RU2607843C2 - High-frequency drilling hammer with hydraulic drive, intended for hard rocks percussion drilling - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to hard rocks drilling. High-frequency impact hammer with hydraulic drive contains housing (8, 9, 10), at one end of which there is drilling head (11), intended to act directly on solid rock, Hammer piston (20) installed with possibility to move in said housing (8, 9, 10) and acting on drilling head (11). Hammer piston (20) has longitudinal flowing channel (41) with specified throughput capacity, which is made with possibility of closing valve in ascending direction with plug (23), partially following hammer piston (20) during its stroke. Valve plug (23) is controlled by means of connected valve stem (49) installed with possibility of sliding by valve stem bushing (51). Valve stem (49) of consists of locking devices (50, 51), made with possibility to abruptly stop valve plug (23) at level, making specified percentage of hammer piston (20) stroke total length, and able to separate valve plug (23) from sealing seat (40) on hammer piston (20), which provides opening said channel (41) with possibility to allow channel fluid medium passage through it, wherein valve stem (49) has properties of tension spring, providing valve plug (23) return with high speed by means of mechanical recoil.

EFFECT: enabling higher drilling speed and reduced power consumption.

9 cl, 34 dwg

Description

The present invention relates to a high-frequency hammer with a hydraulic drive, designed for drilling hard rock, containing a housing, one end of which is equipped with a drill head designed to act directly on the hard rock, in addition, the hammer includes a piston of a hammer mounted to move in the specified case and acting on the drill head, and the piston of the hammer has a longitudinally extending channel with a given throughput, which is made with the possibility of closing in the upward direction by means of a valve plug partially following the piston of the hammer during its stroke.

Hydraulic driven impact hammers designed for rock drilling have been in commercial use for over 30 years. They are used together with connected drill rods, and the drilling depth is limited by the fact that the shock energy is extinguished by passing through the joints, in addition to the weight of the drill rod becoming too heavy, so that only a small amount of energy reaches the drill head.

BOTH hammers, i.e. drill hammers installed directly above the drill head are much more efficient, they are used to a large extent for drilling wells with a depth of 2-300 meters. They are driven by compressed air and are characterized by a pressure of up to approximately 22 bar, which limits the drilling depth to approximately 20 meters if water enters the well. To date, hydraulic drill hammers driven by high-pressure water have been commercially applicable for more than 10 years, but there is a size limit, which means that the hole diameter reaches about 130 mm. In addition, they are known for their limited service life and sensitivity to impurities in water. They are used to a large extent in the mining industry, due to the efficiency of drilling and vertical boreholes. To a limited extent, they are used for drilling vertical wells with a depth of up to 1000-1500 meters, without any directional control.

It is required to produce hydraulic driven downhole hammers that can be used in conjunction with high-performance guiding equipment, in which water can be used as a drilling fluid, and water-based drilling fluid with additives can be used, and which are cost-effective life time. This implies widespread use both in the field of deepwater drilling for geothermal energy and for access to hard-to-reach oil and gas sources. In percussion drilling use drill heads with inserted carbide tines, the so-called "indenters". They are made of tungsten carbide, usually they have a diameter of 8 to 14 mm and a spherical or conical end. Ideally, each indenter should strike with optimal impact energy depending on the hardness and compression strength of the rock so as to form a small hole or hole in the rock. The drill head is rotated so that the next blow, ideally, forms a new hole, having a connection with the previous one. The diameter and geometry of the drilling determine the number of indenters.

The optimal impact energy is determined by the compressive strength of the rock, rock can be drilled with a compressive strength of more than 300 MPa. The consumption of shock energy above the optimal value seems to be a loss of energy, since it is not used to destroy rock, but only spreads in the form of energy waves. Too small impact energy does not form a hole at all. When the shock energy per indenter is known, and the number of indenters is determined, then the optimal shock energy is supplied to the drill head. Thrust, or drilling speed, (drilling penetration rate) can be increased by increasing the frequency of impacts.

The amount of injected drilling fluid is determined by the minimum required tap speed (upstream velocity) in the annular space between the drill rod and the borehole wall. It should be at least more than 1 m / s, preferably 2 m / s, so that the drilled material, drill cuttings, is transported to the surface. The harder and more brittle the rock, and the higher the impact frequency, the finer the drill cuttings can be obtained and the slower retraction speed can be adopted. Hard rock and high frequency will form drill cuttings in the form of dust or fine sand.

The hydraulic action applied to the drill hammer is determined by the pressure drop multiplied by the amount of material pumped per unit time.

This effect provides shock energy per shock multiplied by frequency. If we consider an imaginary example in which drilling is carried out in granite rock with a compressive strength of 260 MPa, the diameter of the borehole is 190 mm, the water supply from the surface is 750 l / min (12.5 l / s), then the calculated value of the optimal impact energy is approximately 900 joules.

Based on the known data for similar boreholes, but with smaller diameters, one can expect a drilling speed of 22 m / h (meters per hour) at a shock frequency of 60 Hz. If the shock frequency increases to 95 Hz, the penetration rate during drilling will be 35 m / h, respectively. The required total impact on the drill head will then be: 0.9 kJ × 95 = 86 kW. We mean that the design of this hammer has a mechanical-hydraulic efficiency of 0.89, which provides the necessary pressure drop of 7.7 MPa on the hammer.

This drill hammer will then drill 60% faster, and consume 60% less energy than the well-known available water-driven percussion hammers.

This is achieved thanks to an impact hammer of the type disclosed in the inlet part, characterized in that the valve plug is controlled by a valve stem connected thereto, which is slidable in the valve stem bushing, said valve stem comprising locking means capable of stopping the valve plug at a level comprising a predetermined percentage of the total piston stroke of the hammer, and allows you to separate the valve plug from the sealing seat on the hammer piston, the specified channel, thus opening etsya channel and allows fluid to flow through the active channel.

Preferably, the locking means comprises a locking plate at the upstream end of the valve stem and an interacting internal locking surface in the valve stem bushing.

In one embodiment, a predetermined percentage of the valve piston stroke length may be of the order of 75%.

Conveniently, the valve plug returns the properties of the tension spring inherent in the valve stem, which is long and thin.

Preferably, the impact hammer further comprises an inlet valve assembly that does not open for the action of the piston of the hammer until the pressure reaches a value of approximately 95% of the total working pressure, said inlet valve assembly being configured to close the main passage, wherein the side passage inside the hammer body creates excess pressure in the annular space between the hammer piston and the body, raising the hammer piston so that it fits snugly against the valve plug Pan.

Conveniently, the hammer piston and valve assembly can be returned by rebound, while the hammer piston and valve assembly have hydraulic damping, which controls the deceleration of the reverse stroke to a stop. Conveniently, hydraulic damping takes place due to an annular piston which is pressed into the corresponding annular cylinder with adjustable gaps, and thereby limits or suppresses the output of the trapped fluid.

In addition, a hole may be located at the top of the valve stem bushing, into which a valve stem retainer plate can be inserted, the radial part of which can be tightly pressed against the inside of the hole with a relatively narrow radial clearance.

In addition, in the annular groove under the opening, an annular backup valve may be arranged to open and refill fluid through the channels of the valve stem bushing.

The hammer body can be divided into the intake valve body, valve body, and hammer body.

The design of the drill hammer according to the present invention relates to a type called a "direct-acting hammer", i.e. the hammer piston has a closing valve located on it, which in the closed position allows pressure to advance the piston forward, and in the open position allows the valve piston to rebound. The previous version of the hydraulic hammer has a valve system that, by means of pressure, propels the piston of the hammer in both directions. This provides low efficiency, but more precise piston control.

The key to good efficiency and high shock frequency is valve design. The valve must operate at high frequency and have good through flow characteristics in the open position.

With great advantage, the design of the drill hammer can also be used as a surface mounted hydraulic hammer for drilling with drill rods, but it is used as a downhole drill hammer, which will be described in detail herein.

Other objects, features and advantages will be apparent from the following description of preferred embodiments of the invention, given for the purpose of description, and data in the context of the accompanying drawings, where:

in FIG. 1 is a schematic view of an exemplary hydraulic hammer drill according to the invention,

in FIG. 2A shows a side view of a downhole drill hammer with a drill head,

in FIG. 2B shows the drill hammer of FIG. 2A rotated 90 °

in FIG. 2C is a view in the direction of arrows AA in FIG. 2A,

in FIG. 2D shows a view in the direction of arrows BB in FIG. 2A,

in FIG. 3A is a longitudinal section along line AA in FIG. 3A,

in FIG. 3C shows a cross section along line BB in FIG. 3A,

in FIG. 3D shows a cross section along the line CC in FIG. 3A,

in FIG. 3E shows a cross section along the line D-D in FIG. 3A,

in FIG. 3F shows the dedicated node H of FIG. 3A in double magnification,

in FIG. 3G shows the dedicated node H of FIG. 3A in double magnification,

in FIG. 3H shows the dedicated assembly F of FIG. 3A in fivefold magnification,

in FIG. 3I shows the dedicated node G of FIG. 3A in fivefold magnification,

in FIG. 4A shows what corresponds to that depicted in FIG. 3A, but at the end of the acceleration phase,

in FIG. 4B is a side view of the valve device shown in section in FIG. 4A,

in FIG. 4C shows a cross-section along line BB in FIG. 4A,

in FIG. 4D shows the dedicated node A of FIG. 4A in fivefold magnification,

in FIG. 4E shows the dedicated node C of FIG. 4A in fivefold magnification,

in FIG. 5A shows what corresponds to that depicted in FIG. 3A and 4A, but at the moment when the hammer of the hammer hits the impact surface with the drill head,

in FIG. 5B shows the highlighted assembly A of FIG. 5A in fivefold magnification,

in FIG. 5C shows the highlighted assembly B of FIG. 5A in quadruple magnification,

in FIG. 6A shows, respectively, the same as in FIG. 3A, 4A and 5A, but at the moment,

when the hammer piston is completely back,

in FIG. 6B shows a section along line EE in FIG. 6C,

in FIG. 6C shows the highlighted assembly A of FIG. 6A in fivefold magnification,

in FIG. 6C 'shows the dedicated node D of FIG. 6C at 20x magnification,

in FIG. 6D shows the dedicated node C of FIG. 6E at 20x magnification,

in FIG. 6E shows the highlighted assembly B of FIG. 6A in quadruple magnification,

in FIG. 7A shows, respectively, the same as in FIG. 3A, 4A, 5A and 6A, but at a time when the valve piston is in the final part of the return,

in FIG. 7B shows the highlighted assembly B of FIG. 7C at 20x magnification,

in FIG. 7C shows the dedicated node A of FIG. 7A in quadruple magnification,

in FIG. 8 is a graph illustrating a duty cycle of a hammer piston and a valve,

in FIG. 9A is a graph illustrating a sudden closure characteristic of a valve with respect to a differential pressure, and

in FIG. 9B shows the flow and pressure drop across a gradually closing valve.

In FIG. 1 shows a typical hydraulic drill hammer attached to the top of a drill stem to be connected, in which the hammer mechanism is located inside a housing 1 made of several casing sections, while the rotary motor 2 rotates the drill rod through the transmission 3, rotating an axis having a threaded portion 4 to be screwing into the drill rod and drill head (not shown). The hammer mechanism is usually equipped with a locking plate 5 for attachment to a feed device on a drilling rig (not shown). The hydraulic drive fluid is supplied through pipes and a sleeve 6 and is hydraulically returned through pipes with a sleeve 7. FIG. 2A and 2B show a downhole drill hammer with a drill head. They will be discussed in the following description. The illustrated housing 1 comprises a first housing section 8, which will then be opened as an inlet valve, while a second housing section 9 comprises a valve, a third housing section 10 comprises a hammer piston, and reference numeral 11 denotes a drill head. The drilling fluid is pumped through an opening or main passage 12, and a threaded portion 13 connects the hammer to a drill rod (not shown). The flat part 14 is intended for use with a tared key when twisting / unscrewing the hammer and drill string. A drain hole 15 is required for operation of the inlet valve disclosed below, the outlet 16 is made to return to the surface of the drilling fluid in the annular space between the wall of the borehole and the body of the drill hammer (not shown).

Carbide projections 17 are those elements that destroy the rock to be drilled. In FIG. 2C is a view in the direction of arrows AA in FIG. 2A, and in FIG. 2D shows the view observed in the direction of the drill head 11 in the direction of the arrows BB in FIG. 2A.

In FIG. 3A shows a longitudinal section through a drill hammer, where the main internal elements are: an intake valve assembly 18, a valve assembly 19, and a hammer piston 20. The drilling fluid is pumped through the inlet 12, and the inlet valve 18 is in the open position through the channels 21 shown in section AA in FIG. 3B, then through channels 22 in section BB in FIG. 3C to the valve plug 23 shown in section CC in FIG. 3D in the closed position relative to the piston 20 of the hammer, and brings the piston to the stop in the lower part 24 of the drill head. In section D-D in FIG. 3E shows a longitudinally extending spline portion 25 in the drill head 11 and the lowermost part of the hammer body 10, transmitting torque while the drill head 11 can axially move within the allowable clearances defined by the locking ring mechanism 26. Due to the impact of the hammer piston 20 on drill head 11, only due to its mass or weight, it is shifted along with the penetration of carbide teeth 17 into the rock. This allows to obtain shock energy sufficient for the destruction of rock, and at the same time minimizing the loss of displacement of the mass relative to the light drill head 11.

The detailed section in FIG. 3F, showing the intake valve 18 in the closed position, is taken from the highlighted assembly H in FIG. 3A. When it is necessary to initiate the hammer operation, the injection of drilling fluid into the passage 12 begins. The lateral or branch channel 27 through the wall of the valve body 8 is in fluid communication with the guide channel 28 in the support plate 29 of the intake valve 18. The support plate 29 is fixed in the valve body 8 and contains a directional valve 30, which is held open by the spring 31. The drilling fluid flows freely to the first guide chamber located above the first guide piston 32, diameter and plate the area of which is larger than the inlet area 12. During the increase in pressure, the limitedly movable valve plug 33 will be forced to move to the closed position on the seat 34 in the housing 8. Under the action of increasing pressure on the closed intake valve 18, in the annular space 35 between the housing 10 and the piston 20 The hammer is pressurized through the lateral channel 27, which feeds the inlet 37 through the longitudinally extending channels 36 in the valve body 9, see detailed view F.

Detailed cuts in FIG. 3H and FIG. 3I taken from F and G in FIG. 3A, show the contact of the hammer piston 20 and the inner wall of the hammer body 9, 10. The diameter of the piston 38 is slightly larger than the diameter of the second piston 39. When using the drill hammer to drill vertically downward, the hammer piston 20 in the unloaded state, due to gravity, will obviously slide down to the impact or working surface 24 in the drill head 11. In these conditions, between the valve plug 23 and its seat 40 (see detailed view F) there will be a gap in the piston 20 of the hammer. Accordingly, the drilling fluid will flow freely through the valve in plug 23, through channel 41 in the hammer piston 20 and channels 16 (see FIG. 2A), and therefore there is too little pressure increase to bring the hammer into action.

The construction shown in the detailed section in FIG. 3F, with the intake valve 18 closed and the pressure increasing in the annular space 35, raises the hammer piston 20 until it is pressed against the valve plug 23. Due to the required clearance between the surface of the piston 38 and the inner wall of the housing 9, the drilling fluid flows out into the space above the valve plug 23 through the lubricating channels 42 and channels 43, as shown by arrows in the detailed view F. So that this leaky volume does not cause an increase in pressure in the space above the valve plug 23, it is drained through the channel 44 in the valve support plate 29 and through the hole 45, which is provided by the guide valve 30 in this position, and further out through the drain hole 15. When the pressure The pressure rises to more than 90% of the working pressure the hammer is designed for, the piston enters the second guide chamber 46, overpowering the closing force of the spring 31, and the guide valve 30 is displaced in the manner illustrated in FIG. 3G

The first guide chamber above the guide piston 32 is drained and the intake valve 18 opens. At the same time, the opening 45 is closed, so that the drainage through the channel 44 is closed, as a result of which, in operating mode, pressure is not lost through this channel. The pressure in the chamber above the piston 20 of the hammer and the closed valve plug 23 leads to the beginning of the working cycle with instant full action. The design with a check valve 47 and a pipe 48 serves to reduce the drainage time of the second guide chamber 46, thereby achieving a relatively slow closing of the inlet valve 18. As a result, the inlet valve 18 remains fully open and does not interfere with operation, since the pressure then varies depending on the shock frequency.

In FIG. 4A shows a hammer at the end of the acceleration phase. The hammer piston 20 at this point reached a maximum speed of usually about 6 m / s. This is the result of applying the available pressure, which here, as an example, is less than 8 MPa, the hydraulic region of the hammer piston here, as an example, has a diameter of 130 mm, and the weight of the hammer piston, also as an example, is 49 kg. The valve plug 23 continues to close the hole of the hammer piston seat, since the hydraulic region of the valve plug 23 here, as an example, has a diameter of 95 mm, which is slightly larger by about 4% than the annular region of the hammer piston shown in section BB in FIG. 4C, numbered 23 and 24, respectively. At this point, the piston of the hammer covered about 75% of its full stroke - approximately 9 mm. The gap between the hammer piston 20 and the impact surface 24 of the drill head is about 3 mm, which is shown in an enlarged detailed view C in FIG. 4E.

A movable valve stem 49 having a locking plate 50 lands on the supporting surface of the stationary valve stem sleeve 51 in the housing 9 and stops the valve stem 49 from further advancement, as shown on an enlarged scale in a detail view A in FIG. 4D, after which the valve plug 23 is separated from the seat 40 in the hammer piston 20, and thus opens. The movable valve assembly 23, 49, 50 is shown in vertical view in FIG. 4B.

The kinetic energy of the pulse of the valve plug 23 due to its abrupt stop will slightly lengthen the relatively long and thin valve stem 49, and therefore transform into a relatively large elastic force, which very quickly accelerates the valve in the opposite direction. The slight elongation of the valve stem 49, calculated here as an example, is about 0.8 mm, it should be less than the degree of use of the material, in this case the material is a high-strength spring steel. The mass of the valve plug 23 should be as small as possible, here, as an example, the plug is made of aluminum, the length, diameter and material properties of the valve stem 49 together determine the natural frequency of the valve assembly.

For practical use, it should be at least 8-10 times the frequency to be used. The natural frequency is determined by the formulas:

где

Where

Of greatest importance are the mass and stiffness coefficient of the spring. The natural frequency for the design shown is about 1100-1200 Hz, and for this reason is applicable for an operating frequency of more than 100 Hz. In the design shown, in this example, the rebound speed is 93% of the impact speed.

In FIG. 5A shows the position and moment when the valve piston 20 hits an impact or abutment surface 24 inside the drill head 11. The valve plug 23 comprising the stem 49 and the retainer plate 50 is at full return speed, see detail view A in FIG. 5B, so that a large hole is created relatively quickly between the valve plug 23 and the valve seat 40 in the hammer piston 20, while the drilling fluid flows with relatively little resistance through the longitudinal channel 41 in the hammer piston 20, see detail view B in FIG. 5C.

The kinetic energy of the pulse of the piston 20 of the hammer is partially transformed into elastic force in the piston 20 of the hammer, since the piston is somewhat compressed during the impact. When the energy waves of the shock pass through the piston 20 of the hammer to the opposite end and back, the piston 20 of the hammer accelerates upon return. The reverse speed at the start in this case is calculated and is about 3.2 m / s - approximately 53% of the impact speed, which is because part of the energy is spent on displacing the mass of the drill head 11, while the rest is spent on pressing indentors in the rock.

In FIG. 6A shows the moment when the hammer piston 20 has its full return speed. The valve plug 23 at this point in time almost returned to the end stop, in a detailed view A in FIG. 6C shows a stem 49 comprising a retaining plate 50 entering a hole 52 at the top of a valve stem bushing 51.

The detailed view D in FIG. 6C 'shows how the radial portion of the locking plate 50 seals the inside of the opening 52 with a relatively narrow radial gap. A slight negative pressure is created in the chamber under the locking plate 50 when the locking plate 50 passes the last 2 mm before stopping. The annular retaining valve 58 opens and is again filled with fluid through the passage 59. The limited or trapped volume under the retainer plate 50 prevents the valve plug 23 from bouncing and leaves it in that position until the next cycle begins.

The check valve 58 of the “annular check valve” type, which in this embodiment is an annular leaf spring, is selected due to its low weight and relatively high elastic force and, accordingly, its ability to operate at a high frequency.

In detail view B of FIG. 6E shows a relatively large hole between the valve plug 23 and the valve seat 40 in the hammer piston 20 so that the flow of drilling fluid has minimal resistance. The lower side of the valve stem sleeve 51 is provided with an annular cylindrical groove 53 shown in a detailed view C in FIG. 6D. The top of the valve plug 23 is designed as an annular piston 54, which, with relatively narrow gaps, enters the annular cylindrical groove 53. The trapped fluid volume when the valve returns to the end stop exits in a controlled manner through the radial clearances between the annular piston 54 and the annular cylinder 53, as well as the outlet 55. The adjustable output acts as a pressure force and stops the valve returning so that the valve does not bounce. The same type of damping structure is found on the hammer piston 20. Detailed view B shows an annular piston 56 at the top of the hammer piston 20 in addition to the annular cylindrical groove 57 at the bottom of the valve body 9.

In FIG. 7A shows the last return portion of the hammer piston 20. The completion of the return stroke is damped in an adjustable way until it stops completely at the same time that the valve seat 40 meets the valve plug 23 shown in a detailed view A in FIG. 7C. Detailed view B in FIG. 7B illustrates how a limited or trapped volume of fluid in the annular cylindrical groove 57 moves through radial clearances between the annular piston 56 and the drain hole 60. The gap between the valve seat 40 and the valve plug 23 must not be completely closed so that pressure builds up and a new one begins cycle. Calculations show that with a hole of 0.5 mm the pressure drop is approximately the same as the value of the working pressure. This leads to the fact that the surface pressing on the contact surface between the valve plug 23 and the seat 40, becomes small, and the components can have a long service life.

In FIG. 8 is a graph illustrating a duty cycle of a hammer piston 20 and a valve. Graph A shows the direction of speed, and graph B the direction of the position in the work cycle. For both graphs, the horizontal axis is the time axis divided by microseconds.

The vertical axis for graph A shows the speed in m / s, the direction of the piston stroke relative to the drill head 11, so + up and down, here the return speed.

The vertical axis for graph B shows the distance in mm from the starting position. The plot of the graph 61 shows the phase of acceleration, where point 62 is the moment when the valve stops and its reverse movement begins. Point 63 - the impact of the piston 20 of the hammer on the drill head 11.

The plot portion 64 represents the displacement of the drill head 11 deep into the rock, 65 represents the acceleration of rebound, 66 is the return speed of the valve without jamming, and 70 is the deceleration of the plug phase to return the valve.

In FIG. 9A is a graph 71 illustrating abrupt valve closure characteristics with respect to pressure drop and the opening between the valve plug 23 and the seat 40 in the hammer piston. This situation is shown in FIG. 9B. The horizontal axis represents the opening passage in mm, and the vertical axis represents the calculated pressure drop in bars at the nominal flow rate of the pumped drilling fluid, which, as an example, is 12.5 l / s. As shown, before significant pressure resistance is achieved, it is necessary to have a closing passage of less than 1.5 mm.

Claims (9)

1. A high-frequency hammer with hydraulic drive, designed for drilling hard rock, containing a housing (8, 9, 10), at one end of which is a drill head (11), designed to act directly on hard rock, and the hammer also contains a piston (20) a hammer installed with the possibility of movement in the specified housing (8, 9, 10) and acting on the drill head (11), while the piston (20) of the hammer has a longitudinally extending channel (41) with a given throughput, which is made with perhaps closing in the upward direction by means of a valve plug (23) partially following the piston (20) of the hammer during its travel, characterized in that the valve plug (23) is controllable by means of an attached valve stem (49) mounted for sliding in the sleeve (51) a valve stem, said valve stem (49) having locking means (50, 51) configured to abruptly stop the valve plug (23) at a level comprising a predetermined percentage of the total piston stroke length (20) of the hammer, and is capable of where remove the valve plug (23) from the sealing seat (40) on the piston (20) of the hammer, which ensures the opening of the specified channel (41) with the possibility of flow of channel fluid through it, and the valve stem (49) has the properties of a tension spring, which ensures the return of the plug (23) Valves at high speed through mechanical rebound. 2. An impact hammer according to claim 1, characterized in that the locking means (50, 51) comprise a locking plate (50) at the upstream end of the valve stem (49) and an interacting internal locking surface in the valve stem bushing (51). 3. An impact hammer according to claim 1, characterized in that the predetermined percentage of the total piston stroke length (20) of the hammer is about 75%. 4. Hammer hammer according to any one of paragraphs. 1-3, characterized in that the hammer further comprises an inlet valve assembly (18) that does not open for operation of the piston (20) of the hammer until the pressure reaches approximately 95% of the total working pressure, said inlet valve assembly (18) ) is configured to close the main passage (12), while the side passage (27) in the hammer body provides increased pressure in the annular space (35) between the hammer piston (20) and the body (10), raising the hammer piston (20) to a tight pressing the valve plug (23). 5. An impact hammer according to claim 4, characterized in that the piston (20) of the hammer and the valve assembly (18) are configured to return by rebound, while both the piston (20) of the hammer and the valve assembly (18) are equipped with hydraulic damping that controls return to stop. 6. An impact hammer according to claim 5, characterized in that hydraulic damping takes place due to an annular piston (54) pressed into the corresponding annular cylinder (53) having adjustable gaps, due to which restriction or suppression of removal of entrained fluid occurs. 7. Impact hammer according to any one of paragraphs. 1-3, 5 or 6, characterized in that at the top of the valve stem sleeve (51) there is an opening (52) into which the locking plate (50) of the valve stem (49) is able to enter, while the radial part of the locking plate (50) is adjacent to the inside of the hole (52) with a radial clearance. 8. An impact hammer according to claim 7, characterized in that the annular retaining valve (58) is located in the annular groove under the hole (52), this retaining valve (58) is configured to open and refill fluid through channels (59) into valve stem bushing (51). 9. Hammer hammer according to any one of paragraphs. 1-3, 5, 6 or 8, characterized in that the hammer housing (1) is divided into an intake valve housing (8), a valve housing (9) and a hammer housing (10).

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