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

Improving the Method of Rotational Broaching in the Production of Profile Openings on the Lathes of Turning Group

We examined methods of manufacturing profile openings on the metal-cutting machines by the rotational broaching method. Based on the generalized results of analysis of the methods for manufacturing profile openings, we proposed a method of rotational broaching. Bits for drilling machines or screwdrivers are used as the tool. Hardness of the bit is quite high; therefore, making a centering opening in it is difficult. The problem is solved by pressing a transition bushing onto the bit, with a centering opening made in advance. Implementation of the method requires a Morse cone with a welded plate. This allows fixing the rotating centre in a tool carrier. The proposed method makes it possible at minimal financial cost to perform the shaping of profile openings within a wide range of both the shape and nominal dimensions. The method is based on the effect of self-centering and, therefore, does not require preliminary adjustment. Adjusting tool entrance angle is achieved by displacing a transverse support of the lathe and by tool carrier rotation. In addition, in the production of profile opening, its input cone is formed, which provides for easy installation of the wrench to transmit rotational moment without losing load capacity. The studies conducted defined suboptimal values of the input variables that are accepted as rational in the examined technological process of rotational broaching. These are: a tool entrance angle (1.5...2.5 degrees), its supply (0.1...0.3 mm/rev) and the rate of processing (15...25 m/min