CLASSIFICATION OF METHODS FOR CALCULATING THE PARAMETERS OF PNEUMATIC HAMMERS

V. I. BABUROV

(Presented by the Department of Mining Machines, Mine Transport, and Mining Mechanics)

Over the long period of operation of pneumatic hammers, extensive experience has been accumulated in design developments and in experimental and theoretical investigations. The Soviet Union occupies a leading position in the world in developing questions of the theory of pneumatic impact-action machines. At present, our literature contains a number of theoretical solutions for determining the principal performance indicators of these machines.

On the basis of an analysis of the literature on methods for determining the parameters and calculating hammers, let us compile a brief classification of these methods.

First group. Analytical methods

1. Calculation of the basic parameters on the basis of the laws of uniformly variable motion. Proposed in the works of A. N. Kryukov (1931), Yu. M. Malakhov (1934), N. M. Shulgin and N. V. Minchenko (1936), and others.

2. The method of successive calculation of the periods and sections of the working cycle, based on the equations of uniformly accelerated or uniformly retarded motion and thermodynamics. Set forth in the works of A. P. German (1933), V. I. Kiselev (1939), and G. I. Sidorenkov [19].

3. A method based on the formulation of differential equations for the state of the gas, its outflow, the motion of the striker, and the energy balance for several periods of the working cycle. Proposed, as applied to various machines, by I. S. Kassatsier [10] and V. M. Mostkovy [14].

4. A method for determining the basic parameters of machines, based on the theory of similarity and dimensions. Considered in the works of B. V. Sudnishnikov [21], N. N. Esin [8], P. M. Alabuzhev [1], and Yu. N. Popov [15].

5. Calculation of the basic parameters of hammers by expressions that include structural dimensions and coefficients determined experimentally. Given in works [2, 23].

Second group. Grapho-analytical methods

1. Methods based on various ways of processing diagrams of the working process:

a) calculation of machine parameters from the diagram of the striker path recorded in time;

b) calculation of machine parameters from the diagram of compressed-air pressure in the rear cavity, using the characteristic features of this diagram. Developed by B. V. Sudnishnikov [23];

c) calculation of machine parameters from combined diagrams of the striker path and air pressures, and also from indicator diagrams in pressure–path coordinates. This is set forth in works [2, 23];

d) calculation of machine parameters from diagrams of the air pressure above and below the striker, on the basis of the theorem on the motion of a mass under the action of a force specified as a function of time. This calculation can be carried out in three ways.

First method. The calculation is performed by dividing the pressure diagrams of the working cycle into two parts, corresponding to the time of the working and idle strokes of the striker. Proposed by B. V. Sudnishnikov [23].

Second method. The calculation is performed without dividing the working cycle into two parts, but taking into account the impulses acting on the striker during the first and second phases of collision with the working tool, that is, taking into account the impact impulse and the rebound impulse, by which the diagram of the resultant pressure of the compressed air on the piston is supplemented.

Developed by B. V. Sudnishnikov and V. I. Baburov [22].

Third method. The calculation is performed without dividing the working cycle into two parts, using formulas derived without taking into account the impact impulse and the rebound impulse. The third method is a further development of the second and is considered in detail in work [3].

1. Calculation of machine parameters on the basis of the method of impulse pairs. Developed by B. V. Sudnishnikov and K. K. Tupitsyn [24].

Third group. Graphical methods

Graphical methods include mainly the determination of hammer characteristics from nomograms constructed according to known analytical dependences and experimental data. Nomograms for calculating the parameters of pneumatic hammers were proposed in the works of O. D. Alimov [2], V. F. Gorbunov and V. I. Baburov [4], Yu. N. Popov [16], and others. A graphical method for processing indicator diagrams is given by G. A. Terekhov in his work [25].

In a number of cases, nomograms can be used to determine the structural dimensions of machines as a function of their parameters.

Fourth group—Experimental methods

1. Methods of direct measurement of parameters.

The principal parameters of hammers are determined on experimental test benches by direct measurement. Thus, for example, the impact energy of the piston can be measured from ball impressions on anvil installations, by various types of workmeters [7, 19], on special test benches of Dobroborsky and Rusetsky, with the aid of an end-velocity sensor (oscillographic tip) [3, 11, 18], and so on. There are many different methods for measuring other characteristics of hammers as well, which, owing to the limited scope of this work, are not considered here.

1. Method of electronic modeling with the aid of mathematical machines. This experimental method has become widespread only in recent years and has begun to be used for investigating the dynamics of hammers.

This classification is the author’s attempt to arrange the known methods for determining hammer parameters in a definite order and, naturally, does not claim to be exhaustive. Some methods may be assigned equally well to one group or another. At present, in the study of pneumatic impact machines, graphoanalytical and experimental methods for determining parameters have become most widespread, as the most

simple and providing comparatively accurate data. Finding hammer parameters from nomograms also presents no difficulty.

The sequence in which the methods have been listed is consistent also in a chronological sense; it was in precisely this order that they were developed. The only exception is the experimental methods, which were adopted by scholars almost simultaneously with the appearance of pneumatic machines.

REFERENCES

1. P. M. Alabuzhev. Application of the theory of similarity and dimensions to the study (modeling) of impact machines. Izvestiya TPI, vol. 73, 1952.

2. O. D. Alimov, I. G. Basov, V. F. Gorbunov, D. N. Malikov. Drilling machines. Gostoptekhizdat, 1960.

3. V. I. Baburov. Investigation of pneumatic riveting-and-caulking hammers. Candidate’s dissertation, Tomsk, 1964.

4. V. I. Baburov, V. F. Gorbunov. On a method for calculating the basic parameters of riveting-and-caulking hammers. Izvestiya TPI, vol. 129, 1965.

5. N. N. Bulanov. Problems in the theory of perforator drilling. Gornyi zhurnal, No. 9, 1949.

6. V. F. Gorbunov, V. M. Razin, A. V. Trikhanov. Some results of modeling the oscillations of pneumatic hammers with vibration-isolating devices. In: Mathematical Methods in Mining, part 1, Novosibirsk, 1963.

7. S. I. Dobroborskii. Investigation of methods for measuring the impact work of pneumatic hammers. Candidate’s dissertation, Leningrad, 1954.

8. N. N. Esin. Calculation of an electropneumatic hammer by the similarity method. Transactions of ZSPh AN SSSR, issue 8, 1950.

9. N. N. Esin. Methodology for investigating and adjusting pneumatic hammers. Novosibirsk, 1965.

10. I. S. Kassatsier. Theory and calculation of pneumatic impact machines with spool distribution. DAN, LXXI, No. 15, 1950.

11. V. Z. Kleimenov. Methodology for determining the energy indicators of pneumatic impact machines. TsNIITEI Uglya. Mining Machines and Automation, No. 6, 1963.

12. N. A. Klushin. Pneumatic hammers with a new cycle reducing recoil. Candidate’s dissertation, Novosibirsk, 1957.

13. G. I. Kusnitsyn. Investigation of air-distribution devices of pneumatic impact machines. Candidate’s dissertation, Leningrad, 1959.

14. V. M. Mostkov. Fundamentals of pneumatic drilling. Ugletekhizdat, 1952.

15. Yu. N. Popov. New methods for calculating pneumatic hammers according to the similarity principle. Scientific Reports of Higher Education. Mining, No. 4, 1958.

16. Yu. N. Popov. Nomogram for calculating drilling hammers. IVUZ. Gornyi zhurnal, No. 9, 1959.

17. G. V. Rodionov. Universal stand for studying pneumatic impact machines. In: Impact Machines. Novosibirsk, 1953.

18. N. P. Ryashentsev. Investigation and creation of electromagnetic and impact machines for the construction and mining industries. Doctoral dissertation, Dnepropetrovsk, 1964.

19. G. I. Sidorenkov. Spring work meter. Izmeritel’naya tekhnika, No. 4, 1957.

20. G. I. Sidorenkov. A rational method for calculating valve-type pneumatic hammers. IVUZ Mashinostroenie, No. 4, 1961.

21. B. V. Sudnishnikov. Dynamic calculation of electric hammers and perforators by the similarity method. Toplivnoe mashinostroenie, No. 6, 1940.

22. B. V. Sudnishnikov, V. I. Baburov. On a method for processing indicator diagrams of pneumatic impact machines. In: Mechanization of Open-Pit and Underground Mining Operations, issue 10, Novosibirsk, 1964.

23. B. V. Sudnishnikov, N. N. Esin. Elements of the dynamics of impact machines. Novosibirsk, 1965.

24. B. V. Sudnishnikov, K. K. Tupitsin. Analysis of oscillations by the method of impulse pairs. In: Development of Mineral Deposits. Novosibirsk, 1965.

25. G. A. Terekhov. A graphical method for processing indicator diagrams of pneumatic chipping hammers. Izvestiya vuzov, Gornyi zhurnal, 1963.

26. G. A. Terekhov, A. D. Shkolnikov. Electronic modeling of the working cycle of pneumatic chipping hammers. Izvestiya vuzov, Gornyi zhurnal, 1963.