Hairspring is a fine spiral spring, which is the key component in mechanical watch movement for timekeeping. According to literatures, there are only few studies on hairsprings or spiral springs. Using the Castiliago’s method, the mechanics of hairspring is studied in details. And Computer simulation with Matlab® and experimental validation are also conducted to show the spring frequency. Experiment shows that the theoretical analysis and computer simulation can be used to guide and facilitate the design of hairspring or spiral spring.
In recent years an increasing interest has grown in using Micro Electro Mechanical System (MEMS) fabrication technology in mechanical timepieces. The UV-LIGA process which combines ultraviolet lithography and electroforming is among micro-production technologies providing exciting possibilities. It has been established as industrial viable for the fabrication of various micromechanical components. Current limitations are that the technology is restricted to the use of nickel. It is too soft (~ 300HV) and has magnetic properties. It is not perfect for the movement of timepieces. However, by adding other materials, e.g. phosphor-Nickel (Ni-P), these alloys have their attractions, being stainless, non-magnetic and very high hardness. As a new technique, details are still being perfected. In this work, the process of Ni-P micro electroforming has been developed to extend UV-LIGA technology. And attempt has been made to investigate the magnetic properties and the hardness of the manufactured Ni-P alloy components. The results showed that the phosphor content can be controlled by different concentration of phosphorous acid (H3PO3) in the electrolyte solution. Corresponding properties have been analyzed which shows good hardness and lower magnetic properties. When the phosphorous content reaches over 12 wt%, the Ni-P alloy is with non-magnetic properties while pure nickel is ferromagnetic material. And the hardness of electroformed Ni-P alloy is about 600 HV and can be above 1000 HV after special heat treatment.
It is known that human body contains rich chemical energy, part of which is converted to mechanical energy up to 200W, especially when human in walking, so human body is an ideal sustainable energy resource for portable electronic devices. The motion pattern of human movement in normal walking is studied, showing that the arm swinging, knee motion and hip motion can be approximated as sinusoidal functions with relatively large amplitude. In order to harvest such human motion, several methods are investigated, including pendulum, translational spring and torsion spring, which can also be mathematically formatted as second order differential equation with damped item. This paper also gives a typical device to harvest human motion: a novel energy harvester which directly converts human motion to electricity based on electromagnetic induction. Detail structures of the harvesting device are illustrated with mathematical analysis. Simulation studies are also made.
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