Process visualisation and monitoring WELDEYE
This high-speed camera system detects all visually detectable irregularities in the weld seam with a high degree of certainty
Fully automated, the lasers in automotive production scurry over the various vehicle parts and weld car doors, tailgates, hairpins, battery boxes, etc. Such laser welding systems work extremely fast, completely independently and almost without malfunction. In order to be able to maintain the weld seam quality at the required high level throughout and to reduce defectively welded components to a minimum, the welding processes must be permanently monitored and, if possible, visualised. Such a process visualisation and monitoring system for laser welding is WELDEYE from the ABICOR BINZEL cooperation partner Lessmüller Lasertechnik GmbH from Munich. The experts for quality assurance of welding processes have been active in laser technology since 1990 and are now market leaders in both visualisation and monitoring systems for the laser joining process.
Process visualisation and monitoring of laser welding processes
Tactile laser welding with wire in vehicle and body construction is highly complex. The reason for this is the variety of parameters that interact with each other as well as with the ambient conditions. Despite short cycle times, every welded seam must be a quality seam. In order to ensure the quality of a seam at the same time as its completion, camera-based imaging processes are ideally used. The WELDEYE process visualisation and monitoring system from Lessmüller Lasertechnik has already been installed in 600 production plants worldwide – and is therefore considered as a benchmark for this online process monitoring technology.
Functionality of the WELDEYE online process monitoring system
The WELDEYE system consists of a high-speed camera coupled and synchronised with a laser illumination. This enables both live images and video recordings to be made of the joining process with a sampling rate of up to 500 Hz. While the laser is welding or brazing, the integrated optical filter and the special illumination ensure that the light radiation from the process and thus disturbing effects are suppressed or reduced. The weld joint and molten pool are thus continuously measured together with the reflection of the cooled weld seam.
From the generation LM7 onwards, the WELDEYE system in combination with the AP3.0 camera has an illumination directly integrated into the camera housing. Therefore, there is no longer any negative influence on the interfering contour of the processing optics.
Save and manage measurement data
Each weld is recorded, analysed using data from reference runs and stored. The data is managed and stored on an industrial PC with an interface to the fieldbus system of the plant control system. The data recorded by video can be played back for up to eight hours after recording using the WELDEYE player function and is available in various formats for export to the user's network.
The modular principle
Since user requirements can differ greatly, WELDEYE is available either as a complete system or equipped with individual functions. The following modules are included in this modular system:
- Illumination modules
- Camera modules
- Illumination and camera modules in combination
- Fibre laser collimator
WELDEYE applications
Depending on the software licence, the following different functions or applications of the WELDEYE process visualisation and monitoring are available.
Detection of seam irregularities
With a continuous analysis of the live images in defined process regions as well as the already solidified weld seam, image evaluation algorithms allow irregularities in the course and formation of the weld seams to be detected. Such weld irregularities are:
- Interruptions of the weld seam
- Surface defects
- Lateral connection defects
The system also offers the possibility to measure the position of the wire to the laser beam as well as of the laser beam to the joint and to monitor it against set values. A communication interface with the system control transfers the data obtained and makes it available to the user for quality assessment. The scale for this is a good weld, on the basis of which warning and error thresholds are usually defined.
Parameter monitoring
With the hardware of the WELDEYE evaluation, data from the welding optics, the robot or the laser source can be recorded and managed synchronised in time with the process video. The communication for this also runs via the fieldbus and makes it possible to assign detected irregularities in the process directly to the corresponding parameter deviations, resolved in terms of time or location. This holistic process monitoring enables the user to react quickly to irregularities and optimise his welding process – both during the start-up of a series and during production without time-consuming troubleshooting or elaborate test series.
Monitoring the swivel axis position
For weld seam guidance, the tactile laser processing optics are equipped with an optomechanical swivel system – a combination of optical and mechanical components - which is coupled to the wire feed. With this control and regulation, the laser beam and welding wire are always guided along the joining edge and along the actual component contour with a contact pressure. However, a welding edge can also have tolerances, be damaged or be incorrectly positioned due to errors in the fixture. In such cases, the continuously acting pressure force would cause the wire and laser beam to deviate from the predefined position and damage the clamping system, the component itself or the laser optics. This process is called wire slip-off. The WELDEYE system monitors the alignment of the actual to the target position of the welding wire and reports deviations via the fieldbus system. The user can thus react quickly and define and automatically execute damage prevention measures.
Welding path correction
An additional feature in the WELDEYE system is an integrated edge detection algorithm. For this type of seam tracking, so-called actuators – drive technology units – are controlled to make path corrections. For this purpose, reflection measurements are carried out on the welding edge and detect its position as well as possible gaps.
Advantages of WELDEYE process visualisation and monitoring
- Detection of seam irregularities
- Holistic process parameter monitoring
- Prevention of wire slip-off
- Integrated weld path correction
With ABICOR BINZEL's worldwide sales and service network and Lessmüller Lasertechnik's WELDEYE process visualisation and monitoring, there are two strong partners for your laser applications in:
- Car body construction
- Power Train
- Mechanical engineering