Search

An automated method for comparing processes obtained by mathematical modeling and experimentally is proposed. The method is based on the use of the concept of characteristic time points, as well as ways to determine them. An example of the use of the methodology is given. The results can be used in the engineering analysis stage of the designed system in the process of their pilot testing, when solving problems of parametric identification of mathematical models.

An electrohydraulic servo actuator is used as an example to show how numerical data on the parameters of the components and assembly units supplied to the assembly section allow control of the assembly process, its qualitative transformation, and refinement of the characteristics of finished products. The described approach to the arrangement of the assembly process may be applied to any product both to ensure that nondefective items are assembled in manufacturing components with apparently extended parameter tolerance ranges and to enhance the characteristics and reduce labor input in the adjustment of products.

The paper considers a problem of quality rating of collection of assembly sets for assembly of production batch. This problem emerges in the course of directional selection of parts in the assembly sets. Advantages and disadvantages of the most widespread systems of quality rating for finished goods with the use of these systems to estimate the quality of collection of the assembly sets was considered. In the course of selection of parts in the assembly sets it was proposed the following: calculate the relative values of serviceability reserve of products from the predicted values of future product performances and take the smallest value from derived values as quality rating of collection of assembly sets. Proposed quality rating system of assembly sets makes possible constructing a fairly easy algorithm for selection of parts in sets for assembling production batch from limited quantity of previously stored parts with known parameters.

An analysis of the process of filling cavities in articles with a control gas in leakage testing is presented. Based on the results of the analysis an algorithm that describes the process of filling cavities with a gas that produces a reduction in filling time is proposed. The proposed algorithm provides a foundation for automation of leakage testing of articles by gas methods.

The turbulent-flow throttles are used in pneumatic systems and gas-supply ones to restrict or measure gas mass flow. It is customary to install the throttles in joints of pipelines (in teejoints and cross tees) or in joints of pipelines with pneumatic automation devices Presently, in designing the pneumatic systems and gas-supply ones a gas mass flow through a throttle is calculated by a known equation derived from the Saint-Venant-Vantсel formula for the adiabatic flow of ideal gas through a nozzle from an unrestrictedly high capacity tank. Neglect of gas velocity at the throttle inlet is one of the assumptions taken in the development of the above equation. As may be seen in practice, in actual systems the diameters of the throttle and the pipe wherein it is mounted can be commensurable. Neglect of the inlet velocity therewith can result in an error when determining the required throttle diameter in design calculation and a flow rate in checking calculation, as well as when measuring a flow rate in the course of the test. The theoretical study has revealed that the flow velocity at the throttle inlet is responsible for two parameter values: the outlet flow velocity and the critical pressure ratio, which in turn determine the gas mass flow value. To calculate the gas mass flow, the dependencies are given in the paper, which allow taking into account the flow rate at the throttle inlet. The analysis of obtained dependencies has revealed that the degree of influence of inlet flow rate upon the mass flow is defined by two parameters: pressure ratio at the throttle and open area ratio of the throttle and the pipe wherein it is mounted. An analytical investigation has been pursued to evaluate the extent to which the gas mass flow through the throttle is affected by the inlet flow rate. The findings of the investigation and the indications for using the present dependencies are given in this paper. By and large the investigation allowed the conclusion that the inlet flow rate must be taken into account when calculating the gas mass flow through the throttles of pneumatic systems and gas supply systems.

Estimation and prediction of the parametric reliability of electro-pneumatic valves for complex gas industry automation systems on the basis of degradation failure are considered. The proposed technique is based on computational determination of the technical characteristics of electro-pneumatic valves and may be used to estimate and predict the parametric reliability of these devices in the case where it is not possible to establish the real values of the technical characteristics. Stages in the development of the technique are considered and problems involved in the estimation and prediction of the reliability of electro-pneumatic valves at different stages of their life cycle are presented.