The “ARC ON” command contains the parameters for moving the welding torch (type of motion, speed, etc.) from the home position to the start point of the seam, and all the ignition parameters. The options set in the $CONFIG.DAT file are taken into account. While the
“ARC ON” program phase is being executed, the system constantly checks whether the weld conditions are satisfied. “ARC ON” ends after ignition has been successfully completed.
The movement from the home position to the start point of the seam can be executed as a
“PTP”, “LIN” or “CIRC” motion. Approximation of the ignition position is not possible; the torch is stopped exactly at the start of the seam. The point before the ignition position may, however, be approximated.
6.4.1 Welding constraints Program run mode
Welding is only possible in the $MODE_OP=#GO program run mode. All other operating modes would be meaningless. Other settings for hot welding result in error messages.
Keyswitch with/without welding
A configured keyswitch can be used to prevent activation of an arc process.
The default setting of the software is configured without a keyswitch!
The keyswitch is always evaluated during ignition in the default configuration as long as the ARC button has been set to ACTIVE.
DECL FCT_IN_T A_I_EN_W_EXT={NO 5, STATE TRUE}
(NO 5 refers to index A_WLD_IN[5] )
A_WLD_IN[5]={IN_NR 37, NAME_NAT[ ]”KEY SWITCH HOT/COLD”}
In External mode, an active welding symbol is expected on the KCP at all times. The external keyswitch allows a cold run of the application at the next ignition process (even from a control room). In all other operating modes, the state of the keyswitch is checked in the event of hot welding and, where appropriate, a corresponding error message is generated.
The keyswitch can also be configured in such a way that the system can instantly be switched off during operation.
Other welding conditions
Condition Variable
Robot on the path $ON_PATH=TRUE *
Process enabled Options bits
PROC_ENABLE=TRUE (general enable) Process enabled in T1
Options bits
PROC_IN_T1=TRUE (only relevant in T1 mode)
Keyswitch See description “ARC ON”
ArcTech OPTION A10_OPTION=#ACTIVE
Block coincidence $MOVE_BCO=FALSE*
Arc--specific status key (ICON symbol “hot”)
A_HOT_WELD=#ACTIVE
Robot on weld seam TECH_MOTION=TRUE
Program run mode $MODE_OP=#GO
*Set automatically during program execution.
The results of the welding conditions are reflected in the variables A_F_WLD_COND(#IDLE,
#ACTIVE).
6.4.2 Gas preflow
Every activation process is preceded by gas preflow. Depending on the gas preflow option that has been set, this can be configured parallel to the motion, in particular the positioning motion to the ignition position.
Condition Variable Meaning
A_PR_GAS_OPT TRUE (Default)
FALSE
Gas preflow “on the fly”
parallel to the positioning motion to the ignition posi-tion, with corresponding gas preflow time
Gas preflow at the ignition position
The ignition parameters, weld mode, and power source readiness are specified in the advance run.
6 Description of the weld commands (continued)
6.4.3 Configuration: monitoring the weld power source
This function checks that the power source is ready and that the cooling water and shielding gas are available. A message is generated in the event of an error. This monitoring is ignored when moving along seams with the torch deactivated (so--called “cold state”). It is configured in the $CONFIG.DAT input group A_I_WLD_COND[ ]:
;input as condition before weld can start DECL FCT_IN_T A_I_WLD_COND[3]
A_I_WLD_COND[1]={NO 1, STATE TRUE}; source ok
A_I_WLD_COND[2]={NO 10,STATE TRUE}; water available A_I_WLD_COND[3]={NO 11,STATE TRUE}; gas available
In this example, physical inputs 1 (source ok), 10 (water available), and 11 (gas available) are checked. The weld process is only enabled once all three inputs are set to HIGH. IN_NR contains the physical input number for each.
A_WLD_IN[1]={IN_NR 1,NAME_NAT[ ]”WELDER_READY “}
A_WLD_IN[10]={IN_NR 10,NAME_NAT[ ]”WATER AVAILABLE “}
A_WLD_IN[11]={IN_NR 11,NAME_NAT[ ]”GAS AVAILABLE “}
6.4.4 Configuration: robot motion start after weld start
This signal group links the input conditions which, combined, enable robot motion. In this example, the motion begins as soon as the “Current flowing” signal is present.
;inputs start moving
DECL FCT_IN_T A_I_STRT_MOV[3]
A_I_STRT_MOV[1]={NO ’H2’,STATE TRUE}
A_I_STRT_MOV[1]={NO ’H0’,STATE TRUE}
A_I_STRT_MOV[1]={NO ’H0’,STATE TRUE}
The condition in this example is met as soon as input no. 11 is set to HIGH. No other inputs are checked.
A_WLD_IN[2]={IN_NR 11,NAME_NAT[ ]”ARC ESTABLISHED “}
6.4.5 Configuration of the weld modes
This signal group toggles the weld modes in all ArcTech commands (inline form settings: PS or MM).
Mode1 (pulse, inline form: PS)
;outputs for MODE1 welding (--> Pulse) DECL FCT_OUT_T A_O_MODE1[3]
A_O_MODE1[1]={NO ’H3’, PULS_TIME 0.0, STATE TRUE) A_O_MODE1[2]={NO ’H0’, PULS_TIME 0.0, STATE TRUE) A_O_MODE1[3]={NO ’H0’, PULS_TIME 0.0, STATE TRUE)
The link set out above sets physical output no. 7 to TRUE. No other outputs are activated.
A_WLD_OUT[3]={OUT_NR 7,INI FALSE,NAME_NAT[ ]”WELD MODE PS/MM “}
Mode2 (MIG / MAG, inline form: MM)
;outputs for MODE2 welding (--> Mig/Mag)
A_O_MODE2[1]={NO ’H3’, PULS_TIME 0.0, STATE FALSE) A_O_MODE2[2]={NO ’H0’, PULS_TIME 0.0, STATE FALSE) A_O_MODE2[3]={NO ’H0’, PULS_TIME 0.0, STATE FALSE)
The link set out above sets output no. 7 to FALSE. No other outputs are activated.
A_WLD_OUT[3]={OUT_NR 7,INI FALSE,NAME_NAT[ ]”WELD MODE PS/MM “}
6.4.6 Configuration of the WELD start signal
Once the ignition position has been reached and the gas preflow time has elapsed, the power source is activated and the wire is fed and ignited. As soon as the “Current flowing” signal is detected, the torch is moved away from the ignition position.
This signal group initiates the weld process. In this example, the gas preflow is activated in parallel.
;outputs for weld start
DECL FCT_OUT_T A_O_WLD_STRT[3]
A_O_WLD_STRT[1]={NO ’H1’, PULS_TIME 0.0, STATE TRUE}
A_O_WLD_STRT[2]={NO ’H2’, PULS_TIME 0.0, STATE TRUE}
A_O_WLD_STRT[3]={NO ’H0’, PULS_TIME 0.0, STATE TRUE}
6 Description of the weld commands (continued)
6.4.7 Configuration of the error handling for an ignition failure Configuration: ignition failure
With this configuration, the weld start and gas flow are aborted in the event of an ignition failure. It is also possible to set a corresponding ignition fault output for a connected PLC.
DECL FCT_OUT_T A_O_FLT_ON[3]
A_O_FLT_ON[1]={NO’H1’,PULS_TIME 0.0, STATE FALSE};reset weld start
A_O_FLT_ON[2]={NO ’H2’,PULS_TIME 0.0, STATE FALSE};disconnect gas
A_O_FLT_OM[3]={NO ’H7’,PULS_TIME 0.0, STATE TRUE};indicate igni-tion fault
Three physical outputs are set here in parallel: output 3 to LOW, output 8 to LOW, and output 9 to HIGH:
A_WLD_OUT[1]={OUT_NR 3, INI FALSE, NAME_NAT[ ]”WELD START “}
A_WLD_OUT[2]={OUT_NR 8, INI FALSE, NAME_NAT[ ]”GAS PREFLOW “}
A_WLD_OUT[7]={OUT_NR 9, INI FALSE, NAME_NAT[ ]”START ERROR “}
Configuration: general fault output
This signal indicates a general fault, irrespective of whether it is an ignition fault, a periphery fault, or a seam fault.
DECL FCT_OUT_T A_O_FLT_SIGN={NO ’H6’,PULS_TIME 0.0,STATE TRUE}
In this example, the signal is switched through to output no. 8:
A_WLD_OUT[6]={OUT_NR 8, INI FALSE, NAME_NAT[]ERR MESSG_SIGNAL “}
6.4.8 Configuration of gas postflow
This signal group is permanently activated when the weld process has been deactivated in order to enable shielding gas postflow. The gas postflow time is defined in the weld parameter list of the last ARC OFF command.
;outputs gas post flow ends
DECL FCT_OUT_T A_O_POST_OFF[3]
A_O_POST_OFF[1]={’H2’,PULS_TIME 0.2, STATE TRUE}
A_O_POST_OFF[1]={’H0’,PULS_TIME 0.2, STATE TRUE}
A_O_POST_OFF[1]={’H0’,PULS_TIME 0.2, STATE TRUE}
The signal is generated here as a HIGH pulse at physical output no. 4:
A_WLD_OUT[2]={OUT_NR 4,INI FALSE, NAME_NAT[ ] “GAS PREFLOW “}
The postflow time is defined in the end crater parameter list.
6.4.9 Configuration of necessary acknowledgement signals
Power sources from certain manufacturers must be acknowledged before a new weld process is started. An additional output can be configured in the KRC for this purpose:
;outputs acknowledge fault
DECL FCT_OUT_T A_O_ACK_FLT[3]
A_O_ACK_FLT[1]=(NO ’H5’,PULS_TIME 0.5,STATE TRUE}
A_O_ACK_FLT[1]=(NO ’H0’,PULS_TIME 0.5,STATE TRUE}
A_O_ACK_FLT[1]=(NO ’H0’,PULS_TIME 0.5,STATE TRUE}
A 0.5 s HIGH pulse is generated at physical output no. 9:
A_WLD_OUT[5]={OUT_NR 9, INI FALSE;NAME_NAT[ ]”RECEIPT ERRORS “}
6 Description of the weld commands (continued)
6.4.10 Activating the ramp function
The ramp function (see Fig. 12) enables modification of the ignition and weld parameters after the weld start. To do so, the variable:
A_RAMP_OPTION=TRUE (default: FALSE) must be modified in the $config.dat file.
In order to complete activation of the ramp function, the HMI then has to be reinitialized.
WELDSET 1
WELDSET 2
Distance
Ramps Ignition voltage/Wire feed
Ramp length Fig. 12 Ramp function
Setting the ramp length with the option active:
Ramp length
0 to 25 mm
Ramp function Ramp function
Ramp length
Select the ramp length so that the distance to the following point is long enough.
If the distance between the points is not long enough, the ramp will ”break” and the output will take on unexpected values.
This function may not be used during sensor operation with “KUKA.ArcSense”
(TRACK command); here, the ramp length has to be set to 0 or the ramp function has to be switched off (A_RAMP_OPTION=FALSE).
6.4.11 Schematic sequence diagram
Arc on Ignition attempts
according to
Process continued with the next data set
(ARC OFF or ARC SWITCH) Y
Monitoring is activated once the “Current flowing” signal (A_I_STRT_MOV[ ]) has been generated and the time defined in A_CTRL_DELAY has elapsed
Early gas preflow
Only with the option:
A_PR_GAS_OPT=TRUE
6 Description of the weld commands (continued)
Input group Meaning
A_I_WLD_COND[ ] Weld enable (max. 3 inputs)
A_I_STRT_MOV[ ] “Current present” signal, enables continua-tion of mocontinua-tion. (max. 3 inputs)
Output group Meaning
A_O_MODE1/2[ ] Weld mode (pulse or MigMag).
(max. 3 output)
A_O_GAS_PRE[ ] Gas preflow active (without Weld Start).
(max. 3 output)
A_O_WLD_STRT[ ] Weld start and Gas preflow active.
(max. 3 output)
A_O_FLT_SIGN[ ] Signal to the PLC in the event of a seam fault or ignition fault. (max. 1 output) A_O_FLT_ON[ ] Signal to the PLC in the event of an
igni-tion fault (max. 3 outputs)
A_O_POST_OFF[ ] Deactivation of the gas flow including post-flow time (max. 3 outputs)
A_O_ACK_FLT[ ] Acknowledgement signal to the periphery before repetition of the ignition process
6.4.12 Ignition process signal flow diagram
In the example shown in Fig. 14, a gas preflow time has been programmed in the “Start parameters” list, shown here by means of the “Gas flow” graph (A_WLD_OUT[2]).
Start parameters Weld parameters
Wire feed setpoint value (channel 2)
Weld voltage setpoint value (channel 1)
Ignition time
Current flowing A_WLD_IN[2]
Gas flow (A_WLD_OUT[2]) Gas preflow time
Weld start (A_WLD_OUT[1])
Fig. 14 Ignition process signal flow diagram
Beside it you see the signal for weld start (A_WLD_OUT[1]) -- this is the point in time at which wire feed is activated -- followed by the “Current flowing” signal from the peripheral interface (A_I_STRT_MOV[ ]), meaning that the arc is now established following successful ignition.
At the conclusion of the ignition time, a transition is made from the start parameters to the weld parameters, as you can see from the curves for both analog channels (setpoint values for weld voltage and wire feed -- channels 1 and 2). The weld parameters (W parameters) are contained in the weld data set of the “ARC OFF” or “ARC SWITCH” command that follows the “ARC ON” command.
6.4.13 Activation of delayed weld process monitoring after ignition
If an arc is established following ignition, the weld process monitoring function is activated after a time delay set by means of the A_CTRL_DELAY variable. The “Current flowing” signal (A_I_STRT_MOVL) from the weld power source is decisive for this. The default time is 1200 milliseconds.
The default time can be changed with the menu function “Monitor -- Variable -- Single”.
Variable Default (ms) A_CTRL_DELAY 1200
To avoid disruptions, this value should not be too low. If the setting is too high, the peripheral interface signals cannot be monitored during this time.