The Analysis of Running Efficiency of Valve Units in Differential Mortar Pump

The object of research is a differential mortar pump with a horizontal pump column, designed for pumping construction mortars of various mobility to the places of their mechanized application to the treated surfaces. To its disadvantages should be attributed insufficiently studied mechanism of formation of return leakage of the mortar, which directly depends on the value of the angle of closure of the valves.As methods of research, methods of physical and mathematical modeling, similarity theory, as well as a personal computer for computation and presentation of their results are used.The issues allowing to estimate the efficiency of the differential mortar pump operation with the horizontal arrangement of the pump column for the efficiency of their valve units are considered. The possibility of estimating the operation of valve assemblies according to the angle of their operation is considered. The calculation procedure is based on the analysis of the design of the valve assemblies and the determination of the time of their opening and closing. Separately, both suction and discharge valves are considered from the point of view of the sequence of their opening – closing and minimizing their operating time. The time of their operation is usually determined based on the speed of the mortar passing through the valve assembly.The operating angle is considered as a universal index that allows comparing pumps of different designs with different technological characteristics and allowing to improve their design, achieving a reduction of this index.In addition, the reasons allowing to influence the reduction of the closing time of the valve without degrading the technological characteristics of the mortar pump itself are considered.The diagrams of the mortar pump are constructed, along which the real angles of operation of the valve assemblies are determined. The results of the comparison testify to the correspondence between theoretical (16.8º) and practical (17.3º) data and the possibility of using numerical values of the valve response angle as an indicator of the efficiency of the mortar pump as a whole

Modernization of the Technique for Rotary Shape-formation of Outer Profiled Surfaces

We have proposed a technique for obtaining outer profiled surfaces, which is characterized by affordability and low cost of equipment used. The technique is based on that a regular rotating center is fixed in a lathe's tool holder in a special way. A basic socket head of the required profile is applied as a profile-forming matrix. A tool holder's rotation angle ensures a fracture angle of the rotating center's axis relative to the axis of a workpiece rotation. A value for the fracture angle reaches 1.5°. The end surface edge of the matrix executes a reciprocating motion per every rotation of the lathe chuck along the surface of a workpiece. In this case, the end surface of the matrix and a workpiece are in contact at a single point, going deeper by the magnitude of feed per every rotation of the chuck.Application of a given technique is an alternative to existing technique of rotational shape-formation of outer profiled surfaces, whose implementation requires specialized equipment and specialized cutting tools, the price for which is quite high (UAH 57,000 and UAH 6,000, respectively). In addition, changing the size or shape of the required profile necessitates installing a new cutting tool, replacing which requires additional adjustment.The tests were carried out when manufacturing the twelve-point outer surface the size of S10. An analysis of vibrograms from the shape-formation process has established the most rational variant of equipment for manufacturing profiled outer surfaces. We have manufactured pilot outer profiled surfaces, such as hexagon the size of S10, the TORX surface the size of E14, and others. They confirmed a possibility for successful manufacturing of different profiled outer surfaces using the proposed tooling.Using the proposed technique, which implies low cost and does not require specialized equipment, could significantly expand the scope of application of conjugated surfaces with a profiled shape in mechanical engineerin