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Most high-pressure waterjet cutting systems use normally closed pneumatic valves (NCV). These valves are designed and used only as nozzle valves to control and operate flow. While the characteristics and performance of a simple NCV are well known, the influence of these parameters on the time response is not so clear. This paper presents an experimental approach for the solution of this problem. An experimental investigation was conducted to investigate the influence of NCV parameters on the time response in abrasive waterjet cutting. High water pressure, air pressure and orifice diameter were the principal variables that were investigated. Using the multifactors method of experiment, four polynomial equations for geometrical and mechanical parameters of the normally closed valve were created. Closure speed function of actual pressure and orifice size were used. Comparison of two different polynomial models such as linear and mixed for NCV were made. The experimental data was compared with the results of a polynomial model and good correlation was found. The result of these equations also suggests a potential for optimizing the design of the NCV and orifice tube composition. |
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For the creation of the continuous flow of liquid, it is necessary to create ultra high pressure in the line or the orifice in a range of 300-400 MPa. To develop this ultra high pressure in most applications, the Double Action Hydraulic Intensifier (DAHI) was used. For calculation parameters of DAHI, it is necessary to know the dependency of viscosity on pressure, the influence of the liquid compressibility, the amount of the useless space in the high pressure cylinders, the deformation of the wall of the hydraulic and high pressure cylinders, etc. This paper represents a theoretical investigation of the mathematical model for determination of several different parameters of the DAHI, including some parameters of the water stream and the cutting or drilling material. The semi-empirical equation for definition of the total cycle time based on the superseding and switch time was obtained. It was shown that the acceleration phase has a negligible duration, compared to the superseding phase and switch time for the main hydraulic valve is more substantial for total cycle time formatting. Finally, new equations for defining the parameters of the DAHI were reached. The advantage of the new method is shown. By using these equations, solutions with high accuracy are obtained. The results of a theoretical investigation were compared to the experimental data and good correlation was found. |
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The way of reducing the influence of vibration of the manual finishing orbital sander (MFOS) on the operator's hands was shown. The design for balanced rotated mass on a rod for reducing influence of vibration on the operator's hands was described. Results of testing of this type of MFOS with and without the balanced rotated mass were compared. Industrial testing of the MFOS was analyzed and good dampening effect was found. |
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A simple, manually operated, compact, the multi functional metal spraying unit (MFMS) is described. It is designed for manual or automatically spraying of all fusible materials in the form of wires and flexible cords for various diameters and quality. The principle of the process of gas - fire metallization is in spraying of metal wire or cord or powder material in acetylene-oxygen flame combined with compressed air. Able to be used manually or by machine. By using MFMS the high accuracy, speed and productivity of spraying, quality of the surface was obtained. |
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An experimental research was conducted to investigate the influence of the clearances in great pair of wear on the jack-hammers with dependent rotation steel (JHDRS) power characteristic. Strong dependence between wear/tolerances in the great pair and power characteristic of the JHDRS was shown. Using the multifactorial method of experiment, seven polynomial equations for geometrical parameters of the wear-couples performance were created. The experimental data was compared with the results of calculation by a polynomial model and good correlation was found. |
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The influence of the angle of turn on efficient boring for rock - drill with rifle bar rotation (with helical splines on rifle bar and a high helical-angle internal thread meshes with a central rifle nut) was considered. A theoretical investigation was conducted to investigate the several different parameters of the jack-hammers with dependent rotation steel (JHDRS), including turning angle between two impacts, and the rocks properties on the speed of impact-turning drilling. The equation for definition the bit or insert steel optimal angle of turn corresponding the moment when specific destroys energy attains the minimum and a boring velocity attains the maximum was obtained. The analysis is based on the dimensionless unit method. By using this method combined with resultant force boundary conditions, solutions with high accuracy are obtained and the optimal turning-angle, which brings to the JHDRS maximum speed of drilling, was determined. The results of calculation were compared with experimental data and good correlation was found. |
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The way of reducing the influence of vibration from the light pneumatic chipping hammer (LPCH) on the operator's hands was shown and the design of the phase-interference pneumatic dampening cylinder was described. Results of the testing of this type of LPCH with and without the phase-interference pneumatic dampening cylinder were compared. Industrial testing of the recoilless LPCH was analyzed and good dampening effect was found. |
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An experimental investigation was conducted to investigate the influence of the clearances in great pair of wear on the jack-hammers with dependent rotation steel (JHDRS) power characteristic. Strong dependence between wear/tolerances in the great pair and power characteristic of the JHDRS was shown. Speed of wear in the great wear couples was determined. Using the multifactorial method of experiment, seven polynomial equations for geometrical parameters of the wear-couples performance were created. The experimental data was compared with the results of calculation by a polynomial model and good correlation was found. The optimal dimensions of clearance which brings maximum power or minimum air consumption per unit to the JHDRS was found. This paper represents an experimental approach to the design optimization. |
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A simple steel-to-steel packing for sealing details of air-compressed pressure is described. Being self-sealing, quick-disconnecting the packing is fairly reliable and can be used repeatedly. |
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The air-distribution is a main part of any characteristic of jack-hammers with free rotation steel (JHFRS). For each type of the air-distribution exists an optimal design which brings maximum power or minimum air consumption per power unit to the JHFRS. This paper represents an experimental approach to the solution of this problem. An experimental investigation was conducted to investigate the influence of air-distribution (as the valve butterfly's type) parameters on the JHFRS power characteristic. Using the multifactorial method of experiment, seven polynomial equations for geometrical and mechanical parameters of the air-distribution as the valve butterfly's type were created. Comparison of three different polynomial models such as linear, mixed and quadratic for JHFRS were made. Strong dependence between air distribution parameters and power characteristics of the JHFRS was shown. The experimental data was compared with the results of calculation by a polynomial model and good correlation was found. The potential for optimizing the design of the air-distribution as the valve butterfly's type are shown. |
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A simple, manually operated, compact, horizontal bore-drilling test bench is described. By automatically locking the bore-drilling machine and developing supportive force, test bench prevents wrong test-data even in the event of pressure loss. Horizontal force's cylinders can even be operated pneumatically. Because of the air's compressibility, it is seldom considered for high unbalanced force applications. |
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An experimental investigation was conducted to investigate the influence of the oscillations of compressed air pressure on the power characteristic of the pneumatic percussion machines (PPM) and on the pressure drop for air flow through a different type of pneumoresistor. The equation for the estimation of the loss of energy for oscillating compressed air pressure was received. The different result for the pressure drop for continuous and oscillated gas flow through the pneumoresistor were described. The experimental data was compared with the results of a semi-empirical equation and good correlation was found. |
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Existing equations based on thermodynamic for the body of variable mass, which describes the behavior of the PPM, are very complicated and inconvenient in use. Besides that, they are unable to optimize (design) parameters of the PPM. An existing method of the multifactorial experiment makes it possible to obtain polynomial equations which are extremely convenient for optimization. This paper represents the same approach for the solution of this problem. The diff. equation for the thermodynamic of the body of variable mass and for the movement of mass for computer-based math-model was used. Multifactorial experiment on the computer-based math- model of the PPM was realized. Eleven geometrical- mechanical parameters of the PPM were participant in the calculation. Using the multifactorial method of experiment, six polynomial equations for power characteristics of the PPM were received. The optimal rate (maximum power or minimum air consumption per power unit) of these parameters of PPM was defined. The data from a polynomial model was compared with the results of computer-based math- model calculation and good correlation was found. |
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A multifactorial experiment on the computer-based math- model of the PPM was realized. The diff. equation for thermodynamic of the body of variable mass for computer-based math-model was used. Eleven geometrical/mechanical parameters of the PPM and seven geometrical/mechanical parameters of the Air-Distribution were included in the calculation. Using the multifactorial method of experiment, seven polynomial equations for power characteristics of the PPM were created. The optimal rates (maximum power or minimum air consumption per power unit) of these parameters of PPM, including Air-Distribution, were found. The data from a polynomial model was compared with the results of computer-based math- model calculation and with the results of physical experiments and good correlation was found. Well-optimized PPM was created and put into the Russian mining and military Industry. |
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The differential pressure strain sensor for industrial air pressure was designed, build, tested in the laboratory conditions and put into practice. Strong linear dependence between differential air pressure and electrical signal from sensor are shown. Sensor well use for 2 chamber PPM and in this case advantages for new method of analysis is shown. By using this method, measurement of kinetic energy with high accuracy are obtained. One differential pressure strain sensor replaced two absolute sensors, which important for two chamber (channel) mechanism analysis. |
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The designs and types of different air distribution systems and valves for portable pneumatic percussion machines were described. Equations for the estimation of stability of the different types of valves were received. The pressure drop in a different air-distribution systems are estimated. Switch time for the different types of valves was calculated. The experimental data was compared with the results of this equation and good correlation was found. Advantage of the butterfly valve is shown. |
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The way of reducing the influence of vibration of the pneumatic percussion machines on the operator's hands was shown and the design of the phase-interference pneumatic dampening cylinder was described. Because of air's compressibility, it is possible for the operator's hands to be fully isolated from the vibration source. Results of testing this type of PPM with and without the phase-interference pneumatic dampening cylinder were compared. Lab testing of the recoilless PPM was analyzed and good dampening effect was found. Finally this design was well used for higher efficiency and improved vibration characteristics on hands of the worker. |
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Several different equations for the pressure drop in gas flow through the pneumoresistor were described. Comparison of the several different methods for calculation of pneumoresistor's pressure drop was made. A new equation for the gas flow was received. Advantage of the new method is shown. By using this method, solutions with high accuracy are obtained. |
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The designs and types of different air distribution systems and valves was described. Two equations for the estimation of stability of the butterfly's valve were received. Special profile cavities and channels of the pressure drop in these equations were included. The experimental data was compared with the results of the calculations of these equations and good correlation was found. |
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The way for reducing influence of vibration in the operator's workplace was shown. The equation for estimation of this influence was received. Isolation and dampening methods were compared. |
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A new method to work out the air pressure diagram is reported. The analysis of these indicator diagrams is based on a seven points approximation. Comparison of the several different methods for approximation of the indicator's diagram was made. Advantages of new method is shown. By using this method combined with a seven points approximation, high accuracy solutions are obtained. |
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The distribution of compressed air energy inside pneumatic percussion machines was shown. The equation for the estimation of the loss of energy was received. The rational rate of compressed air consumption for pneumatic percussion machines was found. |
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The way of reducing influence of vibration of pneumatic percussion machines on the operator's body was shown. The equation for the estimation of this influence was received. Isolation and dampening methods were compared. |
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