Improvements in the Mechanical Structure of the Linear Switched Reluctance Motor

In semiconductor manufacturing, wire bonding of chips and surface mount technology process require precise robotic linear motion. Traditionally, X-Y sliding tables driven by permanent magnet rotary motors, ball-screw and belt are used. However, they have position accuracy problem due to ball-screw backlash. Since motors and high precision grade ball-screws are expensive, high manufacturing cost is another disadvantage. Low reliability results from complex mechanical alignment and low ball-screw lifetime. This paper presents the basic structure of linear switched reluctance motor for high performance motions in manufacturing automation. No magnet is used and the traveling distance has no limitation. Consequently, this motor is extensively robust and applicable in hostile environment. A two-dimensional motor is introduced to replace the conventional X-Y table. Based on switched reluctance driving method, the proposed actuator has a very simple and robust structure with very few mechanical parts for easier manufacturing. 3 designs are compared on their mechanical structure and efficiency. Detailed motor framework description and corresponding mathematical model are shown. Applied control theory would be mentioned.