-welded information and
the welding method information which are entered by the operator
through setting device 5.
The recommended value WFr for the wire feed speed is
calculated as follows.
Fig. 4 shows the relation between board thickness and the
quantity of arc heat required for welding in the first exemplary
embodiment.
Storage unit 10 previously stores a plurality of properties
shown in Fig. 4, which are associated with the object-to-be-welded
information and the welding method information. Fig. 4 shows the
relation between a board thickness T and a quantity of arc heat Q to
achieve satisfactory welding. The board thickness T is the average
value of a board thickness Tl of upper board 16 and a board thickness

T2 of lower board 17. The quantity of arc heat Q indicates the
quantity of heat of an arc created between wire 1 and object 6. The
board thickness T belongs to the object-to-be-welded information, and
the quantity of arc heat Q belongs to the welding method information.
The meaning of "satisfactory welding" includes sufficient strength,
non-defective weld bead, and no burn-through.
Calculation unit 9 selects one property shown in Fig. 4 from
storage unit 10 based on the object-to-be-welded information and the
welding method information entered by the operator through setting
device 5. Calculation unit 9 further calculates the board thickness T,
which is the average value of board thicknesses Tl and T2 of upper and
lower boards 16 and 17, respectively, entered by the operator through
setting device 5. Calculation unit 9 further calculates a quantity of
arc heat Qn required between wire 1 and object 6 from the selected
property and the board thickness T shown in Fig. 4. This process is
performed in a third step S3 shown in Fig. 3.
The wire feed speed WF increases with an increase in the
quantity of arc heat Q. Therefore, the relation between the quantity
of arc heat Q and the wire feed speed WF is uniquely determined based
on the welding method information. A plurality of pieces of
information about the relation (mathematical formulas or tables)
between the quantity of arc heat Q and the wire feed speed WF, which
are associated with the welding method information are previously
stored in storage unit 10.
Calculation unit 9 calculates the wire feed speed WF from the
welding method information entered in the second step S2, the
information about the relation between the quantity of arc heat Q and

the wire feed speed WF stored in storage unit 10, and the
above-determined quantity of arc heat Qn. The wire feed speed WF is
determined to be the recommended value WFr.
The recommended value for the welding current I is calculated
as follows.
The welding current I increases with an increase in the wire
feed speed WF. Therefore, the relation between the wire feed speed
WF and the welding current I is uniquely determined based on the
welding method information. A plurality of pieces of information
(mathematical formulas or tables) about the relation between the wire
feed speed WF and the welding current I, which are associated with the
welding method information are previously stored in storage unit 10.
Calculation unit 9 calculates the welding current I from the
information about the relation between the wire feed speed WF and the
welding current I stored in storage unit 10, the welding method
information entered in the second step S2, and the above-calculated
recommended value WFr for the wire feed speed. The calculated
welding current I is determined to be the recommended value Ir.
The recommended value Vr for the welding voltage V is
calculated as follows.
The quantity of arc heat Q, the welding current I, the welding
voltage V, and the welding speed v are in the relation shown in
Mathematical Formula 1, which is stored in storage unit 10.
Q = (I x V x 60)/v Mathematical Formula 1
Calculation unit 9 then calculates the product of the welding
current I x the welding voltage V from Mathematical Formula 1 stored
in storage unit 10, the above-calculated recommended value vr for the

welding speed, and the above-determined quantity of arc heat Qn.
Calculation unit 9 further calculates the welding voltage V from
the product of the welding current I x the welding voltage V, and the
above-calculated recommended value Ir for the welding current. The
welding voltage V is determined to be the recommended value Vr.
The recommended value Sr for the leg length S is calculated as
follows.
The leg length S, a wire diameter d, the wire feed speed WF, and
the welding speed v are in the relation shown in Mathematical
Formula 2, which is stored in storage unit 10.
S = dV((n x WF)/(2 x v)) Mathematical Formula 2
Calculation unit 9 calculates the leg length S from
Mathematical Formula 2 stored in storage unit 10, the wire diameter d
entered in the second step S2, the above-calculated recommended
value WFr for the wire feed speed, and the above-calculated
recommended value vr for the welding speed. The leg length S is
determined to be the recommended value Sr.
Display unit 15 of setting device 5 displays the recommended
value vr for the welding speed, the recommended value WFr for the
wire feed speed, the recommended value Ir for the welding current, the
recommended value Vr for the welding voltage, and the recommended
value Sr for the leg length, which are calculated as above in calculation
unit 9.
Fig. 5 shows an example of a display screen of the setting device
in the first exemplary embodiment.
Fig. 5 shows an example of a display screen on display unit 15 of
setting device 5. The example in Fig. 5 shows the following

object-to-be-welded information: T joint; the board thickness of the
upper board: 1.6 mm; and the lower board: 1.6 mm. The example
further shows the following recommended values: the welding speed v:
0.8m/min; the welding current I: 120A; the welding voltage V: 16.8V;
and the leg length S: 3.5mm.
Note that Fig. 5 does not show the recommended value WFr for
the wire feed speed. The reason is that the welding current I and the
wire feed speed WF are in proportion to each other, and that it is more
common to set the welding current I than the wire feed speed WFr as a
welding condition.
Thus, the recommended values for the welding current I and the
other conditions can be determined based on the object-to-be-welded
information and the welding method information. This process is
performed in a fourth step S4 shown in Fig. 3.
The following is a description of a method to determine and
displaying new recommended values for the welding speed v, the
welding current I, the welding voltage V, and the wire feed speed WF
when the operator changes the displayed recommended value Sr for
the leg length to a new value.
The leg length S is an element to dominate the welded joint
strength, and hence may be specified in the drawing for welding.
Therefore, setting device 5 of the welding device according to the
present first exemplary embodiment includes leg length setting unit 13,
which allows the operator to change the value of the leg length S by
entering an arbitrary value.
The following is a description of a method to determine new
recommended values for the welding current I and the other welding

conditions assuming that the operator has changed the value of the leg
length S from the recommended value Sr to a leg length Si through leg
length setting unit 13 of setting device 5 when the recommended value
Sr is displayed on display unit 15 of setting device 5.
A new recommended value for the welding speed v is calculated
as follows.
As described above, calculation unit 9 selects one piece of
information about welding speed v as the recommended value vr from
storage unit 10 based on the object-to-be-welded information and the
welding method information which are entered by the operator through
setting device 5. Even when the recommended value Sr is changed to
the leg length Si, the recommended value vr for the welding speed
remains the same because the object-to-be-welded information and the
welding method information remain the same.
A new recommended value for the wire feed speed WF is
calculated as follows.
Calculation unit 9 derives a formula for calculating the wire
feed speed (Mathematical Formula 3) from Mathematical Formula 2
for calculating the leg length S stored in storage unit 10.
WF = (2 x S42 x v)/(n x d2) Mathematical Formula 3
Calculation unit 9 calculates a wire feed speed WFl from
Mathematical Formula 3, the after-change value Si of the leg length,
the recommended value vr for the welding speed, and the wire
diameter d, which is the diameter of wire 1 entered as the welding
method information. The wire feed speed WFl is a new recommended
value for the wire feed speed WF. This process is performed in a feed
speed calculation step S5 shown in Fig. 3.

A new recommended value for the welding current I is
calculated as follows.
The welding current I increases with an increase in the wire
feed speed WF. Therefore, the relation between the wire feed speed
WF and the welding current I is uniquely determined based on the
welding method information. A plurality of pieces of information
(mathematical formulas or tables) about the relation between the wire
feed speed WF and the welding current I, which are associated with the
welding method information are previously stored in storage unit 10.
Calculation unit 9 calculates a welding current II from the
information about the relation between the wire feed speed WF and the
welding current I stored in storage unit 10, the welding method
information entered in the second step S2, and the above-calculated
new recommended value for the wire feed speed WF. The welding
current II is determined to be the new recommended value for the
welding current I. This process is performed in a current value
calculation step S6 shown in Fig. 3.
A new recommended value for the welding voltage V is
calculated as follows.
The welding voltage V increases with an increase in the welding
current I. Therefore, the relation between the welding current I and
the welding voltage V is uniquely determined based on the welding
method information. A plurality of pieces of information
(mathematical formulas or tables) about the relation between the
welding current I and the welding voltage V, which are associated with
the welding method information are previously stored in storage unit
10.

Calculation unit 9 calculates a welding voltage VI from the
information about the relation between the welding current I and the
welding voltage V stored in storage unit 10, and the above-calculated
welding current II (new recommended value). The welding voltage
VI is determined to be the new recommended value. This process is
performed in a voltage value calculation step S7 shown in Fig. 3.
As described above, when the leg length S is changed from the
recommended value Sr to the leg length Si, the welding device can
determine the recommended value vr for the welding speed (no
changes), and the new recommended value for the welding current I,
the new recommended value for the welding voltage V, and the new
recommended value of the wire feed speed WF. These values are
displayed on display unit 15 of setting device 5 so as to be provided as
information to the operator.
Note, however, that the welding device can provide the
information about the new recommended values for the welding
current II and the other conditions to the operator only when the leg
length Si which has replaced the recommended value has an
appropriate value. The following is a description of an example to
determine whether or not the new recommended values should be
displayed on display unit 15, according to the quantity of arc heat Q.
A quantity of arc heat Ql in the after-change value Si of the leg
length is calculated from Mathematical Formula 1, the new
recommended value for the welding voltage V, the new recommended
value for the welding current I, and the recommended value vr for the
welding speed. The quantity of arc heat Ql, which is the quantity of
heat of an arc created between wire 1 and object 6 is not uniquely

determined with respect to the object-to-be-welded information set in
the first step S1.
Fig. 6 shows the relation between board thickness and the
quantity of arc heat required for welding, and the acceptable range of
the quantity of arc heat in the first exemplary embodiment.
The inventors of the present invention have experimentally
confirmed that, as shown in Fig. 6, in the relation between board
thickness and the quantity of arc heat required for welding, the
quantity of arc heat required for welding actually has conditional
margins with upper and lower limits, and that the conditional margins
tend to widen with an increase in the board thickness T.
Therefore, when the operator sets the leg length S1 different
from the recommended value, calculation unit 9 can calculate the
quantity of arc heat Q1 from the value of the welding current
calculated in the current value calculation step S6, the value of the
welding voltage calculated in the voltage value calculation step S7, and
the recommended value vr for the welding speed. This process is
performed in a quantity of heat determination step S8 shown in Fig. 3.
If the determined quantity of arc heat Q1 is above the upper limit or
below the lower limit of the quantity of arc heat Q predetermined and
stored in storage unit 10, the leg length S1 set by the operator is
determined to be outside the acceptable range.
Display unit 15 of setting device 5 displays that the leg length
S1 set by the operator is outside the acceptable range according to the
determination result. Display unit 15 does not display the new
recommended values for the welding current I1, the welding voltage V1,
and the other conditions calculated as above. This can prevent the

operator from setting the new recommended values as the welding
conditions. Display unit 15 further displays a message to urge the
operator to enter a different leg length S1.
Assume, on the other hand, that the set leg length S1 is within
the acceptable range. In this case, display unit 15 displays the
calculated values of the welding current I1, the welding voltage V1,
and the other welding conditions as the new recommended values.
This allows the operator to set the new recommended values as the
welding conditions.
As described above, the welding device and the method to
determine welding conditions of the present first exemplary
embodiment can determine and display the recommended values for
welding conditions which are suitable for the information about the
object to be welded and the information about the welding method set
by the operator. The welding conditions include the welding current I,
the welding voltage V, the wire feed speed WF, the welding speed v, and
the leg length S. Furthermore, if the operator changes the
recommended value for the leg length S to the leg length S1, the
welding device and the method to determine welding conditions can
determine new recommended values for the other welding conditions
compatible with the after-change value S1 of the leg length and display
the new recommended values.
Thus, the welding device and the method to determine welding
conditions according to the present first exemplary embodiment can
minimize the operator's time and effort to determine the welding
conditions, and the amount of objects wasted through trial and error.
The welding device performs calculations using the quantity of

arc heat Q required for object 6, thereby providing appropriate welding
conditions whatever the combination of board thicknesses or whatever
the joint shape.
Fig. 7 shows the relation between the board thicknesses of
different joints and the quantity of arc heat required for welding in the
first exemplary embodiment.
The welding device stores, in storage unit 10, information
(calculation formulas or tables) of the properties indicating the
relation between the quantity of arc heat Q and the board thickness T
for each joint as shown in Figs. 4 and 7. The quantity of arc heat Q is
determined based on the entered object-to-be-welded information.
The welding device then calculates the recommended values for the
welding conditions using the quantity of arc heat Q. The board
thickness T shown in Figs. 4 and 7 is the average value of the board
thicknesses of upper and lower boards 16 and 17. Therefore,
whatever the board thicknesses of upper and lower boards 16 and 17,
the welding device can calculate T as the average value. The welding
device can determine the quantity of arc heat Q based on T, and can
calculate the recommended values for the welding conditions using the
quantity of arc heat Q. Thus, the welding device can cope with any
combination of the board thicknesses.
The welding device allows the operator to change the leg length
S from the recommended value to a different value. If the leg length S
is set outside the acceptable range, a message indicating the leg length
S is outside the acceptable range is displayed, making the welding
device extremely user-friendly.
There are different welding target positions and different

welding torch angles depending on the object-to-be-welded information
set in the first step S1. Therefore, the welding device can also
combine the appropriate condition of the average board thickness (T) of
upper and lower boards 16 and 17, and the appropriate condition of the
difference between their thicknesses included in the
object-to-be-welded information set in the first step S1.
As shown in Fig. 5, the welding device displays the torch angle
and the target position on display unit 15 of setting device 5, thereby
providing them as information to the operator.
Thus, the method to determine welding conditions according to
the present invention includes a first step S1, a second step S2, a third
step S3, a fourth step S4, a feed speed calculation step S5, a current
value calculation step S6, and a voltage value calculation step S7.
The first step S1 receives object-to-be-welded information, which is
information about an object to be welded. The second step S2 receives
welding method information, which is information about an arc
welding method. The third step S3 determines the quantity of arc
heat Q, which is the quantity of heat of an arc created between an
electrode wire and an object to be welded based on the
object-to-be-welded information and the welding method information.
The fourth step S4 determines the recommended value WFr for the
wire feed speed, the recommended value Sr for the leg length, the
recommended value vr for the welding speed, the recommended value
Ir for the welding current, and the recommended value Vr for the
welding voltage based on the object-to-be-welded information, the
welding method information, and the quantity of arc heat Q. The feed
speed calculation step S5, if at least one of the leg length S and the

welding speed v which are displayed as welding conditions after the
fourth step S4 is changed to a value different from the recommended
values determined in the fourth step, calculates the wire feed speed
WF from the after-change value, based on the formula for calculating
the wire feed speed, which is in proportion to the square of the leg
length S and also in proportion to the welding speed v. The current
value calculation step S6 calculates the welding current I from the
wire feed speed WF1 calculated in the feed speed calculation step S5
based either on a formula for calculating the welding current I, which
increases with an increase in the wire feed speed WF, or on a table
showing the relation between the wire feed speed WF and the welding
current I. The voltage value calculation step S7 calculates the
welding voltage V from the welding current I calculated in the current
value calculation step S6. The welding current I calculated in the
current value calculation step S6 and the welding voltage V calculated
in the voltage value calculation step S7 are determined to be a new
recommended value for the welding current I and a new recommended
value for the welding voltage V, respectively.
This method can determine and display the recommended
values for the welding conditions which are suitable for the
information about the object to be welded and the information about
the welding method set by the operator. The welding conditions
include the welding current I, the welding voltage V, the wire feed
speed WF, the welding speed v, and the leg length S. Furthermore, if
the operator changes the recommended value for a welding condition to
a new value, the method can determine new recommended values for
the other welding conditions compatible with the new value and

display the new recommended values.
This reduces the operator's time and effort to determine the
welding conditions, thereby reducing the operator's burden to set
welding conditions. This also reduces the amount of objects wasted
until the definitive welding conditions are determined.
In the method to determine welding conditions according to the
present invention, the feed speed calculation step S5 calculates the
wire feed speed WF1 if the leg length S displayed as a welding
condition after the fourth step S4 is changed to a value different from
the recommended value for the leg length determined in the fourth
step S4. The wire feed speed WF1 is calculated from the after-change
value S1 of the leg length and the recommended value vr for the
welding speed based on the formula for calculating the wire feed speed.
The voltage value calculation step S6 calculates the welding voltage V
from the welding current I calculated in the current value calculation
step S6 based either on a formula for calculating the welding voltage V,
which increases with an increase in the welding current I, or on a table
showing the relation between the welding current I and the welding
voltage V. If the displayed leg length S is changed, the welding
current I1 calculated in the current value calculation step S6 and the
welding voltage V1 calculated in the voltage value calculation step S7
are determined to be the new recommended value for the welding
current I and the new recommended value for the welding voltage V,
respectively.
The method to determine welding conditions according to the
present invention may further include a quantity of heat
determination step S8 of determining the quantity of arc heat Q from

the welding current I1 calculated in the current value calculation step
S6, the welding voltage V1 calculated in the voltage value calculation
step S7, and the recommended value vr for the welding speed. Only
when the quantity of arc heat Q1 determined in the quantity of heat
determination step S8 is within the acceptable range, the welding
current I1 calculated in the current value calculation step S6 and the
welding voltage V1 calculated in the voltage value calculation step S7
are determined to be the new recommended value for the welding
current I and the new recommended value for the welding voltage V,
respectively.
This method can determine the recommended values for the
welding current I and the welding voltage V to generate an appropriate
quantity of arc heat Q.
SECOND EXEMPLARY EMBODIMENT
Fig. 8 is a flowchart showing a procedure to determine
recommended values for welding conditions in a second exemplary
embodiment of the present invention.
The welding device and the method to determine welding
conditions according to the present second exemplary embodiment will
be described mainly with reference to Fig. 8. The same components as
in the first exemplary embodiment are denoted by the same reference
numerals, and hence the description thereof will be omitted. The
present second exemplary embodiment differs from the first exemplary
embodiment mainly in the processes after the recommended values for
welding conditions are determined based on the object-to-be-welded
information and the welding method information. In the first

exemplary embodiment, the recommended value Sr is changed to a new
value for the leg length, and then new recommended values for the
other welding conditions are calculated. In the present second
exemplary embodiment, on the other hand, the recommended value vr
is changed to a new value for the welding speed, and then new
recommended values for the other welding conditions are calculated.
The following is a description of a method to determine and
displaying new recommended values for the welding current I, the
welding voltage V, the wire feed speed WF, and the leg length S when
the operator changes the displayed recommended value vr for the
welding speed to a new value.
As shown in Fig. 8, based on the object-to-be-welded
information and the welding method information, the following values
are calculated: the recommended value vr for the welding speed, the
recommended value Ir for the welding current, the recommended value
Vr for the welding voltage, the recommended value WFr for the wire
feed speed, and the recommended value Sr for the leg length. Since
the processes up to the fourth step S4 are identical to those in Fig. 3,
the description of the fourth step S4 is omitted and the subsequent
processes will be described.
The welding speed v may be determined according to the task
time balance, and therefore, may be changed to a value different from
the recommended value vr. Therefore, setting device 5 of the welding
device according to the present second exemplary embodiment includes
welding speed setting unit 14, which allows the operator to change the
value of the welding speed v by entering an arbitrary value.
The following is a description of a method to determine new

recommended values for the welding current I and the other welding
conditions assuming that the operator has changed the value of the
welding speed v from the recommended value vr to v2 through welding
speed setting unit 14 of setting device 5 when the recommended value
vr is displayed on display unit 15 of setting device 5.
New recommended values for the welding current I and the
welding voltage V are calculated as follows.
Even when the welding speed v is changed from the
recommended value vr to the new welding speed v2, the
object-to-be-welded information and the welding method information
remain the same. Therefore, the board thickness T, which is the
average value of the board thicknesses T1 and T2 of upper and lower
boards 16 and 17 as object 6, remain the same. The relation between
the board thickness T and the quantity of arc heat Qn shown in Fig. 4
also remains the same. As a result, the quantity of arc heat Qn,
which indicates the quantity of heat of an arc created between wire 1
and object 6, has the same value as in the first exemplary embodiment.
Calculation unit 9 then calculates the product of a welding
current 12 x a welding voltage V2 in Mathematical Formula 1 from the
quantity of arc heat Qn, the new value v2 of the welding speed, and
Mathematical Formula 1.
The welding voltage V increases with an increase in the welding
current I. Therefore, the relation between the welding current I and
the welding voltage V is uniquely determined based on the welding
method information. A plurality of pieces of information
(mathematical formulas or tables) about the relation between the
welding current I and the welding voltage V, which are associated with

the welding method information are previously stored in storage unit
10. Calculation unit 9 specifies one piece of information about the
relation between the welding current I and the welding voltage V
based on the entered welding method information. Calculation unit 9
then calculates the welding current 12 and the welding voltage V2
based on the specified piece of information. Thus, one point is
determined on the properties indicating the relation between the
welding current 12 and the welding voltage V2 because the product of
the welding current 12 x the welding voltage V2 is determined. The
welding current I and the welding voltage V on this point become the
welding current 12 and the welding voltage V2, respectively. This
process is performed in a current value/voltage value calculation step
S15 shown in Fig. 8.
A new recommended value for the wire feed speed WF is
calculated as follows.
The welding current I increases with an increase in the wire
feed speed WF. Therefore, the relation between the wire feed speed
WF and the welding current I is uniquely determined based on the
welding method information. A plurality of pieces of information
(mathematical formulas or tables) about the relation between the wire
feed speed WF and the welding current I, which are associated with the
welding method information are previously stored in storage unit 10.
Calculation unit 9 calculates a wire feed speed WF2 based on
the information about the relation between the wire feed speed WF and
the welding current I stored in storage unit 10, the welding method
information entered in the second step S2, and the welding current 12,
which is calculated above as the new recommended value. The wire

feed speed WF2 is determined to be the new recommended value.
This process is performed in a feed speed calculation step S16 shown in
Fig. 8.
A new recommended value S2 for the leg length S is calculated
as follows.
As described in the first exemplary embodiment, the leg length
S, the wire diameter d, the wire feed speed WF, and the welding speed
v are in the relation shown in Mathematical Formula 2, which is stored
in storage unit 10.
Calculation unit 9 then calculates the recommended value S2
for the leg length S from Mathematical Formula 2 stored in storage
unit 10, the wire diameter d entered in the second step S2, the
above-calculated wire feed speed WF2 (recommended value), and the
welding speed v2 which has replaced the recommended value vr. This
process is performed in a leg length calculation/acquisition step S17
shown in Fig. 8.
Thus, when the welding speed v is changed from the
recommended value vr to a different value, the recommended values
for the other welding conditions can be calculated as described above.
Then, the wire feed speed WF2, the welding current 12, the welding
voltage V2, and leg length S2 calculated in the calculation unit 9 are
displayed as the new recommended values on display unit 15 of setting
device 5.
As described above, the method to determine welding conditions
includes the current value/voltage value calculation step S15 of
calculating a welding current and a welding voltage after the fourth
step S4.

When the welding speed v displayed as a welding condition is
changed to the value v2 different from the recommended value vr, the
current value/voltage value calculation step S15 calculates the welding
current 12 and the welding voltage V2 from an integrated value 12 x V2
of the welding current and the welding voltage based on a relational
expression or table showing the relation between welding current and
welding voltage. The integrated value is calculated from the
already-determined quantity of arc heat Qn and the displayed
after-change value of the welding speed based on the formula for
calculating the quantity of arc heat. The formula is used to calculate
the quantity of arc heat, which is in proportion to the welding current
and the welding voltage and is in inverse proportion to the welding
speed.
Thus, when the displayed welding speed vr is changed, the
welding current 12 and the welding voltage V2 calculated in the
current value/voltage value calculation step S15 are determined to be
the new recommended value for the welding current I and the new
recommended value for the welding voltage V, respectively.
This method can determine and display the recommended
values for the welding conditions which are suitable for the
information about the object to be welded and the information about
the welding method set by the operator. The welding conditions
include a welding current, a welding voltage, a wire feed speed, a
welding speed, and a leg length. Furthermore, if the operator changes
the recommended value for a welding condition to a new value, the
method can determine new recommended values for the other welding
conditions compatible with the after-change value and display the new

recommended values.
The method to determine welding conditions includes the feed
speed calculation step S16, and the leg length calculation step S17
after the current value/voltage value acquisition step S15. The feed
speed calculation step S16 calculates the wire feed speed WF2 from the
welding current 12 calculated in the current value/voltage value
calculation step S15 based on the relational expression or table
between the welding current and the wire feed speed. The leg length
calculation step S17 calculates the leg length S2 from the wire feed
speed WF2 calculated in the feed speed calculation step S16.
Alternatively, the recommended values for welding conditions
can be calculated by another approach as described below.
Fig. 9 shows the relation between the product of the welding
current I x the welding voltage V and the wire feed speed WF in the
second exemplary embodiment. Fig. 10 is a flowchart showing
another procedure to determine the recommended values for the
welding conditions in the second exemplary embodiment. Fig. 11
shows the relation between board thickness and welding speed in the
second exemplary embodiment.
The inventors of the present invention have experimentally
confirmed that as shown in Fig. 9, the relation between the welding
current I x the welding voltage V, and the wire feed speed WF are in
proportion to each other. Assume that the welding speed vr is
increased a-fold to become a welding speed v3. In this case, according
to Mathematical Formula 1, the product of the welding current 13 x the
welding voltage V3 is also required to be increased by a times the
product of the welding current Ir x the welding voltage Vr in order to

keep the quantity of arc heat Q constant.
As shown in Fig. 9, the wire feed speed WF and the product of
the welding current I x the welding voltage V are in proportion to each
other. Therefore, when the product of the welding current I x the
welding voltage V is increased a-fold, the wire feed speed WF is also
increased a-fold. In other words, when the welding speed vr is
increased a-fold to become the welding speed v2, the wire feed speed
WF2 is increased by a times the wire feed speed WFr. Thus, according
to Mathematical Formula 2, even when the welding speed v is changed,
the leg length S remains the same as long as the quantity of arc heat Q
is kept constant. When the welding speed v is changed, the wire feed
amount WF can be set to keep the leg length S constant, achieving
appropriate welding with the same quantity of arc heat Q.
In the above-described example, when the recommended value
vr for the welding speed is changed to the welding speed v2, the
welding current 12 and the welding voltage V2 are obtained from
calculation to keep the quantity of arc heat Q constant. Alternatively,
the recommended values for the welding conditions may be determined
by another procedure when the relation shown in Fig. 9 is satisfied.
To be more specific, calculation unit 9 calculates the wire feed speed
WF2 based on Mathematical Formula 3 so as to keep the leg length S
constant. Calculation unit 9 then calculates the welding current 12
based on the relation {a calculation formula or table) indicating that
the welding current I increases with an increase in the wire feed speed
WF. Calculation unit 9 then calculates the welding voltage V2 based
on the relation (a calculation formula or table) indicating that the
welding voltage V2 increases with an increase in the welding current

12.
The above-described other method to determine welding
conditions according to the present second exemplary embodiment will
be described with reference to Fig. 10.
In the method to determine welding conditions according to the
present second exemplary embodiment, when the recommended value
vr is changed to the welding speed v2, the fourth step S4 is followed by
the feed speed calculation step S5, the current value calculation step
S6, and a voltage value calculation step S27. The welding current 12
calculated in the current value calculation step S6, and the welding
voltage V2 calculated in the voltage value calculation step S27 are
determined to be the new recommended value for the welding current I
and the new recommended value for the welding voltage V,
respectively.
To be more specific, the feed speed calculation step S5 calculates
the wire feed speed WF2 if the welding speed v displayed after the
fourth step is changed to a value different from the recommended value
vr. The wire feed speed WF2 is calculated from the after-change value
v2 of the welding speed and the recommended value Sr for the leg
length based on the formula for calculating the wire feed speed.
The voltage value calculation step S27 calculates the welding
voltage V2 from the quantity of arc heat Qn determined in the third
step S3, the after-change value v2 of the welding speed, and the
welding current 12 calculated in the current value calculation step S6
based on the formula for calculating the quantity of arc heat. The
formula is used to calculate the quantity of arc heat which is in
proportion to the welding current and the welding voltage and is in

inverse proportion to the welding speed.
If the displayed welding speed vr is changed to the welding
speed v2, the welding current 12 calculated in the current value
calculation step S6 and the welding voltage V2 calculated in the
voltage value calculation step S27 are determined to be the new
recommended value for the welding current and the new recommended
value for the welding voltage, respectively.
Thus, this method can determine and display the recommended
values for welding conditions which are suitable for the information
about the object to be welded and the information about welding
method set by the operator. The welding conditions include the
welding current I, the welding voltage V, the wire feed speed WF, the
welding speed v, and the leg length S. Furthermore, if the operator
changes the recommended value vr for the feed speed to a new value,
the method can determine new recommended value for the other
welding conditions compatible with the after-change value v2 of the
welding speed and display the new recommended values.
There are different welding target positions and different
welding torch angles depending on the object-to-be-welded information
set in the first step S1. Therefore, the welding device can also
combine the appropriate condition of the average board thickness (T) of
upper and lower boards 16 and 17 and the appropriate condition of the
difference between their thicknesses included in the
object-to-be-welded information set in the first step S1.
As shown in Fig. 5, the torch angle and the target position are
displayed on display unit 15 of setting device 5, thereby being provided
as information to the operator. Note that the welding speed v is not

uniquely determined with respect to the object-to-be-welded
information set in the first step S1.
In reality, as shown in Fig. 11, the welding speed has an upper
limit. The inventors of the present invention have experimentally
confirmed that the upper limit of the welding speed tends to decrease
with an increase in the board thickness T.
Therefore, the welding speed v2, which is different from the
recommended value, may exceed the upper limit of the welding speed v
stored in storage unit 10. In that case, the welding speed v2 set by
the operator is determined to be outside the acceptable range.
Display unit 15 of setting device 5 displays that the welding
speed v2 set by the operator is outside the acceptable range according
to the determination result. Display unit 15 does not display the new
recommended values for the welding current 12, the welding voltage V2,
and the other conditions calculated as above. This can prevent the
operator from setting the new recommended values as the welding
conditions. Display unit 15 further displays a message to urge the
operator to enter a different welding speed v2.
Assume, on the other hand, that the set welding speed v2 is
within the acceptable range. In this case, display unit 15 displays the
calculated values of the welding current 12, the welding voltage V2,
and the other welding conditions as the new recommended values.
This allows the operator to set the new recommended values as the
welding conditions.
THIRD EXEMPLARY EMBODIMENT
Figs. 12A and 12B are first and second flowcharts, respectively,

showing a procedure to determine recommended values for welding
conditions in a third exemplary embodiment of the present invention.
The welding device and the method to determine welding
conditions in the present exemplary embodiment will be described with
reference to Figs. 12A and 12B. The same components as in the first
and second exemplary embodiments are denoted by the same reference
numerals, and hence the description thereof will be omitted. The
present exemplary embodiment differs from the first and second
exemplary embodiments mainly in the processes after the
recommended values for welding conditions are determined based on
the object-to-be-welded information and the welding method
information. In the first exemplary embodiment, the recommended
value Sr is changed to a new value for the leg length, and then new
recommended values for the other welding conditions are calculated.
In the second exemplary embodiment, the recommended value vr is
changed to a new value for the welding speed, and then new
recommended values for the other welding conditions are calculated.
In the present third exemplary embodiment, on the other hand, both
the recommended value Sr for the leg length and the recommended
value vr for the welding speed are changed to new values, and then
new recommended values for the other welding conditions are
calculated.
The operator may sometimes change the displayed
recommended value Sr for the leg length and the displayed
recommended value vr for the welding speed to the leg length S1 and
the welding speed v2, respectively. In that case, the new
recommended values for the welding current I, the welding voltage V,

the wire feed speed WF are determined and displayed as follows.
When the recommended values of the leg length S and the
welding speed v are both changed to new values, the leg length S,
which is an item to determine the weld joint performance, is probably
given priority over the welding speed v. For this reason, the following
is based on the assumption that the welding conditions are calculated
according to the change in the leg length S, and then according to the
change in the welding speed v.
First, the calculations of the welding conditions according to the
change in the recommended value Sr for the leg length are described as
follows. Note that the calculations of the welding conditions
according to the change in the recommended value Sr for the leg length
(the feed speed calculation step S5, the current value calculation step
S6, the voltage value calculation step S7, and the quantity of heat
determination step S8) are not repeated here because they are the
same as in the first exemplary embodiment. In these calculations, the
welding speed v is not the new value v2 of the welding speed, but is the
recommended value vr determined based on the object-to-be-welded
information set in the first step S1 as in the first exemplary
embodiment.
The welding device determines the recommended values for the
other welding conditions to be the welding current I1, the
recommended value for the welding voltage V1, and the wire feed speed
WF1.
Similar to the first exemplary embodiment, the recommended
values for the other welding conditions are calculated after the
determination of whether or not the leg length S1 is within the

acceptable range (the quantity of heat determination step S8).
Next, the calculations of the welding conditions according to the
change in the recommended value vr for the welding speed are
described as follows. Note that no description is given here about the
calculations of welding conditions according to the change in the
recommended value vr for the welding speed, or about the
determination whether or not the welding speed v exceeds the upper
limit because they are the same as in the second exemplary
embodiment. Also note that the leg length S used in these
calculations is the after-change value S1 of the leg length in the same
manner as in the second exemplary embodiment.
The welding device determines the recommended values for the
other welding conditions to be a welding current 112, a welding voltage
V12, and a wire feed speed WF12.
Similar to the second exemplary embodiment, calculation unit 9
calculates the recommended values for the other welding conditions
after determining whether or not the welding speed v2 is within the
acceptable range.
As described above, when the leg length is changed from the
recommended value Sr to the leg length S1, and the welding speed is
changed from the recommended value vr to the welding speed v2, the
welding device calculates the welding current 112, the welding voltage
V12, and the wire feed speed WF12 as the recommended values for the
other welding conditions, and displays them on display unit 15 of
setting device 5. The leg length S1 and the welding speed v2, which
have replaced the recommended value for the leg length S and the
recommended value for the welding speed v, respectively, are displayed

on display unit 15 of setting device 5.
Thus, the method to determine welding conditions includes,
after the fourth step S4, the feed speed calculation step S5, the current
value calculation step S6, the quantity of heat determination step S7,
the quantity of heat calculation step S8, and the current value/voltage
value calculation step S16.
When the leg length and the welding speed which are displayed
as welding conditions are changed to values different from the
recommended values determined in the fourth step S4, the welding
current 112 and the welding voltage V12 calculated in the current
value/voltage value calculation step S16 are determined to be the new
recommended value of the welding current and the new recommended
value for the welding voltage, respectively.
The feed speed calculation step S5 calculates the wire feed
speed WF1 from the after-change value S1 of the leg length and the
recommended value vr for the welding speed based on the formula for
calculating the wire feed speed, which is in proportion to the square of
the leg length and also in proportion to the welding speed.
The current value calculation step S6 calculates the welding
current 11 from the wire feed speed WF1 calculated in the feed speed
calculation step S5 based either on the formula for calculating the
welding current which increases with an increase in the wire feed
speed, or on the table showing the relation between the wire feed speed
and the welding current.
The voltage value calculation step S7 calculates the welding
voltage V1 from the welding current I1 calculated in the current value
calculation step S6 based either on the formula for calculating the

welding voltage which increases with an increase in the welding
current, or on the table showing the relation between the welding
current and the welding voltage.
The quantity of heat determination step S8 determines the
quantity of arc heat Q1 from the welding current I1 calculated in the
current value calculation step S6, the welding voltage V1 calculated in
the voltage value calculation step S7, and the recommended value vr
for the welding speed.
The current value/voltage value calculation step S16 calculates
the integrated value of the welding current and the welding voltage
from the quantity of arc heat Ql determined in the quantity of heat
determination step S8 and the after-change value v2 of the welding
speed based on the formula for calculating the quantity of arc heat.
The current value/voltage value calculation step S16 then calculates
the new recommended values for the welding current I and the welding
voltage V from the integrated value based on the relational expression
or table showing the relation between the welding current and the
welding voltage.
Thus, the welding current 112 and the welding voltage V12
calculated in the current value/voltage value calculation step S16 are
determined to be the new recommended value for the welding current
and the new recommended value for the welding voltage, respectively.
The welding device and the method to determine welding
conditions according to the present third exemplary embodiment can
determine the recommended values for the welding conditions which
are suitable for the information about the object to be welded and the
information about the welding method set by the operator, and can

display the recommended values on display unit 15. The welding
conditions include the welding current Ir, the welding voltage Vr, the
wire feed speed WFr, the welding speed vr, and the leg length Sr.
Furthermore, if the operator changes the recommended value Sr for
the leg length and the recommended value vr for the welding speed to
new values, the welding device and the method can determine new
recommended values for the other welding conditions compatible with
the new values and display the new recommended values. This
greatly reduces the operator's time and effort to determine the welding
conditions, and the amount of objects wasted through trial and error.
Alternatively, the recommended values for welding conditions
can be calculated by another approach as described below.
Figs. 13Aand 13B are first and second flowcharts, respectively
showing a procedure to determine other recommended values for the
welding conditions in the third exemplary embodiment.
Thus, the method to determine welding conditions includes,
after the fourth step S4, the feed speed calculation step S5, the current
value calculation step S6, the quantity of heat determination step S8,
and the voltage value calculation step S27.
The feed speed calculation step S5 calculates the wire feed
speed WF1 if the leg length and the welding speed displayed after the
fourth step S4 are both changed to values different from the
recommended values. The wire feed speed WFl is calculated from the
after-change value S1 of the leg length and the recommended value vr
for the welding speed based on the formula for calculating the wire
feed speed.
The current value calculation step S6 calculates the welding

current I1 from the wire feed speed WF1 calculated in the feed speed
calculation step S5 based either on the formula for calculating the
welding current which increases with an increase in the wire feed
speed, or on the table showing the relation between the wire feed speed
and the welding current.
The quantity of heat determination step S8 determines the
quantity of arc heat Q1 from the welding current I1 calculated in the
current value calculation step S6, the welding voltage V1 calculated
from the welding current I1 based either on the formula for calculating
the welding voltage or on the table showing the relation between the
welding current and the welding voltage, and the recommended value
vr for the welding speed. The formula is used to calculate the welding
voltage which increases with an increase in the welding current.
The voltage value calculation step S27 calculates the welding
voltage V12 from the quantity of arc heat Q1 determined in the
quantity of heat determination step S8, the after-change value v2 of
the welding speed, and the welding current I1 calculated in the current
value calculation step S6 based on the formula for calculating the
quantity of arc heat. The formula is used to calculate the quantity of
arc heat, which is in proportion to the welding current and the welding
voltage and is in inverse proportion to the welding speed.
When the displayed leg length and the displayed welding speed
are changed, the welding current I1 calculated in the current value
calculation step S6, and the welding voltage V12 calculated in the
voltage value calculation step S27 are determined to be the new
recommended value for the welding current and the new recommended
value for the welding voltage, respectively.

In the first through third exemplary embodiments, the operator
enters the object-to-be-welded information which is the information
about object 6 to the welding device in the first step S1. The
object-to-be-welded information includes the material of object 6, the
board thicknesses of upper and lower boards 16 and 17 of object 6, the
board thickness T indicating the average board thickness of upper and
lower boards 16 and 17, and the joint shape of object 6. At least one
item of the information can be used as the object-to-be-welded
information.
The joint shape can be T joint, lap joint, butt joint, corner joint,
edge joint, flare groove joint, etc.
In the first through third exemplary embodiments, the operator
enters welding method information, which is the information about the
arc welding method to the welding device in the second step S2. The
welding method information includes the following items: the use or
non-use of pulse welding in the arc welding, the pulse mode type, the
shielding gas type, the extended length of the welding wire, the method
for controlling the wire feed, the wire material, and the wire diameter.
At least one item of the welding method information can be used.
The use or non-use of pulse welding means whether or not pulse
welding is used in the arc welding. The pulse mode type is selected
from a plurality of pulse mode types. The shielding gas type is
selected from shielding gases used for welding such as CO2 gas, 80%
Ar-20% CO2 gas, or 98% Ar-2% O2 gas. The extended length of the
welding wire means the distance between the chip and the base
material, and is individually set, for example, to 15 mm or 20 mm.
The method for controlling the wire feed means the setting mode of

wire feed, such as continuous forward feeding or alternation of forward
feeding and backward feeding. The wire material means the material
of the welding wire, such as soft steel or stainless. The wire diameter
means the diameter of the welding wire, such as φ 0.9 mm or φ 1,0 mm.
In the first through third exemplary embodiments, the
recommended values for the welding speed v, the welding current I, the
welding voltage V, the wire feed speed WF, and the leg length S are
calculated and displayed as the welding conditions based on the
object-to-be-welded information and the welding method information.
In the first exemplary embodiment, when the value of the leg
length S is changed, new recommended values for the welding speed v,
the welding current I, the welding voltage V, and the wire feed speed
WF are calculated and displayed as the other welding conditions.
In the second exemplary embodiment, when the value of the
welding speed v is changed, new recommended values for the welding
current I, the welding voltage V, the wire feed speed WF, and the leg
length S are calculated and displayed as the other welding conditions.
In the third exemplary embodiment, when the value of the leg
length S and the value of the welding speed v are changed, new
recommended values for the welding current I, the welding voltage V,
and the wire feed speed WF are calculated and displayed as the other
welding conditions.
The operational program stored in storage unit 10 may have an
item corresponding to the welding condition such as the welding
current or the welding voltage whose value has been calculated as a
recommended value or changed to a new value. In that case, control
unit 8 changes the value of the item in the operational program to the

calculated or newly set value so that welding can be performed with
appropriate welding conditions.
INDUSTRIAL APPLICABILITY
The method to determine welding conditions and the welding
device according to the present invention, which can easily determine
welding conditions, are industrially useful for various objects to be
welded.
REFERENCE MARKS IN THE DRAWINGS
1 wire
2 welding torch
3 manipulator
4 robot controller
5 setting device
6 object to-be-welded
7 welding power supply
8 control unit
9 calculation unit

10 storage unit
11 object-to-be-welded information input unit
12 welding method information input unit
13 leg length setting unit
14 welding speed setting unit
15 display unit
16 upper board
17 lower board

We Claim:
1. A method to determine welding conditions, comprising:
a first step of receiving object-to-be-welded information, which
is information about an object to be welded;
a second step of receiving welding method information, which is
information about an arc welding method;
a third step of determining a quantity of arc heat, which is a
quantity of heat of an arc created between an electrode wire and an
object to be welded based on the object-to-be-welded information and
the welding method information;
a fourth step of determining a recommended value for a wire
feed speed, a recommended value for a leg length, a recommended
value for a welding speed, a recommended value for a welding current,
and a recommended value for a welding voltage based on the
object-to-be-welded information, the welding method information, and
the quantity of arc heat;
a feed speed calculation step of, if at least one of the leg length
and the welding speed which are displayed as welding conditions after
the fourth step is changed to a value different from the recommended
values determined in the fourth step, calculating the wire feed speed
from the after-change value, based on a formula for calculating the
wire feed speed, which is in proportion to a square of the leg length and
also in proportion to the welding speed;
a current value calculation step of calculating the welding
current from the wire feed speed calculated in the feed speed
calculation step based either on a formula for calculating the welding

current, which increases with an increase in the wire feed speed or on a
table showing a relation between the wire feed speed and the welding
current; and
a voltage value calculation step of calculating the welding
voltage from the welding current calculated in the current value
calculation step, wherein
the welding current calculated in the current value calculation
step and the welding voltage calculated in the voltage value
calculation step are determined to be a new recommended value for the
welding current and a new recommended value for the welding voltage,
respectively.
2. The method of claim 1, wherein
the feed speed calculation step calculates the wire feed speed if
the leg length displayed as a welding condition after the fourth step is
changed to a value different from the recommended value for the leg
length determined in the fourth step, the wire feed speed being
calculated from the after-change value of the leg length and the
recommended value for the welding speed based on the formula for
calculating the wire feed speed;
the voltage value calculation step calculates the welding voltage
from the welding current calculated in the current value calculation
step based either on a formula for calculating the welding voltage,
which increases with an increase in the welding current or on a table
showing a relation between the welding current and the welding
voltage; and
if the displayed leg length is changed, the welding current

calculated in the current value calculation step and the welding
voltage calculated in the voltage value calculation step are determined
to be a new recommended value for the welding current and a new
recommended value for the welding voltage, respectively.
3. The method of claim 2, further comprising:
a quantity of heat determination step of determining a quantity
of arc heat from the welding current calculated in the current value
calculation step; the welding voltage calculated in the voltage value
calculation step, and the recommended value for the welding speed,
wherein only when the quantity of arc heat determined in the
quantity of heat calculation step is within an acceptable range, the
welding current calculated in the current value calculation step and
the welding voltage calculated in the voltage value calculation step are
determined to be a new recommended value for the welding current
and a new recommended value for the welding voltage, respectively.
4. The method of claim 1, wherein
the feed speed calculation step calculates the wire feed speed if
the welding speed displayed after the fourth step is changed to a value
different from the recommended value for the welding speed, the wire
feed speed being calculated from the after-change value of the welding
speed and the recommended value for the leg length based on the
formula for calculating the wire feed speed;
the voltage value calculation step calculates the welding voltage
from the quantity of arc heat determined in the third step, the
after-change value of the welding speed, and the welding current

calculated in the current value calculation step based on a formula for
calculating the quantity of arc heat, which is in proportion to the
welding current and the welding voltage and is in inverse proportion to
the welding speed; and
if the displayed welding speed is changed to another value, the
welding current calculated in the current value calculation step and
the welding voltage calculated in the voltage value calculation step are
determined to be a new recommended value for the welding current
and a new recommended value for the welding voltage, respectively.
5. The method of claim 1, further comprising:
a quantity of heat determination step of determining a quantity
of arc heat, wherein
the feed speed calculation step calculates the wire feed speed if
the leg length and the welding speed displayed after the fourth step
are changed to values different from the recommended values, the wire
feed speed being calculated from the after-change value of the leg
length and the recommended value for the welding speed based on the
formula for calculating the wire feed speed;
the quantity of heat determination step determines the
quantity of arc heat from the welding current calculated in the current
value calculation step, the welding voltage calculated from the welding
current based either on a formula for calculating the welding voltage
which increases with an increase in the welding current or on a table
showing a relation between the welding current and the welding
voltage, and the recommended value for the welding speed;
the voltage value calculation step calculates the welding voltage

from the quantity of arc heat determined in the quantity of heat
determination step, the after-change value of the welding speed, and
the welding current calculated in the current value calculation step,
based on a formula for calculating the quantity of arc heat, which is in
proportion to the welding current and the welding voltage and is in
inverse proportion to the welding speed; and
if the displayed leg length and the displayed welding speed are
changed, the welding current calculated in the current value
calculation step and the welding voltage calculated in the voltage
value calculation step are determined to be a new recommended value
for the welding current and a new recommended value for the welding
voltage, respectively.
6. The method of claim 5, wherein
when the after-change value of the leg length is outside an
acceptable range, the feed speed calculation step prevents the
displayed leg length from being changed; and
when the after-change value of the leg length is within the
acceptable range, the feed speed calculation step calculates the wire
feed speed from the after-change value of the leg length and the
recommended value for the welding speed based on the formula for
calculating the wire feed speed.
7. The method of claim 5, wherein
when the after-change value of the welding speed is outside an
acceptable range, the voltage value calculation step prevents the
displayed welding speed from being changed; and

when the after-change value of the welding speed is within the
acceptable range, the voltage value calculation step calculates the
welding voltage from the quantity of arc heat determined in the
quantity of heat determination step, the after-change value of the
welding speed, and the welding current calculated in the current value
calculation step, based on the formula for calculating the quantity of
arc heat.
8. A method to determine welding conditions, comprising:
a first step of receiving object-to-be-welded information, which
is information about an object to be welded;
a second step of receiving welding method information, which is
information about an arc welding method;
a third step of determining a quantity of arc heat, which is a
quantity of heat of an arc created between an electrode wire and an
object to be welded based on the object-to-be-welded information and
the welding method information;
a fourth step of determining a recommended value for a wire
feed speed, a recommended value for a leg length, a recommended
value for a welding speed, a recommended value for a welding current,
and a recommended value for a welding voltage based on the
object-to-be-welded information, the welding method information, and
the quantity of arc heat; and
a current value/voltage value calculation step of calculating the
welding current and the welding voltage from an integrated value
based on a relational expression or table showing a relation between
the welding current and the welding voltage if the welding speed

displayed as a welding condition after the fourth step is changed to a
value different from the recommended value for the welding speed, the
integrated value being calculated from the already-determined
quantity of arc heat and the displayed after-change value of the
welding speed based on a formula for calculating the quantity of arc
heat, which is in proportion to the welding current and the welding
voltage and is in inverse proportion to the welding speed, wherein
when the displayed welding speed is changed, the welding
current and the welding voltage calculated in the current value/voltage
value calculation step are determined to be a new recommended value
for welding current and a new recommended value for the welding
voltage, respectively.
9. The method of claim 8, further comprising:
a feed speed calculation step of calculating the wire feed speed
from the welding current calculated in the current value/voltage value
calculation step based on a relational expression or table showing a
relation between the welding current and the wire feed speed; and
a leg length calculation step of calculating the leg length from
the wire feed speed calculated in the wire feed speed calculation step.
10. The method of claim 8, comprising:
a feed speed calculation step of calculating the wire feed speed
if the leg length and the welding speed displayed as welding conditions
after the fourth step are changed to values different from the
recommended values determined in the fourth step, the wire feed speed
being calculated from the after-change value of the leg length and the

recommended value for the welding speed based on the formula for
calculating the wire feed speed which is in proportion to a square of the
leg length and also in proportion to the welding speed;
a current value calculation step of calculating the welding
current from the wire feed speed calculated in the feed speed
calculation step based either on a formula for calculating the welding
current, which increases with an increase in the wire feed speed or on a
table showing a relation between the wire feed speed and the welding
current;
a voltage value calculation step of calculating the welding
voltage from the welding current calculated in the current value
calculation step based either on a formula for calculating the welding
voltage, which increases with an increase in the welding current or on
a table showing a relation between the welding current and the
welding voltage; and
a quantity of heat determination step of determining the
quantity of arc heat from the welding current determined in the
current value calculation step, the welding voltage determined in the
voltage value calculation step, and the recommended value for the
welding speed, wherein
the current value/voltage value calculation step calculates a
new recommended value for the welding current and a new
recommended value for the welding voltage from an integrated value
based on a relational expression or table showing a relation between
the welding current and the welding voltage, the integrated value
being calculated from the quantity of arc heat determined in the
quantity of heat calculation step and the after-change value of the

welding speed based on the formula for calculating the quantity of arc
heat; and
the welding current and the welding voltage calculated in the
current value/voltage value calculation step are determined to be the
new recommended value for the welding current and the new
recommended value for the welding voltage, respectively.
11. The method of claim 1 or 8, wherein
the object-to-be-welded information includes at least one of the
following items: a material, a board thickness of an upper board, a
board thickness of a lower board, an average board thickness of the
upper and lower boards, and a joint shape.
12. The method of claim 1 or 8, wherein
the welding method information includes at least one of the
following items: use or non-use of pulse welding, pulse welding type,
shielding gas type, an extended length of the wire, a method for
controlling the wire feed, wire material, and wire diameter.
13. A welding device comprising:
an object-to-be-welded information input unit to receive
object-to-be-welded information, which is information about an object
to be welded;
a welding method information input unit to receive welding
method information, which is information about an arc welding
method;
a quantity of arc heat determination unit to determine a

quantity of heat of an arc created between an electrode and a base
material based on the object-to-be-welded information and the welding
method information;
a leg length setting unit to change a leg length displayed as a
welding condition to a value different from a recommended value for
the leg length;
a welding speed setting unit to change a welding speed
displayed as a welding condition to a value different from a
recommended value for the welding speed;
a calculation unit to perform calculations used in the method of
claim 1 or 8 to determine welding conditions; and
a display unit to display calculation results of the calculation
unit.
14. The welding device of claim 13, further comprising:
a robot controller to control a manipulator including a welding
torch;
a setting device connected to the robot controller; and
a welding power supply either connected to the robot controller
or disposed in the robot controller, the welding power supply
performing a welding output, wherein
the robot controller comprises:
a storage unit to store an operational program to operate
the manipulator and the welding power supply; and
a control unit to change the operational program stored
in the storage unit, wherein
the control unit changes a value of the welding current, a value

of the welding voltage, and a value of the welding speed in the
operational program stored in the storage unit to the welding current,
the welding voltage, and the welding speed calculated in the
calculation unit.