Hydraulic pick

Abstract

A piston rod with a piston, against which a displaceable valve ring, a short, axially rigid striking pin, guided in a bush, and a pressure transformer piston are set, is immovably placed in one part of the supporting housing. A working tool is placed in the second part of the supporting housing in a tool bush protected on the outside by a lower sealing cover to prevent corrosion. A gas chamber is set up under the supporting housing, the pressure transformer piston and the striking pin. A pressure transformer cylinder and an equalizing chamber are formed between the piston rod and tfe pressure transformer piston. The striking pin is driven by a working fluid under pressure, which is distributed by a system of channels in the piston rod. The striking pin is driven onto the working tool in a striking action by high-pressure gas, which is pressurized in the gas chamber. The movement of the striking pin is controlled by a switching element, fitted in the piston rod, and a valve ring, pushed onto the piston rod surface. It is assisted by the pressure transformer, which eliminates pressure peaks of the working fluid.

Description

The solution concerns hydraulic pick that falls into category of portable drifting devices actuating by stroke a driven by pressure liquid. It is a pick of piston type, where on working tool—cutter hammers impulse element—firing pin.

STATE-OF-THE-ART

Known solutions are based on hydraulic steering of striking pin which has the shape of continuous piston rod. Piston rod has in the middle part increased diameter which takes over the function of slightly sealed piston by gap in the cylinder. Because the striking pin is after eventual touch of striking pin's piston part with cylinder in placing statically designed, this gap has to be sufficiently big what causes big flow losses. This has the biggest influence on decrease in efficiency of picks in present world production. Inlet of pressure oil is led into cylinder's working chambers from steering through supporting housing by channels that are decreasing effectiveness of picks by their hydraulic resistance, especially by movement of striking pin into stroke. Impulse for switching of switching element in upper position is obtained from control channel in cylinder. This channel does not enable sealing of striking pin's piston by a cup. Therefore is the diameter of striking pin as small as possible. But then for required weight increases the length of striking pin. This results in decreasing of axial strength a thereby also strength of stroke by the same achieved speed.

Supporting housings of picks are from assembling reasons and also because of absorption of no-load strokes, respectively for absorption of residual energy after sudden penetration through barrier, designed from more parts, joint by long screws that are by their elasticity decreasing destructive impacts on bottom part of pick and on outrigger of industrial machine. These screws are stressed to such extent that comes not only to plastic deformation of nuts, but also to breakage of screws themselves. Plastic deformation of nuts and screws is eliminated in operation by continuous retightening of nuts. Residual energy of working tool is absorbed by cross pin what damages is placement, cutout from tool and also damages the pin itself. Diminished shaft of working tool causes its breakage by break open.

Working tool is placed in bottom part of pick in thermally hardened steel cases. Here comes to seizing of placement with progressive increase in allowance of placement. The result is penetration of dust and impurities into its placement and also last but not least origination of eccentric stroke of striking pin to head of tool. For work under water is therefore supplied into area of tool's placement compressed air. Nowadays are already known solutions where is this problem solved by flexible placement by contemporary interval supply of oil from aggregate of industrial machine.

Compressive force of industrial machine to pick is transferred by working tool to pick's part by annulus surface which arose by decreasing of tool head's diameter. But that damps tool's head, what is usually the reason of its hammering or abruption.

Picks in bulk are mechanically protected by their placement into other case which will be fixed by adapter to industrial machine. There are known solutions, where in order to decrease in negative impact on industrial machine, the pick is placed into box flexibly or is construed in such way that no-load strokes will be prevented. This concept works with permanent leakage flow and by run of function of this member will be the pressure in hydraulic system increased to value of safety pressure what has negative impact on whole hydraulic system by contemporary overheating of working liquid. Equally are known solutions, where is this box embedded by sound baffle material, to decrease outer noise level of pick.

Common sign of picks from worldwide production is their big technological severity, weight, dimensionality and sensitivity to rough handling.

SUBJECT MATTER OF THE INVENTION

Mentioned negatives are removed by solution according to invention with inverse concept where striking pin is cylinder placed on piston rod that is firmly connected with supporting housing. The controlling is a hydraulic flip-flop circuit that reacts only to both extreme positions of striking pin. Switching element, placed in piston rod, switches the direction of flow of pressure working liquid with high speed. In the extreme positions is hydraulically locked. In case of working tool in extra-work position, the pressure of liquid in system will be decreased, what will cause the interruption of pick's function. There does not come to no-load strokes and working liquid is not overheated.

High pressure accumulator, used in other picks, is here replaced by pressure transformer with cylinder and piston. The piston has from one side low pressure gas chamber, shared with striking pin and from other side equalizing chamber that is connected with gas chamber only in starting position. Pressure transformer's cylinder is connected to inlet of pressure working liquid and in consequence of parallel movement of pressure transformer's piston with striking pin, secures almost constant pressure in hydraulic system and by its regulated damping in dependence on flow, removes also vibrations from the movement of striking pin.

The basis of hydraulic pick according to the invention consists in the fact that in upper part of rotary supporting housing is immovable placed piston rod with piston, on which is slipped-on the piston of pressure transformer, movable valve ring and striking pin, loaded into bush placed to inner wall of supporting housing. In the piston rod body is created continuous inlet channel with taps, terminated by control channel and continuous return duct with tap, through that flows the pressure working liquid. In the piston rod are created also other holes from surface to control channel, in which is placed the switching element with pan construction. Valve ring equipped by inner relive, is slipped-on the piston rod by its lower side in the area of its decreased diameter. Upper side of valve ring is slipped-on the body of piston rod with non-reduced diameter. Into cavity in the ring, which arose by its relive, is into it flowed the first channel from control channel.

Into supporting housing is from the other, lower side, inserted the working tool, which is placed in bush in such way, that there are no pullbacks. From outer side is bush protected against working environment, sealed and closed by cover. Short solid striking pin evokes bigger strength of stroke, and thus the diameter of working tool's head is inversely increased. The tool does not have any damping for safety pin. The new shape of tool is resistant against breakage by break opening. Pick allows the work under water without need for inlet of compressed air. In case of sudden penetration through barrier is the tool axially spring-loaded. Against origination of no-load strokes is the pick equipped by safety circuit, which contrary to known solutions will not increase the pressure in hydraulic system up to value of safety pressure, if the striking pin will come to extra-work position, but on the contrary the pressure will be decreased, whereby the function of pick will be immediately interrupted. Controlling hydraulic flip-flop circuit is switched by full speed, in extreme positions is hydraulically braked and is not the function of hydraulic resistances. Very toilsome noise damping of pick, until now realized on the pick's surface by its placement into box, is brought forward into pick, directly to the source of acoustic performance (striking pin—working tool). Other advantage are small dimensions and less than half of weight in comparison with known picks, what extends its usage to larger ranger of industrial machines. Pick does not contain screw connections. Pick parts are after their assembly into bulk connected by sufficiently big forces, activated by pressure of filling gas, usually by nitrogen. Pick does not require any maintenance. Greasing of working tool's bushings is automatic from low pressure return tap.

VIEW OF THE FIGURES IN THE DRAWINGS

FIG. 1 is schematic representation of hydraulic pick from first example of realization in longitudinal section. On FIG. 2 is in the section magnified detail of control mechanism from FIG. 1. On FIG. 3 is schematic representation of pick in longitudinal section with other security circuit according to second example of realization.

EXAMPLES OF ACCOMPLISHED INVENTION

Hydraulic pick is assembled from four main parts that are: monolithic rotary supporting housing 1, piston rod 2, striking pin 3 and working tool 4. In supporting housing 1 is non-movable placed piston rod 2, secured against protrusion by safety ring 5. On the piston rod 2 is slipped-on movable striking pin 3, executed as rotary body, axially bored according to piston rod's diameter 2, with inner removal, which cavity is after slip-on of striking pin 3 on piston rod 2 divided by sealing piston 21 to first chamber 41 and second chamber 42. In the area of first chamber 41 has the piston rod 2 in one part decreased outer diameter. In this area is on the piston rod 2 slipped-on valve ring 23. The length of valve ring 23 is bigger than length of segment, on which has the piston rod 2 decreased outer diameter. To this situation is adjusted the valve ring 23 in such way, that on the side which is closer to piston 21 has his face axial hole equivalent to diameter of piston rod 2 in its non-tapered part. On opposed end has the valve ring 23 its face with axial hole equivalent to diameter of piston rod 2 in its tapered part. Between both terminal faces has the valve ring 23 inside relive, by which is after slip-on the valve ring 23 on piston rod 2 created between those two bodies the cavity 46 in the ring. In the piston rod 2 is created continuous inlet channel 6 with first tap 7, third tap 9 and fourth tap 10. To the end of inlet channel 6 is connected next space with inserted light switching element 20 with pan construction. Switching element 20 is executed in ring shape with graduated outer and inner diameters in such way that overall surface of its bottom (on Fig. left) faces is bigger than surface of upper (on Fig. right) faces. In switching element 20 is executed the duct 14 filling duct 15. After insertion of switching element 20 are created in stated next space four cavities: lower 47, small 48, middle 49 and upper cavity 50. Lower cavity 47 is connected with cavity 46 in the ring by first channel 16. Small cavity 48 is connected with the surface of piston rod 2 in first chamber 41 by lower nozzle 22 and second channel 17. Into middle cavity 49 is loaded fourth tap 10 of inlet channel 6. From the side of switching element 20 is connected with it the filling duct 15. Upper cavity 50 is connected with inlet channel 6 through its third tap 9 and with the surface of piston rod 2 is connected with fifth channel 31 and upper nozzle 11. To switching element 20 is from the surface of piston rod 2 created on both sides of piston 21 a channel: from first chamber 41 is it the third channel 18, from second chamber 42 is it the fourth channel 19. Through third channel 18 and duct 14 is first chamber 41 permanently connected with return duct 12, created in piston rod 2.

Striking pin 3 is loaded into non-metal sealed axially sliding bush 24, slipped-on into supporting housing 1. In upper (right) part of piston rod 2 is further assembled low-weight pressure transformer, by connection of bell piston 25, sealed cylinder 43 and equalizing chamber 44 in such way, that the cylinder 43 is made of piston's walls 25 and piston rod 2 and is connected to first tap 7 of inlet channel 6. Sealed equalizing chamber 44 is created between piston 25 and piston rod's cover 2. In the area delimited by supporting housing 1, bush 24, striking pin 3, piston rod 2 and pressure transformer's piston 25 is created first gas chamber 45. In basic position of pressure transformer's piston 25 is equalizing chamber 44 interconnected with gas chamber 45 by connecting channel 26. Working tool 4 is in supporting housing 1 placed through non-metal tool bush 27 that is in this example of realization made as three-piece 27.1, 27.2, and 27.3, whereby its middle part consists of spring-loading insertion 27.2. Tool bush 27 is against tool 4 sealed by floating metal stearing ring 28 equipped by sealing, which is against supporting housing 1 axially non-movable. Lower sealing cover 29 is secured against protrusion by safety ring 30 with constant preload implied by strength of gas pressure in gas chamber 45. Sealing of bushes 27 against supporting housing 1, bush 24 against supporting housing 1 and striking pin 3, striking pin 3 against piston rod 2, piston 21 against strikng pin 3, pressure transformer's piston 25 against piston rod 2 ad piston rod 2 against supporting housing 1 is achieved by non-drawn sealing cups. Hydraulic pick described in example of realization is built-up without screw connections.

Pick is equipped by safety circuit made by connection of drilling 51 with inlet channel 6 through first safety channel 53 and with return duct 12 through second safety channel 54. Drilling 51 is made from bottom face of piston rod 2 into its inner space in direction of longitudinal axis of piston rod 2 and into it is inserted movable carpel 52.

Into gas chamber 45 is before usage of hydraulic pick pushed gas to needed pressure through non-drawn channel and cap in piston rod 2. Compressed gas pushes out the striking pin 3 into position, where it leans against the tool bush 27. By this move defers also the head of working tool 4 from face of piston rod 2. The body of striking pin 3 will cover upper nozzle 11 and fifth channel 31. Working liquid acts on the bottom of drilling 51 by pressure to carpel 52, which pushes out into permanent contact with working tool 4. As far as the working tool 4 is not leaned against working object (or other barrier), the striking pin 3 will push it from pick out in such extent, that carpel 52, which follows the movement of working tool 4, will expose at its opposite end, until then by it closed connection of inlet channel 6 with return duct 12 through first and second safety channel 53, 54. In that moment will be lost in pick working pressure of liquid, if there was any. In consequence of this interconnection is the pick non-functional. By pushing the working tool 4 into pick—by pressure of industrial machine to working subject—will be pushed also carpel 52 into piston rod 2, until the connection of inlet channel 6 with return duct 12 will be interrupted in drilling 51. In taps 7 to 10 of inlet channel 6 will be the pressure increased. Cavity 46 in ring will be through first channel 16 filled by pressure working liquid which will move the valve ring 23 into lower (left) position up to stop position. In this position is through lower nozzle 22 and second channel 17 connected small chamber 48 with first chamber 41. As the first chamber 41 is permanently connected with return duct 12, without increased pressure stays also the small cavity 48. Through fourth tap 10 and third tap 9 will be increased also the pressure in middle cavity 49 and upper cavity 50. On face areas of switching element 20 will arose in this way unbalance of strengths, which will steer the switching element 20 into fast movement towards lower cavity 47. During it the working liquid flows from small cavity 48 through second channel 17 and lower nozzle 22 into first chamber 41. By covering of second channel 17 is increased the pressure in small cavity, following that the switching element 20 intensively starts to brake. Turnover of switching element 20 will be finished with small speed by discharge of small cavity 48 into first chamber 41 only through lower nozzle 22. During movement of switching element 20 will connect the filling duct 15 with fourth channel 19 and interrupt the connection of fourth channel 19 with duct 14 of switching element 20. In second chamber 42 will be increased the pressure, which will initiate the movement of striking pin 3 towards gas chamber 45 against gas pressure. By slow start of heavy striking pin 3 will prevent the increase of pressure tip of cylinder 43 of light pressure transformer, which will absorb the difference from constant flow of working liquid supplied by industrial machine. Piston 25 of pressure transformer is by that moved against the movement of striking pin 3. After run of striking pin's job 3 to speed corresponding with supplied flow, the piston 25 of pressure transformer will following increase in gas pressure in gas chamber 45 stop and consequently will start to return into original position. Working liquid that now flows from cylinder 43 of pressure transformer through first tap 7 will be added to the flow supplied by industrial machine. By this will be further increased the sped of strikng pin 3. Reliable return of pressure transformer's piston 25 into original position assures hydraulic damping supported by cooperation of equalizing chamber 44. Following that the striking pin 3 decreases continuously the speed to the value corresponding to flow of liquid from industrial machine, by which it is approaching the upper turning back of firing stroke. By this movement the face of striking pin 3 will be fastened in first chamber 41 of valve ring 23 and is drifting with it. When will be by this movement of valve ring 23 connected the lower nozzle 22 with cavity 46 in ring and second channel 17 will cover the body of valve ring 23, the pressure in small cavity 48 will be increased. Because the surface of faces of switching element 20 in bottom cavity 47 and in small cavity 48 is in total bigger than surface of its faces in middle cavity 49 and upper cavity 50, even though that all cavities are under high pressure of working liquid, the switching element 20 will move itself towards upper cavity 50. The speed of its movement will jump to higher value after connection of second channel 17 with cavity 46 in ring. During this movement the second chamber 42 will be detached from inlet channel 6 and connects to first chamber 41 through fourth channel 19, duct 14 and third channel 18. Interconnection of second chamber 42 with first chamber 41 occurs by filling of small cavity 48 with working liquid through second channel 17. Intensive deceleration and braking of switching element 20 in upper (right) position will be made by upper nozzle 11 after previous closing of fifth channel 31 by switching element 20. After suspension of driving power in second chamber 42, the movement of striking pin 3 will be in actual direction stopped and following overpressure of gas in gas chamber 45 will turn in opposite direction. At the same time because of pressure impact in cavity 46 in ring will be the valve ring 23 returned to left stop and will expose the second channel 17 and lower nozzle 22, by that will be the pressure in small cavity 48 decreased. Low pressure is also in upper cavity 50, because that is by fifth channel 31 and upper nozzle 11 connected with second chamber 42. Because the actuating surface of switching element 20 in lower cavity 47 is bigger than actuating surface of its face in middle cavity 49, the switching element 20 will stay in reached position almost during whole time of striking pin's 3 movements towards working tool 4. Immediately before stroke, when the fifth channel 31 will be covered by striking pin 3 the pressure in upper cavity 50 will be increased, that again starts the switching element 20 and for whole cycle begins the repeating. During movement of striking pin 3 towards working tool 4 does not flow into return duct 12 any working liquid, therefore the second chamber 42, first chamber 41, small cavity 48 and return duct 12 are completely without pressure. Full amount of working liquid supplied by industrial machine flows only into pressure transformer's cylinder 43. Following that the pressure transformer's piston 25 moves concurrent with striking pin 3. This results into deceleration of decrease in gas pressure in gas chamber 45 and increase in speed of striking pin 3. If the working tool pushes on pick, than during the movement of striking pin 3 into stroke, the head of working tool 4 leans against bottom face of piston rod 2, by that is prevented interconnection of inlet channel 6 with return duct 12 through relive 51. After stroke of strikng pin 3 to the head of working tool 4, the kinetic energy from flexible impact is transferred up to the tip of working tool 4. In the case of sudden penetration through barrier, the head of working tool hits the spring loaded insertion 27.2, which continuously absorbs the residual energy of working tool. Striking pin 3 will stay leaned against the bush 27.1 and the operation of pick is interrupted. Return to operation of pick is possible only after repeated pin down of industrial machine to pick through working tool 4.

In other example of realization is safety circuit made from second tap 8, drilled from inlet channel 6 to the surface of piston rod 2, return tap 13, lead from return duct 12 to the surface of piston rod 2 and from safety chamber 40, made from inner space in upper part of striking pin 3. Second tap 8 and also return tap 13 are created in one plain upright to longitudinal axis of pick. Other arrangement of pick is the same as that which is shown on previous example.

Into gas chamber 45 is before usage of hydraulic pick pressed the gas to needed pressure through non-drawn channel and cap in piston rod 2. Pressed gas will push the striking pin 3 into position, in which it will lean against the bush 27. By this movement also the head of working tool 4 defers from the face of piston rod 2. Body of striking pin 3 will cover the upper nozzle 11 and fifth channel 31. Safety chamber 40, second tap 8 and return tap 13 will connect the inlet channel 6 with return duct 12. Following this interconnection is the pick non-functional. By pushing of working tool 4 into pick, will be from pressure of industrial machine to working subject pushed also the safety chamber 40. Connection of inlet channel 6 with return duct 12 will be by this interrupted. In taps 7 to 10 of inlet channel 6 will be the pressure increased. The cavity 46 in ring will be through first channel 16 filled by pressure working liquid, which will move the valve ring 23 into lower (left) position up to stop position. By that will be started the operation of pick described in the first example of realization.

Function of safety circuit will be equally applied also by penetration through working subject. Working tool 4 will be stopped. Pick does not beat with no-load.

Advantage of hydraulic picks according to the invention is markedly increased working output following high effectiveness reaching values 90% and increased strength of stroke induced by multiply axial strength of striking pin 3. By new construction shape of working tool 4 and by the way of its placement into solid smooth monolithic body without holes, with sleeve for anchoring of pick to industrial machine through adapter, are the picks designed for heaviest conditions without limitations of works. High speed of striking pin's 3 switching in bottom position markedly decreases the impulse of slip-in strength. Small dimensions and weight of pick and high resistance against damage allows to use one size of pick for all industrial machines up to weight of 12.5 t. Supporting housing 1 is just one rotary unit without screw connections and lateral holes.

Claims

1. Hydraulic pick made of monolithic rotary supporting housing, cylindrical piston rod, rotary striking pin and rotary working tool, with inlet and outlet of pressure liquid, wherein in the part of supporting housing is non-movably placed piston rod with piston, on which is slipped-on movable valve ring, short and axially solid striking pin, led in bush of striking pin and pressure transtormer's piston, whereby in second part of supporting housing is inserted working tool, placed without pullbacks in tool bush, which is protected from outer side by lower sealing cover, whereby by such arrangement is between supporting housing, pressure transformer's piston and striking pin created gas chamber and between piston rod and pressure transformer's piston is created pressure transformer's cylinder and equalizing chamber, whereby between gas chamber and equalizing chamber is created connecting channel.

2. Hydraulic pick according to claim 1, wherein the striking pin is a rotary body drilled in axis according to piston rod's diameter and created together with inner relive in such way that by slipped-on striking pin on the piston rod is created closed hollow space, which is by piston divided to first chamber and second chamber.

3. Hydraulic pick according to claim 1, wherein the piston rod has in the area of first chamber on the surface continuous segment with limited length with diminished outer diameter, in which is slipped-on it valve ring with bigger length than is the length of the segment with diminished outer diameter of piston rod, therefore is made as hollow annulus with non-equal diameters of loading to piston rod, which is by bigger diameter on the face closer to the piston slipped-on the outer surface of piston rod in its non-diminished part, whereby by inner relive of valve ring and with the surface piston rod is created closed cavity in ring.

4. Hydraulic drilling hammer according to claim 1, wherein in inner space of piston rod are from its face created two continuous channels: return duct, permanently connected with first chamber and equipped by return tap led to the surface of piston rod and inlet channel, equipped by first tap, third tap and fourth tap, to which end is connected the lower cavity of space with inserted switching element, by which is in this space created yet small cavity, middle cavity and upper cavity, whereby the lower cavity is connected with first channel with cavity in ring, small cavity is connected with the surface of piston rod in first chamber, lower nozzle and second channel, into middle cavity is led fourth tap of inlet channel and upper cavity is connected with third tap of inlet channel and fifth channel and upper nozzle is connected with the surface of piston rod, on which is led also the first tap of inlet channel, which is led into pressure transformer's cylinder, whereby from the surface of piston rod is to the switching element created within space of second chamber fourth channel and within space of first chamber third channel, so the lower nozzle, second channel and third channel are in piston rod created at the same side of piston and fourth channel, fifth channel and upper nozzle are created on the opposite side of piston.

5. Hydraulic pick according to claim 1, wherein the switching element is made with the ring shape with graded outer and inner diameters in such way, that overall surface of its bottom faces is bigger than the surface of its upper faces, whereby is in this ring created duct and filling duct.

6. Hydraulic pick according to claim 1, wherein the bush of striking pin and also the tool bush are advantageously non-metal, placement of working tool and striking pin is flexible, whereby the working tool and also striking pin are in the lower position spring-loaded.

7. Hydraulic pick according to claim 1, wherein the sound baffling material is applied in the inner space of pick, directly by the source of acoustic performance.

8. Hydraulic pick according to claim 1, is in stop position safely kept by gas pressure single-shot led into gas chamber.

9. Hydraulic pick according to claim 1, is equipped by safety circuit made from drilling from the surface to the inner space of piston rod, which is connected with inlet channel and with return duct, whereby into drilling is inserted movable carpel.

10. Hydraulic pick according to claim 1, is equipped by safety circuit made from second tap, safety chamber and return tap, whereby the second tap is led from the surface of piston rod into inlet channel in it, return tap is led from the surface of piston rod into return duct and safety chamber is created in the upper part of striking pin from the inner side.