V. V. Chervov

Effect of blow frequency and additional static force on the vibro-percussion pipe penetration rate in soil

The authors describe and discuss experimental investigation of the effect exerted by blow frequency and additional static force on penetration rate of a pipe under vibration-percussion by a pneumatic hammer with using a measuring and recording instrumentation developed at the Institute of Mining, Siberian Branch, Russian Academy of Sciences. The penetration velocity ranges are found for the real blow frequencies of the test pneumatic hammer equipped with additional static load. Determination of static force sufficient to press the pipe in soil in hammer-free regime is reported.

Control of Air Feed to Back-Stroke Chamber of the Pneumatic Impact Device

A new air-distributing system with elastic and inertial valves is described. The results are cited for the experimental investigations of the pneumatic hammer. The vibrating character of the inertial valve motion is revealed. The calculation is performed for the inertial valve mass.

Enhancement of energy carrier performance in air hammers in underground construction

The article concerns with the problem of blow energy increase at the confined air consumption in air hammers used in special underground construction. The solution is the air distribution circuit with an elastic ring valve installed in the back stroke chamber; the valve is closed under mechanical contact with the air hammer housing and opens under action of the elastic force of the material the valve is made of. The use of such valve enables relief of the backward pressure during the direct stroke of the hammer and allows the back stroke length adjustment, which ensures the constant blow energy at the varied air flow.

On Some Features of Solid-Body Motion under Combined Vibrowave and Static Actions

Results are presented for modeling of the effect of anomalously low friction during solid body motion due to vibrowave and static actions. Cases are examined for the motion with different coefficients of static friction between the surfaces of the solid bodies. The stand, and the measurement and control system used are described.

Effect of additional vibration exciter and coupled vibro-percussion units on penetration rate of pipe in soil

Aimed to improve capacity of vibro-percussion driving of steel pipes in soil, the authors describe experimental modeling of the process with additional vibration exciters of axial and transverse vibrations series-linked to impulsive load source. Workability of the combination of two extended action spectrum percussion units as the vibration exciter is illustrated.

Influence of energy parameters of shock pulse generator on the pipe penetration velocity in soil

In the context of the problem of increase in efficiency of vibro-percussion driving of steel pipes in soil, a pilot model of shock generator with step speed adjustment for the bit and anvil impact is described. The authors report experimental modeling of pipe penetration depending on load of stalk. The influence of the stalk load parameters on the amplitude of generated shock pulses and the pipe penetration rate in elastoplastic soil is defined.

Pressure in Damping Device under Impulse Load

Characteristics are considered for transmitting the strain wave excited in the compacted material due to the impact of one metallic body against the other one. The practical solution for great energy absorption in the experimental stands and parametric control of impact impulse acting on the soil through the working member are proposed. A laboratory stand for conducting experiments is described.

Evaluation of Layout of Air Drill Hammer with Smooth Adjustment of Impact Impulse Frequency

Design of an air drill hammer with the smooth adjustment of the percussion frequency at the constant blow energy is considered. The proposed and analyzed modifications of air distribution system are based on using a mechanically closing elastic valve. The test data on experimental prototypes of the air drill hammer with the external distributing elements that set blow frequency are presented. The frequency adjustment ranges are determined.

Experimental estimate of power variation range of pneumatic hammer with mechanical locking of elastic valve

Under discussion is the experimental estimate of an actual power variation range of pneumatic hammer with a ring-type elastic valve arranged in exhaust unit of back-drive cell in order to lock mechanically this cell until exhaust stroke at various values of the hammer travel. The variation ranges of the valve channel cross-section are found to ensure sustained operation of the pneumatic hammer and the minimized air flow rate irrespective of the hammer weight and position (vertical or horizontal) and the ratio of the hammer power-stroke to the hammer power-stroke cell diameter.

Estimate of blow frequency range for an air drill hammer with a ring-shaped elastic valve in the backstroke exhaust line

The authors report and discuss the experimental results on an air drill hammer with an elastic valve installed in the backstroke exhaust line for mechanical closing. It is approved that such air hammer is capable to ensure the wanted blow capacity at the fixed blow energy by varying blow frequency through adjustment of cross section choke coupling the backstroke and front stoke chambers of the hammer. With the larger cross section of the choke coupling, the maximum blow frequency is achieved and remains the same later on.