FR2550983A1 - HYDRAULIC PERCUSSION APPARATUS - Google Patents

Abstract

THIS APPARATUS IS OF THE TYPE INCLUDING A BODY IN WHICH IS HELD A CYLINDER SERVING TO GUIDE A PISTON PISTON PUNCHING THE TOOL. ACCORDING TO THE INVENTION, THE PISTON PISTON IS MADE IN THE FORM OF SEVERAL PISTON TRUNKS 6, 13 COAXIAL AND ARRANGED END TO END, MEANS BEING PROVIDED TO ENSURE THE MAINTENANCE IN CONTACT OF TWO ADJACENT PISTON TRUNKS, DURING THE DIFFERENT PHASES. OF OPERATION, THAT IS DURING THE STRIKE STROKE OF THE PISTON, AT THE TIME OF ITS IMPACT ON THE TOOL AND DURING THE RETURN STROKE. APPLICATION TO THE REALIZATION OF APPARATUS FOR PERFORATING OR BREAKING ROCKS.

Description

"Hydraulic percussion apparatus" The subject of the present invention is

  a hydraulic percussion apparatus, and more particularly an apparatus for perforating or breaking rocks, comprising a body in which a piston is capable of reciprocating axial movement and striking at the end of each stroke, said striking stroke, end of a spike or foil tool mounted on one end of the body and opening into the bore for guiding

of the piston.

  The efficiency of such a device is a function of several parameters. A first parameter is given by the velocity of the percussion piston at the moment of the impact with the tool, and the ratio between the linear mass of the percussion piston and that of the tool. These values condition the intensity of the percussion piston. generated shock wave The value of this intensity can not be increased excessively because it corresponds in the tool metal to compressive stresses which, beyond certain limits, would result in the premature destruction of the tool. 'tool

by fatigue.

  A second parameter is given by the frequency of the impact.

  A third parameter is given by the duration of the passage of the shock wave, which is a function of the speed of movement of the waves.

  in the metal and proportional to the length of the percussion piston.

  Therefore, to improve the efficiency of a percussion device

  it may seem advantageous to increase the length of the piston.

  However, the manufacture of a piston of great length, or great slenderness (ratio of the length to the diameter) is an operation

  difficult technique because, so that the piston can withstand compression stresses as high as possible, it must be hardened by a suitable heat treatment which causes deformation In addition, the geometry of the piston must be very precise in order to 30 allow its circulation with a minimum of play in the bores in which it must slide Finally, the realization of precise bores of very great length is also a delicate technical operation.

  In practice it is therefore not possible to influence favorably

  on the third parameter cited by substantially increasing the length of the striking piston.

  The present invention aims to remedy these disadvantages.

  For this purpose, in the machine that it concerns, of the aforementioned type, the striking piston is made of several coaxial sections and arranged end to end, means being provided to maintain two adjacent sections in contact during the different periods of time. phases of operation that is to say during the stroke stroke of the piston to its impact with the tool, and during its return stroke.

  The fact that the different piston sections remain in contact with each other, especially at the moment of impact on the tool, does not modify the effectiveness of the impact compared to the case where the piston would be made of a only element of length equal to the sum of the lengths of the different piston sections.

  For its part the body of the device is made of several parts

  coaxial assemblies mounted end to end and assembled to each other, each having a bore for guiding a piston portion.

  Each piston section sliding in a bore of short total length and machined with precision makes it possible to obtain an excellent

  guidance, with minimum clearance and maximum sealing lengths.

  As a result, the internal fluid leaks under pressure are limited to negligible values and allow the hydraulic cycle to have

a very good return.

  In any case, the invention will be well understood by means of the

  description which follows, with reference to the appended diagrammatic drawing, representing by way of nonlimiting examples, four embodiments of

  FIGS. 1 and 2 are two longitudinal cross-sectional views of a first apparatus comprising a striking piston made in two sections, respectively during the stroke stroke of the piston and during the movement of the return thereof. Figure 3 is a longitudinal sectional view of an apparatus comprising a striking piston made of three sections

  Figure 4 is a longitudinal sectional view of an apparatus constituting a variant of that shown in Figure 3.

  Figure 5 is a longitudinal sectional view of an apparatus constituting a variant of that shown in Figure 1.

  The different apparatus shown in the drawing operate according to a principle described in French Patent 2,369,908 in the name of the Applicant.

  The apparatus (2) shown in Figures I and 2 comprises a body

  made in two parts (3 and 4).

  Inside the portion (3) of the body is bored a cylinder (5) inside which is slidably mounted a first section (6) of the striking piston One end of the piston (6) is arranged opposite 5 of the tool (7) of which only one end is shown It should be noted that the cylinder (5) comprises two zones of different sections, corresponding to the two sections of the piston section (6), and ensuring the care of an annular chamber (8) permanently connected by a channel (9) to the high-pressure fluid supply conduit (10). Inside the body portion (4) is a cylinder (12) wound inside

  slide a piston section (13) or thrust section and a tubular piece (14) fulfilling the function of distributor The parts (3 and 4) of the body are arranged in such a way that the cylinders (5 and 12) are coaxial, machining tolerances close, allowing contact 15 between the piston sections (6 and 13) by their end faces respectively (15 and 16).

  The section (13) has on the side of its face (16) in contact

  with the piston section (6) an annular groove (17) delimited on the side of the piston section (6) by an enlarged portion (18) of lower section 20 than that of the cylinder (12). As shown in the drawing, this enlarged part, is generally frustoconical in shape and decreasing in cross-section from the face (16) of the piston section (13) to the annular groove (17). This frustoconical portion may have a reduction of constant section or may consist of a succession of adjacent cylindrical parts. to each other of decreasing sections.

  A groove (19) in the body part (4), and located

  in the zone in which the faces in contact (15, 16) of the elements (6, 13) are permanently connected to the low pressure conduit (20) on which a hydraulic accumulator 30 not shown in the drawing can be connected.

  In the cylinder (12) emerges a lumen (22) communicating with a channel (23) also opening into the annular portion between the cylinder (12) and the flange (24) serving as a stop at the dispenser (14). 22) opens out at the annular groove (17) of the piston section near the annular groove

  (19) formed in the cylinder (12).

  This apparatus also comprises, and in a known manner, in particular by French patent 2,369,908, a plunger (25), a hydraulic accumulator (26) connected to the supply duct (10) in high pressure fluid, a channel (27) ) a high pressure fluid supply at the top of the piston section (13), a device (28) for triggering the cycle, and at least one channel (29) opening into the cylinder (12) and connected

  continuously at the low pressure conduit (20).

  As mentioned before, the description of the functioning

  this device is limited to that of the elements involved in the cycle

  particular that requires a piston in several sections.

  FIG. 1 represents the moving parts in the operating phase corresponding to the striking stroke of the elements (6 and 13). The hydraulic pressure applied to these elements via the fluid conveyed by the channels (9 and 27) strongly plates them. against each other, in view of the fact that their faces in contact (15, 16) are only subjected to a low pressure, since they are located in

  an area (19) communicating with the low pressure conduit (20).

  During the return stroke of the moving element, represented in FIG. 2, the piston section (13) drives the distributor (14) and the plunger (25) in its movement. the interior of the distributor (14) largely escapes through the channel (29) and the low pressure conduit (20), allowing a

  fast moving speed of the moving equipment.

  In a second step, the distributor (14) closes the conduit (29) and forces the fluid to escape through the channel (23), the lumen (22), the annular groove (17) and the annular groove (19). ) before passing through the low-pressure conduit (20) The swollen part (18) of the piston section (13) then progressively reduces the exhaust section of the fluid towards the low-pressure conduit (20) which it provides with the upper edge of the groove (19), creating a fluid pressure capable of braking vigorously the movable element constituted by the two piston sections (6 and 13), the distributor (14) and the plunger (25). decreasing fluid flow section, the slowdown of the moving element is progressive, until a sufficiently low speed is achieved compatible with a contact without deterioration between the distributor (14) 35 and the flange (24) serving as a stop to that- This arrangement also ensures during the m return opening of the piston sections (6 and 13) a close contact therebetween because their bearing faces (15, 16) remain in an area in communication with the circuit

low pressure.

  The apparatus shown in FIG. 3 is a variant of the one described above comprising three piston sections and in which the same elements are designated by the same references as in FIGS. 1 and 2. An intermediate element (30) arranged between the elements (6 and 13), is slidably mounted in a cylinder (32) formed inside a portion (33) of the body disposed between the parts (3 and 4), coaxially with them to promote the maintenance of contact between the two faces 10 facing the piston sections (6 and 30) an annular groove (34) is formed at their level in the cylinder (32), which communicates via a channel

  (35) with the low pressure conduit (20).

  The operation of this apparatus is identical to that of the apparatus which has just been described with reference to FIGS. 1 and 2.

  It should be noted that the larger bore diameter of the cylinder (6), the bore (32) and the bore (12) are made at the same diameter, which avoids the creation of a flow of fluid at the grooves (19 and 34) during the active stroke of the three piston sections This embodiment corresponding to piston sections (6, 30 and 13) having substantially a constant section from one end to the other of the piston and allowing

  generating in the tool (7) a shock wave with constant stress.

  FIG. 4 represents an alternative embodiment of the apparatus of FIG. 3 in which the sections of the bores (5a, 32a and 12a) increase from that of the bore (5a) to that of the bore (12a) which allows generation in the tool (7) of a shock wave with progressive stress, or the stress at the end of the impact is higher than at the beginning of impact This property is obtained very easily because the piston sections (6, 30 and 13) and the corresponding bores of the three

  parts of the machine body are machined separately.

  FIG. 5 represents an alternative embodiment of the apparatus of FIG. 1 in which the same elements are designated by the same references. In this case, the thrust section (13) of the piston has an annular groove (36) delimited on the of the second section (6) by an inclined surface (37) of increasing cross section until it returns to the same cross-section as the portion of the piston situated on the other side of the groove. An annular groove (38) formed in the cyclinder (12) ) is in continuous communication with the low pressure conduit (20) via a

  channel (39) opening into the channel (29).

  In the cylinder (12) emerges a lumen (40) communicating via the channel (23) with the chamber located above the pushing portion of the piston. This lumen (40) is located near the annular groove

(38).

  The relative positions of the grooves (36) and (38) are such that during the rise of the piston the inclined surface (37) thereof progressively reduces the fluid passage section of the channel (23) towards the

low-pressure conduit (20).

  The operation of this apparatus is exactly the same as that of the apparatus of FIG. 1, the only difference residing in the fact that the escape of fluid towards the low-pressure conduit is no longer done by the groove (19), but by the throat (38), which fills this

only function.

  As is apparent from the foregoing, the invention provides a great improvement to the existing art by providing a hydraulic percussion apparatus having excellent performance due to the large piston length which can be obtained in a simple manner, and the excellent performance of the hydraulic cycle due to the limitation of internal fluid leakage under pressure to negligible values, given the weakness of the games and the lengths of

  important guidance of the moving elements relative to the body.

  It goes without saying that the invention is not limited to

  embodiments of this apparatus described above by way of example, it encompasses, on the contrary, all the variants.

  Thus, in particular, the bulged part (18) of the piston section (13) could be of purely cylindrical shape; that the sections of the two sections of elements of the apparatus shown in FIGS. 1 and 2 could be different, that the number of piston sections 30 could be greater than three or that the means for controlling the movement of the piston could be different, without it being possible

of the scope of the invention.

Claims (7)

  1 Hydraulic percussion apparatus, of the type comprising a   body in which is formed a cylinder for guiding a striking piston striking the tool, characterized in that the striking piston is formed in the form of several coaxial piston sections (6, 13) arranged end to end. end, means being provided for maintaining in contact two adjacent piston sections, during the different operating phases, that is to say during the strike stroke of the piston until its impact with the tool and during the race 10 back.   2 Apparatus according to claim 1, characterized in that its body is made of several parts (3,4,33) coaxial and assembled to each other, each having a bore (5,12,32) serving guiding a piston part.   Apparatus according to any of claims 1 and 2,   characterized in that in each zone of the body in which the bearing faces move between two adjacent sections (6, 13; 30, 6) of the piston is formed an annular groove (19, 34) permanently connected. at the low pressure circuit (20).   4 Apparatus according to claim 3, characterized in that the thrust section (13) of the piston, that is to say the one undergoing the pressure ensuring the displacement of the moving assembly during the striking stroke comprises an annular groove ( 17,) delimited on the side of the second piston section by an inclined surface corresponding to a progressive increase of the section of the piston, while an annular groove (19),   in communication with the low pressure conduit (20) is formed in the bore for guiding the piston so as to be opposite the groove (17,) of the thrust section (13) when the piston hits the tool , and that the upper edge of said groove with the inclined surface of the thrust section (13) only provides a passage of small section, a slot (22) being provided which, opening into the bore for guiding the thrust portion (13), and in communication with a conduit (23) opening into the chamber limited by the upper face of the thrust section, is located near the groove in communication with the low pressure conduit (20).   Apparatus according to claim 4, characterized in that on the one hand the groove formed in the bore (12) of the body, capable of communicating 2550983 -   with the chamber situated above the thrust portion (15) coincides with the groove (19) situated in the zone in which the bearing faces are located one on the other side of the thrust section (13) and of the second section (6) of the piston and secondly the annular groove (17) formed in the thrust section is delimited on the side of the considered end of the thrust section by a bulging portion (18) of section smaller than the section of the cylinder (12) for guiding the thrust section. 6 Apparatus according to claim 5, characterized in that the swelling portion (18) of the thrust section is of decreasing section 10 from its end (16) bearing against the second section (6) piston towards the annular groove (20).   Apparatus according to claim 6, characterized in that the   the bulged portion (18) of the thrust section is generally frustoconical in shape.   Apparatus according to claim 6, characterized in that the   the bulged portion (18) of the thrust portion (13) is constituted by a series of juxtaposed cylindrical zones and decreasing sections.   9 Apparatus according to any one of claims 1 to 8, characterized in that the respective sections of the different piston sections 20 are increasing from the section on the side of the tool to the section thrust.