KR20210144399A - Piston for hydraulic breaker - Google Patents

Abstract

The present invention provides a piston for a hydraulic breaker, installed inside a cylinder of the hydraulic breaker to hit a chisel while being lifted and lowered by hydraulic pressure, which comprises: a connection shaft unit formed to extend upward from the upper end of the piston; a soft compressed elastic body inserted and installed on the outside of the connection shaft unit and when the piston is lowered to hit the chisel, pushing the piston in the direction of the chisel to increase the hitting force on the chisel while being compressed in the direction of the chisel due to inertia; and a coil-type elastic spring installed inside the compressed elastic body so as to be disposed on the outer side of the connection shaft unit to increase the compression time duration of the compressed elastic body compressed in the direction of the chisel due to inertia when the piston is lowered to hit the chisel and the compressed elastic body is elastically supported. The present invention can maximize the hitting force on the chisel and reduce the vibration and repulsive force generated in the process of hitting the chisel.

Description

Piston for hydraulic breaker

The present invention relates to a piston for a hydraulic breaker capable of reducing vibration and shock repulsion generated while increasing a striking force in the process of striking a chisel of a hydraulic breaker mounted on an excavator.

In general, a hydraulic breaker is an equipment that is installed in construction machines such as excavators and loaders to crush rock or concrete, and when the cylinder is operated, the piston moves up and down and strikes a chisel, which is a crushing tool, and the chisel is used in concrete and rock, etc. It crushes by applying an impact force.

The noise generated during the crushing operation using the hydraulic breaker is divided into a hitting noise generated when the piston hits the chisel and a crushing noise generated when the chisel crushes concrete and rock. Most of these are hitting noise, and the number varies depending on the size of the hydraulic breaker, but it is approximately 90~110dB.

Recently, as regulations on noise and vibration have been strengthened, the noise level indication of construction equipment has been changed from a notification system to a mandatory system, and products such as excavators, bulldozers, loaders, and breakers have been designated as obligatory noise level indication targets. In order to respond to these noise and vibration regulations, the development of low-noise type breakers is being actively carried out.

In particular, related organizations are also encouraging the development of low-noise breakers, such as certifying low-noise breakers for breakers that satisfy noise regulations.

Looking at the conventional hydraulic breaker 1 with reference to FIG. 1 , a hydraulic cylinder 10 , a piston 20 installed movably up and down inside the hydraulic cylinder 10 , and the lower part of the hydraulic cylinder 10 . It includes a front head 30 coupled to, and a chisel 40 coupled to the front head 30 and hit by the piston 20 . A gas chamber 12 is provided at the upper end of the hydraulic cylinder 10, a valve 14 is formed on the side surface of the hydraulic cylinder 10, and hydraulic oil is temporarily stored in the lower side adjacent to the valve 14 as a kinetic energy source. An accumulator 50 for use is formed. In addition, the chisel 40 is supported by the upper bush 60 provided inside the middle of the front head 30 and the lower bush 70 coupled to the lower end of the front head 30 . And an insertion groove 72 is formed in the inner side of the lower bush 70 , and a vibration-proof material 80 is installed in the insertion groove 72 .

Although not shown in the drawings, the conventional hydraulic breaker 1 absorbs noise and vibration by using a soundproofing material that surrounds the entire hydraulic cylinder 10 in addition to the vibration-proof material 80 . Therefore, the operating heat generated inside the hydraulic cylinder 10 is not easily discharged to the outside, and there is a risk that the oil, which is the working medium of the hydraulic cylinder 10 , may be carbonized. In addition, when the hydraulic breaker 1 is used for a long time, it may cause deformation of the piston 20 by operating heat.

In addition, in the conventional hydraulic breaker 1, when the chisel 40 is struck with the piston 20, the piston 20 moves upward by the impact repulsion force, and the shock force transmission to the chisel 40 is not stably performed. In addition to this, there is a problem in that vibration and noise are generated through the vibration of the piston 20 .

Such a technology related to the hydraulic breaker is presented in Japanese Utility Model Registration No. 03059016 (March 10, 1999).

An object of the present invention is to provide a piston for a hydraulic breaker capable of maximizing the striking force against the chisel and reducing vibration and shock repulsion generated in the process of striking the chisel.

The present invention is a piston for a hydraulic breaker that is installed inside the cylinder of the hydraulic breaker and ascends and descends by hydraulic pressure and hits the chisel. When the chisel is struck by descending of the piston, it is compressed in the chisel direction by inertia, and the piston is pushed in the chisel direction to increase the striking force against the chisel. It provides a piston for a hydraulic breaker comprising a coil-type elastic spring that elastically supports the compressive elastic body and increases the compression duration of the compressive elastic body compressed in the chisel direction by inertia when the chisel is struck by the descent of the piston.

In addition, the connecting shaft portion is formed such that the outer diameter increases from the upper side to the lower side, the lower rim outer diameter size of the connecting shaft portion is formed smaller than the outer diameter size of the piston, and the upper rim of the connecting shaft portion catches the upper edge of the compressive elastic body A separation prevention end protruding outward to make it possible may be formed.

In addition, a plurality of contact insertion grooves are formed on the outer surface of the connecting shaft portion to be spaced apart from each other by a predetermined interval in the vertical direction, and the contact protrusions may be formed to protrude to be inserted into the contact insertion grooves on the inner circumferential surface of the compressive elastic body.

In addition, the size of the inner diameter of the elastic spring may be formed to increase from the upper side to the lower side of the connecting shaft portion.

In addition, the contact insertion groove may be formed in a tapered shape such that the diameter of the connecting shaft portion increases from the upper side to the lower side of the connecting shaft portion.

In the piston for a hydraulic breaker according to the present invention, when the chisel is struck by the downward movement of the piston by hydraulic pressure inside the cylinder, the compression elastic body and the elastic spring are compressed by the inertial force while transmitting the compressive force to the piston, thereby reducing the contact time between the piston and the chisel. By pushing in the increased state, the striking force through the chisel is increased. Through this, the vibration and shock repulsive force transmitted to the upper end of the piston is reduced when the chisel is struck, and the vibration and shock repulsive force transmitted to the upper end of the piston is absorbed while the compressed elastic body and the elastic spring are elastically restored from the compressed state to the original state. , to minimize the transmission of vibration and shock repelling forces to the excavator arms and booms.

1 is a cross-sectional view of a conventional hydraulic breaker.
2 is a perspective view of a piston for a hydraulic breaker according to an embodiment of the present invention.
3 is an enlarged perspective view of a portion 'A' shown in FIG. 2 .
4 is an exploded perspective view of part 'A' shown in FIG. 2 .
FIG. 5 is a cross-sectional view of part 'A' shown in FIG. 3 .
Figure 6 is a simulation image showing the stress state when hitting the chisel of the piston for a hydraulic breaker according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a perspective view of a piston for a hydraulic breaker according to an embodiment of the present invention, FIG. 3 is an enlarged perspective view of part 'A' shown in FIG. 2, and FIG. 4 is an exploded perspective view of part 'A' shown in FIG. and FIG. 5 is a cross-sectional view of part 'A' shown in FIG. 3 . Referring to FIGS. 2 to 5 , the piston 100 for a hydraulic breaker according to an embodiment includes a connecting shaft portion 110 , a compression elastic body 120 , and an elastic spring 130 . Here, the piston 100 for the hydraulic breaker operates so that the crushed material is crushed by the chisel by striking the chisel while performing a reciprocating operation by hydraulic pressure inside the cylinder. At this time, the hydraulic breaker has the same configuration as that of the prior art, and a description of the configuration of the hydraulic breaker is omitted here. In addition, an oil pocket 101 having a concave-convex shape for allowing oil to stay so as to form an oil film when the piston 100 is moved up and down inside the cylinder may be formed on the outer circumferential surface of the piston 100 according to an embodiment.

When the lower end of the piston 100 hits the chisel while raising and lowering the piston 100 in the cylinder by hydraulic pressure, the connecting shaft 110 is a compression elastic body 120 and an elastic spring 130, which will be described later. It is a shaft portion that is transmitted to the piston (100). That is, the connecting shaft portion 110 supports the compression elastic body 120 and the elastic spring 130 to be connected and disposed on the upper side of the piston 100 , and the compression elastic body 120 and the elastic spring according to the chisel strike of the piston 100 . 130 is stably compressed, and after a certain time elapses, that is, when the magnitude of the inertial force becomes smaller than the magnitude of the elastic restoring force, it is supported so that it can be elastically restored to its original state.

This, the connecting shaft portion 110 is formed to extend in the upper direction of the piston 100 from the upper edge of the piston 100, more specifically, from the center of the upper surface of the piston 100. At this time, the connecting shaft part 110 is formed so that the outer diameter increases from the upper side to the lower side, so that the hydraulic pressure applied to the upper end of the connecting shaft part 110 from the inside of the cylinder is stably transmitted to the piston 100 and by hydraulic pressure When the chisel is struck by the descending of the piston 100, the compressive force is transmitted to the connecting shaft 110 in a dispersed state during compression of the compressive elastic body 120 and the elastic spring 130 according to the inertia in the direction of the connecting shaft portion. In a state in which a decrease in durability of 110 is prevented, the striking force transmission of the chisel through the piston 100 is stably made.

And, the lower edge outer diameter size of the connecting shaft part 110 is formed smaller than the outer diameter size of the piston 100, so that the lower end of the compression elastic body 120 is placed in a seating state on the upper edge surface of the piston 100 while the piston When the chisel is struck by the descending of 100, the compression of the elastic elastic body 120 according to the inertia is stably made, and the compressive force of the compressed elastic body 120 is also stably transmitted in the descending direction of the piston 100 while the piston (100) to ensure that the transmission and compression force transmission of the chisel through the stably. At this time, when the compression elastic body 120 is compressed while the lower part of the compressive elastic body 120 is partially caught on the upper edge surface of the piston 100, the compressive elastic body 120 is separated from the upper part of the piston 100 A locking insertion groove 102 may be formed to prevent it from doing so. In addition, the separation prevention end 111 formed to protrude outward in a direction perpendicular to the connecting shaft part 110 from the upper edge of the connecting shaft part 110 is formed on the upper edge of the connecting shaft part 110 . The separation prevention end 111 is engaged with the upper edge portion of the compressive elastic body 120 inserted and disposed on the outside of the connecting shaft part 110, and the compressive elastic body 120 and the elastic spring 130 are connected to the connecting shaft part 110 ) to prevent separation from the connecting shaft part 110 when elastically restored from the compressed state to the original state in a state inserted and disposed on the outside.

In addition, a contact insertion groove 112 is formed around the outer surface of the connecting shaft portion 110 . A plurality of the contact insertion grooves 112 are formed to be spaced apart from each other by a predetermined distance in the vertical direction of the connecting shaft portion 110 , that is, in the axial direction of the connecting shaft portion 110 . In addition, the contact insertion groove 112 is formed in a tapered shape such that the outer diameter of the connecting shaft portion 110 increases from the upper side to the lower side of the connecting shaft portion 110 . As such, the contact insertion groove 112 is formed in a tapered shape to increase the contact area with the inner circumferential surface of the compressive elastic body 120 and the compressive elastic body 120 is inserted into the connecting shaft part 110 in a stable and fixed state. . Therefore, the contact insertion groove 112 allows the compression force to be stably distributed and transmitted to the piston 100 through the connecting shaft part 110 when the compression elastic body 120 and the elastic spring 130 are compressed, and the compression elastic body 120 is It also serves to support the inner circumferential surface of the compressed elastic body 120 so that it can be stably restored to its original state after compression. In addition, the contact insertion groove 112 enables the corresponding insertion of the contact protrusion 121 formed on the inner circumferential surface of the compressed elastic body 120 , and the inner surface of the compressed elastic body 120 is on the outer surface of the connecting shaft portion 110 . A stable coupling is made in the inserted state. In this way, when the contact insertion groove 112 of the connecting shaft part 110 and the contact protrusion 121 of the compressive elastic body 120 are disposed to correspond to each other, the inner circumferential surface of the compressive elastic body 120 is on the outer circumferential surface of the connecting shaft part 110 When the chisel strikes by the descent of the piston 100 while maintaining a constant position, the compression force to the connecting shaft part 110 through the compressive elastic body 120 is distributed and transmitted, and damage due to the stress concentration of the connecting shaft part 110 occurs. make it possible to prevent

In addition, an absorption insertion groove 113 is formed in the center of the upper surface of the connecting shaft 110 to extend inward in the axial direction. In addition, an auxiliary absorption member 114 having an elastic force may be inserted into the absorption insertion groove 113 . The auxiliary absorbing member 114 is formed of rubber or synthetic resin having ductility and elasticity, so that when the chisel is struck by the descending of the piston 100, a compression force through compression by an inertial force is applied to the piston 100 from the connecting shaft portion 110. ) direction, and after a certain period of time has elapsed, it is restored to its original state by the shock and repulsive force transmitted to the piston 100, thereby reducing vibration and noise.

The compressive elastic body 120 moves the piston 100 downward by hydraulic pressure and is compressed when the lower side of the piston 100 hits the chisel while in contact with the chisel. It is a part that primarily absorbs the vibration and shock repulsion generated from the blow of the chisel while increasing the striking force against the chisel. That is, when the compression elastic body 120 hits the chisel by the downward movement of the piston 100 by hydraulic pressure, it is compressed in the chisel direction through the inertial force and transmits the compressive force to the upper end of the piston 100, and through this, the piston 100 Push in the direction of the chisel to increase the contact time with the chisel. As such, the compressive elastic body 120 increases the contact time between the piston 100 and the chisel when the chisel is struck with the piston 100 to increase the striking force against the chisel and reduces the impact and repulsive force generated from the piston 100 make it In addition, the compressed elastic body 120 is transferred from the lower end to the upper end of the piston 100 while elastically restoring the original state when a certain time has elapsed in the compressed state, that is, when the magnitude of the inertia force becomes smaller than the magnitude of the elastic restoring force. It absorbs and reduces vibration and shock repulsion forces. In this way, when the vibration and shock repulsion transmitted to the upper end of the piston 100 are reduced, the distance between the outer surface of the piston 100 and the inner wall of the cylinder is stably maintained so that the oil pocket 101 on the outside of the piston 100 is The piston 100 stably moves up and down inside the cylinder while preventing damage to the inner wall due to the contact between the formed part and the inner wall of the cylinder and forming an oil film through the oil.

This, the compressive elastic body 120 is compressed by the inertial force when the chisel is hit with the piston 100, and is coupled and installed on the outside of the connecting shaft part 110 so that the compression force can be transmitted in the piston 100 direction. . Here, the compression elastic body 120 is compressed by the inertial force when the chisel is struck by the downward movement of the piston 100, and then elastically restored to its original state after a certain time has elapsed. It can be formed of soft rubber or synthetic resin. have.

And, the compressive elastic body 120 has a tube shape with both ends open so that it can be inserted and disposed on the outside of the connecting shaft part 110 . At this time, the inner circumferential surface of the compressive elastic body 120 is formed so that the inner diameter size increases from the upper side to the lower side so that it can be inserted and coupled to correspond to the outer surface of the connecting shaft part 110 . In addition, a plurality of contact protrusions 121 are formed to protrude to be inserted into the contact insertion groove 112 of the connecting shaft part 110 on the inner circumferential surface of the compressive elastic body 120 , so that the compressive elastic body 120 and the elasticity to be described later When the spring 130 is compressed, the compression force transmission to the piston 100 through the connecting shaft part 110 is stably transmitted, and when the compressive elastic body 120 is elastically restored, a separation prevention end on the outer circumferential surface of the connecting shaft part 110 . While blocking the concentration of stress to (111), it prevents damage to the part of the escape prevention end 111 from occurring.

In addition, a step-shaped multi-end portion 122 may be formed on the outer circumferential surface of the compressive elastic body 120 from the upper side to the lower side. This, the multi-end portion 122 has a different elastic force with respect to the upper side to the lower side of the compressive elastic body 120, regardless of the position from the upper side to the lower side of the compressive elastic body 120, the compressive force of the compressive elastic body 120 is connected to the shaft portion 110 ), while enabling a stable fixation through the operator's grip or a separate jig means (not shown), and facilitates installation on the outside of the connecting shaft part 110 .

The elastic spring 130 is a part that elastically supports the compression elastic body 120 . In addition, when the elastic spring 130 moves the piston 100 downward by hydraulic pressure and hits the chisel while the lower side of the piston 100 comes into contact with the chisel, it is compressed and elastically restored to its original state after a certain period of time has elapsed. In addition to increasing the striking force against the chisel, it is a part that secondaryly absorbs the vibration and shock repulsive force generated from the striking of the chisel. That is, the elastic spring 130 is compressed in the chisel direction through the inertial force when the chisel is struck by the downward movement of the piston 100 by hydraulic pressure like the compressed elastic body 120 described above. In this way, the piston 100 is pushed in the direction of the chisel to increase the contact time with the chisel. As such, the elastic spring 130 increases the compression duration of the compressed elastic body 120 compressed in the chisel direction when the chisel is struck by the piston 100, thereby further increasing the contact time between the piston 100 and the chisel. In addition to increasing the striking force against the chisel, the impact repulsive force generated from the piston 100 is reduced. In addition, the elastic spring 130 is transferred from the lower end to the upper end of the piston 100 while elastically restoring motion to the original state after a certain time has elapsed in the compressed state, that is, when the magnitude of the inertia force becomes smaller than the magnitude of the elastic restoring force. It absorbs and reduces vibration and shock repulsion forces.

Such, the elastic spring 130 is compressed by the inertial force when the chisel is hit with the piston 100, and the compression elastic body 120 is disposed on the outside of the connecting shaft part 110 so that the compression force can be transmitted to the piston 100. It is installed in the state of being inserted into the inside of the More preferably, the elastic spring 130 is molded in an integral state in a state in which the compression elastic body 120 is placed on the mold when the compression elastic body 120 is molded by a mold so that it is coupled and disposed inside the compression elastic body 120 in an integral state. .

Here, the elastic spring 130 has a coil-type spring structure so that it can be disposed in a state surrounding the outside of the connecting shaft portion 110 . In addition, the elastic spring 130 is formed to increase in inner diameter from the upper side to the lower side of the connecting shaft part 110 when the connecting shaft part 110 is inserted. In this way, the elastic spring 130 is formed to have an inner diameter that increases from the upper side to the lower side with respect to the longitudinal direction of the connecting shaft part 110, and through this, the elastic force becomes weaker toward the lower side of the connecting shaft part 110. , by making the compression time through the compressive elastic body 120 longer from the upper part to the lower part, when the chisel strikes with the downward movement of the piston 100 by hydraulic pressure, it is compressed by the inertial force while providing a stable compressive force at the upper end of the piston 100 to increase the striking force against the chisel.

In this way, the compression elastic body 120 and the elastic spring 130 are compressed by the inertial force when the chisel strikes through the downward movement of the piston 100 by hydraulic pressure. By transmitting the compressive force in the downward direction, the striking force against the chisel is increased. In addition, the compression elastic body 120 and the elastic spring 130 increase the contact time between the piston 100 and the chisel through the compression force generated when the chisel strikes through the downward movement of the piston 100 by hydraulic pressure to increase the piston 100. It is possible to absorb the vibration and shock repulsion transmitted to the upper end of the piston 100 when the chisel strikes while reducing the transmission of the shock repulsive force to the upper end and elastically restoring it from the compressed state to the original state. At this time, the compression elastic body 120 and the elastic spring 130 have different specific gravity, that is, the specific gravity of the elastic spring 130 made of metal is higher than the specific gravity of the compression elastic body 120 having ductility. energy also increases. Therefore, when the chisel is hit with the piston 100, different compressive forces of the compressive elastic body 120 and the elastic spring 130 by inertial force are transmitted from the upper end to the lower end of the piston 100 through the connecting shaft part 110, respectively. While making it possible to stably increase the blow of the chisel by the piston 100 .

In addition, the piston for a hydraulic breaker according to an embodiment may be provided with an auxiliary compression member (not shown) in the form of a ring having elasticity inserted outside the compression elastic body 120 . This auxiliary compression member prevents the compression elastic body 120 from bursting while supporting the outer circumferential surface of the compressive elastic body 120 when the compressive elastic body 120 and the elastic spring 130 are compressed, and the compressive elastic body 120 is connected. It makes it possible to maintain a stable fixed state so as not to depart from the shaft 110 . In addition, the auxiliary compression member stably transmits the compression force in the direction of the piston 100 when the compression elastic body 120 and the elastic spring 130 are compressed, and stably applies the striking force to the chisel when hitting the chisel with the piston 100 . make it possible to increase Here, the auxiliary compression member makes it possible to easily install the compression elastic body 120 to the outside, and the compression and restoration of the compression elastic body 120 and the elastic spring 130 to the original state can be stably performed on one side. It may have a structure in which an opening connecting the outside is formed.

Figure 6 is a simulation image showing the stress state when hitting the chisel of the piston 100 for a hydraulic breaker according to an embodiment, the piston 100 moving downward by hydraulic pressure hits the chisel, and the chisel hits the chisel with a thickness of 500t It is time to hit the plate (iron plate). At this time, when the piston 100 hits the chisel, the piston 100 loses kinetic energy and receives compressive stress. At this time, the piston 100 is separated from the chisel for 1/1000 second, has a stop time of 3/1000 second, and the compression duration due to the inertia of the compression elastic body 120 and the elastic spring 130 has 1/30 second do. The compression due to the inertia of the compression elastic body 120 and the elastic spring 130 is continuously compressed even during the secondary compression time of the piston 100 generated due to the compression repulsion of the chisel, and the piston 100 and the chisel are separated. It prevents vibration due to the impact and repulsive force of the piston 100 while preventing it from becoming, and increases the striking force of the chisel. In this way, it can be seen that by reducing the impact repulsive force transmitted to the piston 100, the impact transmitted to the arm and the boom of the excavator can also be reduced.

As described above, the absorption action of vibration and shock repulsive force generated when the chisel strikes of the piston for a hydraulic breaker according to an embodiment configured as described above will be described.

First, when the piston 100 moves downward by hydraulic pressure, the lower end of the piston 100 hits the upper end of the chisel.

At this time, the compressive elastic body 120 and the elastic spring 130 press the piston 100 downward in a compressed state by the inertial force, and thereby increase the contact time between the lower end of the piston 100 and the chisel to remove the chisel. Increases striking power through

Due to this, the vibration and impact repulsive force transmitted from the chisel to the piston 100 is first reduced, and the vibration and impact repulsive force transmitted to the connecting shaft part 110 is elastic to the original state of the compressive elastic body 120 and the elastic spring 130 . Secondary absorption of vibration and shock repelling forces during the restoration motion makes it possible to reduce the transmission of vibration and shock repelling forces to the excavator arm and boom.

As such, the piston for a hydraulic breaker of one embodiment is a piston 100 while the compression elastic body 120 and the elastic spring 130 are compressed by the inertial force when the chisel strikes by the downward movement of the piston 100 by hydraulic pressure inside the cylinder. ), the piston 100 is pushed in a state in which the contact time with the chisel is increased, thereby increasing the striking force through the chisel. Through this, the vibration and shock repulsive force transmitted to the upper end of the piston 100 is reduced when the chisel strikes, and the vibration and shock repulsive force transmitted to the upper end of the piston 100 is compressed by the compressive elastic body 120 and the elastic spring 130. It is absorbed while elastically restoring motion from the state to the original state, and the transmission of vibration and shock repulsive force to the excavator arm and boom is minimized.

Although the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the true technical protection scope of the present invention should be defined by the technical spirit of the appended claims.

100: piston 101: oil pocket
102: engaging insertion groove 110: connecting shaft portion
111: separation prevention end 112: contact insertion groove
113: absorption insertion groove 114: auxiliary absorption member
120: compressed elastomer 121: contact protrusion
122: multi-end 130: elastic spring

Claims (5)

In the piston for a hydraulic breaker installed inside the cylinder of the hydraulic breaker, lifting and lowering by hydraulic pressure to hit the chisel,
a connecting shaft portion extending upwardly from the upper end of the piston;
a soft compressive elastic body inserted and installed on the outside of the connecting shaft portion and for increasing the striking force against the chisel by pushing the piston in the chisel direction while being compressed in the chisel direction by inertia when the chisel is struck by the descending of the piston; and
Coil for increasing the compression duration of the compressed elastic body that is compressed in the chisel direction due to inertia when the chisel is struck by the descent of the piston and installed inside the compressive elastic body to be disposed on the outside of the connecting shaft part. Piston for hydraulic breaker including; elastic spring of the type. The method according to claim 1,
The connecting shaft portion is formed such that the outer diameter increases from the upper side to the lower side,
The outer diameter of the lower edge of the connecting shaft is formed smaller than the outer diameter of the piston,
A piston for a hydraulic breaker in which a separation prevention end protruding outward to catch the upper end of the compression elastic body is formed on the upper edge of the connecting shaft portion. The method according to claim 1 or 2,
A plurality of contact insertion grooves are formed on the outer surface of the connecting shaft portion to be spaced apart from each other at regular intervals in the vertical direction,
A piston for a hydraulic breaker in which a contact protrusion is formed so as to be inserted into the contact insertion groove corresponding to the contact insertion groove on the inner circumferential surface of the compressed elastic body. The method according to claim 1,
The size of the inner diameter of the elastic spring is a piston for a hydraulic breaker formed to increase from the upper side to the lower side of the connecting shaft. 4. The method according to claim 3,
The contact insertion groove is a piston for a hydraulic breaker formed in a tapered shape so that the diameter of the connecting shaft portion increases from the upper side to the lower side of the connecting shaft portion.

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