3-D profiling shapes machine tool
Kitchen cutlery is generally produced by stamping a hard steel tool against a piece of raw material. Although such stamping tools can be machined directly from computer-aided-design (CAD) models, CAD is often not used because many cutlery items are crafted by hand. Making such tools involves first crafting a design by hand and then digitizing the item so that a CAD program can build a model and mass-produce the tool.
To digitize such designs, researchers at 3D Scanners (London, England) are using optical laser triangulation, a noncontact technique that is used in gauging, profiling, and three-dimensional (3-D) surface mapping. When measuring surfaces, laser triangulation produces surface maps and measures deformable objects made from materials such as rubber, plastic, and soft clay.
Depth measurement by triangulation uses a sheet of laser light projected onto a scene with the resulting 3-D stripe observed through one or more charge-coupled-device cameras. The cameras are arranged so that the image of the stripe intersects each image row (or column) uniquely, and depth information can be automatically calculated.
Because surfaces of objects such as fork handles are highly reflective, they must be sprayed with a water-based paint that can be removed after scanning. Typically, such objects are relatively small and detailed. Consequently, the company uses its Replica 500/3 system to scan an area of 30 ¥ 150 mm at 20 points/mm.
The dataset produced by Replica and displayed using the company`s Riscan viewing tools (Range Image, 2D, and 3D) is used to inspect the data immediately after scanning. Some of Riscan`s filters and manipulation tools improve the quality of the data. After data are digitized, they are imported into the Duct CAD/CAM system from Delcam plc (Birmingham, England). A system module called DigiCAM manipulates the scan data and creates a 2-D outline of the cutlery.
After the 2-D outline is smoothed and saved, the original scan data set is retrieved, and the 2-D outline of the fork is projected onto the triangulated surface to create a 3-D outline around the area of interest. The Duct system is used to generate machining paths to build the tool.
