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Use reverse engineering to align the CAD world with the real world

Create and update CAD surfaces with digitized data


Reverse engineering generates a CAD surface model that precisely represents a scanned object. Reverse engineering is used everywhere work is performed manually on real objects and a CAD model is required for the subsequent process. In model manufacturing, design objects and vehicles modeled in clay are scanned and converted to CAD surfaces. In die manufacturing, manual changes to sheet-metal dies in the tryout phase are scanned, and the existing CAD model is updated based on the scanned data. CAD surfaces often need to be created for dies in which there was previously no CAD data. 

The scanned surface is first modeled with meshes consisting of millions of triangles. Although meshes can be used to calculate NC paths, the design possibilities with meshes are limited.

Reverse engineering generates a fully usable CAD surface model for design work.


How does Tebis reverse engineering work?

Tebis designers use reverse engineering to quickly create free-form surfaces based on underlying scanned data. In the same CAD file, they analyze and optimize the quality of the digitized data and then create a wire-frame model; and then the surface model is created based on that. They supplement the surface design created by reverse engineering using curve and surface methods from Tebis free-form technology. Using Tebis surface technology, a trained designer can quickly achieve free-form surfaces, even at Class-A quality. See also CAD surface quality.

No special knowledge is required to create CAD design data from scanned sheet-metal parts.

The video shows how easily the surface structures are drawn on the digitized data for the sheet-metal part, and how quickly a surface model with tangential free-form surfaces is created from that.

These are the steps for using reverse engineering to generate high-quality CAD surfaces:

  • Import STL data
  • Analyze and edit mesh data
  • Draw wire-frame model on mesh data
  • Create individual surfaces in the wire-frame model
  • Analyze surfaces
  • Optimize surfaces
  • Continue design work on the part

Always close to the mesh: Design intuitively using the wire-frame and surface models

Using the semi-automatic and interactive drawing functions, users create a wire-frame model based on the scanned object (mesh model), on which the degree and segmentation of the surfaces and the surface transitions are automatically controlled. The boundary curves of all individual surfaces are contiguous. Using the wire-frame model, you can define the layout of the surfaces and the qualities of the transitions to the adjacent surfaces. Tebis calculates the surface model completely automatically from the wire-frame model and the meshes. Changes made to the wire-frame model are automatically reflected in the surfaces. Using tolerance values, the user determines how tightly the wire-frame model and surfaces "adhere" to the digitized data.

More functions developed specifically
for working with saved meshes are available for generating the wire-frame model.

 


Reverse engineering in die and mold manufacturing

Reverse engineering in Die manufacturing

Reverse engineering in Mold manufacturing

Tebis reverse engineering quickly generates virtual twins of real forming and injection molding dies. Existing CAD data can also be
considered. In the following cases, reverse engineering is an extremely useful tool that yields significant time savings:

  • Feedback of manual changes to the die from tryouts into the existing CAD model and ongoing work with a realistic, updated geometry
  • Scanning drawn sheet-metal parts and providing it as the surface model for subsequent operations (e.g., trimming) and fixtures
  • Generating surfaces based on FEM meshes from simulation systems
  • Production of a second die set, e.g., for additional production locations
  • Repair after die breakage

Reverse engineering based on simulation data

Mesh data from the drawing simulation can also be used as the basis for reverse engineering. The drawing system is first analyzed for curvature. The designer then generates the surface layout and fills the individual areas with four-cornered surfaces and N-cornered surfaces trimmed as desired. Method planners can very quickly obtain surface models in this way.

 


Updating CAD surfaces on manual changes

Die makers manually change dies in the tryout phase. This causes the CAD model to lose its validity. With reverse engineering, manual changes are scanned and conveniently imported into the CAD model file. This yields tremendous time savings for further optimization of the die and for duplicates.

The video demonstrates how the modified area in this reinforcing sheet is incorporated into the CAD model file.

Tebis compares the CAD surfaces with the digitized data to detect where the die maker has made changes. The user updates the CAD surfaces in just a few minutes.


Reverse engineering in design model making

CAD surfaces are the starting point for all design and manufacturing processes after model making. However, they are often not available, because the form is developed by manual design methods like clay models, or because the items are parts for antiques or art objects. With reverse engineering, you combine manual work and design technology and benefit from both worlds.  You can create CAD surfaces for your physical models with very little effort.

High-quality approximation techniques ensure high-end surface quality

Real-time analyses support the designer in curve and surface modelling

Changes of polynomial degree, continuity, segmentation, curvature properties etc. are made in real time

Highly sensitive tools for curvature analysis are available to evaluate surface quality

Tebis manages the mesh data from the scanning system along with the curve and surface data and allows users to compare both worlds using the analysis functions

Functions for reverse engineering are available in the same GUI as those for designing curves and surfaces

High-quality approximation methods ensure high-end surface quality

The user controls the curvature quality of the surfaces with the surface layout


Your benefits from the reverse engineering method:

  • Quickly adapt a virtual CAD model to the real part
  • High surface quality in a short time
  • Generated CAD surfaces can be used immediately
  • Large time savings in die manufacturing tryout and reproductions
  • Large time savings during form development in design model making

Additional links

 


Customer feedback

The new process enables exactly the same dies to be quickly and efficiently fabricated and tried out for multiple locations at the same time. Our die manufacturers worldwide have benefited from this process. It allowed us to very quickly produce the dies for Mexico in a standardized process.

Roland Schöbel, head of machining, Wolfsburg die manufacturing, Volkswagen AG

Tebis enables a very simple and fast realization of reasonable extension designs to the scanned mesh data. It is a unique advantage that in Tebis you can combine meshes and surface elements extremely well and then mill them all at once using the CAM modules.

Christoph Schneeberger, responsible for die making at MS Design


Are you interested in reverse engineering, and would you like us to contact you? Please click here

 

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