MSG has developed a groundbreaking technology for objective contour scanning of long products, the so-called Weightless Contouring™.
The combination of MSG’s 2D profiling systems together with its EP and US patented straightness and twist measurement device, which continuously and objectively determines the straightness curve of long products in the weightless state, lead to the real Digital Twin.
1. Geometric requirements for straightness and twis
Straightness and twist are playing an important role in the manufacture of semi-finished products. Their requirements are defined jointly by manufacturers and users of long products in standardization committees.
In the field of manufacturing straightness is of great importance to ensure problem-free downstream processes.
In the field of application, the area of use plays a key role. For example, ERW welded tubes (e.g., according to ASTM A513 or DIN EN 10305-5) with excessive deviations in their straightness and/or twist must be joined with increased effort in building constructions.
LSAW or SSAW welded large-diameter pipes (according to API 5L) are also examined for joining processes, especially regarding bent ends. A pipe that is too much deformed can only be integrated into a pipeline in the field with a great deal of effort.
Drill pipes should also have good straightness so that less friction is generated on the pipe surface during rotation due to centrifugal forces. Excessive resistance forces could also lead to breakage, for example.
Products deviating from the ideal contour that are used at high rotation speeds, e.g. in turbines, would lead to centrifugal forces and thus to vibrations that are harmful to the process.
In summary, it can be said that straighter bar products require less effort in further proceedings.
2. Definition of straightness and twisting in the state of the art
In DIN EN ISO 12780-1, straightness is defined as the "deviation of a point on the straightness profile from the reference straight line". But at which points should straightness be measured on a free-form product such as an ERW squared tube? Or where should the reference line be placed?
DIN EN 10305-5, for example, specifies that the light gap of the concave bent side of a square tube is to be evaluated in relation to a ruler (reference).
However, this approach to straightness assessment is ambiguous. This is based due to the fact that in almost all standardization papers, cross-sectional defects (roundness, radii, perpendicularity) are considered separately from longitudinal defects (straightness or twist).
To understand this ambiguity Figure 2 presents three pipe segments with an identical concave straightness deviation on the same side (e1 = e2 = e3). Tube a) is concave on the opposite side with the same oddity. According to the standard, the product might be be labeled with an error e1 even though it has none. In case b), the concave bent side is measured with the straightness error e2. Since the opposite side is convexly bent with the same deflection, the tube is actually odd. Even more ambiguous would be case c), where the product on the convex bent side might be specified as still OK, but it would no longer be straight on the opposite side due to a cross-sectional deviation (within the cross-sectional tolerance).
In summary, it should be noted that an assessment of the straightness of e.g. ERW pipes due to longitudinal variances in the cross-sectional geometry is ambiguous!
3. Weightless Contouring™ - The concept
In order to solve the ambiguity described above, it may seem obvious to use state-of-the-art profiling measurement systems. The color representations of a contour of the profiled pipe are well known on the market.
These are also the right tool for analyzing the quality of the 2D cross-section profile However, it is important to know that all individual 2D profiles are recorded independently of location. Due to transport movements in the transverse direction, they have no local connection. For better visualization, they are mathematically aligned with each other in the software. The image derived from this correctly describes the individual 2D profiles, but by no means the actual contour of the pipe. This pseudo-contour is often incorrectly referred to as a "digital twin". However, it does not contain the longitudinal contour parts like straightness and twist.
For this reason, MSG has established for the first time that only a combination of 2D profiling systems and MSG’s EP and US patented straightness and twist measurement, which continuously and objectively determines the straightness of profiled bar products in the weightless state, describes a true contour measurement: So-called Weightless Contouring™.
4. Added values through Weightless contouring™
The advantages of objective, unambiguous contouring of bar products can be divided into two main areas.
Firstly, MSG now provides the market with a digitization process that enables maximum objective and uniform quality certification of semi-finished products along the supply chain.
Furthermore, Weightless Contouring™ forms the basis for process optimization. Increasing efficiencies during tube production can only run stable if the underlying measurement data is objective and beyond doubt.
In current projects, MSG displays the straightness and cross-shape results based on Weightless Contouring™ on monitors alongside the production line so that the operator can see the influence of his manipulations directly on the geometry-producing and straightness-correcting machineries.
5. How Weightless contouring™ works in detail
In preparation for the Tube and Wire show 2024 in Düsseldorf, the topic of Weightless Contouring™ will be explained in detail on the MSG LinkedIN profile as part of a campaign. Be part of it and follow us!