© 2001 by CRC Press LLC Bottom Heating Closed-Loop Control and Interfacing — The bottom heater unit is altered to control the heating process. This is done by separating the main power supply from the air fan and heat resistant unit so the heat resistant unit can be switched on/off by the bottom controller’s relay depending on the thermal demand while the air fan is operated constantly during the bottom heating (see Figure 6.30b). FIGURE 6.29 Interfacing between SM and TH rework devices to the corresponding signal lines at the I/O module. FIGURE 6.30 (a) Interfacing and control diagram of closed loop control of IR heating and (b) The bottom heater. © 2001 by CRC Press LLC 7 Model of Conceptual Design Phase and Its Applications in the Design of Mechanical Drive Units 7.1 Introduction Design as a Process of Conceptual Design of Products Leading to Manufacturing Design — Duhovnik’s Perspective • Iterativeness of the Design Process — Supplementing of Information • Levels of Design 7.2 Model of Conceptual Design Expressions Required to Understand the Model • Basic Function Structure • Attribute Vector • Rules for Binding Models of Shape • Flexible Function (Model) Structure • Synthesis of a Design Model 7.3 Implementation of the Model Formal Record of Certain Crucial Rules 7.4 Assessment of Appropriateness of Working Principles and Models of Shape Analytic Hierarchy Process 7.5 Application Inclusion and Exclusion of Criteria 7.6 Assessment of a CAD System for the Conceptual Design of Mechanical Drive Units Assessment of the Conceptual Design Model • Assessment of the AHP Method 7.7 How Should We Continue? 7.8 Conclusions 7.1 Introduction Engineering design is a series of activities necessary for finding a satisfactory solution to a given task. Solutions are embodied in the resulting technical systems. A satisfactory solution is a solution that performs a given task within a certain time limit, with a certain reliability, for certain (production and operating) costs [1–3], and with a certain environmental impact. Roman avbi University of Ljubljana Jo e Duhovnik University of Ljubljana ˇ Z ˇz . Model of Conceptual Design Phase and Its Applications in the Design of Mechanical Drive Units 7.1 Introduction Design as a Process of Conceptual Design of Products Leading to Manufacturing. Leading to Manufacturing Design — Duhovnik’s Perspective • Iterativeness of the Design Process — Supplementing of Information • Levels of Design 7.2 Model of Conceptual Design Expressions. Exclusion of Criteria 7.6 Assessment of a CAD System for the Conceptual Design of Mechanical Drive Units Assessment of the Conceptual Design Model • Assessment of the AHP Method 7.7 How Should