Reverse Engıneerıng in Glass Mould Engravıng Desıgn

Emre TACIR, Merkad Glassware Moulds Ltd., Turkey Introduction

Contents: 1. Reverse engineering 2. 3D Scanning tecniques 3. Mould design applications 4. Softwares 5. Examples

Reverse engineering

Reverse engineering is the process of taking a finished product and reconstructing design data in a format from which new parts or molds can be produced. [1]

Reverse engineering has become a viable method to create a 3D virtual model of an existing physical part for use in 3D CAD (Computer aided design), CAM (Computer aided manufacturing), CAE (Computer aided engineering) and other software. The reverse engineering process involves measuring an object and then reconstructing it as a 3D model.

Methods of analyses 3D Scanning tecniques

In reverse engineering the physical object can be measured using 3D scanning (digitising) technologies.

Fig. 1 Objects that can be scanned in glass mould industry.

A 3D scanner is a device that analyzes a real-world object or environment to collect data on its shape and possibly color. The collected data can then be used to construct digital, three dimensional models that are used in a wide variety of applications. These devices are used extensively by industry in the industrial design and prototyping.

Three types of scanning techniques are common: 1- Contact 3D Scanning 2- Laser Scanning 3- Photogrammetry

1- Contact 3D Scanning

Contact 3D scanners probe the subject through physical touch and gathers points from surface.

Fig. 2 Contact 3D scanning.

Fig.3 Scanning probe.

CMM (Coordinate measuring machine) probing systems, microscribes etc.used to contact scan.

Fig.4 Microscribe.

Fig.5 CMM scanning system.

Fig.6 Engraving model scanning.

2- Laser Scanning

Laser scanning is to 3D objects what photocopying is to 2D objects. An object that is to be scanned is placed on the bed of the digitizer and scan control software then drives the laser sensor above the surface of the object. 3D coordinate locations which lie on the surface of the object are recorded by the scanning system according to scan density and pattern parameters set by the user.

3D laser scanner is an active scanner that uses laser light to probe the subject. These XYZ coordinate locations are stored in a file that can be converted to IGES or ASCII formats for input into nearly any CAD/CAM system or specialized point-cloud processing software.

The heart of the laser scanning technology is a dual camera probe which emits a diode based laser beam from the center as shown in the picture. The beam is split into a plane of laser light that comes out of the probe and shines below on the surface of the object being scanned. Thus it forms a profile on the surface of the part.

Fig.7 Laser scanning.

The shape of that single "2D" profile is recorded by the digital CCD (Charge Coupled Device is similar to the one used in a home video camera is mounted on either side of the probe) and subsequently, based on the calibration and look up tables of the lasers, a Z position is determined and stored for each pixel value by the software.

Fig.8 Laser scanning principle.

3 - PHOTOGRAMMETRY Photogrammetry converts or maps the flat 2-dimensional images back into the

real 3-dimensional world. However, since information is lost in the photographic process, we cannot reconstruct the 3-dimensional world completely with just one photograph. As a minimum, we require two different photographs to reconstruct the 3-dimensional world.

Fig.9 Miniature Projection Technique

Fig.10 Projected fringes.

The purpose of a 3D scanner is usually to create a point cloud of geometric samples on the surface of the subject.

Point cloud, lacks topological information and is therefore often processed and modeled into a more usable format such as a triangular faced mesh, a set of surfaces or a CAD model.

A point cloud is a set of three-dimensional points describing the outlines or surface features of an object.

Fig.11 Point cloud and triangulation.

Mould Design Applications

Fig.12 Based on glass product.

Fig.13 Based on glass mould.

Fig.14 Based on thoughts or drafts

Softwares

Step 1: Point cloud data gathered with scanning.

Fig.15 Point cloud

Step 2: Point cloud converted to set of surfaces.

Fig.16 Surface.

Step 3:Relief editing.

Fig.17 Engraving.

Step 4:Final model formed.

Fig.18 Final model.

Examples

As you can see Fig.19 design process steps are: 1- The process for engraved moulds begins with a rough draft, which is formed

by an artist. 2- This initial draft is than converted accurately into a 2D technical drawing. 3- Conversion the 2D drawing into a 3D relief using artistic CAD /CAM software.

Fig.19 Design process.

Conclusion

Advantages of reverse engineering and outsourcing of mould design: No need to employ a designer. Easily editable digital data of old designs. Engraving data is applicable to all products. More accurate according to handmade design.

References

http://www.merkad.com http://en.wikipedia.org/wiki/Laser_scanning http://www.immersion.com/digitizer/products/laser.php http://www.renishaw.com http://www.zcorp.com/products/zscanner700.asp?ID=1

http://www.laserdesign.com http://www.amrcc.com/pdtt/reverse.asp#reverse_benefits http://www.steinbichler.de/en/main/comet_iv.htm http://www.3d3solutions.com/index.php

Emre TACIR (mba), Regional Marketing Manager EU, Asia - Pacific & Africa Region, Merkad Glassware Moulds Ltd., Gumussuyu Cad. Karacabey Sok. No:10, 34020 Davutpasa / Istanbul / Turkey, e-mail:etacir@merkad.com, phone: +90 212 483 07 10 - (121), fax: +90 212 483 07 27, www.merkad.com