Smoothness of C-Bezier Curves

This paper presents G1 and G2 continuity conditions of c-Bezier curves. It shows that the collinear condition for G1 continuity of Bezier curves is generally no longer necessary for c-Bezier curves. Such a relaxation of constraints on control points is beneficial from the structure of c-Bezier curves. By using vector weights, each control point has two extra free design parameters, which offer the probability of obtaining G1 and G2 continuity by only adjusting the weights if the control points are properly distributed. The enlargement of control point distribution region greatly simplifies the design procedure to and enhances the shape control on constructing composite curves.

G1 Continuity of C-Bezier Rectangular Surfaces

This paper probes G1 continuity between two adjacent c-Bezier rectangular patches. The necessary and sufficient conditions are derived. It shows that the coplanar condition for G1 continuity of two adjacent Bezier patches is not necessary for c-Bezier patches. Such a relaxation of constraints on control points is beneficial from vector weights of c-Bezier surfaces, which leads to two extra free design parameters for each control point. C-Bezier surfaces offer the possibility of obtaining G1 continuity by just adjusting the weights, which greatly simplifies the design to construct composite surfaces.

Using Computer Simulation to Validate and Optimize the Design of an Innovative Electronic Packaging Concept

Reducing integrated circuit (IC) plastic packaging production costs by improving the transfer mold and leadframe designs is a costly and time-consuming process. Rather than building mold and leadframe prototypes to perform empirical studies, this research describes how C-MOLD, a microchip encapsulation simulation software application, was used to validate and optimize an innovative mold and leadframe design that has the potential to reduce raw material waste associated with packaging by more than 59%. Estimates indicate that the proposed design will cut annual production costs by more than $600,000.

CMM Measurement Planning in FAPPS

FAPPS (Feature-based Automatic Process Planning System) is developed as a comprehensive metal cutting process planning system operated in PC environments. It can recognize the machining features automatically from a given 3D part design model, and then generates operation sheets, divided process drawings, NC codes, and inspection sheet. It consists of the following modules: tolerance input module for menu-driven input of tolerances, feature recognition module for automatic recognition of pre-defined machining features and compound features, process planning module for rule based determination of machining processes, divided process drawing module for automatic generation of divided process drawings, operation planning module for rule based generation of specific operation plans, and measurement planning module for automatic generation of CMM measurement plans. The CMM measurement planning in FAPPS uses both geometric information and tolerance information from CAD files in order to determine measurement surfaces, number and positions of measurement points, and measurement sequences for inspecting machined parts. The measurement plan is represented in DMIS format for automated measurements using CMM’s. The measurement planning module that is realized in FAPPS is explained in this paper with the developed algorithms. Fuzzy logic calculation is used to determine the number of measurement points and geometric consideration for selecting measurement positions is performed.

“Thin” vs. “Fat” Client of Web-Based CAD Tools

Internet technology in particular opens up another domain for building future CAD/CAM environment. This environment will be a global, network-centric environment with various members providing different software tools, manufacturing facilities, and analysis services for distributed design and fabrication. Web-based CAD tools play a prominent role in the environment. Two kinds of clients can be used to develop a web-based CAD tool now, one is “thin” client, and another is “fat” client. This paper compares the advantage of “thin” and “fat” client, and explains the advantage of using low-cost, configurable, CAD components.

Synthesis of Cutting Tool Placement, Orientation and Motion Based on Surface Analysis

Engineers and designers use a wide variety of curve and surface formulations to describe products. The process of producing the physical shape of these products has remained essentially unchanged for many years. Traditionally, the process of finish surface machining has been error prone and inefficient due in large part to the mathematical basis used to control the positioning, orientation and movement of cutting tools in five-axis machining centers. This paper presents swept silhouette curvature matching algorithms for positioning and orienting a cutter such that tool and surface curvatures match. Formulations are given for both flat and filleted end mill cutters. The benefits of curvature matching are: reduction of local machining errors, reduction or elimination of grinding of the finished machined surface, and the improvement of machine tool efficiency. Examples are given that compare curvature matching to traditional machining methods. The paper concludes by discussing current research into a priori gouge detection methods based on intersection contact between the cutting tool and the design surface or the lower tolerance-bound offset surface to the design surface. An a priori gouge detection algorithm is necessary for the development of optimal tool motion and the reduction of time spent in tool path editing and verification. Techniques involving collinear normals, Bézier clipping, triangulation, normal intersection and swept volumes are suggested as techniques for examining the positional and translational tool gouge problem.

Multi-Direction Slicing for Layered Manufacturing

Parts made by Layered Manufacturing (LM) have a limited surface accuracy and their build time is often long due to the deposition of sacrificial support structure. However, LM machines with an ability to deposit along multiple directions can improve upon the surface quality and reduce the support volume. In this paper we consider multi-directional slicing, present algorithms and implemented examples.

A Requirement-Centered Design Support System for the Environmentally Conscious Product

We have developed the Green Browser to support a team of designers to collaboratively construct and share the product life cycle information for environmentally conscious design. We developed the ReqC model (Requirement-Centered Model) and the GLC model (Green Life-Cycle Model) for structuring design information in the Green Browser. The system allows the design team to construct the GLC model by chunking discourse and assigning types. It provides a visual presentation of the concept and scenario, and allows the user outside the team to share the model across different computer environments. We used Java2 and CORBA for system implementation. To test implementation of the system, we built a GLC model by using data collected in an industrial design project.

Fast Product Development Capabilities With Efficient Management and Use of Product Requirements

Short time to market is a key for success. Information management in product development is one factor for it’s influence. In this paper, the need for a methodology and an IT support for the collection and management of product requirements from identification of customer demands up to the preparation of the final design documents is highlighted. For this, triggers for time consuming iterations are identified and the basic reasons for iterations determined. The lacks of existing approaches in the U.S. and Germany for collecting and handling requirements are discussed, and an integrated concept for requirements management and an appropriate IT support for it are presented.

Construction and Functions of Self-Study System for Power Plant Operation

In this paper, the Construction and functions of the self-study system for power plant operation is introduced. As a self-study system, it consists of two parts, a simulator and knowledge base. The knowledge base has been built by the combination of expert system and artificial neural network, which supports the system with practical experience and theoretic knowledge. The trainees’ knowledge can be improved by using the system. The realization of the intelligent training function, applications of expert system and artificial neural network are mainly introduced in this paper.