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

Designing an Improved Structure of the Tool for Repairing the Brake Pipe Connectors in Vehicles

This paper addresses the issue of difficulties in servicing the brake pipe connectors for passenger cars, the service life of which exceeds 8‒10 years, which is associated with the deteriorated loosening of connectors. The existing ways to loosen the connectors of brake pipes have been investigated, especially those whose dismantling is complicated due to the corrosion and contamination of mated surfaces as a result of their wetting when driving a car. A conventional structure of the connector has been analyzed, which is installed in that place of the car that is the most unprotected from moisture and dirt – on the brake cylinder. The conditions that do not contribute to its failure-free loosening have been examined. The design of a specialized split clamping ring wrench has been considered, which can transmit the greatest value of the torque to the connector when loosening it; sometimes, however, its predefined value would not suffice. A computer-based finite-element simulation was employed to derive the models of the deformation state for the node «connector ‒ wrench». Based on the analysis of the models of different deformation state of a specialized split clamping ring wrench, the required profile of the geometrically balanced locked hexagonal profile of the wrench was defined. The analysis of the efficiency of the tightening and loosening level is determined by comparing the numerical values of the torque, which is applied to the connectors of the brake pipes. The torque values are measured by a specially devised technique. The introduction of the developed measurement technique makes it possible to compare the efficiency of wrenches of different designs by analyzing the maximum values of torques, which the wrenches can transmit to the connectors. Taking into consideration the identified shortcomings in the structure of the brake pipe connectors, the shape of the connector has been designed that is free from the specified drawbacks. The new structure provides for the possibility of using a conventional carob wrench for loosening when the mated surfaces are exposed to contamination and corrosio

Study of the Operating Element Motion Law for a Hydraulic-driven Diaphragm Mortar Pump

A mathematical model of the process of operation of a hydraulic diaphragm mortar pump has been developed. It is aimed to describe the processes occurring during automatic reciprocating motion of the hydraulic cylinder piston under the action of high-pressure oil. Oil flows are formed using a hydraulic distributor. Eight phases of the solution pump cycle were identified.The use of a hydraulic drive in this mortar pump allows one to get rid of the main drawback inherent in mortar pumps with a reciprocating drive mechanism. This drawback consists in the sinusoidal law of the piston velocity variation. As a result, there is a significant pulsation of the mortar supply pressure. Uniformity of velocity of the hydraulic cylinder during the working cycle helps reduce the level of pulsations and improve technical, economic and operational characteristics of the mortar pump.Knowledge of the mathematical model of the hydraulic cylinder provides for a better understanding of operational parameters such as:– sucking capacity of the mortar pump;– the nature of response of the valves for opening and closing;– the mechanism of formation of reverse mortar leaks at the closure of valves;– the mechanism of formation of the level of volumetric efficiency of the mortar pump;– the degree of uniformity of pulsations in the mortar supply pressure.The results obtained from the theoretical relationships were confirmed experimentally

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