A method for controlling the surface roughness of metallic materials

Abstract

This invention provides a method for roughening the surface roughness of metal materials with controllable roughness, characterized by the following steps: 1) metal workpiece surface treatment, 2) pre-placement of metal powder particles, 3) electrode treatment, 4) electrode process parameter setting, and 5) electrode treatment of the metal workpiece surface to complete the roughening treatment of the metal workpiece surface. This method fully utilizes the movement of the electrode between the workpiece surface and the metal powder particles to form a discharge between the electrode and the metal workpiece. The low-melting-point electrode is melted into a binder, which then binds and encapsulates the high-melting-point powder particles into the gap between the rotating electrode and the metal surface. Subsequently, an electric spark is formed again between the metal workpiece and the metal powder particles, melting and bonding the low-melting-point metal material on the surface of the high-melting-point metal powder to the workpiece surface. This results in higher efficiency in roughening and texturing the metal surface. The selection of metal powder particles of different sizes allows for controllability of the workpiece surface roughness.

Description

Technical Field

[0001] This invention relates to a method, particularly a roughening method for controllable surface roughness of metallic materials, belonging to the field of metal processing technology. Background Technology

[0002] Equipment operating in environments involving high-speed rotation, abrasion from mud and sand, mechanical friction, and corrosion often suffers severe damage, resulting in wear marks or corrosion pits on its surface. Damaged equipment experiences significantly reduced efficiency and increased vibration, jeopardizing its safe operation. Currently, coatings / paints or metal repair agents are used to repair these surfaces to prevent wear marks or corrosion pits. However, the lifespan of these coatings and repair agents depends on the surface roughness of the metal. Methods to improve surface roughness include sandblasting, implantation, electrical discharge machining (EDM) texturing, and laser texturing. However, for localized repairs, sandblasting easily damages the existing coating; EDM texturing requires a texturing fluid and achieves relatively low roughness; laser texturing equipment is expensive and unsuitable for on-site application; implantation is suitable for repairing localized wear pits on complex workpieces, but its roughness is not high, and while it doesn't damage the old coating, its efficiency is low. Therefore, it is necessary to improve existing technologies. Summary of the Invention

[0003] To address the problems of low efficiency, easy damage to old coatings, high equipment cost, and low surface roughness in existing metal surface texturing methods, this invention provides a texturing method for controllable surface roughness of metal materials.

[0004] This invention is achieved through the following technical solution: a method for roughening the surface roughness of metallic materials with controllable roughness, characterized by comprising the following steps:

[0005] 1) Metal work surface treatment: Place the metal workpiece horizontally with the grinding marks or pits facing upwards, and use a grinder to smooth the inner surface of the grinding marks or pits, eliminating sharp corners, surface oxide scale, corrosion products, and oil stains in the pits, so that the metal base surface is exposed in the grinding marks or pits.

[0006] 2) Pre-place metal powder particles. Based on the size and depth of the wear marks or pits on the exposed metal substrate surface in step 1), and the required target roughness Ra, select the average particle size d. 50 Metal powder particles of 2×Ra are placed in the grinding marks or pits of the metal workpiece in step 1);

[0007] 3) Electrode processing: The front end of the rough electrode with a diameter of φ10~15mm and a hardness of less than 100HV is processed into a hemispherical shape.

[0008] 4) Electrode process parameter settings: mount the electrode processed in step 3) onto the electrode gun, start the pulse voltage, and adjust the pulse voltage to 50-90V, the pulse peak current to 5-20A, the pulse width to 100-500μs, and the electrode speed to 50-80r / min;

[0009] 5) Electrode treatment of the metal workpiece surface: Connect the cathode of the EDM equipment to the workpiece, using the rotating electrode as the anode, insert the rotating electrode into the metal powder particles in the grinding marks or pits of the metal workpiece from step 2), and move the rotating electrode back and forth to sweep across all surfaces in the grinding marks or pits, bringing the high-melting-point metal powder particles into the space between the grinding marks or pits and the electrode. Use the powder particles as the extension end of the electrode, and after generating an EDM on the surface of the grinding marks or pits, melt the low-melting-point electrode into a binder, bonding and encapsulating the high-melting-point powder particles into the gap between the rotating electrode and the grinding marks or pits of the metal workpiece. Then, another EDM is formed between the metal workpiece and the metal powder particles, melting and bonding the low-melting-point metal material on the surface of the high-melting-point metal powder to the inner wall of the grinding marks or pits of the metal workpiece, completing the roughening treatment of the inner wall of the grinding marks or pits.

[0010] The desired roughness in step 2) is controlled by selecting metal powder particles of different sizes, with a roughness Ra≈0.5d. 50 , where d 50 The average particle size of the powder.

[0011] The metal powder particles in step 2) are one or more of iron-based alloys, cobalt-based alloys, nickel-based alloys, tungsten, or molybdenum, and the ratio of these alloys is arbitrary. The metal powder particles have a hardness higher than 180 HV and an average particle size d. 50 It ranges from 30 to 100 micrometers.

[0012] The metal powder particles in step 2) are atomized spherical powders.

[0013] The conductive part of the electrode in step 3) is made of copper or aluminum with a hardness of less than 100 HV.

[0014] The invention generates a discharge between the electrode and the metal workpiece during the movement of the electrode on the workpiece surface and between metal powder particles. This melts the low-melting-point aluminum and copper electrodes, and the molten metal acts as a binder to bind and encapsulate the high-melting-point powder particles into the gap between the rotating electrode and the metal surface. Subsequently, an electric spark is generated again between the metal workpiece and the metal powder particles, melting and bonding the low-melting-point metal material on the surface of the high-melting-point metal powder to the workpiece surface.

[0015] The electrode material used as an adhesive has low strength, is easy to break away from the original electrode, and can detach from the original electrode surface and adhere to the workpiece surface, thereby forming the required roughness on the inner wall of the metal workpiece's grinding marks or pits, or on the surface of the metal workpiece.

[0016] By selecting metal powder particles of different sizes, the surface roughness of the workpiece can be controlled.

[0017] The present invention has the following advantages and effects: By adopting the above scheme, the movement of the electrode on the workpiece surface and between metal powder particles can be fully utilized to form a discharge between the electrode and the metal workpiece. Then, the low-melting-point electrode is melted into a binder, and the high-melting-point powder particles are bonded and wrapped into the gap between the rotating electrode and the metal surface. Then, an electric spark is formed again between the metal workpiece and the metal powder particles, melting and bonding the low-melting-point metal material on the surface of the high-melting-point metal powder to the workpiece surface. This makes the roughening and texturing of the metal surface more efficient. By selecting metal powder particles of different sizes, the surface roughness of the workpiece can be controlled without damaging the coating. It can be completed using conventional electric spark deposition equipment, saving investment. The operation is simple and convenient. More importantly, the roughening and processing of the surface roughness of the metal workpiece can be completed on-site, and the roughness is adjustable and controllable. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the present invention;

[0019] Figure 2 This is a diagram showing the state of the texturing process according to the present invention. Detailed Implementation

[0020] The present invention will be further described below through embodiments.

[0021] Example 1

[0022] A method for roughening the surface of a metallic material with controllable roughness, comprising the following steps:

[0023] 1) Place the metal workpiece horizontally with the wear pits on its surface facing upwards. Use a conventional grinder to smooth the inner surface of the wear pits, eliminate sharp corners, remove surface oxide scale, corrosion products, oil stains, etc., so that the wear pits are exposed on the metal base surface.

[0024] 2) Based on the exposed metal substrate in step 1), a metal workpiece surface with a roughness Ra of 50 micrometers is required. Therefore, the average grain size d is selected. 50 Cobalt-based alloy powder particles of 80-120 are pre-placed in the recess of the metal workpiece in step 1);

[0025] 3) Select an aluminum rod with a diameter of φ10mm as the coarse electrode, and process its front end into a hemispherical shape;

[0026] 4) Install the electrode processed in step 3) into the electrode gun, start the pulse voltage, adjust the voltage to 50V, the pulse peak current to 5A, the pulse width to 200μs, and the electrode rotation speed to 50r / min.

[0027] 5) Connect the cathode of the EDM equipment to the workpiece, using the rotating electrode as the anode. Insert the rotating electrode into the powder of the wear pit of the metal workpiece in step 2), and move the rotating electrode back and forth to sweep across all surfaces in the wear mark or pit. This brings the high-melting-point metal powder particles into the space between the wear mark or pit and the electrode. The powder particles serve as the extension end of the electrode. After generating an EDM on the surface of the wear mark or pit, the low-melting-point electrode is melted into an adhesive. The high-melting-point powder particles are then bonded and encased in the gap between the rotating electrode and the wear mark or pit of the metal workpiece. Then, an EDM is formed again between the metal workpiece and the metal powder particles, melting and bonding the low-melting-point metal material on the surface of the high-melting-point metal powder to the inner wall of the wear mark or pit of the metal workpiece, thus completing the roughening treatment of the inner wall of the wear mark or pit.

[0028] Example 2

[0029] A method for roughening the surface of a metallic material with controllable roughness, comprising the following steps:

[0030] 1) Place the metal workpiece horizontally with the grinding marks on its surface facing upwards. Use a conventional grinder to smooth the grinding marks, removing sharp corners, surface oxide scale, corrosion products, oil stains, etc., to expose the metal base surface.

[0031] 2) Based on the exposed metal substrate in step 1), a metal workpiece surface with a roughness Ra of 50 micrometers is required. Therefore, the average grain size d is selected. 50 Iron-based alloy powder particles of 80-120 are pre-placed in the grinding marks of the metal workpiece after grinding in step 1).

[0032] 3) Select an aluminum rod with a diameter of φ15mm as the coarse electrode, and process its front end into a hemispherical shape;

[0033] 4) Install the motor processed in step 3) into the electrode gun, start the pulse voltage, adjust the voltage to 90V, the pulse peak current to 20A, the pulse width to 500μs, and the rotating electrode speed to 80r / min;

[0034] 5) Connect the cathode of the EDM equipment to the workpiece, using the rotating electrode as the anode. Insert the rotating electrode into the powder of the metal workpiece grinding marks from step 2), and move the rotating electrode back and forth to sweep across all surfaces within the grinding marks or pits. This brings high-melting-point metal powder particles into the space between the grinding marks or pits and the electrode. The powder particles serve as the extension ends of the electrode. After generating an EDM on the surface of the grinding marks or pits, the low-melting-point electrode is melted into an adhesive. This adhesive binds and encapsulates the high-melting-point powder particles into the gap between the rotating electrode and the metal workpiece grinding marks or pits. Then, an EDM is formed again between the metal workpiece and the metal powder particles, melting and bonding the low-melting-point metal material on the surface of the high-melting-point metal powder to the inner wall of the metal workpiece grinding marks or pits, thus completing the roughening treatment of the inner wall of the grinding marks or pits.

[0035] Example 3

[0036] 1) Place the metal part horizontally with the wear pits on its surface facing upwards. Use a grinder to smooth the inner surface of the wear pits, eliminate sharp corners, remove surface oxide scale, corrosion products, oil stains, etc., and expose the metallic luster.

[0037] 2) Based on the exposed metal substrate in step 1), a roughness of Ra of 30 micrometers is required. Therefore, an average particle size d is selected. 50 Nickel-based powder particles of 50-80 micrometers are pre-placed in the recesses of the metal workpiece in step 1);

[0038] 3) Select an aluminum rod with a diameter of φ13mm as the coarse electrode, and process its front end into a hemispherical shape;

[0039] 4) Install the motor processed in step 3) into the electrode gun, start the pulse voltage, adjust the voltage to 75V, the pulse peak current to 15A, the pulse width to 300μs, and the rotating electrode speed to 70r / min.

[0040] 5) Connect the cathode of the EDM equipment to the workpiece, using the rotating electrode as the anode. Insert the rotating electrode into the powder of the wear pit of the metal workpiece in step 2), and move the rotating electrode back and forth to sweep across all surfaces in the wear mark or pit. This brings the high-melting-point metal powder particles into the space between the wear mark or pit and the electrode. The powder particles serve as the extension end of the electrode. After generating an EDM on the surface of the wear mark or pit, the low-melting-point electrode is melted into an adhesive. The high-melting-point powder particles are then bonded and encased in the gap between the rotating electrode and the wear mark or pit of the metal workpiece. Then, an EDM is formed again between the metal workpiece and the metal powder particles, melting and bonding the low-melting-point metal material on the surface of the high-melting-point metal powder to the inner wall of the wear mark or pit of the metal workpiece, thus completing the roughening treatment of the inner wall of the wear mark or pit.

[0041] The following comparative examples illustrate the difference between the effects not produced within the scope of the claims of this invention and the effects of the above-described embodiments 1-3:

[0042] Comparative Example 1: Comparative Example 1 is the prior art, and its electrode material is an iron-based material with a hardness greater than 100HV; the effect produced is that no adhesive is generated, and although it carries metal powder particles, the metal powder particles cannot adhere to the workpiece surface.

[0043] Comparative Example 2: Comparative Example 2 is the prior art, and its electrode diameter is 8mm. The effect is that the electrode surface is too small to adhere to metal powder particles, and the number of metal powder particles carried each time it moves or rotates is limited, resulting in low texturing efficiency.

[0044] Comparative Example 3: Comparative Example 3 is the prior art, with an electrode diameter of 18mm; the result is that the electrode is too thick and not suitable for small abrasion pits.

[0045] Comparative Example 4: Comparative Example 4 is the prior art, and its particle material uses low-hardness copper powder with a hardness of less than 220HV; the effect is that it is flattened by the rotating electrode under local high temperature and high pressure, and cannot be detached from the original electrode, thus it cannot be planted on the surface of the metal workpiece.

[0046] Comparative Example 5: Comparative Example 5 is the prior art, in which the metal particle material is a non-spherical powder, but an elongated powder; the effect is that the liquid metal used in the low melting point adhesive cannot firmly bond the metal powder particles, causing the metal powder particles to fall off easily.

[0047] Comparative Example 6: Comparative Example 6 is the prior art, and its electrode rotation speed is 200 r / min; the effect is that the electric spark intensity is insufficient and the efficiency is low.

[0048] Comparative Example 7: Comparative Example 7 is the prior art, and its electrode rotation speed is higher than 400 r / min; the effect is that the powder is driven out by the rotating electrode, resulting in a large amount of material waste, and the metal powder particles need to be repeatedly filled.

[0049] Comparative Example 8: Comparative Example 8 is the prior art, with a power supply voltage of 40V, a pulse peak current of 3A, and a pulse width of 70μs; low power supply parameters will result in low texturing efficiency, low roughness, and inability of powder to adhere.

[0050] Comparative Example 9: Comparative Example 9 is the prior art, with a power supply voltage of 100V, a pulse peak current of 30A, and a pulse width of 600μs. The high power supply parameters result in higher temperatures and severe deformation of the metal powder particles. In particular, when the pulse width is higher, it also affects the texturing efficiency.

[0051] Table 1

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Claims

1. A method for roughening a metal material surface with controllable roughness, characterized by It comprises the following steps: 1) metal workpiece surface treatment, the metal workpiece is placed horizontally, and the grinding mark or pit on the surface is upward, the inner surface of the grinding mark or pit is polished smooth by a polisher, the sharp corners, surface oxide, corrosion products, oil stains in the pit are eliminated, and the metal base surface in the grinding mark or pit is exposed; 2) Pre-positioning of metal powder particles, with average particle size d 50 Metal powder with average particle size d of 2 x Ra is pre-positioned in the metal workpiece scratch or pit of step 1. The desired target roughness is achieved by selecting metal powders of different particle sizes, with roughness Ra≈0.5d 50 where d 50 is the average particle size of the metal powder; The metal powder is one or several of iron-based alloy, cobalt-based alloy, nickel-based alloy, tungsten or molybdenum, and the proportion of the several is arbitrary, and the particle hardness of the metal powder is higher than 180HV, the average particle size d 50 is 30-100 microns; 3) electrode treatment, the front end of a rough electrode with a diameter of φ10-15mm and a hardness lower than 100HV is processed into a semispherical shape; The conductive part of the electrode is copper or aluminum with a hardness lower than 100HV; 4) electrode process parameter setting, the electrode processed in step 3) is installed on the electrode gun, the pulse voltage is started, and the pulse voltage is adjusted to 50-90V, the pulse peak current is adjusted to 5-20A, the pulse width is adjusted to 100-500μs, and the electrode speed is adjusted to 50-80r / min; 5) electrode treatment metal workpiece surface, the cathode of the electric spark device is connected to the workpiece, the rotating electrode is taken as the anode, the rotating electrode is inserted into the metal powder in the grinding mark or pit of the metal workpiece in step 2), the rotating electrode is moved back and forth to sweep all the surfaces in the grinding mark or pit, the high-melting-point metal powder is brought into the gap between the grinding mark or pit and the electrode, the metal powder is taken as the extension of the electrode, and after the electric spark is generated on the surface of the grinding mark or pit, the low-melting-point electrode is melted into the adhesive, the high-melting-point metal powder is bonded and entrapped into the gap between the rotating electrode and the grinding mark or pit of the metal workpiece, then the electric spark is generated again between the metal workpiece and the metal powder, the low-melting-point metal material on the surface of the high-melting-point metal powder is melted and bonded to the inner wall surface of the grinding mark or pit of the metal workpiece, and the roughening treatment of the inner wall surface of the grinding mark or pit is completed.

2. The metal material surface roughness controllable texturing method according to claim 1, wherein The metal powder in step 2) is atomized spherical powder.

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