Sheet metal forming analysis
Encyclopedia
The technique of sheet metal forming analysis requires a non-contact optical 3D deformation measuring system. The system analyzes, calculates and documents deformations of sheet metal
parts, for example. It provides the 3D coordinates of the component's surface as well as the distribution of major and minor strain on the surface and the material thickness reduction. In the Forming Limit Diagram
, the measured deformations are compared to the material characteristics. The system supports optimization
processes in sheet metal forming by means of;
The optical forming analysis with Forming analysis system provides for precise and fast measurement of small and large components using a high scanning density. Forming analysis system operates independently of the material. It can analyze components made from flat blanks, tubes or other components manufactured by an internal high pressure forming process (IHPF, Hydro forming).
positions of measuring points in a flat and in a deformed state.
Prior to the deformation, a regular point pattern is applied to the surface of the measuring object. For measuring objects which undergo high friction
during the forming process, the measuring points are applied, for example, with the help of electrolytic methods. After the forming process of the measuring object, a camera
(online or stand-alone operation) records the measuring points in several different images with different views.
Forming analysis system works with two point types.
In the Forming analysis system, the 3D computation
of the measuring points is done using photogrammetric methods. For the automatic spatial orientation of the individual images or views, coded points are position close to or on the measuring object.
The basic idea of Photogrammetry
is to look at points (coded and uncoded) from different directions and to calculate the 3D coordinates of these points from the images or point rays thus obtained. The points visible in an image have a fixed relation to each other. Therefore, by means of images made from other angles of view, it is possible to calculate the camera location using this point relation. During the acquisition of an image set it is the goal to record points from multiple different directions that show the largest possible angles (A, B, C) to each other.
It is the task of the Forming analysis system software to precisely find ellipse
s (a perspective view of point surfaces) in all images of the image set and their 3D orientation. The Forming analysis system software interprets the images and generates 3D measuring data.
In order to compute the strain, the flat state is compared to the deformed state. (#1 & #2)
In a standard measuring project, the flat state, the strain reference, is not captured optically but results from the theoretical point distance defined in the project parameters.
As a default, Forming analysis system presumes an exactly regular initial pattern which is on one plane and for which the point distance is known. This is called the "virtual reference stage" and is marked with Stage 0 in italic
letters in the software. All strain values refer to the adjusted computation parameter Point distance.
The Forming analysis system software is also capable of analyzing several static deformation states (stages) within one project where each deformation stage can be set as strain reference any time. This procedure may be used, for example, for the deformation analysis of tubes.
To allow for a full-field view of the strain, the software changes to the so-called grid mode (#3 & #4). This means that based on the center points of the measuring points a grid surface is created. Each grid line intersection point represents a 3D measuring point. The full-field color representation of the strain results from the 3D positions of these grid line intersection points. (#5 & #6)
Sheet metal
Sheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material...
parts, for example. It provides the 3D coordinates of the component's surface as well as the distribution of major and minor strain on the surface and the material thickness reduction. In the Forming Limit Diagram
Forming limit diagram
A forming limit diagram, also known as a forming limit curve, is used in sheet metal forming for predicting forming behaviour of sheet metal. The diagram attempts to provide a graphical description of material failure tests, such as a punched dome test....
, the measured deformations are compared to the material characteristics. The system supports optimization
Optimization
Optimization or optimality may refer to:* Mathematical optimization, the theory and computation of extrema or stationary points of functionsEconomics and business* Optimality, in economics; see utility and economic efficiency...
processes in sheet metal forming by means of;
- Fast detection of critical deformation areas
- Solving complex forming problems
- Verification of numerical simulationSimulationSimulation is the imitation of some real thing available, state of affairs, or process. The act of simulating something generally entails representing certain key characteristics or behaviours of a selected physical or abstract system....
s - Verification of FE models
- Creation of Forming Limit Curves, FLC
- Comparison of measured deformations to the material characteristics by means of a Forming Limit DiagramForming limit diagramA forming limit diagram, also known as a forming limit curve, is used in sheet metal forming for predicting forming behaviour of sheet metal. The diagram attempts to provide a graphical description of material failure tests, such as a punched dome test....
.
The optical forming analysis with Forming analysis system provides for precise and fast measurement of small and large components using a high scanning density. Forming analysis system operates independently of the material. It can analyze components made from flat blanks, tubes or other components manufactured by an internal high pressure forming process (IHPF, Hydro forming).
Functional principle explained by means of a standard measuring project
The forming analysis system compares the 3DThree-dimensional space
Three-dimensional space is a geometric 3-parameters model of the physical universe in which we live. These three dimensions are commonly called length, width, and depth , although any three directions can be chosen, provided that they do not lie in the same plane.In physics and mathematics, a...
positions of measuring points in a flat and in a deformed state.
Prior to the deformation, a regular point pattern is applied to the surface of the measuring object. For measuring objects which undergo high friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
during the forming process, the measuring points are applied, for example, with the help of electrolytic methods. After the forming process of the measuring object, a camera
Camera
A camera is a device that records and stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images...
(online or stand-alone operation) records the measuring points in several different images with different views.
Forming analysis system works with two point types.
In the Forming analysis system, the 3D computation
Computation
Computation is defined as any type of calculation. Also defined as use of computer technology in Information processing.Computation is a process following a well-defined model understood and expressed in an algorithm, protocol, network topology, etc...
of the measuring points is done using photogrammetric methods. For the automatic spatial orientation of the individual images or views, coded points are position close to or on the measuring object.
The basic idea of Photogrammetry
Photogrammetry
Photogrammetry is the practice of determining the geometric properties of objects from photographic images. Photogrammetry is as old as modern photography and can be dated to the mid-nineteenth century....
is to look at points (coded and uncoded) from different directions and to calculate the 3D coordinates of these points from the images or point rays thus obtained. The points visible in an image have a fixed relation to each other. Therefore, by means of images made from other angles of view, it is possible to calculate the camera location using this point relation. During the acquisition of an image set it is the goal to record points from multiple different directions that show the largest possible angles (A, B, C) to each other.
It is the task of the Forming analysis system software to precisely find ellipse
Ellipse
In geometry, an ellipse is a plane curve that results from the intersection of a cone by a plane in a way that produces a closed curve. Circles are special cases of ellipses, obtained when the cutting plane is orthogonal to the cone's axis...
s (a perspective view of point surfaces) in all images of the image set and their 3D orientation. The Forming analysis system software interprets the images and generates 3D measuring data.
In order to compute the strain, the flat state is compared to the deformed state. (#1 & #2)
In a standard measuring project, the flat state, the strain reference, is not captured optically but results from the theoretical point distance defined in the project parameters.
As a default, Forming analysis system presumes an exactly regular initial pattern which is on one plane and for which the point distance is known. This is called the "virtual reference stage" and is marked with Stage 0 in italic
Italic type
In typography, italic type is a cursive typeface based on a stylized form of calligraphic handwriting. Owing to the influence from calligraphy, such typefaces often slant slightly to the right. Different glyph shapes from roman type are also usually used—another influence from calligraphy...
letters in the software. All strain values refer to the adjusted computation parameter Point distance.
The Forming analysis system software is also capable of analyzing several static deformation states (stages) within one project where each deformation stage can be set as strain reference any time. This procedure may be used, for example, for the deformation analysis of tubes.
To allow for a full-field view of the strain, the software changes to the so-called grid mode (#3 & #4). This means that based on the center points of the measuring points a grid surface is created. Each grid line intersection point represents a 3D measuring point. The full-field color representation of the strain results from the 3D positions of these grid line intersection points. (#5 & #6)