Method for composite modification of roller surface of hob shaft

Abstract

The invention relates to the technical field of surface modification and remanufacturing, in particular to a hob shaft roller surface composite modification method which comprises the following steps: pretreating the surfaces of an upper main shaft and a lower main shaft of a hob shaft; the surface of the hob shaft is subjected to chromium plating by selecting a proper additive process according to the characteristics of the base material; post-treatment is conducted on the surface of the hobbing cutter shaft subjected to chromium plating; carrying out nitriding treatment on the hob shaft subjected to post-treatment by adopting an ion nitriding process; and the hobbing cutter shaft subjected to nitriding treatment is polished. According to the chromium plating and surface nitriding composite treatment process for the hobbing cutter shaft, the hobbing cutter shaft has the properties such as wear resistance, stability and corrosion resistance on the premise that the hobbing cutter shaft has the original properties. Nitriding treatment is carried out on the surface of the hobbing cutter shaft after chromium plating, and the nitrided roller surface not only retains all properties of a base material, but also has properties such as wear resistance, stability and corrosion resistance. The method for preparing the nitride layer on the surface of the hob shaft roller body is an effective method for improving the surface wear resistance and prolonging the service life of the hob shaft roller body.

Description

Technical Field

[0001] The invention relates to the technical field of surface modification and remanufacturing, and in particular to a method for composite modification of a roller surface of a hob shaft. Background Art

[0002] The hob shaft is a precision component on the finishing equipment of the cold-rolled strip production line. Its accuracy and stability are directly related to the quality of the finished strip products. The original roller surface hardness is HRC50, and the wear resistance is poor. The components are prone to wear and fatigue during service, resulting in a large gap between the hob ring and the hob shaft, causing shear waves, creases, extrusion and other events that affect product quality.

[0003] During the use of the hob shaft, the distance between the hob rings often needs to be adjusted to achieve the shearing of different widths of strip steel products. Therefore, in addition to the HRC56+6 hardness, it also needs to have strong wear resistance. Therefore, it is necessary to perform surface modification on the repair area of ​​the hob shaft parts to improve its wear resistance. Summary of the invention

[0004] The purpose of the present invention is to provide a method for composite modification of the roller surface of a hob shaft, which uses chrome plating and vacuum ion nitriding as basic remanufacturing means, has the characteristics of low heat input, small heat-affected zone and deformation, low repair cost, short construction period, strong surface bonding, wear resistance, etc., and can achieve a significant improvement in the service capacity after repair.

[0005] The solution adopted by the present invention to achieve the purpose is: a method for composite modification of the roller surface of a hob shaft, comprising the following steps:

[0006] (1) Pre-process the upper and lower spindle surfaces of the hob shaft;

[0007] (2) Selecting a suitable additive process according to the characteristics of the substrate to chrome plate the surface of the hob shaft;

[0008] (3) Post-processing the chrome-plated hob shaft surface;

[0009] (4) The hob shaft after post-treatment is nitrided by an ion nitriding process;

[0010] (5) Polish the hob shaft after nitriding treatment.

[0011] Preferably, in step (1), the hob shaft is a hob shaft made of 42CrMo-QT, 42CrMo, 35Cr2Mo, or 25Cr2MoVA.

[0012] Preferably, in step (1), the pre-treatment includes machining to grind off the fatigue layer, cleaning, and drying in sequence.

[0013] Preferably, in step (2), a ZD-B intelligent electrolytic thickness gauge is used to monitor the coating thickness, and the chromium plating process parameters are optimized according to the characteristics of the substrate.

[0014] Preferably, in step (2), the formula of the chromium plating solution is: Cr2(SO4)3·6H2O is 25-35g·L -1 , complexing agent is 50~70g·L -1 , buffer is 40~60g·L -1 , conductive salt is 100~150g·L -1 , additives are 10~20mg·L -1 .

[0015] Preferably, the complexing agent is H2C2O4·2H2O, the buffer is H3BO3, the conductive salt is Na2SO4, and the additive is a mixture of an alcohol-containing organic compound and a sulfur-containing organic compound.

[0016] The alcohol-containing organic compound is 2-butyne-1,4-diol or ethanol.

[0017] The sulfur-containing organic compound is at least one of saccharin, sodium thiocyanate and its other salts, sodium dimethyldithiocarbamate, dialkylthiocarbamate, thiourea and its derivatives, sodium mercaptopropane sulfonate, soluble mercaptoalkane, sodium allyl sulfonate and / or allylthiourea, and sodium vinyl sulfonate.

[0018] Preferably, the additive is a mixture of an alcohol-containing organic compound and a sulfur-containing organic compound in a molar ratio of 1:1-3.

[0019] Preferably, in step (2), the process parameters of chromium plating are: electroplating time 3-5min, anode is DSA anode, cathode is copper or nickel-plated copper, pH value is 3-4, current density is 3.5-7.5A / dm 2 , the temperature is 50±5℃.

[0020] Preferably, in step (3), the post-processing includes grinding and cleaning in sequence to restore the size and accuracy of the roller body.

[0021] Preferably, in step (4), the nitriding process parameter conditions are: nitrogen pressure is 200-500 Pa, nitriding temperature is 500-650° C., and nitriding time is 3-9 hours.

[0022] Further preferably, the parameter conditions of the nitriding process are: nitrogen pressure of 200-500 Pa, nitriding temperature of 540-650° C., and nitriding time of 3-8 hours.

[0023] According to the above process parameters and methods, the roller of the hob shaft is nitrided to obtain a controllable high-performance nitrided layer on the surface of the repaired part, and a nitrided layer with uniform thickness, high hardness and high wear resistance is formed on the surface of the roller of the hob shaft. The method of the present invention can achieve high-quality repair and surface modification, the hardness of the surface modification layer is greatly improved, and the wear resistance is improved by 3 times compared with the base material.

[0024] The present invention mainly adopts plasma gas nitriding to perform nitriding treatment on the surface of the roller body of the hob shaft, and the depth of the nitriding layer is 0.4mm-0.6mm.

[0025] Preferably, in step (4), when the vacuum degree of the vacuum chamber in the nitriding furnace is less than 1×10 -4 Pa, nitrogen was introduced.

[0026] The present invention has the following advantages and beneficial effects:

[0027] The present invention provides a composite treatment process of chrome plating and surface nitriding of a hob shaft. The method can ensure that the hob shaft has the original performance while having the properties of wear resistance, stability, corrosion resistance and the like. After chrome plating, the surface of the hob shaft is subjected to nitriding treatment. After nitriding, the roller surface retains all the properties of the substrate and also has the properties of wear resistance, stability, corrosion resistance and the like. Preparing a nitrided layer on the surface of the hob shaft roller body is an effective method to improve its surface wear resistance and extend its service life. DETAILED DESCRIPTION

[0028] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0029] Example 1

[0030] The material is 42CrMo-QT, the diameter is Taking the hob shaft as an example, a method for composite modification of the roller surface of the hob shaft comprises the following steps:

[0031] Step 1: Pre-process the surface of the roller shaft, including machining, using cylindrical grinding equipment and silicon carbide grinding wheel to grind and remove the fatigue layer on the roller surface, 0.3mm on one side, and clean and dry it;

[0032] Step 2: Use electroplating chrome technology to monitor the coating thickness on the roller surface using a ZD-B intelligent electrolytic thickness gauge;

[0033] Step 3: Optimize the chrome plating process parameters according to the characteristics of the substrate to obtain the optimized additive repair process parameters and routes;

[0034] Step 4: Use optimized process parameters to perform additive manufacturing on the roller surface, grind and clean the roller surface after additive manufacturing, and restore the roller body size and accuracy;

[0035] Step 5: The hob shaft after additive manufacturing is subjected to ion nitriding process and nitriding treatment is performed in an ion nitriding furnace: the nitrogen pressure is 200Pa, the nitriding temperature is 650°C, the nitriding time is 8 hours, the duty cycle is 80; the voltage is -500V;

[0036] Step 6: Polish the roller surface.

[0037] In step 4, the main parameters and route of the electroplating chromium process are as follows: the material is electroplated chromium, and the preferred formula of the plating solution is: Cr2(SO4)3·6H2O (main salt) 30g·L -1 , H2C2O4·2H2O (complexing agent) 50g·L -1 , H3BO3 (buffer) 40g·L -1 , Na2SO4 (conductive salt) 100g·L -1 , mixture of alcoholic organic compounds and sulfur-containing organic matter (additives) 10 mg·L -1 .

[0038] The additive is a mixture of 2-butyne-1,4-diol and saccharin in a molar ratio of 1:1.

[0039] The optimal process parameters are: electroplating time 3-5min, anode is DSA anode, cathode is copper or nickel-plated copper, pH value is 3-4, current density is 3.5A / dm 2 , the temperature is 50℃.

[0040] In step five, the heating condition is as follows: when the vacuum degree of the vacuum chamber in the nitriding furnace is less than 1×10-4Pa, nitrogen is introduced.

[0041] According to the above process parameters and methods, the roller of the hob shaft is chrome plated and nitrided, and a controllable high-performance nitrided layer can be obtained on the surface of the repaired part, and a nitrided layer with uniform thickness, high hardness and high wear resistance can be formed on the surface of the roller of the hob shaft. The method of the present invention can obtain high-quality repair and surface modification, and the hardness of the surface modification layer is as high as HRC57-61, and the wear resistance is improved by 3 times compared with the base material.

[0042] Example 2

[0043] The material is 35Cr2Mo and the diameter is Taking the hob shaft as an example, a method for composite modification of the roller surface of the hob shaft comprises the following steps:

[0044] Step 1: Pre-process the surface of the roller shaft, including machining, using cylindrical grinding equipment and silicon carbide grinding wheel to grind and remove the fatigue layer on the roller surface, 0.3mm on one side, and clean and dry it;

[0045] Step 2: Use electroplating chrome technology to monitor the coating thickness on the roller surface using a ZD-B intelligent electrolytic thickness gauge;

[0046] Step 3: Optimize the chrome plating process parameters according to the characteristics of the substrate to obtain the optimized additive repair process parameters and routes;

[0047] Step 4: Use optimized process parameters to perform additive manufacturing on the roller surface, grind and clean the roller surface after additive manufacturing, and restore the roller body size and accuracy;

[0048] Step 5: The hob shaft after additive manufacturing is subjected to ion nitriding process and nitriding treatment is performed in an ion nitriding furnace: the nitrogen pressure is 500Pa, the nitriding temperature is 540°C, the nitriding time is 3 hours, the duty cycle is 80, and the voltage is -500V;

[0049] Step 6: Polish the roller surface.

[0050] In step 4, the main parameters and route of the electroplating chromium process are: the material is electroplated chromium, and the preferred formula of the plating solution is: Cr2(SO4)3·6H2O (main salt) 35g·L -1 , H2C2O4·2H2O (complexing agent) 70g·L -1 , H3BO3 (buffer) 60g·L -1 , Na2SO4 (conductive salt) 150g·L -1 , mixture of alcoholic organic compounds and sulfur-containing organic matter (additives) 20 mg·L -1 .

[0051] The alcohol-containing organic compound is 2-butyne-1,4-diol or ethanol.

[0052] The sulfur-containing organic compound is at least one of saccharin, sodium thiocyanate and its other salts, sodium dimethyldithiocarbamate, dialkylthiocarbamate, thiourea and its derivatives, sodium mercaptopropane sulfonate, soluble mercaptoalkane, sodium allyl sulfonate and / or allylthiourea, and sodium vinyl sulfonate.

[0053] The additive is a mixture containing 2-butyne-1,4-diol and sodium mercaptopropane sulfonate in a molar ratio of 1:2.

[0054] The optimal process parameters are: electroplating time 3-5min, anode is DSA anode, cathode is copper or nickel-plated copper, pH value is 3-4, current density is 5A / dm 2 , the temperature is 55℃.

[0055] In step five, the heating condition is as follows: when the vacuum degree of the vacuum chamber in the nitriding furnace is less than 1×10-4Pa, nitrogen is introduced.

[0056] According to the above process parameters and methods, the roller of the hob shaft is chrome plated and nitrided, and a controllable high-performance nitrided layer can be obtained on the surface of the repaired part, and a nitrided layer with uniform thickness, high hardness and high wear resistance can be formed on the surface of the roller of the hob shaft. The method of the present invention can obtain high-quality repair and surface modification, and the hardness of the surface modification layer is as high as HRC57-63, and the wear resistance is improved by 3.5 times compared with the base material.

[0057] Example 3

[0058] The material is 42CrMo and the diameter is Taking the hob shaft as an example, a method for composite modification of the roller surface of the hob shaft comprises the following steps:

[0059] Step 1: Pre-process the surface of the roller shaft, including machining, using cylindrical grinding equipment and silicon carbide grinding wheel to grind and remove the fatigue layer on the roller surface, 0.3mm on one side, and clean and dry it;

[0060] Step 2: Use electroplating chrome technology to monitor the coating thickness on the roller surface using a ZD-B intelligent electrolytic thickness gauge;

[0061] Step 3: Optimize the chrome plating process parameters according to the characteristics of the substrate to obtain the optimized additive repair process parameters and routes;

[0062] Step 4: Use optimized process parameters to perform additive manufacturing on the roller surface, grind and clean the roller surface after additive manufacturing, and restore the roller body size and accuracy;

[0063] Step 5: The hob shaft after additive manufacturing is subjected to ion nitriding process and nitriding treatment is performed in an ion nitriding furnace: the nitrogen pressure is 400Pa, the nitriding temperature is 600°C, the nitriding time is 5 hours, the duty cycle is 80; the voltage is -500V;

[0064] Step 6: Polish the roller surface.

[0065] In step 4, the main parameters and route of the electroplating chromium process are as follows: the material is electroplated chromium, and the preferred formula of the plating solution is: Cr2(SO4)3·6H2O (main salt) 25g·L -1 , H2C2O4·2H2O (complexing agent) 60g·L -1 , H3BO3 (buffer) 50g·L -1 , Na2SO4 (conductive salt) 130g·L -1 , alcohol-containing organic compounds and sulfur-containing organic mixtures (additives) 15 mg·L -1 .

[0066] The additive is a mixture of ethanol and thiourea in a molar ratio of 1:3.

[0067] The optimal process parameters are: electroplating time 3-5min, anode is DSA anode, cathode is copper or nickel-plated copper, pH value is 3-4, current density is 7.5A / dm 2 , the temperature is 45℃.

[0068] In step five, the heating condition is as follows: when the vacuum degree of the vacuum chamber in the nitriding furnace is less than 1×10-4Pa, nitrogen is introduced.

[0069] According to the above process parameters and methods, the roller of the hob shaft is chrome plated and nitrided, and a controllable high-performance nitrided layer can be obtained on the surface of the repaired part, and a nitrided layer with uniform thickness, high hardness and high wear resistance can be formed on the surface of the roller of the hob shaft. The method of the present invention can obtain high-quality repair and surface modification, and the hardness of the surface modification layer is as high as HRC57-61, and the wear resistance is improved by 2.8 times compared with the base material.

[0070] The above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principle of the present invention, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. A method for composite modification of a roller surface of a hob shaft, characterized in that: The following steps are involved: (1) Pre-process the upper and lower spindle surfaces of the hob shaft; (2) Selecting a suitable additive process according to the characteristics of the substrate to chrome plate the surface of the hob shaft; (3) Post-processing the chrome-plated hob shaft surface; (4) The hob shaft after post-treatment is nitrided by an ion nitriding process; (5) Polish the hob shaft after nitriding treatment.

2. The method for composite modification of the roller surface of a hob shaft according to claim 1, characterized in that: In step (1), the hob shaft is a hob shaft made of 42CrMo-QT, 42CrMo, 35Cr2Mo, or 25Cr2MoVA.

3. The method for composite modification of the roller surface of a hob shaft according to claim 1, characterized in that: In step (1), the pretreatment includes machining to grind off the fatigue layer, cleaning, and drying.

4. The method for composite modification of the roller surface of a hob shaft according to claim 1, characterized in that: In step (2), a ZD-B intelligent electrolytic thickness gauge is used to monitor the coating thickness, and the chrome plating process parameters are optimized according to the characteristics of the substrate.

5. The method for composite modification of the roller surface of a hob shaft according to claim 1, characterized in that: In step (2), the formula of the chromium plating solution is: Cr2(SO4)3·6H2O is 25-35g·L -1 , complexing agent is 50~70g·L -1 , buffer is 40~60g·L -1 , conductive salt is 100~150g·L -1 , additives are 10~20mg·L -1 .

6. The method for composite modification of the roller surface of a hob shaft according to claim 5, characterized in that: The complexing agent is H2C2O4·2H2O, the buffer is H3BO3, the conductive salt is Na2SO4, and the additive is a mixture of an alcohol-containing organic compound and a sulfur-containing organic compound.

7. The method for composite modification of the roller surface of a hob shaft according to claim 1, characterized in that: In step (2), the process parameters of chromium plating are: electroplating time 3-5min, anode is DSA anode, cathode is copper or nickel-plated copper, pH value is 3-4, current density is 3.5-7.5A / dm 2 , the temperature is 50±5℃.

8. The method for composite modification of the roller surface of a hob shaft according to claim 1, characterized in that: In step (3), the post-processing includes grinding and cleaning in sequence to restore the roller body size and accuracy.

9. The method for composite modification of the roller surface of a hob shaft according to claim 1, characterized in that: In step (4), the nitriding process parameters are as follows: nitrogen pressure is 200-500 Pa, nitriding temperature is 500-650° C., and nitriding time is 3-9 hours.

10. The method for composite modification of the roller surface of a hob shaft according to claim 1, characterized in that: In step (4), when the vacuum degree of the vacuum chamber in the nitriding furnace is less than 1×10 -4 Pa, nitrogen was introduced.