Tool and method for friction stir modification of the surface of a crystallizer copper plate

Abstract

The application discloses a tool and method for realizing the modification treatment of the stir-frying of the surface of the copper plate of a crystallizer, and relates to the technical field of defect repair. The tool comprises a shaft body and a stationary shaft sleeve. The shaft body comprises a shaft neck, a shaft shoulder, a rolling body and a stirring needle. The shaft neck is sequentially connected with the shaft shoulder and the stirring needle. The rolling body is arranged around the shaft neck of the shaft body and rotates coaxially. The rolling body is provided with a connecting part and a rolling end. The rolling end is arranged in the same direction with the shaft shoulder and is used for rolling and stir-frying the repaired component with surface cracks. The stationary shaft sleeve comprises a sleeve, a positioning hole, a connecting rib plate, a front rolling body, a powder laying hopper and a cooling block. The application realizes the modification strengthening of the local organization of the repaired area by the stir-frying repair of the cracks, and improves the stress corrosion resistance and the fatigue resistance of the repaired area.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of defect repair, in particular to a friction stir modification tool for strengthening the surface of a crystallizer copper plate and a repair method. BACKGROUND

[0002] During the manufacturing, forming and use of engineering components, damage and micro-defects inevitably occur on the surface of the components. The existence and expansion of such micro-defects are the main reasons for the reduction of the strength, stiffness, toughness and service life of the material. Under certain external factors, these micro-defects will continuously expand and merge to form macro-cracks, and eventually lead to the fracture failure of the components or structures. Taking the crystallizer in a continuous casting machine as an example, the copper plate of the crystallizer is subjected to the simultaneous action of thermal stress, strand-pulling force, vibration device force, and is continuously impacted and corroded by molten steel, and is also subjected to friction with the steel billet, which easily leads to erosion and local micro-cracks, and under the action of continuous load, the cracks gradually expand and fracture, eventually leading to structural failure. Eliminating the cracks generated during the manufacturing and use of components is an important way to improve the reliability and safety of use. The main ways of crack elimination include crack repair and machining removal. Machining removal has a limited number of repair times for the same component, greatly shortens the overall service life of the component, consumes a large amount of resources, and increases the cost, while crack elimination through repair can prolong the service life of the component, which has high economic benefits and resource utilization value.

[0003] At present, the main crack repair method is based on the melting of the material to be repaired, including traditional arc welding, ion welding, etc. However, because of the excessive local heat input, it is easy to cause problems such as coarse structure, high residual stress in the repair area, pores and new cracks generated by fusion welding, etc. The conventional large plastic deformation repair method has the characteristics of strong dynamic recovery and recrystallization and second phase crushing and redistribution caused by deformation heat energy, and the overall temperature during the repair process is lower than the melting point of the material, which can avoid the adverse effects of the traditional fusion welding repair on the structure and performance. However, this method easily causes stress concentration on the surface of the repaired metal, has certain influence on the fatigue life and corrosion resistance of the repaired metal, and has certain limitations. SUMMARY

[0004] The problem solved by the present application is how to improve the conventional repair method to avoid the adverse effects of stress concentration on the surface of the repaired metal on the fatigue life and corrosion resistance of the repaired metal.

[0005] To solve the above problems, the application provides a stirring friction modification treatment tool for strengthening the surface of a crystallizer copper plate, comprising a shaft body and a stationary shaft sleeve, the shaft body comprises a shaft neck, a shaft shoulder, a rolling body, a stirring needle, the shaft neck is sequentially connected with the shaft shoulder and the stirring needle, the rolling body is arranged around the shaft neck of the shaft body and rotates coaxially, the rolling body is provided with a connecting part and a rolling end, and the rolling end is arranged in the same direction as the shaft shoulder; the stationary shaft sleeve comprises a sleeve, a positioning hole, a connecting rib plate, a front rolling body, a powder distribution hopper and a cooling block, the positioning hole is arranged on one side of the sleeve and penetrates through the side wall of the sleeve, the connecting rib plate is arranged on both sides of the sleeve in the advancing direction, one end of the connecting rib plate is provided with the powder distribution hopper, the outlet of the powder distribution hopper is provided with the front rolling body in the opposite direction of the advancing direction, and the other end of the connecting rib plate is connected with the cooling block.

[0006] Further, the rolling end is provided with a spherical ball, and the front rolling body is provided with an ellipsoidal ball.

[0007] Further, the diameter of the rolling body is 2:1 of the diameter of the shaft shoulder.

[0008] Further, the diameter of the rolling body is 2:1 of the diameter of the shaft shoulder.

[0009] Further, the diameter of the shaft shoulder is 5-10 mm.

[0010] Further, the stirring needle is connected to the bottom of the shaft shoulder, the number of the stirring needles is 1-7, and the stirring needles are coaxially or non-coaxially arranged.

[0011] To solve the above problems, the application further provides a stirring friction modification treatment method for strengthening the surface of a crystallizer copper plate, which is based on the stirring friction modification treatment tool for strengthening the surface of a crystallizer copper plate and comprises the following steps.

[0012] Step 1: selecting the material and size of the stirring friction modification treatment tool and the type and size of the metal powder according to the position, size and base material characteristics of the surface crack of the repaired part;

[0013] Step 2: cleaning the surface crack part of the repaired part and fixing the repaired part;

[0014] Step 3: using the stirring friction modification treatment tool to perform stirring friction treatment on the surface crack, in the treatment process, the stationary shaft sleeve moves along the advancing direction with the shaft body, the metal powder is uniformly distributed along the crack direction through the powder distribution hopper, the area treated by the shaft body and the rolling body is cooled by the cooling block after compaction by the front rolling body, and the treatment is completed.

[0015] Further, in step 3, the rotation speed of the shaft body is 10-10000 rpm.

[0016] Further, in step 3, the travel speed of the shaft body of the friction stir modification tool is 10-2000 mm / min.

[0017] Further, in step 3, the metal powder type includes but is not limited to copper-nickel alloy powder or chromium-zirconium-copper alloy powder.

[0018] The advantages of the friction stir modification tool and method for strengthening the surface of the crystallizer copper plate according to the present application over the prior art are that the pre-rolling body is an outward convex ellipsoidal surface, which can roll the metal powder into the crack and eliminate part of the stress at the crack; the shaft shoulder of the shaft body of the friction stir modification tool can rub the surface crack, so that the material in the repaired area is plasticized at high temperature, the whole process is at a temperature lower than the melting point of the material, effectively avoiding the influence on the microstructure and performance of the base material, and the deformation and residual stress are lower than those of the traditional friction stir repair; at the same time, the rolling end is rolled while being acted on by the shaft shoulder, realizing the function of stirring and rolling, so that the hot plastic material has a high strain rate; the cooling block can cool the area treated by the friction stir in time, which is helpful to form fine equiaxed grains on the surface of the repaired area and form a gradient fine grain structure in the depth direction, realizing the modification and strengthening of the local microstructure of the repaired area, and the friction stir and welding rolling repair makes the surface of the repaired area smooth and flat, and the rolling force in the depth direction of the repaired area is beneficial to improve the stress corrosion and fatigue resistance of the repaired area, and the repair process is simple, time-saving and labor-saving, pollution-free and low-cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The figure is a repair process schematic diagram of the friction stir modification tool for strengthening the surface of the crystallizer copper plate in the embodiment of the present application.

[0020] Figure 2 The figure is a shaft body structure schematic diagram of the friction stir modification tool for strengthening the surface of the crystallizer copper plate in the embodiment of the present application.

[0021] Figure 3 The figure is a static shaft sleeve structure schematic diagram of the friction stir modification tool for strengthening the surface of the crystallizer copper plate in the embodiment of the present application.

[0022] Figure 4 The figure is a structure schematic diagram of the repaired part with surface cracks in the embodiment of the present application.

[0023] Figure 5 The figure is a schematic diagram of the microstructure before and after the surface crack repair area in the embodiment of the present application.

[0024] Reference signs:

[0025] 1 - to be repaired; 2 - surface crack; 3 - shaft body; 301 - journal; 302 - shoulder; 303 - rolling body; 304 - connecting part; 305 - rolling end; 306 - stirring needle; 4 - stationary sleeve; 401 - sleeve; 402 - positioning hole; 403 - connecting rib plate; 404 - powder laying hopper; 405 - cooling block; 406 - pre-rolling body. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. The present application will be further described in detail: the present embodiment is implemented on the premise of the technical scheme of the present application, and a detailed implementation manner is given, but the protection scope of the present application is not limited to the following embodiments.

[0027] Specifically, as shown in Figures 1 to 5 The embodiment of the present application provides a stirring friction modification treatment tool for realizing surface strengthening of a crystallizer copper plate, which comprises a shaft body 3 and a stationary sleeve 4. The shaft body 3 comprises a journal 301, a shoulder 302, a rolling body 303 and a stirring needle 306. The journal 301 is sequentially connected with the shoulder 302 and the stirring needle 306. The rolling body 303 is arranged around the journal 301 of the shaft body 3 and rotates coaxially. The rolling body 303 is provided with a connecting part 304 and a rolling end 305. The rolling end 305 is arranged in the same direction as the shoulder 302, and is used for rolling and stirring friction of a to-be-repaired member having a surface crack. The stationary sleeve 4 comprises a sleeve 401, a positioning hole 402, a connecting rib plate 403, a pre-rolling body 406, a powder laying hopper 404 and a cooling block 405. The positioning hole 402 is arranged on one side of the sleeve 401 and penetrates through the side wall of the sleeve 401. The connecting rib plate 403 is provided in two groups and is correspondingly arranged on both sides of the sleeve 401 along the direction of travel. The front end of one group of connecting rib plates 403 is provided with the powder laying hopper 404 along the direction of travel. The outlet of the powder laying hopper 404 is provided with the pre-rolling body 406 along the opposite direction of travel. The rear end of the other group of connecting rib plates 403 is connected with the cooling block 405 along the direction of travel.

[0028] In the present application, the metal powder is uniformly distributed along the crack direction through the powder distribution hopper 404, and then is compacted and partially pressed into the crack gap through the front roller 406, the shaft shoulder 4 can rub the surface crack 2, so that the material of the repaired area is plasticized at high temperature, the whole process is below the melting point of the material, which effectively avoids the influence on the microstructure and performance of the base material, and has lower deformation and residual stress compared with the traditional friction stir repair; the stirring pin 306 is inserted into the substrate for stirring, and at the same time, the roller 303 is used to roll through the rolling end 305 while the shaft shoulder 302 is acting, so as to realize the function of stirring and rolling, so that the hot plastic material has a high strain rate, and the cooling block 405 can cool the area treated by the friction stirring in time, which is helpful to form fine equiaxed grains on the surface layer of the repaired area, and form a gradient fine grain structure in the depth direction, as shown in Figure 4 The present application realizes the modification and strengthening of the local structure of the repaired area, and the friction stir rolling repair makes the surface of the repaired area smooth and flat, and the rolling force in the depth direction of the repaired area is beneficial to improve the stress corrosion resistance and fatigue resistance of the repaired area. The repair process is simple, time-saving and labor-saving, pollution-free and low in cost.

[0029] Specifically, the present application realizes the friction heat production of the shaft shoulder 302 and the surface of the repaired material by rotation, so that the repaired area reaches the hot plastic state, and then the rotation of the shaft shoulder 302 and the stirring pin 306 realizes the rotation stirring and upset effect, so that the hot plastic metal around the crack is dynamically recovered and recrystallized, and the crack is repaired; the roller 303 can reduce the deformation of the repaired material during the repair process, especially for thin plates, because the transverse extrusion force is applied to the repaired position by the rolling end 305 during the repair process, so that the material in the high temperature plastic state can flow more fully, the deformation of the repaired area is extended, and the longitudinal deformation degree is relieved. The plastic deformation of the crack area is extended by the rolling with the welding, and the longitudinal residual stress is further reduced. Compared with pure friction, the present application has better flattening effect and forms a gradient fine grain structure in the depth direction of the repaired area, has higher strength, better stress corrosion resistance and fatigue resistance.

[0030] In some specific embodiments, the roller 303 comprises a connecting part 304 and a rolling end 305, the rolling end 305 is arranged through the annular end face of the roller 303, and the rolling end 305 is arranged at one end of the connecting part 304.

[0031] Specifically, the connecting part 304 is made of H13 steel, the rolling part 305 is a cylindrical 304 stainless steel bolt, and is threadedly connected with the roller 303, so that the rolling depth can be adjusted by threads, and the installation method is simple.

[0032] In some specific embodiments, the rolling end is provided with spherical balls; the front roller is provided with ellipsoidal balls. In this way, uniform rolling is realized, and stress concentration is reduced.

[0033] In some specific embodiments, the ratio of the diameter of the roller 303 to the diameter of the shaft shoulder 302 is 2:1. Thus, the simultaneous friction and stirring is effectively realized, and full coverage of the crack site is realized.

[0034] In some specific embodiments, the shaft sleeve 401 has a diameter larger than the maximum diameter of the shaft body 3. Thus, the shaft sleeve 401 can freely move up and down along the shaft body 3, facilitating the fitting.

[0035] In some specific embodiments, the diameter of the shaft shoulder 302 includes 5-10mm. Thus, it is beneficial to realize the rapid achievement of the thermoplastic state of the material surface, realizing the friction repair.

[0036] In some specific embodiments, the roller end 305, the front roller 406 and the bottom of the cooling block 405 are coplanar. Thus, the common repair of the crack is effectively realized, and the effective effect is improved.

[0037] In some specific embodiments, the bottom aperture of the powder laying hopper 404 is 1-10mm. Thus, the powder laying amount on the unit length crack can be controlled.

[0038] In some specific embodiments, the cooling block 405 is a hollow box, and the lower part of the side wall of one end of the hollow box is provided with a cooling liquid inlet, and the upper part of the side wall of the other end is provided with a cooling liquid outlet. Thus, the rapid cooling of the repaired area is realized, and the repair effect is improved.

[0039] In some specific embodiments, the cooling block 405 is bolted with the connecting rib plate 403, and no relative movement occurs during use. Thus, the cooling effect of the cooling block 405 on the modified area can be ensured.

[0040] In some specific embodiments, the stirring needle 306 is connected to the bottom of the shaft shoulder 302, and the number of the stirring needles 306 includes 1-7, which are coaxial or non-coaxial. Thus, it is beneficial to fully stir the surface metal, making the performance more uniform.

[0041] In some specific embodiments, the material of the ball is zirconia. Thus, the influence of the heat input of the shaft shoulder 4 is reduced, no secondary heat input is generated, and the material is stable.

[0042] The embodiment of the present application also provides a stirring friction modification processing method for realizing the surface strengthening of the crystallizer copper plate, which is realized based on a stirring friction modification processing tool for realizing the surface strengthening of the crystallizer copper plate, and includes the following steps:

[0043] Step 1: The material and size of the stirring friction modification processing tool and the type and size of the metal powder are selected according to the site, size and base material characteristics of the surface crack 2 of the repaired part 1.

[0044] Step 2: After cleaning the surface crack 2 of the repaired part 1, fix the repaired part 1;

[0045] Step 3: The surface crack 2 is treated by using a friction stir modification tool. In the treatment process, the static shaft sleeve 4 moves along with the shaft body 3 in the direction of travel, and the metal powder is uniformly distributed along the crack direction through the powder distribution funnel 404. After compaction by the pre-roller 406, the area treated by the shaft body 3 and the roller is cooled by the cooling block 405, and the treatment is completed.

[0046] Specifically, as shown in Figures 1 to 5 The material of the repaired part 1 in step 1 can also be aluminum, magnesium, titanium and other metals, their alloys and metal matrix composites, etc., which can all use the tool in the present application. At the same time, according to the position, size and base material characteristics of the surface crack 2 of the repaired part 1, the material and size of the friction stir surface modification tool and the type and size of the metal powder are selected to achieve targeted and efficient repair. It should be noted that for aluminum and magnesium alloys, the repair tool is made of ordinary tool steel; for steel, titanium alloy and other high-melting-point materials, the repair tool is preferably made of high-temperature and high-toughness special materials.

[0047] In step 2, cleaning the surface crack 2 of the repaired part 1 includes: polishing the surface crack 2, ultrasonic cleaning, and then cleaning with anhydrous ethanol and drying. Specifically, during polishing, the surface oxides and impurities are removed, and then the surface is cleaned with ultrasonic waves, preferably for 15 minutes, and then cleaned with anhydrous ethanol and dried. In this way, the mixing of impurities during the repair process is reduced, which affects the performance of the repaired part.

[0048] In step 3, after the repaired part 1 is fixed, the heat generated by the friction between the high-speed rotating shaft shoulder 302 and the surface of the crack area makes the surrounding metal reach a thermoplastic state. Then, the tool's stirring, upset, rolling and cooling effects are used to achieve the flow and transfer of the thermoplastic metal and the surface modification of the repair area, making the repair area smooth and flat, and the depth direction showing a gradient fine-grained structure. The rolling effect of the rolling end 305 can make the repair area around the crack smooth and flat, without the need for secondary processing to remove burrs and burrs.

[0049] In some specific embodiments, in step 3, the rotation speed of the shaft body is 10-10000 rpm, and the travel speed is 50-2000 mm / min. In this way, the material reaches a thermoplastic state quickly and stably, providing conditions for efficient repair.

[0050] In some specific embodiments, in step 3, the types of metal powder include but are not limited to copper-nickel alloy powder and chromium-zirconium-copper alloy powder. In this way, different materials are treated with different materials for different materials.

[0051] In some specific embodiments, in step 3, the cooling mode of the cooling block 405 is that the cooling liquid is injected from the cooling liquid inlet of the cooling block 405 and discharged from the cooling liquid outlet. In this way, a better cooling effect is obtained.

[0052] In some specific embodiments, in step 3, the cooling liquid includes but is not limited to water, ethanol or glycerol. In this way, different cooling liquids are used for different cooling needs.

[0053] In some specific embodiments, after the repair is completed, the repaired part is subjected to heat treatment to improve the performance of the repaired part.

[0054] Embodiment 1

[0055] The tool and method for realizing the surface strengthening of the crystallizer copper plate in this embodiment include the following steps:

[0056] Step 1: For the repair of a long straight crack on the surface of a 8mm thick Cr-Zr-Cu material, the crack depth is 1mm and the length is 200mm, H13 steel is selected as the tool for friction stir repair, as shown in Figure 1 The shoulder 4 has a diameter of 5mm, the stirring needle 306 has a length of 1.5mm, the rolling end 305 has a diameter of 10mm, the powder hopper 404 has a bottom hole diameter of 2mm, the metal powder is selected to be copper-nickel alloy powder with a particle size of 50nm, and the cooling liquid is water.

[0057] Step 2: Use sandpaper to polish the surface around the crack to remove the surface oxide skin, then ultrasonic clean for 15 minutes, then clean and dry with anhydrous ethanol, then rigidly fix the repaired part 1 on the workbench of the tool for friction stir surface modification treatment;

[0058] Step 3: Select the rotation speed of the shaft body 3 to be 1000rpm, the travel speed to be 100mm / min, the down pressure of the shoulder 4 to be 0.2mm, and the depth of the filler roller to be 0.1mm, so that the shoulder 4 runs along the starting end of the crack to the tail end of the crack for repair until the repair is completed.

[0059] After the repair method in this embodiment is used for repair, the Cr-Zr-Cu plate of the repaired part is detected, and no cracks or other defects are found through non-destructive testing. Therefore, it can be seen that the repair method in this embodiment has the effect of realizing the modification and strengthening of the local structure of the repaired area.

[0060] The above merely describes preferred specific embodiments of the present application, which are all different implementations based on the overall concept of the present application, and the protection scope of the present application is not limited thereto, any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application shall be encompassed within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A tool for friction stir modification of a crystallizer copper plate surface for strengthening, characterized by, The application relates to a surface crack repairing device, which comprises a shaft body (3) and a static shaft sleeve (4), the shaft body (3) comprises a shaft neck (301), a shaft shoulder (302) and a rolling body (303), the shaft neck (301) is sequentially connected with the shaft shoulder (302) and a stirring needle (306), the diameter ratio of the rolling body (303) to the shaft shoulder (302) is 2:1, the rolling body (303) is arranged around the shaft neck (301) of the shaft body (3) and rotates coaxially, the rolling body (303) is provided with a connecting part (304) and a rolling end (305), the rolling end (305) is connected with the rolling body (303) through thread rolling depth adjustment, the rolling end (305) is arranged in the same direction with the shaft shoulder (302), the shaft shoulder (302) can rub the surface crack (2) to make the material of a to-be-repaired area plasticize at high temperature, and the rolling end (305) can realize stirring and rolling of the to-be-repaired area under the action of the shaft shoulder (302); the static shaft sleeve (4) comprises a shaft sleeve (401), a positioning hole (402), connecting rib plates (403), a front rolling body (406), a powder spreading hopper (404) and a cooling block (405), the positioning hole (402) is arranged on one side of the shaft sleeve (401) and penetrates through the side wall of the shaft sleeve (401), the connecting rib plates (403) are arranged on the two sides of the shaft sleeve (401) in the advancing direction, one group of the connecting rib plates (403) is provided with the powder spreading hopper (404) at the front end in the advancing direction, the powder spreading hopper (404) is provided with the front rolling body (406) at the outlet in the reverse direction of the advancing direction, the front rolling body (406) is provided with ellipsoidal balls capable of rolling the metal powder into the crack, the other group of the connecting rib plates (403) is connected with the cooling block (405) at the rear end in the advancing direction, the rolling end (305), the front rolling body (406) and the bottom of the cooling block (405) are coplanar, the cracks are repaired together, and the surface of the repaired area is smooth and flat.

2. The tool for friction stir modification of crystallizer copper plate surface for strengthening according to claim 1, characterized in that, The rolling end (305) is provided with spherical balls.

3. The tool for friction stir modification of crystallizer copper plate surface for strengthening according to claim 1, characterized in that, The bottom aperture of the powder spreading hopper (404) is 1-10 mm.

4. The tool for friction stir modification of crystallizer copper plate surface for strengthening according to claim 1, characterized in that, The diameter of the shaft shoulder (302) is 5-10 mm.

5. The tool for friction stir modification of a crystallizer copper plate surface for strengthening according to claim 1, characterized in that, The stirring needle (306) is connected to the bottom of the shaft shoulder (302), the number of the stirring needles (306) is 1-7, and the stirring needles (306) are coaxially or non-coaxially arranged.

6. A method of implementing a surface strengthening of a crystallizer copper plate by a friction stir modification process, implemented by a tool for implementing a surface strengthening of a crystallizer copper plate by a friction stir modification process according to any one of claims 1 to 5, characterized in that, The application further discloses a surface crack repairing method, which comprises the following steps: Step 1: selecting the material and size of a stir-friction modification tool and the type and size of metal powder according to the position, size and base material characteristics of a surface crack of a to-be-repaired part; Step 2: cleaning the surface crack position of the to-be-repaired part and fixing the to-be-repaired part; Step 3: the surface crack is treated by the friction stir modification tool, the stirring pin (306) is inserted into the substrate for stirring during the treatment, the static shaft sleeve (4) moves along with the shaft body (3) in the advancing direction, and the metal powder is uniformly distributed along the crack direction through the powder laying hopper (404) arranged on the static shaft sleeve (4), the metal powder is rolled into the crack through the outer convex ellipsoidal surface of the end of the front roller (406) arranged on the static shaft sleeve (4), and part of the stress at the crack is eliminated, the surface crack (2) is treated by the friction stir modification tool through the shaft shoulder (302) of the shaft body (3), and the roller (303) is used to roll through the rolling end (305) while the shaft shoulder (302) is acted on, the friction stir area after the rolling end (305) is rolled is cooled by the cooling block (405), the repair area around the crack is smooth and flat without burrs and burrs due to the coplanar of the rolling end (305), the front roller (406) and the bottom of the cooling block (405), and the treatment is completed.

7. The method of friction stir modification for achieving grain refinement of the surface of a copper plate of a mold according to claim 6, wherein In step 3, the rotating speed of the shaft body (3) is 10-10000 rpm.

8. The method of claim 6, wherein the method is characterized by: In step 3, the advancing speed of the shaft body (3) of the friction stir modification tool is 10-2000 mm / min.

9. The method of claim 6, wherein the method is characterized by: In step 3, the types of the metal powder include but are not limited to copper-nickel alloy powder or chromium-zirconium-copper alloy powder.

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