A method of straightening a curved continuous-casting roll mandrel

Abstract

The present application relates to a kind of methods for straightening curved continuous casting roller mandrel, comprising the following steps: disassembly, cleaning mandrel, and nondestructive testing is carried out to mandrel;With the mandrel of flaw detection qualified is clamped on laser numerical control processing machine tool, laser scanning and laser cladding are sequentially carried out to carry out rough straightening;After cooling, the coaxiality of bearing position after straightening is measured, if eccentricity is greater than or equal to 1mm, repeat rough straightening process, until eccentricity is less than 1mm;Wherein the mandrel of needing straightening bearing position in multiple places, laser scanning and laser cladding of bearing position in each place are completed using the above steps;When all bearing positions are completed straightening, turning is carried out by numerical control machine tool, and nondestructive testing is carried out to mandrel after processing, and flaw detection is defect-free mandrel is applied with rust-proof oil and is ready for use.The present application realizes the repair of curved continuous casting roller mandrel, prolongs the service life of mandrel, avoids the early scrapping of mandrel due to bending, and process is simple, low in cost, with remarkable economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal surface engineering, and particularly relates to a method for straightening a bent continuous casting roller shaft. BACKGROUND

[0002] The continuous casting roller is one of the key components of various slab continuous casting equipment, and its main functions are to control the guiding, cooling, driving and shaping of the cast slab. The temperature of the continuous casting slab out of the crystallizer is generally 1200-1400 DEG C, and the maximum temperature of the continuous casting roller at the contact surface with the cast slab can reach nearly 600 DEG C. For a wider slab, the continuous casting roller adopts a three-section or two-section mode for stringing, and the three-section or two-section rollers are connected in series through a shaft, and the roller faces are connected with the shaft through keys to keep synchronous rotation with the shaft.

[0003] In the continuous casting production, the coaxiality of the shaft is strictly required, and the coaxiality is generally required to be less than 0.15 mm. However, in actual work, due to the continuous adjustment of the slab size caused by order changes, the external load borne by each roller of the three-section roller or the two-section roller is different, the bearings in each bearing seat supporting the shaft are worn differently due to the eccentric load, and then the local eccentric radial force is borne by the bearing position of the shaft, and the local bending of each bearing position of the shaft after use often occurs, and the bending degree can even reach 1-5 mm of eccentricity. The use of the bent shaft causes the jumping of the continuous casting slab of the production line, the change of the section size of the slab at different positions, the exceeding of the tolerance, and a large number of unqualified products, which seriously affect the product quality and economic benefits.

[0004] At present, the shaft is generally made of 42CrMo material by forging, numerical control machining and heat treatment, and the machining cost is high. However, the bent shaft is a slender shaft after quenching, and it is difficult to straighten the shaft by traditional process, so the shaft is generally directly scrapped, resulting in increased cost. At the same time, the early scrap of the bent shaft also causes great economic loss. SUMMARY

[0005] The present application aims to provide a method for straightening a bent continuous casting roller shaft, which utilizes the advantages of rapid heating and temperature controllability of laser to heat the bent bearing position of the shaft through rapid and controllable temperature rise of laser scanning, utilizes the gravity of the shaft itself to straighten the bent bearing position on a large scale, then completes the cladding of the coarsely straightened bearing position by laser cladding, and finally realizes the precise straightening of the bent shaft bearing position on a small scale through numerical control turning, so that the coaxiality deviation of the turned bent shaft bearing position is less than or equal to 0.15 mm, which fully meets the process requirements.

[0006] The technical scheme adopted by the present application is as follows:

[0007] The method for straightening a bent continuous casting roller shaft provided by the present application comprises the following steps:

[0008] S1, disassemble three-section and two-section continuous casting rollers that do not meet the coaxiality requirement;

[0009] S2, clean the surface of the disassembled mandrel, and remove surface rust and oil stains by using acetone or anhydrous ethanol;

[0010] S3, perform non-destructive testing on the mandrel, and mount the mandrel that passes the testing on a laser numerical control machining tool to determine the position of each bearing site of the mandrel that is bent and the eccentricity; mark the maximum outer convex point and inner concave point of each bearing site that is bent;

[0011] S4, continuously rotate the bent bearing site by laser scanning, control the appropriate laser power so that the surface temperature at the bent bearing site is 600-750°C and is maintained for 10-15 minutes, after stopping the scanning, control the numerical control machine tool, keep the maximum outer convex point of the heated bent bearing site above the mandrel and the inner concave point below the mandrel, and slightly loosen the tail top of the numerical control machine tool to still keep the axial support of the stationary mandrel, so that the mandrel is slightly contracted and expanded at the upper convex point and the lower concave point under the action of gravity; after cooling, measure the coaxiality of the straightened bearing site, if the eccentricity is greater than or equal to 1mm, repeat the above process to continue laser straightening until the eccentricity is less than 1mm;

[0012] S5, for the straightened bearing site with an eccentricity less than 1mm, perform laser cladding by cladding alloy powder;

[0013] S6, for the mandrel that needs to be straightened at multiple bearing sites, sequentially use the above steps S4 and S5 to complete the laser straightening and laser cladding of each bearing site;

[0014] S7, after all the bearing sites are completed with laser straightening and laser cladding, perform turning processing by the numerical control machine tool so that the size, tolerance and surface finish of all the bearing sites meet the process requirements;

[0015] S8, perform non-destructive testing on the mandrel after turning processing, apply anti-rust oil to the mandrel that passes the testing, and scrap the mandrel that has defects.

[0016] Further, in steps S3 and S8, the non-destructive testing method is surface coloring and ultrasonic non-destructive testing.

[0017] Further, in step S4, the laser power for laser straightening processing is 1500-2000W, the spot size is 2x14mm, the scanning speed is 800-1000mm / min, and the overlap rate is 20-50%.

[0018] Further, in the step S5, the laser power of the laser cladding is 3500-4000W, the spot size is 2*14mm, the scanning speed is 300-350mm / min, and the overlap rate is 30-50%.

[0019] Further, the alloy powder comprises the following components in mass percentage: Mn: 0.8%-1.3%, Cr: 14%-16%, C: 0.16%-0.18%, Ni: 4.7%-5.6%, and the balance is Fe.

[0020] Further, each component in the alloy powder is a powder with a purity greater than 99.9%, and the powder particle size is 125-325 mesh.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. The present application makes full use of the advantages of laser that can quickly heat and the controllable temperature rise, and accurately realizes straightening of the continuous casting roll shaft with a curved bearing position by laser, achieves the process effect that the traditional process cannot achieve, significantly prolongs the service life of the shaft, avoids waste of materials, and prolongs the service life.

[0023] 2. The present application realizes two steps of straightening the bearing position of the curved shaft from large-scale straightening to small-scale straightening through laser heating rough straightening treatment, laser cladding, and numerical control turning precise straightening treatment, and realizes precise control of the eccentricity of the straightened curved shaft to be within 0.15mm with an eccentricity of 1-5mm.

[0024] 3. The present application optimizes the ratio of the alloyed powder, which can meet the use requirements of wear resistance, high temperature resistance, and wear resistance, so that the performance of the bearing position after laser cladding repair is significantly improved, not only meeting the straightening requirements, but also significantly improving the wear resistance of the shaft.

[0025] 4. The present application realizes straightening treatment of the curved continuous casting roll shaft through comprehensive application of laser scanning heating and laser cladding process, and has the advantages of simple process, saving materials, low cost, and turning waste into treasure.

[0026] 5. Laser scanning heating has the technical feature of precise control, which avoids the problem that the traditional oxyacetylene and induction coil heating methods are not easy to precisely control the temperature, thereby causing local overburning of the bearing position of the shaft to be straightened, and further causing problems such as organization coarsening at the bearing position and shaft scrap. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a schematic diagram of laser cladding precise straightening of the bearing position;

[0028] Figure 2 is a schematic diagram of straightening and cutting of multiple bearing positions;

[0029] Figure 3 is the schematic diagram of the product after straightening by the method of the present application and applying rust-proof oil. DETAILED DESCRIPTION

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0031] Embodiment 1

[0032] The method for straightening the bent continuous casting roller shaft proposed in this embodiment is as follows:

[0033] S1, disassemble two-section or three-section continuous casting rollers that do not meet the coaxiality requirement;

[0034] S2, clean the surface of the disassembled shaft, and remove surface rust, oil stains and the like by using acetone or anhydrous ethanol;

[0035] S3, perform non-destructive detection on the shaft by surface coloring and ultrasonic non-destructive testing, and mount the detected shaft on a laser numerical control machining tool to determine the position of each bearing of the bent shaft and the eccentricity; mark the maximum outer convex point and the inner concave point of each bearing of the bent shaft;

[0036] S4, control the laser power by laser scanning the continuously rotating bent bearing, the laser power used in the laser straightening process is 1500W, the spot size is 2x14mm, the scanning speed is 800mm / min, the overlap rate is 20%, so that the surface temperature at the bent bearing is 600℃ and is maintained for 10 minutes, after stopping the scanning, control the numerical control machine tool, keep the maximum outer convex point of the heated bent bearing above the shaft, the inner concave point below the shaft, and slightly loosen the tail top of the numerical control machine tool, still keep the axial support of the stationary shaft, so that the shaft can be slightly contracted and expanded at the upper convex point and the lower concave point under the action of gravity; after cooling, measure the coaxiality of the straightened bearing, if the eccentricity is greater than or equal to 1mm, repeat the above process to continue the laser straightening until the eccentricity is less than 1mm;

[0037] S5, perform laser cladding on the straightened bearing with an eccentricity less than 1mm by cladding alloy powder, the laser power used in the laser cladding is 3500W, the spot size is 2x14mm, the scanning speed is 300mm / min, and the overlap rate is 30%;

[0038] The alloy powder used comprises the following components in mass percentage: Mn: 0.8%, Cr: 14%, C: 0.16%, Ni: 4.7%, and the balance of Fe, wherein each component is a powder with a purity greater than 99.9%, and the powder particle size is 125-325 mesh;

[0039] S6, for the mandrel needing straightening of multiple bearing positions, sequentially adopting the above S4 and S5 to complete laser straightening and laser cladding of each bearing position;

[0040] S7, when the laser straightening and laser cladding of all bearing positions are completed, turning is performed by a numerical control machine tool, so that the size, tolerance and surface finish of all bearing positions meet the process requirements, the eccentricity of the straightened curved mandrel is equal to 0.1 mm, and the process requirements are met;

[0041] S8, after the turning of the mandrel, non-destructive testing is performed by surface coloring and ultrasonic non-destructive testing, the mandrel without defects is coated with rust-proof oil for use, and the straightened mandrel with defects is scrapped.

[0042] Example 2

[0043] The method for straightening the curved continuous casting roller mandrel proposed in the embodiment has the following specific implementation process:

[0044] S1, two or three sections of continuous casting rollers not meeting the coaxiality requirements are disassembled;

[0045] S2, the surface of the disassembled mandrel is cleaned, and acetone or anhydrous ethanol is used to remove surface rust, oil stains and the like;

[0046] S3, the mandrel is subjected to non-destructive testing by surface coloring and ultrasonic non-destructive testing, the mandrel passing the testing is clamped on a laser numerical control machining tool, the positions and eccentricities of the bearing positions of the curved mandrel are determined, and the maximum outer convex point and inner concave point of each bearing position are marked;

[0047] S4, control the laser power by laser scanning the continuously rotating curved bearing position, the laser power used in the laser straightening process is 2000W, the spot size is 2x14mm, the scanning speed is 1000mm / min, the overlap rate is 50%, so that the surface temperature at the curved bearing position is 750℃ and is maintained for 15 minutes, after stopping the scanning, control the numerical control machine tool, keep the maximum convex point of the heated curved bearing position above the mandrel and the concave point below the mandrel, and slightly loosen the tail top of the numerical control machine tool, still keep the axial support of the stationary mandrel, so that the mandrel can have small-scale contraction and extension at the upper convex point and the small concave point under the action of gravity; after cooling, measure the coaxiality of the straightened bearing position, if the eccentricity is greater than or equal to 1mm, repeat the above process to continue laser straightening until the eccentricity is less than 1mm;

[0048] S5, laser cladding alloy powder is used to the straightened bearing position with eccentricity less than 1mm, the laser power used in the laser cladding is 4000W, the spot size is 2x14mm, the scanning speed is 350mm / min, and the overlap rate is 50%;

[0049] The alloy powder used includes the following components with mass percentage: Mn: 1.3%, Cr: 16%, C: 0.18%, Ni: 5.6%, and the balance is Fe, each component of the alloy powder is a powder with purity greater than 99.9%, and the powder particle size is 125-325 mesh;

[0050] S6, for the mandrel with multiple straightened bearing positions, the above S4 and S5 steps are used in turn to complete the laser straightening and laser cladding of each bearing position;

[0051] S7, after all the bearing positions are completed laser straightening and laser cladding, turning processing is performed by the numerical control machine tool, so that the size, tolerance and surface finish of all the bearing positions meet the process requirements, the eccentricity of the straightened curved mandrel bearing position is equal to 0.1mm, which meets the process requirements;

[0052] S8, after the turning processing, the mandrel is subjected to non-destructive testing by surface coloring and ultrasonic non-destructive testing, the mandrel without defects after the testing is coated with rust-proof oil for use, and the straightened mandrel with defects is scrapped.

[0053] Example 3

[0054] The method for straightening the curved continuous casting roller mandrel proposed in this embodiment has the following specific implementation process:

[0055] S1, disassemble the two-section and three-section continuous casting rollers that do not meet the coaxiality requirements;

[0056] S2, clean the surface of the disassembled mandrel, remove surface rust, oil stains and the like by using acetone or anhydrous ethanol;

[0057] S3, nondestructive detection is carried out on the mandrel by surface coloring and ultrasonic nondestructive detection, the mandrel qualified after detection is clamped on a laser numerical control processing machine tool, the positions of each bearing of the mandrel which is bent are determined, and the eccentricity of the bent mandrel is marked;

[0058] S4, the bent bearing is continuously rotated by laser scanning, the laser power is controlled, the laser power used in the laser straightening process is 1750W, the spot size is 2*14mm, the scanning speed is 900mm / min, the lap rate is 35%, the surface temperature of the bent bearing is about 675℃, and is maintained for about 12.5 minutes, after stopping scanning, the numerical control machine tool is controlled, the maximum outer convex point of the heated bent bearing is kept above the mandrel, the inner concave point is kept below the mandrel, and the tail top of the numerical control machine tool is slightly loosened, the axial support of the static mandrel is still kept, so that the mandrel can be contracted and stretched at the upper convex point and the small concave point under the action of gravity; after cooling, the coaxiality of the straightened bearing is measured, if the eccentricity is greater than or equal to 1mm, the above process is repeated to continue laser straightening until the eccentricity is less than 1mm;

[0059] S5, laser cladding is carried out on the straightened bearing with an eccentricity less than 1mm by cladding alloy powder, the laser power used in the laser cladding is 3750W, the spot size is 2*14mm, the scanning speed is 325mm / min, and the lap rate is 40%;

[0060] The alloy powder used includes the following components with mass percentage: Mn: 1.05%, Cr: 15%, C: 0.17%, Ni: 5.15%, and the balance is Fe, the components of the alloy powder are powders with a purity greater than 99.9%, and the powder particle size is 125-325 mesh;

[0061] S6, for the mandrel which needs to be straightened at multiple positions, the above S4 and S5 steps are sequentially used to complete the laser straightening and laser cladding of each bearing position;

[0062] S7, after the laser straightening and laser cladding of all bearing positions are completed, turning processing is carried out by the numerical control machine tool, so that the size, tolerance and surface finish of all bearing positions meet the process requirements, the eccentricity of the straightened bent mandrel is equal to 0.1mm, and the process requirements are met;

[0063] S8, the mandrel after turning processing is detected by surface coloring and ultrasonic nondestructive detection, the mandrel without defects after detection is coated with rust-proof oil for use, and the straightened mandrel with defects is scrapped.

[0064] The details of the present application are all known technologies.

[0065] The above-described embodiments are merely intended to describe the preferred embodiments of the present application, and are not intended to limit the scope of the present application. Various changes and modifications made by those skilled in the art to the present application without departing from the spirit of the present application should fall within the scope of the present application defined by the claims.

Claims

1. A method of straightening a curved continuous-casting roll mandrel, characterized by, The method comprises the following steps: S1, disassembling three-section and two-section continuous casting rollers that do not meet the coaxiality requirement; S2, cleaning the surface of the disassembled mandrel, removing surface rust and oil stains by using acetone or anhydrous ethanol; S3, non-destructive testing of the mandrel, clamping the mandrel that passes the non-destructive testing on a laser numerical control machining tool, determining the position of each bearing of the mandrel that is bent and the eccentricity, and marking the maximum outer convex point and the inner concave point of each bearing that is bent; S4, continuously rotating the bent bearing by laser scanning, controlling the appropriate laser power so that the surface temperature of the bent bearing is 600-750 DEG C and is maintained for 10-15 minutes, after stopping the scanning, controlling the numerical control machine tool, keeping the maximum outer convex point of the heated bent bearing above the mandrel and the inner concave point below the mandrel, and slightly loosening the tail top of the numerical control machine tool to still keep the axial support of the stationary mandrel, so that the mandrel is slightly contracted and expanded at the upper convex point and the small concave point under the action of gravity; after cooling, the coaxiality of the straightened bearing is measured, if the eccentricity is greater than or equal to 1mm, the above process is repeated to continue laser straightening until the eccentricity is less than 1mm; S5, laser cladding of the straightened bearing with an eccentricity less than 1mm by alloy powder; S6, for the mandrel that needs to be straightened at multiple places, the laser straightening and laser cladding of each bearing are completed by using the above steps S4 and S5 in turn; S7, after the laser straightening and laser cladding of all bearings are completed, turning is performed by the numerical control machine tool so that the size, tolerance and surface finish of all bearings meet the process requirements; S8, non-destructive testing of the mandrel after turning, applying anti-rust oil to the mandrel that passes the non-destructive testing for use, and scrapping the straightened mandrel that has defects; In the step S4, the laser power for laser straightening is 1500-2000W, the spot size is 2x14mm, the scanning speed is 800-1000mm / min, and the overlap rate is 20-50%; In the step S5, the laser power for laser cladding is 3500-4000W, the spot size is 2x14mm, the scanning speed is 300-350mm / min, and the overlap rate is 30-50%.

2. A method of straightening a curved continuous-casting roll mandrel as defined in claim 1, characterized in that: In the steps S3 and S8, the non-destructive testing method is surface coloring and ultrasonic non-destructive testing.

3. A method of straightening a curved continuous-casting roll mandrel as defined in claim 1, characterized in that: The alloy powder comprises the following components by mass percentage: Mn: 0.8%-1.3%, Cr: 14%-16%, C: 0.16%-0.18%, Ni: 4.7%-5.6%, and the balance is Fe.

4. A method of straightening a curved continuous casting roll mandrel as claimed in claim 3 wherein: Each component in the alloy powder is a powder with a purity greater than 99.9% and a particle size of 125-325 mesh.

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