tailieunhanh - McGraw-Hill - Robot Mechanisms and Mechanical Devices Illustrated Part 2

Tham khảo tài liệu 'mcgraw-hill - robot mechanisms and mechanical devices illustrated part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Introduction xxv water-soluble supports are formed by a separate extrusion head and they can be washed away after the model is complete. Three-Dimensional Printing 3DP The Three-Dimensional Printing 3DP or inkjet printing process diagrammed in Figure 6 is similar to Selective Laser Sintering SLS except that a multichannel inkjet head and liquid adhesive supply replaces the laser. The powder supply cylinder is filled with starch and cellulose powder which is delivered to the work platform by elevating a delivery piston. A roller rolls a single layer of powder from the powder cylinder to the upper surface of a piston within a build cylinder. A multichannel inkjet head sprays a water-based liquid adhesive onto the surface of the powder to bond it in the shape of a horizontal layer of the model. In successive steps the build piston is lowered a distance equal to the thickness of one layer while the powder delivery piston pushes up fresh powder which the roller spreads over the previous layer on the build pis- Figure 6 Three-Dimensional Printing 3DP Plastic powder from a reservoir is spread across a work surface by roller onto a piston of the build cylinder recessed below a table to a depth equal to one layer thickness in the 3DP process. Liquid adhesive is then sprayed on the powder to form the contours of the layer. The piston is lowered again another layer of powder is applied and more adhesive is sprayed bonding that layer to the previous one. This procedure is repeated until the 3D model is complete. It is then removed and finished. xxvi Introduction ton. This process is repeated until the 3D model is complete. Any loose excess powder is brushed away and wax is coated on the inner and outer surfaces of the model to improve its strength. The 3DP process was developed at the Three-Dimensional Printing Laboratory at the Massachusetts Institute of Technology and it has been licensed to several companies. One of those firms the Z Corporation of Somerville Massachusetts