CN114673787A - A large-sized hydraulic breaker piston and its manufacturing method - Google Patents

Abstract

The invention discloses a large-sized hydraulic breaker piston and a manufacturing method thereof, wherein the large-sized hydraulic breaker piston comprises a piston base body made of high-carbon alloy steel 9CrV, and the piston base body is made by quenching and tempering treatment; The end face is provided with a circular countersunk hole. By cooperating with the corresponding processing and heat treatment process, the invention can balance the strength and toughness of the entire section of the large-sized hydraulic breaker piston, and significantly improve the comprehensive strength of the large-sized hydraulic breaker piston. toughness.

Description

A large-sized hydraulic breaker piston and its manufacturing method

technical field

The invention belongs to the technical field of heavy machinery manufacturing, and in particular relates to a large-sized hydraulic breaker piston and a manufacturing method thereof.

Background technique

As a new type of hydraulic engineering equipment, hydraulic breaker is widely used in the crushing of rock in mines and various large-scale construction projects; and the piston in the impact system of hydraulic breaker is the key component that directly performs work, and it is also the most important part of hydraulic breaker. critical working parts.

For a long time, well-known international rock drilling machinery companies such as Atlas have dominated the market. In the prior art, the pistons in the hydraulic breakers are all made of low-carbon alloy steel after quenching and tempering treatment and then surface strengthening treatment (including carburizing, etc.) It has a long life and is expensive to manufacture.

In recent years, high carbon alloy steel such as GCr15 has been used in China to manufacture the piston of hydraulic breaker, and it has achieved certain market applications.

However, with the upgrading of hydraulic crusher models, the piston size has gradually increased.

In the field application process, the impact end face of the piston made of high carbon alloy steel is prone to chipping and cracking, thus shortening the service life of the hydraulic breaker.

The root cause of the above problems is that the quench hardened layer of high carbon alloy steel is unbalanced with the internal strength and toughness.

For this reason, the present invention designs the special structure and corresponding manufacturing method of the large-sized hydraulic breaker piston by analyzing the reasons for the cracking failure of the steel used for the piston, aiming at the special working environment of the large-sized hydraulic breaker piston; The strength and toughness of the overall cross-section are balanced, which effectively alleviates the sudden change in hardness and toughness caused by the size effect, and significantly improves the comprehensive strength and toughness of the large-sized hydraulic breaker piston.

SUMMARY OF THE INVENTION

The main technical problem to be solved by the present invention is to provide a large-sized hydraulic breaker piston and a manufacturing method thereof.

In order to solve the above-mentioned technical problems, the present invention provides the following technical solutions:

The utility model relates to a large-sized hydraulic breaker piston. The piston includes a piston base body made of high carbon alloy steel 9CrV, and the piston base body is made by quenching and tempering treatment; one end face of the piston base body is provided with a circular countersunk hole.

The following is the further optimization of the present invention to the above-mentioned technical scheme:

The surface hardness of the piston is: 57-63HRC; ultrasonic flaw detection ≤ grade 2.

Further optimization: a first transition section, a second transition section and a third transition section that are integrally connected in sequence are arranged on the outer surface of the piston base near the position with one end surface of the circular counterbore.

The present invention also provides a manufacturing method for preparing the above-mentioned large-size hydraulic breaker piston, the manufacturing method comprising the machining steps:

S1. Blanking: Select high-carbon alloy steel 9CrV that is suitable for manufacturing large-sized hydraulic breaker pistons for production. 9CrV steel needs to be inspected before entering the factory;

S2. Machining is carried out according to the overall size of the piston of the large-sized hydraulic breaker, and finally a blank product is obtained.

The following is the further optimization of the present invention to the above-mentioned technical scheme:

The manufacturing method also includes a tempering step:

T1. Heating: Put the blank product into the heating furnace, and heat it up to 820-850 °C at a heating rate of 5-10 °C/min. The carbon potential protective atmosphere in the heating furnace is maintained at 0.8-1.1%, and then kept for 5 Hour;

T2. Quenching: Put the finished product in the air for pre-cooling for 1min. After the pre-cooling is completed, put it into the quenching medium for quenching. The quenching time is 2.5-4min. 290℃;

T3. Nitrate bath: the quenched blank product is subjected to a nitrate bath, wherein the nitrate bath temperature is 230°C; the nitrate bath holding time is 4 hours;

T4. The first low-temperature tempering: the first low-temperature tempering is performed on the blank product after the nitrate bath treatment, the tempering temperature is 230-300 ° C, the tempering holding time is 4 hours, and the first tempering treatment is completed After cooling to room temperature;

T5. The second low temperature tempering: the first low temperature tempering completed blank product is subjected to the second low temperature tempering, wherein the tempering temperature is 230-350 ° C, the tempering holding time is 4 hours, and the temperature is cooled to room temperature. Finally, a large size hydraulic breaker piston is obtained.

Further optimization: in step 22, after the production of the blank product is completed, the processing standard of the blank product is that the diameter dimensional tolerance is -0.085～-0.075mm; the surface finish is Ra0.2, the outer diameter roundness is 0.003; the cylindricity is 0.003, and the concentricity is The degree is φ0.005.

Further optimization: in the step T1, the heating furnace is a pit furnace, and the furnace loading method is: hanging plate hoisting; the number of furnaces is 4-5 per furnace.

Further optimization: in step T1, when heat preservation is performed, the fluctuation of the heat preservation temperature is ±5°C.

Further optimization: in step T2, the initial temperature of the quenching medium is 20-50°C, and the outlet temperature of the quenching medium is 200-240°C.

Further optimization: in step T2, the quenching medium is brine, and the concentration of the brine is 3%.

The present invention adopts the above-mentioned technical scheme, has ingenious conception and reasonable structure, and solves the problem that the internal and external strength and toughness of large-sized hydraulic breaker pistons are difficult to match by using high carbon steel; , which can balance the strength and toughness of the whole section of the large-sized hydraulic breaker piston, effectively alleviate the phenomenon of sudden changes in hardness and toughness caused by the size effect, and significantly improve the comprehensive strength and toughness of the large-sized hydraulic breaker piston.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Description of drawings

1 is a schematic diagram of the overall structure of an embodiment of the present invention;

2 is a cross-sectional view of a piston base in an embodiment of the present invention;

3 is a side view of the end face of the piston base with a circular counterbore in the embodiment of the present invention;

4 is a schematic diagram of the tensile properties of Comparative Examples 1-3 of the present invention;

Figure 5 is a schematic diagram of the tensile properties of Examples 1-3 of the present invention;

Fig. 6 is the hardness comparison diagram of comparative example 1-3 of the present invention and embodiment 1-3;

Fig. 7 is the comparison diagram of impact absorption energy of Comparative Example 1-3 of the present invention and Example 1-3;

Fig. 8 is the residual stress diagram of the comparative examples 1-3 of the present invention

FIG. 9 is a residual stress diagram of Examples 1-3 of the present invention.

In the figure: 1-piston base; 2-circular counterbore; 3-first transition segment; 4-second transition segment; 5-third transition segment.

Detailed ways

Embodiment 1: Please refer to Figures 1-3, a large-sized hydraulic breaker piston, including a piston base 1, the overall structure of the piston base 1 is cylindrical, and one end surface of the piston base 1 is provided with a circular shape. Counterbore 2.

The piston base 1 is made of high carbon alloy steel, and the specific model of the high carbon alloy steel is 9CrV steel.

After the piston base body 1 made of high carbon alloy steel 9CrV is quenched and tempered, the overall section strength and toughness of the piston base body 1 is balanced, and there is no sudden change in performance.

The quenching and tempering treatment includes heating, quenching, nitrate bath and tempering process.

The finished hydraulic breaker piston has the overall parameters: surface hardness: 55-65HRC; core hardness: 35-45HRC, ultrasonic flaw detection ≤ grade 2.

The overall diameter Φ1 of the piston base 1 is 180-260 mm, the overall height of the piston base 1 is 410 mm, and the overall diameter Φ2 of the circular counterbore 2 is 25-45 mm; the circular counterbore 2 The depth L2 is 75-100mm.

A plurality of transition sections are arranged on the outer surface of the base body 1 of the piston at a position close to one end surface of the counterbore 2 having a circular shape.

In this embodiment, the number of the transition sections is three, and the three transition sections are respectively a first transition section 3, a second transition section 4 and a third transition section 5. The first transition section 3, the third transition section The second transition section 4 and the third transition section 5 are integrally connected in sequence.

The outer surface shape of the first transition section 3 is a conical surface, the outer surface shape of the second transition section 4 is a cylindrical surface, and the outer surface shape of the third transition section 5 is a conical surface.

The outer surface diameter Φ4 of the second transition section 4 is 180 mm.

The piston base 1 has an outer surface diameter Φ3 of one end face of a circular counterbore 2 of 150 mm.

In this implementation, take the piston base body 1 with the overall diameter Φ1 of 190mm as an example, wherein the overall height L1 of the piston base body 1 is 410mm; the overall diameter Φ2 of the circular counterbore 2 is 30mm; the depth L2 of the circular counterbore 2 is 100mm; the diameter Φ4 of the outer surface of the second transition section 4 is 180mm; the diameter Φ3 of the outer surface of the piston base 1 with one end face of the circular counterbore 2 is 150mm.

The present invention adopts the above technical scheme, the piston base body 1 is made of 9CrV high carbon alloy steel, and after the piston is quenched and tempered, the overall section strength and toughness of the piston base body 1 is balanced, and the hardness caused by the size effect is effectively relieved The phenomenon of sudden change in toughness significantly improves the comprehensive strength and toughness of the large-sized hydraulic breaker piston, and the piston has excellent fatigue strength and corrosion resistance.

This embodiment 1 also discloses a method for manufacturing a large-sized hydraulic breaker piston, and the manufacturing method includes the steps of machining:

S1. Blanking: Select high-carbon alloy steel 9CrV that is suitable for manufacturing large-sized hydraulic breaker pistons for production. 9CrV steel needs to be inspected for raw materials before entering the factory.

In the step S1, the inspection of the 9CrV steel raw material is carried out according to the following steps:

1. Supply status: The preparation process of 9CrV steel raw materials includes: die casting, forging, spheroidizing annealing.

2. Chemical composition: Sampling and testing is carried out at the end face of the 9CrV steel raw material and 0.5R from the surface (R represents the radius of the 9CrV steel raw material), and the sampling quantity is 1 piece/heat;

The percentage content of each element in the tested 9CrV steel is shown in the following table:

3. Low magnification structure: sampling location: the end of 9CrV steel raw material; sampling quantity: 1 piece/heat;

Requirements: Referring to GB/T18254-2016, there should be no harmful defects such as residual shrinkage cavities, cracks, subcutaneous bubbles, over-burning, and white spots on the transverse acid leaching samples.

4. Supply hardness: spheroidizing annealing hardness is not greater than HBW179-229.

5. Decarburization layer: Sampling location: the end of the 9CrV steel raw material; Sampling quantity: 1 piece/heat; Requirements: The total decarburization layer depth on each side is not greater than 1% of the nominal diameter.

6. Non-metallic inclusions:

7. Microstructure

8. Ultrasonic non-destructive testing: sampling quantity: one by one; requirements: refer to GB/T 4612, the diameter of a single discontinuous flat-bottom hole is less than or equal to 2.0.

S2. Machining is carried out according to the overall size of the piston of the large-sized hydraulic breaker. First, the lathe is used for rough turning to obtain a rough turning blank, and then the rough turning blank is subjected to a lathe for finishing turning to obtain a finishing turning blank, and the finishing turning blank is milled with a milling machine. Finally, a rough product is obtained.

After the production of the blank product is completed, the processing standard of the blank product is that the diameter dimensional tolerance is -0.085～-0.075mm; the surface finish is Ra0.2, the outer diameter roundness is 0.003; the cylindricity is 0.003, and the concentricity is φ0.005 .

Said manufacturing method also comprises a tempering step:

T1. Heating: Put the blank product into the heating furnace, and heat it up to 850 °C at a heating rate of 5-10 °C/min. The carbon potential protective atmosphere in the heating furnace is maintained at 0.8-1.1%, and then kept for 5 hours.

In the step T1, the heating furnace is a well-type furnace, and the furnace loading method is: hanging plate hoisting; the number of furnaces to be loaded is 4 pieces/furnace.

In the step T1, when the heat preservation is performed, the fluctuation of the heat preservation temperature is ±5°C.

T2, quenching: put the finished product of heating and heat preservation in the air for pre-cooling, the pre-cooling time is 1min, after the pre-cooling is completed, put it into the quenching medium for quenching, wherein the initial temperature of the quenching medium is 20-50 ℃, quenching The time is 2.5min, the outlet temperature of the quenching medium is 200-240°C, and after the quenching is completed, the temperature of the blank product is 200°C.

In the step T2, the quenching medium is brine, and the concentration of the brine is 3%.

In the step T2, the purpose of pre-cooling is to relieve the stress of the piston and avoid stress concentration.

In step T2, when brine is used as the quenching medium for quenching, it is easy to obtain a higher hardness and a smooth surface, and it is not easy to produce soft spots that are not hardened, and pre-cooling the blank product before quenching can relieve the stress of the piston. , to avoid stress concentration, thereby preventing serious deformation of the workpiece, resulting in cracking problems.

And through the quenching process, the hardness, strength and wear resistance of the piston can be improved to prepare the structure for the subsequent heat treatment.

T3. Nitrate bath: the quenched blank product is loaded into a nitrate furnace for nitrate bath, wherein the temperature of the nitrate bath is 230°C; the holding time of the nitrate bath is 4 hours.

In step T3, through the nitrate bath treatment, the piston can obtain an excellent quenched structure, and can reduce the quenching deformation, reduce the tendency of the piston to crack, and further improve the service life of the piston.

T4. The first low-temperature tempering: put the blank product treated in the nitrate bath into the low-temperature tempering furnace for the first low-temperature tempering, wherein the tempering temperature is 230°C, and the tempering holding time is 4 hours. After the secondary tempering treatment was completed, it was cooled to room temperature.

T5, the second low temperature tempering: put the blank product completed by the first low temperature tempering into the low temperature tempering furnace for the second low temperature tempering, wherein the tempering temperature is 230 ℃, and the tempering holding time is 4 hours. After the second tempering treatment is completed, it is cooled to room temperature, and finally a large-sized hydraulic breaker piston is obtained.

In this way, the use of two low temperature tempering can fully eliminate the residual stress generated when the piston is quenched, prevent deformation and cracking; and can adjust the hardness, strength, plasticity and toughness of the piston to meet the performance requirements; and can also stabilize the structure and size to ensure accuracy.

Embodiment 2: In this embodiment, the overall structure of the large-sized hydraulic breaker piston is the same as that in the above-mentioned Embodiment 1.

This embodiment 2 also discloses a manufacturing method of a large-sized hydraulic breaker piston, and the manufacturing method includes the machining steps:

S1. Blanking: Select high-carbon alloy steel 9CrV that is suitable for manufacturing large-sized hydraulic breaker pistons for production. 9CrV steel needs to be inspected before entering the factory.

The inspection steps of the raw materials are the same as those in the above-mentioned Example 1.

S2. Machining is carried out according to the overall size of the piston of the large-sized hydraulic breaker. First, the lathe is used for rough turning to obtain a rough turning blank, and then the rough turning blank is subjected to a lathe for finishing turning to obtain a finishing turning blank, and the finishing turning blank is milled with a milling machine. Finally, a blank product is obtained. The processing standard of the blank product is that the diameter dimensional tolerance is -0.085～-0.075mm; the surface finish is Ra0.2, the outer diameter roundness is 0.003; the cylindricity is 0.003, and the concentricity is φ0.005.

Said manufacturing method also comprises a tempering step:

T1. Heating: Put the blank product into the pit furnace, and the loading method is: hanging plate hoisting; the number of furnaces is 4 pieces/furnace. The carbon potential protective atmosphere in the furnace was maintained at 1%, and then the temperature was kept for 5 hours. During the insulation, the temperature fluctuation of the insulation was: ±5°C.

T2, quenching: put the finished product of heating and heat preservation in the air for pre-cooling, the pre-cooling time is 1min, after the pre-cooling is completed, put it into the brine with a concentration of 3% for quenching, wherein the initial temperature of the brine is 35 ℃, The quenching time is 4 minutes, the outlet temperature of the quenching medium is 220°C, and after the quenching is completed, the temperature of the blank product is 245°C.

T3. Nitrate bath: the quenched blank product is loaded into the nitrate furnace for nitrate bath, wherein the temperature of the nitrate bath is 230°C; the holding time of the nitrate bath is 4 hours.

T4. The first low-temperature tempering: put the blank product treated in the nitrate bath into the low-temperature tempering furnace for the first low-temperature tempering, wherein the tempering temperature is 230°C, and the tempering holding time is 4 hours. After the secondary tempering treatment was completed, it was cooled to room temperature.

T5, the second low temperature tempering: put the blank product completed by the first low temperature tempering into the low temperature tempering furnace for the second low temperature tempering, wherein the tempering temperature is 350 ℃, and the tempering holding time is 4 hours. After the second tempering treatment is completed, it is cooled to room temperature, and finally a large-sized hydraulic breaker piston is obtained.

In this way, the use of two low temperature tempering can fully eliminate the residual stress generated when the piston is quenched, prevent deformation and cracking; and can adjust the hardness, strength, plasticity and toughness of the piston to meet the performance requirements; and can also stabilize the structure and The size is guaranteed to ensure accuracy, and the final overall tempering at 350 ° C can allow the entire piston to be tempered in the bainite medium temperature tempering zone.

Embodiment 3: In this embodiment, the overall structure of the large-sized hydraulic breaker piston is the same as that in the above-mentioned Embodiment 1.

This embodiment 3 also discloses a method for manufacturing a large-sized hydraulic breaker piston, and the manufacturing method includes the machining steps:

S1. Blanking: Select high-carbon alloy steel 9CrV that is suitable for manufacturing large-sized hydraulic breaker pistons for production. 9CrV steel needs to be inspected before entering the factory.

The inspection steps of the raw materials are the same as those in the above-mentioned Example 1.

S2. Machining is carried out according to the overall size of the piston of the large-sized hydraulic breaker. First, the lathe is used for rough turning to obtain a rough turning blank, and then the rough turning blank is subjected to a lathe for finishing turning to obtain a finishing turning blank, and the finishing turning blank is milled with a milling machine. Finally, a blank product is obtained. The processing standard of the blank product is that the diameter dimensional tolerance is -0.085～-0.075mm; the surface finish is Ra0.2, the outer diameter roundness is 0.003; the cylindricity is 0.003, and the concentricity is φ0.005.

Said manufacturing method also comprises a tempering step:

T1. Heating: put the blank product into the pit furnace, and the loading method is: hanging plate hoisting; the number of furnaces is 4 pieces/furnace. The carbon potential protective atmosphere in the furnace is maintained at 1.1%, and then the temperature is kept for 5 hours. When the insulation is performed, the temperature fluctuation of the insulation is: ±5°C.

T2, quenching: put the finished product of heating and heat preservation in the air for pre-cooling, the pre-cooling time is 1min, and after the pre-cooling is completed, put it in brine with a concentration of 3% for quenching, wherein the initial temperature of the brine is 50 ℃, The quenching time is 4min, the outlet temperature of the quenching medium is 240°C, and after the quenching is completed, the temperature of the blank product is 290°C.

T3. Nitrate bath: the quenched blank product is loaded into the nitrate furnace for nitrate bath, wherein the temperature of the nitrate bath is 230°C; the holding time of the nitrate bath is 4 hours.

T4. The first low-temperature tempering: put the blank product after the nitrate bath treatment into the low-temperature tempering furnace for the first low-temperature tempering, wherein the tempering temperature is 300 ° C, and the tempering holding time is 4 hours. After the secondary tempering treatment was completed, it was cooled to room temperature.

T5, the second low temperature tempering: put the blank product completed by the first low temperature tempering into the low temperature tempering furnace for the second low temperature tempering, wherein the tempering temperature is 350 ℃, and the tempering holding time is 4 hours. After the second tempering treatment is completed, it is cooled to room temperature, and finally a large-sized hydraulic breaker piston is obtained.

In this way, the use of two low temperature tempering can fully eliminate the residual stress generated when the piston is quenched, prevent deformation and cracking; and can adjust the hardness, strength, plasticity and toughness of the piston to meet the performance requirements; and can also stabilize the structure and The size is guaranteed to ensure accuracy, and the final overall tempering at 350 ° C can allow the entire piston to be tempered in the bainite medium temperature tempering zone.

Comparative Example 1:

A method of manufacturing a large-sized hydraulic breaker piston, the manufacturing method comprising the steps of machining:

S1, blanking: select high carbon alloy steel 9CrV for production, 9CrV steel needs to be inspected for raw materials before entering the factory, and the inspection steps are the same as those in the above-mentioned embodiment 1.

S2. Machining is carried out according to the overall size of the piston of the large-sized hydraulic breaker, and the rough product is finally obtained through rough turning, finishing turning and milling.

Said manufacturing method also comprises a tempering step:

T1. Heating: put the blank product into the pit furnace, the number of furnaces is 4 pieces/furnace, and the temperature is raised to 850 °C at a heating rate of 10 °C/min during heating, and the carbon potential protective atmosphere in the heating furnace is maintained at 0.8% , and then incubated for 5 hours.

T2. Quenching: Pre-cool the finished product after heating and heat preservation in air for 1 min. After the pre-cooling is completed, put it into brine with a concentration of 3% for quenching. The initial temperature of the brine is 20 °C, and the quenching time is 2.5 min. The outlet temperature of the medium is 200°C.

T3. Nitrate bath: the quenched blank product is loaded into the nitrate furnace for nitrate bath, wherein the temperature of the nitrate bath is 230°C; the holding time of the nitrate bath is 4 hours.

T4. The first low-temperature tempering: put the blank product treated in the nitrate bath into the low-temperature tempering furnace for the first low-temperature tempering, wherein the tempering temperature is 230°C, and the tempering holding time is 4 hours. After the secondary tempering treatment is completed, it is cooled to room temperature, and finally a large-sized hydraulic breaker piston is obtained.

Comparative Example 2:

A method of manufacturing a large-sized hydraulic breaker piston, the manufacturing method comprising the steps of machining:

S1, blanking: select high carbon alloy steel 9CrV for production, 9CrV steel needs to be inspected for raw materials before entering the factory, and the inspection steps are the same as those in the above-mentioned embodiment 1.

S2. Machining is carried out according to the overall size of the piston of the large-sized hydraulic breaker, and the rough product is finally obtained through rough turning, finishing turning and milling.

Said manufacturing method also comprises a tempering step:

T1. Heating: put the blank product into the pit furnace, the number of furnaces is 4 pieces/furnace, and the temperature is raised to 800 ℃ at a heating rate of 7 ℃/min during heating, and the carbon potential protective atmosphere in the heating furnace is maintained at 1% , and then incubated for 5 hours.

T2. Quenching: Pre-cool the finished product after heating and heat preservation in air for 1 min. After the pre-cooling is completed, put it into brine with a concentration of 3% for quenching. The initial temperature of the brine is 35°C, the quenching time is 4min, and the quenching medium The outlet water temperature is 220℃.

T3. Nitrate bath: the quenched blank product is loaded into a nitrate furnace for nitrate bath, wherein the temperature of the nitrate bath is 230°C; the holding time of the nitrate bath is 4 hours.

T4. The first low-temperature tempering: put the blank product after the nitrate bath treatment into the low-temperature tempering furnace for the first low-temperature tempering, wherein the tempering temperature is 400°C, and the tempering holding time is 4 hours. After the secondary tempering treatment was completed, it was cooled to room temperature.

T5, the second low temperature tempering: put the blank product completed by the first low temperature tempering into the low temperature tempering furnace for the second low temperature tempering, wherein the tempering temperature is 400 ℃, and the tempering holding time is 4 hours. After the second tempering treatment is completed, it is cooled to room temperature, and finally a large-sized hydraulic breaker piston is obtained.

Comparative Example 3:

A method for manufacturing a large-sized hydraulic breaker piston, the manufacturing method comprising the steps of machining:

S1, blanking: select high carbon alloy steel 9CrV for production, 9CrV steel needs to be inspected for raw materials before entering the factory, and the inspection steps are the same as those in the above-mentioned embodiment 1.

S2. Machining is carried out according to the overall size of the piston of the large-sized hydraulic breaker, and the rough product is finally obtained through rough turning, finishing turning and milling.

Said manufacturing method also comprises a tempering step:

T1. Heating: put the blank product into the pit furnace, the number of furnaces is 4 pieces/furnace, and the temperature is raised to 800°C at a heating rate of 10°C/min during heating, and the carbon potential protective atmosphere in the heating furnace is maintained at 1.1% , and then incubated for 5 hours.

T2. Quenching: Pre-cool the finished product after heating and heat preservation in air for 1 min. After the pre-cooling is completed, put it into brine with a concentration of 3% for quenching. The initial temperature of the brine is 50°C, the quenching time is 4min, and the quenching medium The outlet water temperature is 240℃.

T3. Nitrate bath: the quenched blank product is loaded into a nitrate furnace for nitrate bath, wherein the temperature of the nitrate bath is 230°C; the holding time of the nitrate bath is 4 hours.

T4. The first low-temperature tempering: put the blank product treated in the nitrate bath into the low-temperature tempering furnace for the first low-temperature tempering, wherein the tempering temperature is 230°C, and the tempering holding time is 4 hours. After the secondary tempering treatment was completed, it was cooled to room temperature.

T5, the second low temperature tempering: put the blank product completed by the first low temperature tempering into the low temperature tempering furnace for the second low temperature tempering, wherein the tempering temperature is 400 ℃, and the tempering holding time is 4 hours. After the second tempering treatment is completed, it is cooled to room temperature, and finally a large-sized hydraulic breaker piston is obtained.

The large-sized hydraulic breaker pistons prepared in the above-mentioned Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests:

1. The tensile properties of the large-sized hydraulic breaker pistons prepared in Example 1-3 and Comparative Example 1-3 at different radial positions of the piston cross-section were tested, and the testing structure is shown in Figure 4-5.

2. Detect the hardness at different positions in the radial direction of the piston cross section of the large-size hydraulic breaker prepared in Example 1-3 and Comparative Example 1-3, and the detection structure is shown in Figure 6 .

3. The impact absorption energy at different positions in the radial direction of the piston cross section of the large-size hydraulic breaker prepared in Example 1-3 and Comparative Example 1-3 was detected, and the detection structure is shown in Figure 7.

4. Detect the residual stress at different radial positions of the piston cross section of the large-size hydraulic breaker prepared in Example 1-3 and Comparative Example 1-3, and the detection structure is shown in Figure 8-9.

After the above detection, the tensile properties, hardness and impact absorption energy of the piston produced by the process of the present invention are better than those of the piston manufactured by the prior art, and then the overall structural strength of the piston can be improved, and the service life and use effect can be improved.

For those of ordinary skill in the art, according to the teachings of the present invention, without departing from the principle and spirit of the present invention, changes, modifications, substitutions and alterations to the embodiments still fall within the protection scope of the present invention within.

Claims (10)

1. A large-sized hydraulic breaker piston, characterized in that: the piston comprises a piston base (1) made of high-carbon alloy steel 9CrV, and the piston base (1) is made by quenching and tempering; the piston base (1) A circular counterbore (2) is opened on one end face of the . 2. A large-sized hydraulic breaker piston according to claim 1, characterized in that: the surface hardness of the piston is: 57-63HRC; ultrasonic flaw detection≤grade 2. 3. A large-sized hydraulic breaker piston according to claim 2, characterized in that: on the outer surface of the piston base (1), a position close to one end face of the circular counterbore (2) is arranged in sequence. The first transition section (3), the second transition section (4) and the third transition section (5) are integrally connected. 4. The manufacturing method of a large-sized hydraulic breaker piston according to any one of claims 1-3, wherein the manufacturing method comprises the machining steps: S1. Blanking: Select high-carbon alloy steel 9CrV that is suitable for manufacturing large-sized hydraulic breaker pistons for production. 9CrV steel needs to be inspected before entering the factory; S2. Machining is carried out according to the overall size of the piston of the large-sized hydraulic breaker, and finally a blank product is obtained. 5. The manufacturing method of a large-sized hydraulic breaker piston according to claim 4, characterized in that: the manufacturing method further comprises a conditioning step: T1. Heating: Put the blank product into the heating furnace, and heat it up to 820-850 °C at a heating rate of 5-10 °C/min. The carbon potential protective atmosphere in the heating furnace is maintained at 0.8-1.1%, and then kept for 5 Hour; T2. Quenching: Put the finished product in the air for pre-cooling for 1min. After the pre-cooling is completed, put it into the quenching medium for quenching. The quenching time is 2.5-4min. 290℃; T3. Nitrate bath: the quenched blank product is subjected to a nitrate bath, wherein the nitrate bath temperature is 230°C; the nitrate bath holding time is 4 hours; T4. The first low-temperature tempering: the first low-temperature tempering is performed on the blank product after the nitrate bath treatment, the tempering temperature is 230-300 ° C, the tempering holding time is 4 hours, and the first tempering treatment is completed After cooling to room temperature; T5. The second low temperature tempering: the first low temperature tempering completed blank product is subjected to the second low temperature tempering, wherein the tempering temperature is 230-350 ° C, the tempering holding time is 4 hours, and the temperature is cooled to room temperature. Finally, a large size hydraulic breaker piston is obtained. 6. The method for manufacturing a large-sized hydraulic breaker piston according to claim 5, wherein in step 22, after the production of the blank product is completed, the processing standard of the blank product is that the diameter dimensional tolerance is -0.085～-0.075 mm; the surface finish is Ra0.2, the outer diameter roundness is 0.003; the cylindricity is 0.003, and the concentricity is φ0.005. 7. The method for manufacturing a large-sized hydraulic breaker piston according to claim 6, characterized in that: in step T1, the heating furnace adopts a well-type furnace, and the furnace loading method is: hoisting on a hanging plate; loading furnace The quantity is 4-6 pieces/furnace. 8 . The method for manufacturing a large-sized hydraulic breaker piston according to claim 7 , wherein in step T1 , when heat preservation is performed, the fluctuation of the heat preservation temperature is ±5° C. 9 . 9 . The method for manufacturing a large-sized hydraulic breaker piston according to claim 8 , wherein in step T2 , the initial temperature of the quenching medium is 20-50° C., and the outlet temperature of the quenching medium is 200-240° C. 10 . . 10 . The method for manufacturing a large-sized hydraulic breaker piston according to claim 9 , wherein in step T2 , the quenching medium is brine, and the concentration of the brine is 3%. 11 .

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