APPLICABILITY EVALUATION AND SHAPE OPTIMIZATION OF THE ELASTIC VALVE STATIONARILY INSTALLED IN PNEUMATIC IMPACT MACHINES

The possibility of using construction design with a stationarily installed conical ring-shaped elastic valve in pneumatic impact machines is considered. Using a simulation model of the contact interaction of the striker with the valve, the shape of the valve was optimized and its applicability was proved for sealing the return strike chamber.

DESIGNING ANNULAR ELASTIC VALVE THAT CONTROLS AIR EXHAUST FROM WORKING CHAMBER OF PNEUMATIC IMPACT MACHINE

The paper considers one of the promising shut-off and control elements of the air distribution system of pneumatic impact machines - an annular elastic valve (CUV). This element allows you to reduce the energy consumption of pneumatic devices. Unfavorable combinations of factors that hinder the movement of the valve necessary for sealing the working chamber are considered. The paper presents a method for calculating the elastic valve that controls the release of energy from the return chamber of the pneumatic impact machine, which allows determining the main geometric dimensions of the valve device at the design stage, which provides a stable self-oscillating cycle of the pneumatic impact machine with the specified energy characteristics. The developed technique was used in the modernization of the air distribution system of the ring impact machine (KUM), designed for immersion of rod elements in the ground. Tests of the resulting sample in production conditions confirmed the increase in energy performance compared to previously produced machines of a similar type.

JUSTIFICATION OF PRINCIPAL DIAGRAM AND STUDY OF THE OPERATING CYCLE OF VOLUMETRIC HYDROPERCUSSIVE MECHANISM

The approaches to justification of design diagrams of volumetric hydropercussive machines are presented. Simulation models of hydraulic impact systems are constructed and investigated. It is found that the diagram with an intermediate chamber allows decreasing peak pressure in the idle stroke chamber by two times, compared with the diagram without an intermediate chamber. It is concluded that hydropercussive machine with an elastic valve and intermediate chamber would hardly decrease the velocity of striking part in the end of power stroke.

CALCULATUION OF DYNAMIC PARAMETERS OF REVERSE CHAMBER OF PNEUMATIC HAMMER WITH MECHANICAL LOCKING OF ELASTIC VALVE

In paper short description of construction and functioning of pneumatic hammer with air distribution system based on application of elastic valve in exhaust line of reverse chamber is carried out. Using specified parameters of pneumatic hammer (percussion energy, percussion speed, ration of chamber squares, form of working chamber, compressed air pressure and etc.) mass of striking pin, working path, diameters of working chamber and cylindrical part of reverse chamber, dimensions of circle elastic valve are calculated. Proposed method of calculation considers change of cross-section of reverse chamber when striking pin moves back. Obtained calculated values have allowed to develop diagram chart of change of air pressure in reverse chamber in dependence on time.

JUSTIFING OF PARAMETERS OF PNEUMOPERCUSSION MACHINE FOR FORMATION MAIN CRACKS FROM HOLE OF NATURAL STONE

In the work, issues of development of percussive machine for directed destruction of stone rocks are considered. The percussive machine impacts to rock destructive tool implemented into the hole, after that rock wedging and growth of main crack along blast-hole line occur. For that purpose, pneumatic machine of percussion action and gravitational type is chosen. Scheme of the machine is justified based on dynamic simulation of its key assembly units, numerical analysis of constructive and energetic parameters is carried out. Working cycle of the device has been estimated by energy value, percussion frequency, compressed air discharge. It is established that working cycle of gravitational pneumo-percussion machine with elastic valve provides economy of compressed air discharge and high energy of the strike. Results of numerical simulation are proved by experimental data of Institute of Mining.