Endless pipe welding
The usually used nondestructive testing methods for welded seam control as eddy current examination and ultrasonic examination fails at cold fusion points (bond seams).
with the newly developed measuring of the heat field via ThermoProfileScanner, these and all other welding irregularities can also be recognized at welding speeds up to 180 m/min.
The view in the welded seam
While welding materials they are melted by a local application of energy and are changed in the structure.
The correct heat input as well as the undisturbed heat propagation are essential characteristics to judge the welded seams.
The human eye cannot register thermal radiation. The visible part of the glowing seam outshines the warmth information completely.
Therefore a technique is necessary, which can measure this temperature information durably, highly precise and reproducible under production conditions (pollution, smoke..).
The same temperature field guaranteed the same welding quality. For that reason and with 18 years experience the TPS was developed and patented.
ThermoProfilScanner as acomponent of the monitoring system WeldQAS
Connection schema in a high frequency welding plant
Example: Conductive HF-welding
- Realizing a set up help for optimal welding parameters based on the heat signature
- Recogognition of visible and invisible welding faults, cold joints, and excessive root penetration.
- Color marking faults
- Re-place Eddy Current Detection Systems since these can not detect these faults
Heat field when fault through cold fusion joint
When the melting temperature is not reached, the temperature is falling in the joining zones.
The sensor is calculating the heat field width via a set temperature threshold. Cold welding joints can be clearly seen in the diminishing heat field width.
Detecting cold fusion points
Width of heat filed and learned thresholds values.
Example: High frequency-induction tube welding (HFI)
- Detection of cold fusion points , (bond seams), which the integrated eddy current system and ultrasonic system could not recognize.
- Up till now only a destroying punctual testing of materials was possible. Pipes which got leaky later at the costumer could not be sorted out.
- Warranty of a constant quality based on the thermal field
Failure in the adaption of energy power
steel - tube 13*2,2 mm, 5,6 m length
to high energy caused a very strong on-heating (for the duration of 0,85 s. The temperatures are higher and the heat field is considerably expanded (further zoom next page).
cold fusion points (0,3s long)
These faulty sections are recognized and marked by the TPS and the additional monitoring system.
Example for the sensibility of the thermal measuring at the seam
The area zoomed with to high energy (from previous foil) has a cold point at the end.
Cold point (energy fall-off) for the duration of 40 ms .These faulty sections are recognized and marked by the TPS and the additional monitoring system.
Example: Longitudinal pipe manufacturing TIG/Plasma
Example: Laser welding
Monitoring and presentation of the penetration while production of an afterwards calibrated and completely closed welding wire.
Reference: plant manufacturer Bühler Würz Kaltwalztechnik GmbH, Pforzheim
tube: 12* 2mm filled with pouder
welding speed: 15 m/min
The WeldQAS-System calculates for each profile (200 times per sec) characteristics of the thermal field which find use as monitoring values.
It is able to measure other parametres of the machine, e.g. laser power and speed beside the temperature field, take them up synchronically and to monitore at the same time.