Determination Of Dynamic Characteristics Of Heat Fire Detectors

The proposed methods for determining the dynamic characteristics of heat fire detectors in the time and frequency domains, focused on the use of existing thermal chambers. The proposed method for determining the transition function of the detector is implemented as follows. Heat fire detector creates a thermal effect in the form of a linearly increasing function. The response of the output signal to the influence of this type is measured and approximated using the Heaviside function at regular intervals.It is shown that information on the transition function of a heat fire detector can be used to determine its frequency characteristics by approximating it with Heaviside functions at the same time intervals. This method of determining the frequency characteristics will significantly reduce the time to determine them compared to the classical method, and also eliminate the need for additional equipment.As a result of the studies, the choice of the sampling interval was justified on the example of a class A1 heatfire detector and certain sampling intervals for determining their transition function (τ0≤1.05 s), amplitude-frequency characteristic (τ0≤0.27 s) and phase-frequency characteristic (τ0≤2.0 s).The proposed methods for determining the dynamic characteristics of heat fire detectors open up new opportunities for developing methods for monitoring their technical condition. This is because the information about the transition function of the detector can be used in two ways. The first method involves comparing a certain transition function of the detector with an exemplary one. The second method consists in determining other characteristics of the detector based on information about its transient function and comparing them with standard values

Research of the Milling Process of A Cylindrical Surface by an Oriented Instrument

The object of research is the milling process with the crossed axes of the cylindrical surface and the tool. During the research, general modular three-dimensional models of the tool surface, the processes of removing the allowance and the shaping of the cylindrical surface are used on the basis of three unified modules: tool, shaping and orientation. Computer simulation is also used to build a three-dimensional model of the milling process of a cylindrical surface with an oriented tool. A graphic scheme of milling a cylindrical surface with an oriented tool has been created. The developed cylindrical module for shaping the tool surface, which is described by the product of the displacement matrices along the corresponding axes and the surface of the machined part, is represented by the product of the radius of the tool vector and its orientation module in the shaft coordinate system. The resulting graph of the distribution of the specific productivity of the milling process along the tooth profile of the tool during processing with crossed axes of the cutter and part. An analysis of this graph shows that the milling method with an oriented tool makes it possible to increase the accuracy of the shaping process due to uniform wear of the tool. The intersection angle of the cylindrical surface and the tool is also determined, the value of which is taken from the condition of ensuring the maximum removal of the material layer with uniform loading of the end part of the cutter. For this, a three-dimensional model of the process of milling a cylindrical surface with crossed axes of the tool and the part is developed, in which rough milling is carried out by the end part of the tool, and the finish – by the peripheral. In the course of the research, it is found that when finishing milling, the value of the rotation angle of the cutter is taken from the condition that the peripheral part of the cutter is fully loaded. Improving the processing efficiency is achieved by crossing the axes of the tool and the part, which allows to program the intersection point, and uniform wear of the cutter, which improves the quality of the machined surface. It is also possible to use high-speed milling to provide increased processing productivity