Finding a weld seam in longitudinally welded tubes or in welded coil material is becoming increasingly important, especially in automated manufacturing processes, and is gaining ever greater significance for the quality of the final product. Requirements for ensuring mechanical properties such as strength demand that the weld seam, for example when bending longitudinally welded tubes, lies in the neutral axis, or that drill holes are not placed within the weld seam.

In press lines, for instance, the coil material to be processed is increasingly welded automatically at the ends to avoid loss of time and material. However, this means that the position of the weld seams in relation to the tooling must be known in order to protect it from damage.

ROLAND ELECTRONIC GmbH has been successfully engaged for many years in developing solutions for the localization of weld seams in modern production processes. Various non-destructive testing methods are used for this purpose. These methods are based on the metallurgical differences in structure between the weld seam and the base material. Whether the material is ferrous or non-ferrous is of secondary importance.

In simplified terms, a process-specific electrical and/or magnetic field penetrates the material to be tested. In a comparative measurement, deviations in structure (inhomogeneities) from the base material are detected and identified.

Based on this measurement principle, it is possible to detect weld seams that are invisible to the naked eye.

In general, the following conditions must be ensured for successful measurement:

• The sensor must be placed on the material to be tested and remain there during the measurement cycle.
• There must be constant relative movement between the sensor and the material.

Using this measurement principle, weld seams can be detected in all ferritic and austenitic materials.

In many cases, however, a deeper understanding of weld seam signal evaluation is required to determine the best possible settings for the measuring device depending on the material to be tested. Finding the optimal setting can therefore be challenging. Depending on material type, wall thickness or sheet thickness, and welding process, various measurement methods and corresponding program parameters are possible. Optimal measurement results can often only be achieved through testing and extensive experience. Additionally, operators are often uncertain about the meaning and impact of parameters such as low-pass, high-pass, signal strength, and measuring frequency.

Easily Determining Parameters for Weld Seam Localization

ROLAND ELECTRONIC has addressed this challenge with a comprehensive revision of its operating software. An intuitive menu structure now allows users to determine optimal weld seam localization parameters based on the product—without requiring in-depth knowledge of the measuring device or measurement method.

The innovative assistant mode significantly reduces system setup effort. The operator simply enters the tube diameter, wall thickness, material type, optional post-treatment information, and the desired target angle for seam positioning. These parameters are conveniently queried step by step. Suitable “recipes” are then calculated and verified and optimized in a subsequent automated process. A valuable foundation for this process is the extensive database that Roland Electronic has continuously built and maintained over the years.

The Roland weld seam detection system type SND40 consists of a sensor, cable connections, and control/evaluation electronics. All common bus interfaces as well as a simple I/O interface are available for connection to higher-level control systems.

Particularly in tube processing, correct positioning of the weld seam within the manufacturing system is essential after detection. Via the interface of the SND40 weld seam detection system, the customer’s drive system can also be controlled (start/stop) if required. When creating the corresponding recipe file, the operator can easily define the desired “target angle.”

ROLAND ELECTRONIC provides consulting and support already during the project planning phase of such systems. Necessary preliminary laboratory tests—during which the most suitable device configuration and required program parameters for the respective application are determined—are carried out free of charge.

The weld seam detection system can additionally be equipped with a remote maintenance unit, allowing ROLAND ELECTRONIC’s service department to provide support during ongoing production. This is particularly recommended for frequently changing tube types or in cases with increased requirements regarding detectability or positioning accuracy.