The Design, Simulation and Fabrication of an Omnidirectional Inertial Switch with Rectangular Suspension Spring

An omnidirectional inertial switch with rectangular spring is proposed in this paper, and the prototype has been fabricated by surface micromachining technology. To evaluate the threshold consistency and stability of omnidirectional inertia switch, the stiffness of rectangular suspension springs is analyzed. The simulation result shows that the coupling stiffness of the rectangular spring suspension system in the non-sensitive direction is a little more than that in the sensitive direction, which indicated that the omnidirectional switching system’s stability is reinforced, attributed to the design of rectangular springs. The dynamic response simulation shows that the threshold of the omnidirectional inertial switch using the rectangular suspension spring has high consistency in the horizontal direction. The prototype of an inertial switch is fabricated and tested successfully. The testing results indicate even threshold distribution in the horizontal direction. The threshold acceleration of the designed inertial switch is about 58 g in the X direction and 37 g in the Z direction; the contact time is about 18 μs.

Recent Advancements in Inertial Micro-Switches

Inertial micro-switches have great potential in the applications of acceleration sensing, due to the integrated advantages of a small size, high integration level, and low or even no power consumption. This paper presents an overview of the recent advancements made in research on the sensitive direction, threshold acceleration, contact effect, and threshold accuracy of inertial micro-switches. The reviewed switches were categorized according to the performance parameters, including multi-directional switches, multi-threshold switches, persistent closed switches, flexible-electrode switches, and low-g high-threshold-accuracy switches. The current challenges and prospects are also discussed.

Influence of adhesive non-uniformity on zero offset of micro accelerometer

Adhesive attaching is a common method used in the packaging of high accurate MEMS devices. A full understanding of the effects of adhesive on device performance, therefore, plays a significant role in MEMS design because the thermal stress formed in packaging process highly depends on the shape, size, amount, properties and layout of the die attach adhesive. This paper investigates intensively the influence of adhesive nonuniformity in the sensitive direction of microaccelerometers on the distribution of thermal stress during the variation of environment temperature. The thermal stress will induce a movement of anchors and lead to nonzero voltage output of microaccelerometer. The influence of the adhesive with different levels of nonuniformity [Formula: see text] on zero voltage output is investigated and the results show that the adhesive nonuniformity significantly influences the zero offset of the sensors, and the maximum one can reach 8.6 mV when nonuniformity factor is 0.975.

The tool following function-based identification approach for all geometric errors of rotary axes using ballbar

This paper proposes a tool following function-based identification approach (TFFIA) for geometric errors of two rotary axes for one five-axis machine tool. It is comprehensive to identify all geometric errors of rotary errors. Firstly, synthetic error formulas of ballbar originate from the geometric error model of machine tools in order to consider the influences of 21 errors of three translational axes. It makes the approach more reasonable and precise. Secondly, the structures of three measurement patterns of TFFIA are described. Thirdly, in each pattern, errors of rotary axes affecting the accuracy of the sensitive direction are identified. As the result, the identification equations of all 20 errors coincide with the geometric properties of errors. Moreover, the impacts of setup errors of ballbar are eliminated with least square method to improve the precise of TFFIA. According to the structures of three patterns, only three installation of workpiece ball of ballbar are needed in the whole identification of two rotary axes to obtain the required ballbar readings. It greatly shortens the measurement time. Twenty geometric errors of two rotary axes are calculated with identification equations and ballbar readings. Finally, TFFIA is applied to a SmartCNC500 five-axis vertical machining center. The corresponding comparisons are proposed to verify the effectiveness and accuracy of TFFIA.

Study on Spindle Dynamic Errors of Domestic NC Machine Tools

This paper explains a set of tests necessary for ensuring spindle performance focus on the rotating sensitive direction of spindle. It is found that the original signals of spindle dynamic rotation could be separated and reconstructed to spindle dynamic signal and random signal according to their different frequency components. The asynchronous error and synchronization error of spindle dynamic rotation in radial direction and axial direction could be computed from spindle dynamic signal. The distribution trend of spindle dynamic errors is studied, it is found without considering the shift speed of machine tool spindle and the natural frequency of machine tool, the distribution of spindle dynamic errors presented a trend of rising with the rotation speed increasing.

Simulation Analysis of Dynamic Characteristics on Three-Body Vibrating Screen

However three-body vibrating screen is widely used in engineering practice, many dynamics of it have not well been addressed. For studying three-body vibrating screen dynamics, the vibrating screen dynamic model and the virtual model were established. Through deriving the dynamic equations and simulating the vibrating screen start - running process, the analytical equations and the trajectories were obtained. Studies have shown that the VBVS vibration in the Z direction is complex and the X direction which perpendicular to the axis of exciters is the sensitive direction for the installation error. In addition, the SBD’s trajectories in the direction which does not exist exciting force are superimposed by the trajectories of USB and LSB.