CHAPTER 15 Computer- Integrated Manufacturing Systems

Transcription

1 CHAPTER 15 Computer- Integrated Manufacturing Systems

2 Computer- Integrated Manufacturing System FIGURE 15.1 A schematic illustration of a computer-integrated manufacturing system. Source: U. Rembold et al., Computer-Integrated Manufacturing and Engineering, Addison- Wesley, 1993.

3 Modeling for CAD FIGURE 15.2 Various types of modeling for CAD.

4 Types of Splines FIGURE 15.3 Types of splines. (a) A Bezier curve passes through the first and last control point and generates a curve from the other points. Changing a control point modifies the entire curve. (b) A B-spline is constructed piecewise, so that changing a vertex affects the curve only in the vicinity of the changed control point. (c) Third-order piecewise Bezier curve constructed through two adjacent control points, with two other control points defining the curve slope at the end points. A third-order piecewise Bezier curve is continuous, but its slope may be discontinuous.

5 Boundary Representation of Solids FIGURE 15.4 (a) Boundary representation of solids, showing the enclosing surfaces and the generated solid model. (b) A solid model represented as compositions of solid primitives. (c) Three representations of the same part be CAD. Source: P. Ranky.

6 Parametric Design FIGURE 15.5 An example of parametric design. Dimensions of part features can be easily modified to quickly obtain an updated solid model.

7 Octree Representation of a Solid Object FIGURE 15.6 The octree representation of a solid object. Any volume can be broken down into octants, which are then identified as solid, void, or partially filled. Shown is twodimensional, or quadtree, version, for representation of shapes in a plane.

8 Skeleton Data Structure for Solid Objects FIGURE 15.7 (a) Illustration of the skeleton data structure for solid objects. The skeleton is the dashed line in the object s interior. (b) A skeleton model used for kinematic analysis of a clamp. Source: S. D. Lockhart and C. M. Johnson, Engineering Design Communication, Prentice Hall, 2000, p. 299.

9 Simple Routing Sheet FIGURE 15.8 An example of a simple routing sheet. These operation sheets may include additional information on materials, tooling, estimated time for each operation, processing parameters (such as cutting speeds and feeds), and other details. The routing sheet travels with the part from operation to operation. The current trend is to store all relevant data in computers and to affix to the part a bar code that serves as a key into the database of parts information.

10 Robotic Welding Station FIGURE 15.9 Simulation of a robotic welding station. A collision has been detected that production engineers can rectify before building the assembly line, thereby reducing development time and cost. Source: Mechanical Engineering, March 2001.

11 Grouping of Parts FIGURE Grouping parts according to their geometric similarities.

12 Machine Tools in a Traditional Plant FIGURE Functional layout of machine tools in a traditional plant. Arrows indicate the flow of materials and parts in various stages of completion. (b) Group-technology (cellular) layout. Legend: L= lathe; M= milling machine; D= drilling machine; G= Grinding machine; A= assembly. Source: M. P. Groover.

13 Decision-Tree Classification FIGURE Decision-tree classification for a sheet-metal bracket. Source: G. W. Millar.

14 Classification and Coding System FIGURE A classification and coding system using the Opitz system, consisting of five digits and a supplementary code of four digits.

15 Multiclass Code for a Machined Part FIGURE Typical MultiClass code for a machined part. Source: Organization for Industrial research.

16 System for Rotational Components FIGURE The structure of a KK-3 system for rotational components. Source: Japan Society for the Promotion of Machine Industry.

17 Flexible Manufacturing Cell FIGURE Schematic view of a flexible manufacturing cell, showing two machine tools, and automated art inspection system, and a central robot serving these machines. Source: P. K. Wright.

18 Flexible Manufacturing System FIGURE A general view of a flexible manufacturing system, showing several machine tools and an automated guided vehicle. Source: Courtesy of Cincinnati Milacron, Inc.

19 Comparison of Transfer Lines and Flexible Manufacturing Systems Characteristic Transfer line FMS Types of parts made Generally few Infinite Lot size > 100 1Ğ50 Part changing time 1/2 to 8 hr 1 min Tool change Manual Automatic Adaptive control Difficult Available Inventory High Low Production during breakdown None Partial Efficiency 60Ğ70% 85% Justification for capital expenditure Simple Difficult TABLE 15.1 Comparison of the characteristics of transfer lines and flexible manufacturing systems.

20 Topology for a Local Area Network FIGURE Three basic types of topology for a local area network (LAN). (a) the star topology is suitable for situations that are not subject to frequent configuration changes. All messages pass through a central station. Telephone systems in office buildings usually have this type of topology. (b) In the ring topology, all individual user station are connected in a continuous ring. The message is forwarded from one station to the next until it reaches its assigned destination. Although the wiring is relatively simple, the failure of one station shuts down the entire network. (c) In the bus topology, all stations have independent access to the bus. This system is reliable and is easier than the other two to service. Because its arrangement is similar to the layout of the machines in the factory, its installation is relatively easy, and it can be rearranged when the machines are rearranged.

21 Reference Model for Open Communication FIGURE The ISO/OSI reference model for open communication. Source: U. Rembold et al., Computer Integrated Manufacturing and Engineering, Addison-Wesley, 1993.

22 Expert System Structure FIGURE The basic structure of an expert system. The knowledge base consists of knowledge rules (general information about the problem) and inference rules (the way conclusions are reached). The results may be communicated to the user through the natural-language interface. Source: K. W. Goff, Mechanical Engineering, October 1985.

23 Vision Guided Robot FIGURE Expert system as applied to an industrial robot guided by machine vision.

24 Solid Model of an Engine Compartment FIGURE Every vehicle component, from body panels to knobs on the instrument panel, has a solid model associated with it. Source: Ford Motor Company.

25 Instrument-Panel Concept FIGURE A clay sculptor working on an instrument-panel concept. Source: Ford Motor Company.

26 Flange and Fillet FIGURE First flange and fillet.