KR20050046529A - A hydraulic breaker housing, having hydraulic breaker and manufacturing method thereof - Google Patents

Abstract

The disclosed hydraulic breaker housings each comprise a hollow backhead, a cylinder and a fronthead, wherein at least one of them is a casting of Ostemperite nodular cast iron. Since the hydraulic brake housing is made of casted main parts, the product is not only lighter but also eliminates the need for difficult forging, thereby significantly reducing the production cost, and in particular, the tensile strength and Wear resistance can be significantly improved.

Description

A hydraulic breaker housing, having a hydraulic breaker housing provided with the hydraulic breaker housing and a method for manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic breaker housing, a hydraulic breaker equipped with the hydraulic breaker housing, and a manufacturing method thereof, and particularly, a hydraulic breaker housing suitable for a place where strong tensile strength and toughness are required, and a hydraulic breaker housing thereof. A hydraulic breaker provided with a housing and a method of manufacturing the same.

In general, the hydraulic breaker is a device mounted on the end of the excavator for excavating soil or rock, and is a work tool for performing excavation by directly impacting the ground. The hydraulic breaker, however, impacts the ground and receives external force from the ground. Therefore, in order to increase the resistance against external force, a hydraulic breaker housing having high tensile strength and elongation is required.

Such a hydraulic breaker housing is typically manufactured by a forging method using low carbon chromium molybdenum steel (SCM415, SCM420) and high carbon chromium molybdenum steel (SCM440, etc.) as materials. Thus, the hydraulic breaker housing has been made by tapping the appearance into the shape desired by the manufacturer.

 1 is a perspective view of a hydraulic breaker including a conventional hydraulic breaker housing manufactured by such a forging method, Figure 2 is a cross-sectional view of the cylinder according to the line I-I of FIG.

Referring to the drawings, the hydraulic breaker housing 180 provided in the hydraulic breaker 100 is a back head (110), the cylinder (cylinder) 120 and the front head (130), each of which is hollow Include. They are forged low-carbon chromium molybdenum steels, which are carburized, quenched, or tempered by more than 50% of its weight after cutting to improve wear resistance on the surface, give toughness to the core, and then deform due to heat treatment. It was used supplementally in the final polishing process.

 However, since the hydraulic breaker housing 180 having such a structure must be made by machining more than 50% of the weight, the machining is difficult and takes a long time. In particular, a bolt hole 150 for coupling the back head 110, the cylinder 120, and the front head 130 to a bolt (not shown) should be made at each corner. When using a forged material such as molybdenum, the machining of the bolt hole 150 is very difficult and takes a lot of processing time. In addition, it is not easy to produce a constant length and diameter, the inner peripheral surface of the cylinder 120 has a problem that a lot of difficulty of polishing because shrinkage and distortion occurs during heat treatment. Therefore, there is a demand for a solution to such a problem.

The present invention has been made in view of the above necessity, and an object thereof is to provide an improved hydraulic breaker housing, a hydraulic breaker, and a method of manufacturing the same, which can simplify the manufacturing process, lighten the product, and improve durability.

The hydraulic breaker housing of the present invention for achieving the above object comprises a hollow backhead, a cylinder and a fronthead, respectively, wherein at least one of the backhead, the cylinder and the fronthead is a casting.

In addition, the hydraulic breaker according to the present invention is a hydraulic breaker having a hollow backhead, a hydraulic breaker housing including a cylinder and a front head and a piston embedded in the hydraulic breaker housing, wherein the backhead and the At least one of the cylinder and the fronthead is characterized in that the casting.

In addition, the method of manufacturing a hydraulic breaker housing according to the present invention, in manufacturing a housing of a hydraulic breaker comprising a back head each of which is hollow, and a cylinder and a front head, at least one of the back head, the cylinder and the front head Making into a casting; And combining the backhead, the cylinder and the fronthead.

In addition, the hydraulic breaker manufacturing method according to the present invention is a hydraulic breaker manufacturing method comprising a back brake that is hollow each, a hydraulic breaker housing including a cylinder and a front head and a piston embedded in the hydraulic breaker housing, the bag Casting at least one of a head, the cylinder and the front head; Coupling the backhead, the cylinder and the fronthead; And coupling the piston with the coupled hydraulic breaker housing.

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

Figure 3 shows a perspective view of a hydraulic breaker with a hydraulic breaker housing according to the present invention, Figure 4 shows a cross-sectional view of the cylinder along the line II-II of FIG.

As shown, the hydraulic breaker housing 280 of the hydraulic breaker 200 of the present invention includes a hollow backhead 210, a cylinder 220 and a fronthead 230, each of which is at least one of these three parts. One is made of cast material instead of demanding forged materials. In this embodiment, in particular, the center cylinder 220 is manufactured by casting. Of course, if necessary, the back head 210 and the front head 230 may also be manufactured by the same casting method. The detailed manufacturing method by this casting is mentioned later. In addition, the back head 210, the cylinder 220 and the front head 230 is formed with a bolt hole 250 for fastening them integrally. That is, a through bolt (not shown) fastens the back head 210, the cylinder 220, and the front head 230 integrally through the bolt hole 250. In particular, the bolt hole of the cylinder 220 is preferably formed in the central diameter is 1 ~ 20mm larger than the diameter of both ends. In this case, the processing is easy and the processing time can be reduced, and also the distortion or shrinkage occurring during the heat treatment can be reduced. In addition, since the inner circumferential surface of the cylinder 220 is in contact with a piston 240, frictional force is generated during linear reciprocation of the piston 240. Therefore, in the case of using a conventional forged material to improve the wear resistance of the inner circumferential surface of the cylinder 220 was subjected to a post-heat treatment for the surface hardening treatment of the inner circumferential surface portion, in the present invention will be described in more detail later, cast nodular cast iron It is used as a material, and the austempering heat treatment is used to make the base structure a large amount of bainite spheroidal graphite cast iron as a material of the cylinder, which significantly reduces the heat treatment deformation, thereby reducing the difficulty of post-polishing work. Improved. In other words, the austenite nodular cast iron has more than 30% of retained austenite (austenite) in the bainite matrix, the residual austenite is a compressive stress in the friction surface of the piston 240 and the cylinder 220 Due to the transformation into martensite (martensite), the strength is stronger and wear resistance is improved. In addition, since graphite itself, which is distributed in a large amount in the ost-tempered nodular cast iron, has abrasion resistance, it is possible to obtain an effect comparable to that of surface hardening treatment on an existing forged material. In addition, when higher wear resistance is required in some products, it is preferable to perform high frequency surface hardening treatment, nitriding treatment, and low temperature oil soaking treatment on the inner circumferential surface portion of the cylinder 220.

The hydraulic breaker is made by installing a piston hitting an object while vertically reciprocating in the interior of the hydraulic breaker housing as described above.

Hereinafter, a process of casting the hydraulic breaker housing of the present invention will be described.

First of all, the metal used as the casting material is osstem spheroidal graphite cast iron, and the components of the osstem spheroidal graphite cast iron are as shown in Tables 1 to 3 below to secure homogenization of the tissue according to the thickness of the product, and the remaining wt% Is made of Fe.

First component of Osstemford Spheroidal Graphite Cast Iron (unit: wt%) ingredient C Si Mn P S Mg Mo Cu 3.3 ~ 3.9 2.5 ~ 3.0 0.3 or less 0.05 or less 0.02 or less 0.02-0.04 0.1-0.8 0.4 ~ 1.5 or Ni0.6 ~ 2.0

       As shown in Table 1, the content of C is suitable 3.3 ~ 3.9wt%. If it is less than 3.3 wt%, castability is inferior, and if it is 3.9 wt% or more, coarse graphite is crystallized and mechanical properties fall. In addition, the Si component exhibits a carbon equivalent together with C, which is preferably 2.5 to 3.0 wt%. As Si% increases to 2.5 ~ 3.0wt%, there is a tendency of coarsening of bainite structure after heat treatment, and the fracture toughness against impact increases, resulting in a ductile wavefront upon fracture. In addition, when the content is more than 3.0wt%, the compound carbon is graphitized to increase the amount of ferrite and decrease in elongation. Mn is an element to increase the strength to less than 0.3wt% sufficient residual austenite can be present, the impact value increases. Cu is added for strength. 1.5 wt% or more deteriorates workability due to excessive increase in strength. Instead of Cu, Ni 0.6 ~ 2.0wt% can be used as a substitute for Cu. Mo, a component that promotes bainite formation and increases strength and uniformity of the matrix structure, is 0.1 to 0.8 wt% or less. If it is out of this range, elongation and impact value decrease, which is not good. P and S are present as impurities and may cause embrittlement of the material, so that the content of each is as small as possible. Mg is a component added for the spheroidization of graphite, 0.02 ~ 0.04wt%. The spheroidization of the nodular graphite cast iron is composed of appropriate components in the melting furnace, ladle inoculation, inoculation treatment in a mold to refine the graphite, and to obtain the maximum graphite strength, the maximum graphite inlet is 95 / mm² or more. Should be increased to. In the state of the raw material having such a component is heat-treated to make the osstem-hard nodular cast iron. Ostemford nodular cast iron is thus economical because it is cheap to manufacture.

Secondary Components of Ostemford Spheroidal Graphite Cast Iron (Unit: wt%) ingredient C Si Mn P S Mg Cu Ni 3.3 ~ 3.9 2.5 ~ 3.0 0.3 or less 0.05 or less 0.02 or less 0.02-0.04 0.4-1.5 0.6 to 2.0

In Table 2, the components of C, Si, Mn, P, S, Mg, and Cu are the same as in Table 1, where 0.6 to 2.0 were added as an essential component in which Ni is not an optional component, and Mo was omitted. Osstemford Spheroidal Graphite Cast Iron made by heat-treatment in the state of material having such a component has little shrinkage expansion and is suitable for making small precision products.

Third component of Ostemford Spheroidal Graphite Cast Iron (unit: wt%) ingredient C Si Mn P S Mg Mo Cu Ni 3.3 ~ 3.9 2.5 ~ 3.0 0.3 or less 0.05 or less 0.02 or less 0.02-0.04 0.1-0.8 0.4-1.5 0.6 to 2.0

In Table 3, the components of C, Si, Mn, P, S, Mg, Mo, Cu are the same as in Table 1, Ni was added as an essential component 0.6 ~ 2.0wt%. Osstemford nodular cast iron produced by heat treatment in the state of a material having such a component can remove segregation of Mo, and can secure sufficient hardenability.

5 is a flow chart illustrating a process of austempering of spheroidal graphite iron which is a casting material of the hydraulic breaker housing according to the present invention.

As shown in the drawing, first, the tissue is maintained at a temperature of 900 to 940 ° C. for 2 to 4 hours to austenite the tissue (S300). At the above temperature, C is diffused from the graphite to the matrix structure. At least 1.0wt% of C is employed in the matrix structure to obtain bainite structure supersaturated with C after heat treatment. If the temperature is lower than 900 ° C, the diffusion of C from graphite is slowed and the solid solution limit is reduced. In addition, when it is 940 degreeC or more, it becomes too coarse structure, toughness falls and it is not good to become weak to an impact. At a temperature of 900 to 940 ° C., the diffusion of C is sufficient to obtain a bainite structure in which C is supersaturated after heat treatment. At this time, to improve the fatigue strength of the surface of the product to maintain the C wt% in the furnace atmosphere of 1.0wt% or more. If the C wt% of the furnace atmosphere is 1.0 wt% or less, decarburization occurs on the surface of the product, and the fatigue strength is lowered. When the wt wt% is more than 1.4 wt%, carbides may grow in the matrix structure.

Subsequently, quenching is started by immersing the heated product in a salt bath (NaNO₂50wt% + KNO₃50wt%) maintained at a temperature of 250-350 ° C. (S310). At this time, the salt bath is provided with a stirrer capable of sufficiently stirring the salt bath to be able to quickly remove the latent heat in the center of the product to suppress the formation of partial pearlite tissue.

In the above operation, the product temperature is quickly lowered and the temperature of the salt bath is raised to a temperature of 350 to 390 ° C. to maintain 1.5 to 2.5 hours to complete the constant temperature transformation process (S320).

Here, integrating the quenching step (S310) and constant temperature transformation step (S320), that is, soak the product at a suitable temperature between 250 ~ 390 ℃ to cool the salt bath so that the temperature in the salt bath does not rise, 1.5 to 2.5 hours To complete the constant temperature transformation process.

At this time, the elongation increases as the constant temperature transformation temperature increases from 300 ° C. to 390 ° C., and as the temperature decreases, the elongation decreases, whereas the strength increases. If the holding time is shorter or longer than 1.5 ~ 2.5 hours, the elongation decreases. This is the result of a decrease in the amount of retained austenite in the tissue.

After completing the constant temperature transformation process (S320), the product is cooled to room temperature in the air (S330). This process leads to the formation of Austenford nodular cast iron with bainite structure. Osstemford spheroidal graphite cast iron manufactured by the above manufacturing method has high tensile strength and excellent elongation, and also reduces warping and cracking, so that it can be used as a substitute for forging or rolled products, and it is possible to reduce cost and light weight of the product.

The following shows the component ratios and mechanical properties of the low carbon chromium molybdenum steel (SCM415, etc.) and the high carbon chromium molybdenum steel (SCM440, etc.) and the casting material of osmolded nodular cast iron.

Alloying elements in forged materials for cylinders, backheads and frontheads (unit: wt%) Ingredients C Si Mn P S Cr Mo SCM415 0.13 ~ 0.18 0.15-0.35 0.6-0.85 0.03 or less 0.03 or less 0.9-1.2 0.15-0.3

Mechanical properties after heat treatment of materials such as Table 4 division Heat treatment method Tensile Strength (㎏ / ㎜²) Yield strength (㎏ / ㎜²) Elongation (%) Hardness (HB) 18T center 930 ℃ 4 hours carburizing, 850 ℃ 0.5 hours oil quenching, 180 ℃ 2 hours tempering 97.1 76.8 14.5 284 50T center Same as above 87.9 69.6 15.6 258

Alloying component of forged material for back head and front head (unit: wt%) Ingredients C Si Mn P S Cr Mo SCM440 0.38-0.43 0.15-0.35 0.6-0.85 0.03 or less 0.03 or less 0.9-1.2 0.15-0.3

Mechanical properties after heat treatment of materials such as Table 6 division Heat treatment method Tensile Strength (㎏ / ㎜²) Yield strength (㎏ / ㎜²) Elongation (%) Hardness (HB) 18T center 850 ℃ 2hr oil quenching, 600 ℃ 2hr tempering 100.4 78 12 294 50T center Same as above 94.5 73.5 13.5 275

First component of nodular cast iron material (unit: wt%) ingredient C Si Mn P S Mg Mo Cu 18T component 3.50 2.70 0.30 0.02 0.015 0.03 0.24 0.56 50T component 3.45 2.75 0.250 0.015 0.012 0.025 0.36 0.95

Mechanical Properties of Spherical Graphite Cast Iron First Component Tensile Strength (㎏ / ㎜²) Yield strength (㎏ / ㎜²) Elongation (%) Hardness (HB) Ferrite amount (%) Pearlite amount (%) Nodularity (%) 18T 71.20 43.10 6.2 261 20 80 85 50T 75.30 47.90 5.1 270 18 82 85

After austenitizing the nodular cast iron consisting of Table 8 for 3 hours at 925 ℃ Salt bath temperature Tensile Strength (㎏ / ㎜²) Yield strength (㎏ / ㎜²) Elongation (%) Hardness (HB) Organization 18T center After quenching at 340 ℃, kept at 375 ℃ for 2 hours 110 87 14 303 Bainite 50T center Same as above 116 92.5 12.8 312 Same as above

Second Component of Spheroidal Graphite Cast Iron Material (Unit: wt%) ingredient C Si Mn P S Mg Cu Ni 18T component 3.40 2.80 0.17 0.015 0.009 0.030 0.68 1.45 50T component 3.30 2.65 0.14 0.018 0.005 0.020 0.73 1.43

Mechanical Properties of Spheroidal Graphite Cast Iron Second Component Tensile Strength (㎏ / ㎜²) Yield strength (㎏ / ㎜²) Elongation (%) Hardness (HB) Ferrite amount (%) Pearlite amount (%) Nodularity (%) 18T 72.60 46.40 5.2 249 24 76 85 50T 70.20 44.50 5.5 241 25 75 85

After the austenitization of spheroidal graphite cast iron (Table 11) at 925 ° C for 3 hours Salt bath temperature Tensile Strength (㎏ / ㎜²) Yield strength (㎏ / ㎜²) Elongation (%) Hardness (HB) Organization 18T center After quenching at 340 ℃, kept at 375 ℃ for 2 hours 102.7 82.9 13.5 298 Bainite 50T center Same as above 107.4 85.6 11.7 302 Same as above

Third component of spheroidal graphite iron material (unit: wt%) ingredient C Si Mn P S Mg Mo Cu Ni 18T component 3.63 2.60 0.21 0.022 0.010 0.03 0.20 0.68 0.9 50T component 3.48 2.58 0.27 0.014 0.012 0.02 0.22 0.69 1.07

Mechanical Properties of the Third Component of Spheroidal Graphite Cast Iron Materials Tensile Strength (㎏ / ㎜²) Yield strength (㎏ / ㎜²) Elongation (%) Hardness (HB) Ferrite amount (%) Pearlite amount (%) Nodularity (%) 18T 73.30 44.20 6.0 258 25 75 85 50T 71.60 43.90 6.2 255 25 75 85

After austenitizing the nodular cast iron consisting of Table 14 for 3 hours at 925 ° C Salt bath temperature Tensile Strength (㎏ / ㎜²) Yield strength (㎏ / ㎜²) Elongation (%) Hardness (HB) Organization 18T center After quenching at 340 ℃, kept at 375 ℃ for 2 hours 108 85 12.5 309 Bainite 50T center Same as above 107 84.3 11.7 309 Same as above

Comparing Table 5 with Tables 10, 13, and 16 above, the heat treatment of the spheroidal graphite cast iron, which is a casting material, is higher than that of the conventional forged material, and the tensile strength is higher, and the elongation is slightly lower, but the product has no problem. It can be seen that it is suitable for use as a material of the back head 210, the cylinder 220 and the front head 230 because it can be seen that there is no level. Therefore, in the present embodiment, the cylinder 220 is cast using the Osstemford spherical graphite cast iron, and the back head 210 and the front head 230 are bolted through the bolt hole 250. The hydraulic breaker housing 280 is completed by integrally fastening. On the other hand, as described above, not only the cylinder 220 but also the back head 210 and the front head 230 may be cast with the same material and then fastened with bolts to complete the hydraulic breaker housing 280. .

The hydraulic breaker 200 may be completed by coupling the piston 240 to the inside of the hydraulic breaker housing 280 that is cast and combined by the above materials.

As described above, since the hydraulic breaker housing and the hydraulic breaker of the present invention are manufactured by a casting method made of cast iron made of Au-Stempard nodular cast iron, the product is lighter, the processing area is reduced, and the production cost is drastically reduced. Tensile strength, elongation and wear resistance can also be secured.

It is to be understood that the invention is not limited to that described above and illustrated in the drawings and that many more modifications and variations are possible within the scope of the following claims.

1 is a perspective view of a hydraulic breaker equipped with a conventional hydraulic breaker housing,

FIG. 2 is a sectional view of a cylinder taken along line II of FIG. 1;

3 is a perspective view of a hydraulic breaker having a hydraulic breaker housing according to an embodiment of the present invention;

4 is a sectional view of a cylinder taken along line II-II of FIG.

5 is a flow chart showing an ostempering process of nodular cast iron according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

200 ... Hydraulic breaker 210 ... Backhead

220 ... Cylinder 230 ... Fronthead

240 ... piston 250 ... bolt hole

280 ... hydraulic breaker housing

Claims (27)

A hydraulic breaker housing comprising a hollow backhead and a cylinder and a fronthead, respectively, And at least one of said backhead, said cylinder and said fronthead is a casting. The method of claim 1, The casting is a hydraulic breaker housing, characterized in that the nodular graphite cast iron. The method of claim 2, The spheroidal graphite cast iron is an hydraulic breaker housing, characterized in that the osstem spheroidal graphite cast iron is made of bainite structure by performing an ostempering heat treatment. The method of claim 2, The nodular cast iron is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Mo 0.1 ~ 0.8wt% , 0.4 to 1.5wt% Cu and 0.6 to 2.0wt% Ni, and the remaining wt% is a hydraulic breaker housing, characterized in that the Ostemford Spheroidal Graphite Cast Iron is Fe. The method of claim 2, The nodular cast iron is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Cu 0.4 ~ 1.5wt% , Ni 0.6 ~ 2.0wt% and the rest wt% is a hydraulic breaker housing, characterized in that the Osstemford spheroidal graphite iron is Fe. The method of claim 2, The nodular cast iron is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Mo 0.1 ~ 0.8wt% , Cu 0.4 ~ 1.5wt%, Ni 0.6 ~ 2.0wt% and the rest wt% is a hydraulic breaker housing, characterized in that the Osstemford spheroidal graphite cast iron is Fe. The method according to any one of claims 2 to 6, In the cylinder, a plurality of bolt holes are formed at each corner of the cylinder for fastening with the back head and the front head, and the central diameter of the bolt hole is larger than the diameter of both ends of the bolt hole. Hydraulic breaker housing. The method of claim 7, wherein The central diameter of the bolt hole is a hydraulic breaker housing, characterized in that formed 1 ~ 20mm larger than both ends of the bolt hole. A hydraulic breaker having a hollow backhead, a hydraulic breaker housing including a cylinder and a front head, and a piston embedded in the hydraulic breaker housing, And at least one of said backhead, said cylinder and said fronthead is a casting. The method of claim 9, The casting is a hydraulic breaker, characterized in that the nodular graphite cast iron. The method of claim 10, The nodular cast iron is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Mo 0.1 ~ 0.8wt% , Any one of 0.4 ~ 1.5wt% Cu and 0.6 ~ 2.0wt% Ni, and the remaining wt% is a hydraulic breaker, characterized in that the Ostemford Spheroidal Graphite Cast Iron is Fe. The method of claim 10, The nodular cast iron is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Cu 0.4 ~ 1.5wt% , Ni 0.6 ~ 2.0wt% and the rest wt% is a hydraulic breaker, characterized in that the Osstemford spheroidal graphite iron is Fe. The method of claim 10, The nodular cast iron is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Mo 0.1 ~ 0.8wt% , Cu 0.4 ~ 1.5wt%, Ni 0.6 ~ 2.0wt% and the rest wt% is Fe hydraulic Ostempered nodular cast iron, characterized in that the cast iron. The method according to any one of claims 10 to 13, In the cylinder, a plurality of bolt holes are formed at each corner of the cylinder for fastening with the back head and the front head, and the central diameter of the bolt hole is larger than the diameter of both ends of the bolt hole. Hydraulic breaker. The method of claim 14, The central diameter of the bolt hole is a hydraulic breaker, characterized in that formed 1 ~ 20mm larger than both ends of the bolt hole. A method of manufacturing a hydraulic breaker housing comprising a back head, each of which is hollow, and a cylinder and a front head, Casting at least one of the backhead, the cylinder and the fronthead; And And coupling said backhead, said cylinder and said fronthead. The method of claim 16, Hydraulic breaker housing manufacturing method further comprising the step of high-frequency surface hardening treatment, nitriding treatment and low temperature immersion treatment of the inner peripheral surface of the cylinder. The method of claim 16, Metal forming the casting is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Mo 0.1 ~ 0.8 Any one of wt%, 0.4 to 1.5wt% Cu and 0.6 to 2.0wt% Ni, and the remaining wt% is Fe ostium spherical nodular cast iron. The method of claim 16, Metal forming the casting is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Cu 0.4 ~ 1.5 Wt%, Ni 0.6 ~ 2.0wt% and the remaining wt% is a method of manufacturing a hydraulic breaker housing, characterized in that the Osstemford spherical graphite cast iron is Fe. The method of claim 16, Metal forming the casting is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Mo 0.1 ~ 0.8 Wt%, Cu 0.4 ~ 1.5wt%, Ni 0.6 ~ 2.0wt% and the remaining wt% is Fe ostomized spheroidal graphite cast iron manufacturing method characterized in that. The method according to any one of claims 18 to 20, The Osstemford Spheroidal Graphite Cast Iron, (A) austenitic the tissue by heating spheroidal graphite iron at a temperature of 900-940 ° C. for 2-4 hours in an atmosphere of C 1.0-1.4 wt%; (B) quenching the austenitized nodular cast iron in a salt bath (NaNO₂50wt% + KNO₃50wt%) maintained at a temperature of 250-390 ° C., (C) constant temperature transformation step to maintain isothermal 1.5 ~ 2.5 hours in the salt bath, (D) The hydraulic breaker housing manufacturing method characterized in that it is produced by the air-cooling step of cooling the thermostatically treated spheroidal graphite iron in the air. In the method of manufacturing a hydraulic breaker having a hollow backhead, a hydraulic breaker housing including a cylinder and a front head and a piston embedded in the hydraulic breaker housing, Casting at least one of the backhead, the cylinder and the fronthead; Coupling the backhead, the cylinder and the fronthead; And Coupling the piston with the coupled hydraulic breaker housing; hydraulic breaker manufacturing method comprising a. The method of claim 22, Hydraulic breaker manufacturing method characterized in that it further comprises the step of high-frequency surface hardening treatment, nitriding treatment and low temperature immersion treatment of the inner peripheral surface of the cylinder. The method of claim 22, Metal forming the casting is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Mo 0.1 ~ 0.8 Any one of wt%, 0.4 to 1.5wt% Cu and 0.6 to 2.0wt% Ni, and the remaining wt% is Fe ostemford spheroidal graphite cast iron. The method of claim 22, Metal forming the casting is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Cu 0.4 ~ 1.5 wt%, Ni 0.6 ~ 2.0wt% and the rest wt% is Fe ostomized nodular graphite cast iron manufacturing method characterized in that the Fe. The method of claim 22, Metal forming the casting is C 3.3 ~ 3.9wt%, Si 2.5 ~ 3.0wt%, Mn 0.3wt% or less, P 0.05wt% or less, S 0.02wt% or less, Mg 0.02 ~ 0.04wt%, Mo 0.1 ~ 0.8 wt%, Cu 0.4 ~ 1.5wt%, Ni 0.6 ~ 2.0wt% and the remaining wt% is Fe Ostomford Spheroidal Graphite Cast Iron manufacturing method characterized in that the Fe. The method according to any one of claims 24 to 26, The Osstemford Spheroidal Graphite Cast Iron, (A) austenitic the tissue by heating spheroidal graphite iron at a temperature of 900-940 ° C. for 2-4 hours in an atmosphere of C 1.0-1.4 wt%; (B) quenching the austenitized nodular cast iron in a salt bath (NaNO₂50wt% + KNO₃50wt%) maintained at a temperature of 250-390 ° C., (C) constant temperature transformation step to maintain isothermal 1.5 ~ 2.5 hours in the salt bath, (D) The hydraulic breaker manufacturing method characterized in that it is produced by the air-cooling step of cooling the thermostatically treated spheroidal graphite iron in the air.