Surface treatment process for piston of hydraulic breaking hammer

Abstract

The hydraulic breaking hammer piston surface treatment process is characterized by comprising the following steps that S1, cobalt-based tungsten carbide powder is obtained; s2, the surface of the piston of the hydraulic breaking hammer is preprocessed; s3, a cobalt-based tungsten carbide coating is prepared on the surface of the piston of the hydraulic breaking hammer through a hypersonic flame spraying method; the average thickness of the cobalt-based tungsten carbide coating ranges from 100 micrometers to 600 micrometers. The cobalt-based tungsten carbide composite coating which is good in bonding strength, high in hardness and high in abrasion resistance is prepared on the surface of the hydraulic breaking hammer piston in a supersonic flame spraying mode, the use performance of the hydraulic breaking hammer piston can be improved, and the service life of the hydraulic breaking hammer piston can be prolonged. Test results show that the obtained coating is good in macroscopic morphology, and the hardness and wear resistance of the coating are remarkably improved compared with those of a piston base body of a hydraulic breaking hammer.

Description

Technical Field

[0001] The invention belongs to the field of surface strengthening, and specifically relates to a surface treatment process for a hydraulic breaker piston, and in particular to a surface treatment process for improving the service life and performance of the hydraulic breaker piston. Background Art

[0002] A hydraulic breaker is a device that converts the hydraulic energy input by the main engine into mechanical impact energy. It is usually used on hydraulic engineering machinery such as loaders and excavators. It can complete rock crushing, building demolition and other tasks. It is widely used in mining engineering and civil engineering. With the development of hydraulic breaker rock breaking technology and the continuous improvement of performance, hydraulic breaker rock breaking has been more and more widely used due to its safety, economy and efficiency. At present, the hydraulic breaker industry has become a sunrise industry. Entering the 21st century, with the development of urban and rural infrastructure and engineering construction, the market scale of construction machinery in my country has also made a qualitative leap, especially the market scale of excavators has expanded rapidly, from 140,300 units in 2017 to 327,600 units in 2020. The piston inside the breaker cylinder needs to bear severe impact and friction during the operation of the breaker, so the piston is severely worn during actual use and is one of the items with high consumption.

[0003] A good piston can increase the service life of a good breaker. In order to increase the service life and repair work of the piston inside the breaker cylinder under land and underwater operating environments, surface modification technology is used to increase the service life of the piston from a coating perspective, thereby increasing the market share and competitiveness of the breaker in the mining machinery market.

[0004] According to the use conditions of the breaker hammer piston, different breaker hammer manufacturers will adopt different technical means to extend the service life of the breaker hammer, such as Cr plating on the surface of the breaker hammer piston to increase the service life of the breaker hammer, or directly increasing the gap between the piston and the cylinder to delay the wear and tear of the breaker hammer surface. The Cr plating process has disadvantages such as environmental approval and poor bonding strength of the Cr plating layer and easy falling off. Directly increasing the gap between the piston and the cylinder cannot increase the service life from the perspective of breaker hammer wear, and cannot achieve improvement and life extension of the breaker hammer piston under impact wear conditions. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned prior art, the present invention provides a surface treatment process for a hydraulic breaker piston, and uses a supersonic flame spraying method to prepare a cobalt-based carbide coating on the surface of the breaker piston to improve its service life and performance.

[0006] The specific technical solutions are as follows:

[0007] One of the purposes of the present invention is to provide a hydraulic breaker piston surface treatment process, comprising the following steps:

[0008] S1. Obtaining cobalt-based tungsten carbide powder;

[0009] S2. Pre-processing the surface of the hydraulic breaker piston;

[0010] S3. A cobalt-based tungsten carbide coating is prepared on the surface of a hydraulic breaker piston by supersonic flame spraying; the average thickness of the cobalt-based tungsten carbide coating is 100 to 600 μm.

[0011] The invention prepares a cobalt-based tungsten carbide coating on the surface of a hydraulic breaker piston by a supersonic flame spraying method. The coating has good bonding strength, high hardness and high wear resistance, and can improve the performance of the hydraulic breaker piston and extend its service life.

[0012] Further, in step S3, the conditions for supersonic flame spraying preferably include:

[0013] The oxygen flow rate of the combustion aid is 5~15m 3 / h;

[0014] The spray fuel kerosene flow rate is 2 to 6 L / min;

[0015] The powder feeding amount is 20~80g / min.

[0016] Further, in step S3, the conditions for supersonic flame spraying preferably include:

[0017] Spraying distance is 100~400mm;

[0018] The average movement speed of the spray gun is 2-7 mm / s.

[0019] Further, in step S3: it is preferred to perform spraying treatment multiple times.

[0020] Furthermore, in step S1, the cobalt-based tungsten carbide powder is preferably WC-12Co.

[0021] Further, in step S1: the average particle size of the cobalt-based tungsten carbide powder is preferably 50-100 μm.

[0022] Further, in step S2: the pre-processing treatment preferably includes turning, cleaning and sandblasting the hydraulic breaker piston in sequence.

[0023] Wherein, in step S2: the cleaning preferably includes cleaning with an alkaline cleaning agent; the oil stains on the surface of the substrate can be removed by cleaning.

[0024] Wherein, in step S2: the average particle size of the sand used in the sandblasting process is preferably 1 to 2 mm.

[0025] A second object of the present invention is to provide a hydraulic breaker piston, which is obtained through the above-mentioned hydraulic breaker piston surface treatment process.

[0026] The beneficial effects of the present invention are as follows:

[0027] The present invention prepares a cobalt-based tungsten carbide composite coating with good bonding strength, high hardness and high wear resistance on the surface of the hydraulic breaker piston by supersonic flame spraying, which can improve the performance of the hydraulic breaker piston and extend its service life. The test results show that the coating obtained by the present invention has good macroscopic morphology, and the hardness and wear resistance are significantly improved compared with the hydraulic breaker piston substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the breaker and the service status of the piston in the cylinder of the electric breaker;

[0029] Figure 2 It is a schematic diagram of the coating structure of the present invention;

[0030] Figure 3 This is a photo of the cobalt-based tungsten carbide coating prepared on the piston surface in Example 1;

[0031] Figure 4 The friction coefficient diagram of the cobalt-based tungsten carbide coating in the test (wear resistance test);

[0032] Figure 5 This is the friction coefficient diagram of the piston base of the hydraulic breaker in the test (wear resistance test);

[0033] Figure 6 Wear morphology of cobalt-based tungsten carbide coating in the test (wear resistance test);

[0034] Figure 7 This is the wear morphology of the hydraulic breaker piston base in the test (wear resistance test). DETAILED DESCRIPTION

[0035] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0036] Example 1

[0037] A hydraulic breaker piston surface treatment process, the steps are as follows:

[0038] S1. Select commercially available cobalt-based tungsten carbide powder WC-12Co as the spraying material for supersonic flame spraying; the average particle size of the cobalt-based tungsten carbide powder WC-12Co is 75 μm.

[0039] S2. Pre-process the surface of the hydraulic breaker piston; select a hydraulic breaker piston substrate and first turn its surface to a thickness of 300 μm; then use an alkaline cleaning agent to clean it to remove surface oil stains; then sandblast the surface of the substrate and blow dry the residual sandblasting sand on the surface of the workpiece, and the average particle size of the sand used for sandblasting is 1 mm.

[0040] S3. A cobalt-based tungsten carbide coating was prepared on the surface of the hydraulic breaker piston by supersonic flame spraying. The main process parameters were: the oxygen flow rate of the combustion agent was 12m3 / h; the kerosene flow rate of the spraying fuel was 3L / min; the powder feeding amount was 60g / min; the spraying distance was 300mm; the average movement speed of the spray gun was 5mm / s; the spraying was repeated for many times, and the average thickness of the final coating was 300μm. The coating obtained by the surface treatment process is as follows Figure 3 shown.

[0041] test

[0042] The cobalt-based tungsten carbide coating obtained in Example 1 and the piston substrate same as Example 1 were tested for hardness and wear resistance. The size of the sample to be tested was 10 mm×10 mm×15 mm. Before the test, the sample to be tested was ground and polished; the grinding was performed using 240#, 400#, 800#, and 1200# sandpapers respectively.

[0043] 1. Hardness test: Use a microhardness tester to test the cobalt-based tungsten carbide coating and the hydraulic breaker piston substrate. The hardness of the cobalt-based tungsten carbide composite coating is 1305HV. 0.2 The hardness of the hydraulic breaker piston base is 436HV 0.2 It can be seen that the hardness of the cobalt-based tungsten carbide coating of the present invention is significantly higher than that of the piston substrate.

[0044] 2. Wear resistance test: The friction and wear tester was used to test the cobalt-based tungsten carbide coating and the hydraulic breaker piston substrate. The test method was based on the standard GB / T 17754-2012. Under a load of 100N, the average wear depth of the cobalt-based tungsten carbide coating was 2.15μm, while the wear depth of the hydraulic breaker piston substrate was 19.93μm. It can be seen that the coating of the present invention can significantly reduce the wear. The friction coefficient of the cobalt-based tungsten carbide coating is as follows: Figure 4 As shown, the friction coefficient of the hydraulic breaker piston base is as follows Figure 5 As shown, the wear morphology of cobalt-based tungsten carbide coating is as follows Figure 6 As shown in the figure, the wear morphology of the piston base of the hydraulic breaker is as follows Figure 7 The wear scar data of the cobalt-based tungsten carbide coating are shown in Table 1, and the wear scar data of the hydraulic breaker piston substrate are shown in Table 2.

[0045] Table 1 Wear scar data of cobalt-based tungsten carbide coating

[0046] parameter unit hole vertex Projected area <![CDATA[μm 2 ]]> 1537991 1761390 volume <![CDATA[μm 3 ]]> 3312663 1952513 Maximum depth / height μm 7.0028 2.6452 Average depth / height μm 2.1539 1.1085

[0047] Table 2 Wear scar data of hydraulic breaker piston base

[0048] parameter unit hole vertex Projected area <![CDATA[μm 2 ]]> 6032455 706545 volume <![CDATA[μm 3 ]]> 120211352 3180537 Maximum depth / height μm 71.690 38.718 Average depth / height μm 19.927 4.5015

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A surface treatment process for a hydraulic breaker piston, characterized in that: The steps include: S1. Obtaining cobalt-based tungsten carbide powder; S2. Pre-process the surface of the hydraulic breaker piston; S3. A cobalt-based tungsten carbide coating is prepared on the surface of a hydraulic breaker piston by supersonic flame spraying; the average thickness of the cobalt-based tungsten carbide coating is 100 to 600 μm.

2. The surface treatment process of the hydraulic breaker piston according to claim 1 is characterized in that: In step S3, the conditions for supersonic flame spraying include: The oxygen flow rate of the combustion aid is 5~15m 3 / h; The spray fuel kerosene flow rate is 2 to 6 L / min; The powder feeding amount is 20~80g / min.

3. The surface treatment process of the hydraulic breaker piston according to claim 1 is characterized in that: In step S3, the conditions for supersonic flame spraying include: Spraying distance is 100~400mm; The average movement speed of the spray gun is 2-7 mm / s.

4. The surface treatment process of the hydraulic breaker piston according to any one of claims 1 to 3, characterized in that: In step S1: the cobalt-based tungsten carbide powder is WC-12Co.

5. The surface treatment process of the hydraulic breaker piston according to any one of claims 1 to 3, characterized in that: In step S1: the average particle size of the cobalt-based tungsten carbide powder is 50-100 μm.

6. The surface treatment process of the hydraulic breaker piston according to any one of claims 1 to 3, characterized in that: In step S2: the pre-processing treatment includes turning, cleaning and sandblasting the hydraulic breaker piston in sequence.

7. The surface treatment process of the hydraulic breaker piston according to claim 6 is characterized in that: In step S2: the cleaning includes cleaning with an alkaline cleaning agent.

8. The surface treatment process of the hydraulic breaker piston according to claim 6 is characterized in that: In step S2: the sand material used in the sandblasting process has a particle size of 1 to 2 mm.

9. A hydraulic breaker piston obtained by the hydraulic breaker piston surface treatment process according to any one of claims 1 to 8.

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