Digital COMARC arc sensor
Digital COMARC is MOTOMAN's arc sensor (weld seam tracking) function. It detects seam deviation from changes in welding current, with no camera or laser sensor.
Principle
With a constant-voltage welding power source, the welding current changes when the distance between the contact tip and the base metal changes. The arc sensor makes use of this.
- Left–right correction: the torch weaves left and right, and the welding currents at the two ends are compared. If the torch is centred, the currents are equal; if it has drifted to one side, they differ. The path is corrected so that the currents at both ends become equal.
- Up–down correction: the vertical path is corrected so that the welding current stays constant.
Application range
| Joint | Plate thickness | Welding speed |
|---|---|---|
| T fillet | 3.2 mm or more | 60 cm/min or less |
| Lap | 8.0 mm or more | 60 cm/min or less |
Compatible power sources and restrictions
- Compatible welding power sources: MOTOWELD-RL350 (from a specified version), MOTOWELD-X350, MOTOWELD-X500, Fronius TPSi.
- Cannot be used together with the ACP02 board. With MOTOWELD it also cannot be combined with the welding diagnosis function.
- For CMT welding with a Fronius TPSi, the TPSi must be at or above the version specified in the manual.
- Tracking performance depends on the power source and welding waveform, so testing before introduction is recommended.
- The function is configured at shipment. Do not change its settings unless you need to disable it. Adding it to existing equipment requires set-up by a field engineer.
After delivery, the only steps are connecting the welding power source to the YRC1000 (a LAN cable to LAN2 (CN106) on the ACP01 CPU board, or LAN3 (CN107) if LAN2 is used by another function) and setting up the welding power source.
Registering in a job
Enclose the section where arc sensing is to be performed between COMARCON and COMARCOF.
- Set the up/down tracking condition (U/D) to the same value as the current setting of the ARCON instruction.
- Set the left/right tracking condition (L/R) to 0.
- Weld for real, and if the aim position needs adjusting, adjust U/D and L/R.
In some current ranges, the current set in ARCON differs from the current the welder actually outputs. In that case, measure the sensing conditions when you register COMARCON.
When tracking is poor
- Increase the weaving half-amplitude.
- Increase the weaving frequency.
- Lower the welding speed.
- Lower the welding command voltage (most effective when droplet transfer is spray or pulse transfer).
Make these adjustments only within welding and weaving conditions that still give stable welding.
Source: Based on YASKAWA manual HW1486253.