CN110216420B - Manufacturing method of welded steel pipe for chord web arm of crawler crane - Google Patents
Manufacturing method of welded steel pipe for chord web arm of crawler crane Download PDFInfo
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Abstract
The invention discloses a manufacturing method of a welded steel pipe for a chord web arm of a crawler crane, which comprises the following steps: (1) steel plate preparation (2), bending and forming (3) and high-frequency welding. Compared with the prior art, the invention has the following advantages: (1) the steel plates are bent and welded into the steel pipes, a series of defects of the seamless steel pipes applied to the string web arm of the crawler crane are overcome, and the manufactured welded steel pipes can well meet the technical requirements of the string web arm of the crane. (2) The steel plate is gradually bent into a W shape and then closed for forming, so that two longitudinal edges of the bent steel plate are longitudinally straight and have no difference in height, the welding stability is achieved, and the problem of unstable welding caused by overlarge resilience of the steel plate due to C-shaped bending in the prior art is solved. (3) The method has simple steps and convenient operation.
Description
Technical Field
The invention relates to the field of welded steel pipe manufacturing, in particular to a method for manufacturing a welded steel pipe for a chord web arm of a crawler crane.
Background
The crawler crane is a movable arm rotating crane which runs by using a crawler and is main hoisting equipment indispensable to engineering hoisting operation. Because the operating characteristics of the crawler crane determine that the crawler crane belongs to special and safety equipment, strict requirements can be put on safety indexes.
The steel pipes used for the chord web arm of the conventional crawler crane are all seamless steel pipes which are manufactured by adopting a solid round bar, rolling the solid round bar into a hollow steel pipe through perforation, and then performing head making, acid cleaning, cold drawing, heat treatment and straightening on the hollow steel pipe, because the manufacturing process of the seamless steel tube is limited, the decarburization of the inner surface and the outer surface of the seamless steel tube is difficult to control, the wear resistance of a workpiece is poor and the design requirement of the chord web arm of the crawler crane is difficult to meet, the radial wall thickness difference of the seamless steel tube is large, so that defects such as pits, warping and the like on the surface of the steel tube cannot be avoided during perforation, corrosion resistance omission is easily formed after the chord belly arm of the crane is assembled and sprayed, therefore, the seamless steel pipe with poor comprehensive performance can not adapt to the development trend and the requirement of the crane industry gradually, therefore, the technicians think of using steel coils to weld welded steel pipes to replace seamless steel pipes so as to improve the safety index of the crane.
However, the existing welded steel pipe is directly subjected to C-shaped bending when steel strips are used for coil welding, and due to the fact that steel strips have resilience when being bent, the thicker the steel strips are, the greater the resilience is, the greater the welding stability is greatly influenced, the quality of the welded steel pipe manufactured subsequently is influenced, and the welded steel pipe manufactured in the way cannot meet the technical requirements of the crane chord web arm due to poor quality.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a method for manufacturing a welded steel pipe for a chord web arm of a crawler crane, which has the advantages of simple steps and convenience in operation, can well overcome the rebounding force generated when a steel strip is bent, improves the welding stability, and can well meet the technical requirements of the chord web arm of the crane.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method of manufacturing welded steel tubing for a crawler crane chord web arm, the method comprising the steps of:
(1) preparing a steel plate: the smelted steel ingot is flat rolled into a steel plate with uniform thickness, and the steel plate is subjected to quenching and tempering heat treatment;
(2) bending and forming: bending the steel plate subjected to quenching and tempering heat treatment in the step (1) into a W shape gradually according to a certain decreasing coefficient, and finally closing and forming the steel plate;
(3) high-frequency welding: and (3) carrying out high-frequency welding on the joint of the steel plates formed in the closed mode in the step (2), and obtaining the required welded steel pipe.
Preferably, the manufacturing method further comprises the step of
(4) Intermediate frequency annealing: and (4) performing intermediate frequency annealing on the welded steel pipe obtained in the step (3), and keeping the temperature for 2 minutes, wherein the annealing temperature is 850 +/-20 ℃.
Further preferably, the manufacturing method further comprises the step of
(5) Defect identification: and (4) flaw detection is carried out on the welded steel pipe annealed in the step (4), defects on the welded steel pipe are identified, defective steel pipes with the defects are cut off and sorted out, and a good-quality steel pipe is obtained.
Even more preferably, the manufacturing method further comprises the step of
(6) Radial and axial sizing: use design mould right obtain in step (4) non-defective products steel pipe carries out radial design and axial design respectively, the design mould has a plurality ofly, and round the circumference of non-defective products steel pipe becomes the circumference and distributes, a plurality ofly becomes the circumference and distributes design mould forms the mould group, the mould group have the multiunit and along the length direction interval of non-defective products steel pipe sets up.
Preferably, in the step (1), the steel ingot comprises the following components in percentage by mass: 0.04-0.20% of C, 0.08-0.70% of Si, 1.0-1.90% of Mn, 0.4-1.20% of Cr, 0.2-1.0% of Ni, 0.1-0.9% of Cu, 0.001-0.04% of V, 0.03-0.06% of Nb0.05-0.18% of Ti, 0.01-0.06% of Al and the balance of Fe.
Preferably, in the step (1), the quenching and tempering heat treatment of the steel sheet includes the steps of:
a. heating the steel plate to 930-950 ℃ at a heating speed of 16-21 ℃/s, and preserving heat for 40-45 minutes;
b. rapidly cooling the steel plate subjected to heat preservation in the step a to below 300 ℃ at the speed of 210-230 ℃/s, and then naturally cooling to room temperature;
c. and c, heating the steel plate naturally cooled in the step b to 300-350 ℃ at a heating speed of 15-20 ℃/s, preserving the temperature for 70-80 minutes, and naturally cooling to room temperature.
Further preferably, in the step b, the cooling medium for rapid cooling is water.
Preferably, in the step (2), the steel plate is rolled into a W shape by a rolling die, wherein the rolling die comprises an upper die and a lower die, one side surface of the upper die and the lower die, which are close to each other, is a W shape, and the upper die and the lower die can cooperate to roll the steel plate into a W shape.
Further, the method can be used for preparing a novel materialPreferably, in the step (2), the decreasing coefficient is
Wherein D is the outer diameter of the welded steel pipe, S is the wall thickness of the welded steel pipe, N is the rolling pass of the rolling die, and pi is the circumferential ratio.
Preferably, in the step (2), a lubricant is simultaneously injected into the steel sheet when the steel sheet is bent and formed.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:
(1) the steel plates are bent and welded into the steel pipes, a series of defects of the seamless steel pipes applied to the string web arm of the crawler crane are overcome, and the manufactured welded steel pipes can well meet the technical requirements of the string web arm of the crane.
(2) The steel plate is gradually bent into a W shape and then closed for forming, so that two longitudinal edges of the bent steel plate are longitudinally straight and have no difference in height, the welding stability is achieved, and the problem of unstable welding caused by overlarge resilience of the steel plate due to C-shaped bending in the prior art is solved.
(3) The method has simple steps and convenient operation.
Drawings
FIG. 1 is a schematic cross-sectional view of a rolling die of the present invention;
FIG. 2 is a schematic view of the welder of the present invention;
FIG. 3 is a schematic diagram of a defect identification sorting system of the present invention;
FIG. 4 is a schematic cross-sectional view of the setting device of the present invention in the radial direction of a welded steel pipe;
FIG. 5 is a schematic cross-sectional view of the setting device of the present invention in the axial direction of a welded steel pipe.
Wherein: 1. an upper die; 2. a lower die; 3. a power source; 4. an inductor; 5. an impeder; 6. a control module; 7. identifying a sensing module; 7a, an eddy current sensor; 7b, a first regulator; 8. a defect identification module; 8a, a defect identifier; 8b, a second regulator; 8c, a marking liquid storage pressurizing device; 9. a defect removal and sorting module; 9a, a defect removing device; 9b, a sorting control system; 10. shaping the mold;
100. and (5) welding the steel pipe.
Detailed Description
The technical solution of the present invention is further explained with reference to the drawings and the specific embodiments.
1-5, a method of manufacturing welded steel tubing for a crawler crane web arm, the method comprising the steps of:
(1) preparing a steel plate: and (4) rolling the smelted steel ingot into a steel plate with uniform thickness, and carrying out quenching and tempering heat treatment on the steel plate. The welded steel pipe is manufactured by bending the steel plate, so that the problems that the anti-damage capability is inconsistent due to the unavoidable radial wall thickness difference determined by the seamless steel pipe process, the surface decarburization is caused by the unavoidable repeated heating in multiple passes determined by the seamless steel pipe process, and the corrosion prevention omission is caused by the defects of pits, warping and the like formed by perforation are solved.
The steel ingot comprises the following components in percentage by mass: 0.04-0.20% of C, 0.08-0.70% of Si, 1.0-1.90% of Mn, 0.4-1.20% of Cr, 0.2-1.0% of Ni, 0.1-0.9% of Cu, 0.001-0.04% of V, 0.03-0.06% of Nb0.05-0.18% of Ti, 0.01-0.06% of Al and the balance of Fe. The steel ingot also contains a few inevitable impurities in the smelting process, and the performance of the prepared steel plate is not influenced.
Here, C: the method is a main index for determining material performance, a proper amount of index is beneficial to the requirement of the method, yield point and tensile strength cannot be achieved when the yield point and the tensile strength are too low, plasticity, welding performance and corrosion performance are reduced when the yield point and the tensile strength are too high, and cold brittleness and aging sensitivity are improved; si: the steel has the functions of reduction and deoxidation, the elastic limit of the steel is improved, and the welding performance is reduced and the surface corrosion resistance is poor due to overhigh elastic limit; mn: the method has the effects of improving hardenability, improving hot workability, ensuring that the material has enough toughness, strength and hardness, and reducing welding performance and corrosion performance if the hardenability is too high; cr: the function is to improve the hardness, corrosion resistance and wear resistance, and the plasticity and toughness are reduced when the hardness is too high; ni: the function is to improve the strength, and simultaneously keep good plasticity, toughness and corrosion resistance; cu: the toughness and the corrosion resistance are improved, and if the toughness and the corrosion resistance are too high, hot brittleness is easily generated; v: the function is to refine the structure grains and improve the tempering strength; nb: the function is to refine the structure crystal grains, improve the toughness, and reduce the toughness when the toughness is too high; ti: the function is to strengthen the internal organization compactness, reduce the aging sensitivity and cold brittleness and improve the welding performance; al: the deoxidizer is used for refining structure grains, improving impact toughness, and reducing welding and cutting processing performances when the deoxidizer is too high.
By proportioning certain contents of C, Cr and main alloy elements, the strength of the steel can be effectively guaranteed, and the weldability and plasticity indexes of the material are improved; mn is a main alloy element of the material, and can play an effective solid solution strengthening role in a certain proportion content; the proportion of Nb, V and Ti minor alloy elements can prevent coarse and refined grain size of crystal grains and improve the mechanical property of the steel; the elasticity and impact toughness of the steel can be effectively improved by proportioning certain Al; the corrosion resistance and the wear resistance of the steel can be effectively improved by proportioning a certain amount of Cr and Cu; the Si with a certain proportion can effectively improve the adhesive force of the material surface to the preservative solution. The assembly welding effectiveness is effectively guaranteed through effective proportioning of C, Mn, Cr, Mo, V, Ni and Cu. The prepared steel plate has the comprehensive properties of high strength, long fatigue life, strong wear resistance, coexistence of performance and plasticity, strong anti-damage capability, easy corrosion resistance, easy welding and the like.
Compared with steel of national standard Q355B in the prior art, the tensile strength of the steel ingot is increased from original Rm 470-670 MPa to Rm not less than 820MPa, the yield strength is increased from original ReH not less than 355MPa to ReH not less than 780MPa, and the steel ingot can better meet the technical requirements of the chord web arm of the crawler crane.
The quenching and tempering heat treatment of the steel plate comprises the following steps:
a. and heating the steel plate to 930-950 ℃ at a heating speed of 16-21 ℃/s, and preserving the heat for 40-45 minutes.
b. And (b) rapidly cooling the steel plate subjected to heat preservation in the step a to below 300 ℃ at the speed of 210-230 ℃/s, and then naturally cooling to room temperature. The cooling medium for rapid cooling is water.
c. And c, heating the steel plate naturally cooled in the step b to 300-350 ℃ at a heating speed of 15-20 ℃/s, preserving the temperature for 70-80 minutes, and naturally cooling to room temperature.
Here, the steel sheet is heated by the heating coil and rapidly cooled by tap water.
Through quenching and tempering heat treatment on the steel plate, the phenomena of large grain size, residual Widmannstatten structure, unstable structure, low mechanical property and poor plasticity in the steel plate are changed, so that the comprehensive performance is improved, and the aims of super wear resistance, high toughness, long fatigue and strong safety are fulfilled. And simultaneously, the follow-up bending forming is ensured not to generate microcracks.
(2) Bending and forming: and (3) bending the steel plate subjected to quenching and tempering heat treatment in the step (1) into a W shape gradually according to a certain decreasing coefficient, and finally closing and forming the steel plate. Here, the steel plate is rolled into a W shape by the rolling die 1, wherein the rolling die includes an upper die 1 and a lower die 2, the roll surfaces of the upper die 1 and the lower die 2 are W-shaped, and the upper die 1 and the lower die 2 can cooperate to roll the steel plate into the W-shaped. A decreasing coefficient of
Wherein D is the outer diameter of the welded steel pipe, S is the wall thickness of the welded steel pipe, N is the rolling pass of the rolling die, and pi is the circumferential ratio. The steel plate is gradually bent into a W shape and then closed for forming, so that two longitudinal edges of the bent steel plate are longitudinally straight and have no difference in height, the welding stability is achieved, and the problem of unstable welding caused by overlarge resilience of the steel plate due to C-shaped bending in the prior art is solved.
After the steel plate is rolled into a W shape, the steel plate is gradually bent into a closed welded steel pipe through a closed roller. The closed rollers comprise vertical roller assemblies and horizontal roller assemblies which are arranged at intervals, each vertical roller assembly comprises two vertical rollers which are respectively arranged on two sides of the steel plate in the vertical direction, and the rotating axes of the vertical rollers extend along the horizontal direction and are vertical to the moving direction of the steel plate; the transverse roller assembly comprises two transverse rollers which are respectively arranged on two sides of the steel plate in the horizontal direction, and the rotating axis of the transverse roller assembly extends along the vertical direction and is perpendicular to the moving direction of the steel plate.
In this embodiment, when the steel plate is bent and formed, the lubricant is synchronously injected onto the steel plate so as to reduce the huge pressure and friction generated when the steel plate is bent, prevent the magnetic conductivity of an impedor inside the inductor from being reduced along with the rise of welding heat during welding, and ensure that metal is completely fused at high temperature. The lubricant is an oil having a kinematic viscosity of 80 to 90mm/S at 40 ℃ and a solidifying point of-3 to 12 ℃.
(3) High-frequency welding: and (3) carrying out high-frequency welding on the joint of the steel plates formed in the closed mode in the step (2), and obtaining the required welded steel pipe. In this embodiment, the high-frequency welding of the steel plate is performed by a welder including a power source 3, an inductor 4 and an impeder 5, and when the preliminarily closed welded steel pipe 100 having the high-temperature fusion welding condition is fed into a welding area formed by the inductor 4 and the impeder 5, an alternating current of a proper frequency is applied to the inductor 4 to generate an alternating magnetic field to penetrate through the welded steel pipe 100, and a huge eddy current is generated in the inner impeder 5 in a direction opposite to the heating current to form a resistance to generate joule heat to rapidly raise the temperature of the part to be welded of the welded steel pipe, so that finally the metals are completely fused together at a high temperature to form the welded steel pipe.
Here, input power control at the time of high-frequency welding is important. When the power is too low, the groove of the tube blank is heated insufficiently to reach the welding temperature, so that the defects of insufficient welding, desoldering, clamping welding and the like can be caused, when the power is too high, the welding stability is influenced, and the heating temperature of the bevel face of the tube blank is higher than the temperature required by welding, so that the defects of serious splashing, pinholes, slag clamping and the like are caused. In this example, the process parameters of the welding are shown in table 1.
TABLE 1
(4) Intermediate frequency annealing: and (4) performing intermediate frequency annealing on the welded steel pipe obtained in the step (3), and keeping the temperature for 2 minutes, wherein the annealing temperature is 850 +/-20 ℃.
Here, since "welding stress" is generated in the weld zone when welding, the welding stress is not enough to affect the use of performance for the welded steel pipe required by the general steel grade and general use, but the existence of the welding stress causes the flattening and flaring of the weld to be unqualified for the high-strength welded steel pipe for the crane chord web arm.
The welding seam intermediate frequency annealing process requires less heating power and lower welding seam annealing cost, simultaneously, because the rapid local heating of the welding seam enables the oxidation and deformation of the steel pipe to be minimum, and the accurate and consistent heat penetration enables the whole welding seam area to obtain fine grain tissues, thereby meeting the requirements of the annealing process, improving the comprehensive mechanical property of the welded pipe and prolonging the service life of the welded pipe.
(5) Defect identification: and (4) identifying the defects of the welded steel pipe annealed in the step (4), cutting off defective steel pipes with the defects, and sorting out the defective steel pipes to obtain good-crystal steel pipes. The crawler crane belongs to special and safety equipment, and directly relates to the operation property of personal and property safety, so that in order to avoid putting defective welded steel pipes into use, the invention adds a defect identification and sorting procedure, and prevents the quality deficiency or defect in the manufacturing process of the welded steel pipes.
In this example, the defect identification sorting process is implemented by using a defect identification sorting system, which includes a control module 6, an identification module 7, an identification module 8 and an execution module 8, and by the mutual cooperation of the control module 6, the identification module 7, the identification module 8 and the execution module 9, the welding defects generated in the welding process can be effectively identified, and the pipe body with the defects can be cut off and sorted out, so that the welded steel pipe 100 with the defects is prevented from being put into use. Here, the control module 6 is a computer system, and the control module 6 is configured to calculate the required time according to the distance from the position where the defect is identified by the identification module 7 to the identification module 8 and the execution module 9, and control the identification module 8 and the execution module 9 to operate with a delay time, so as to realize defect identification and sorting of the welded steel pipe 100 during the movement process.
Here, the identification module 7 is used for identifying the defect characteristics of the welded steel pipe 100 and uploading a defect signal to the control module 6, and comprises an eddy current sensor 7a and a first controller 7b, wherein the eddy current sensor 7a is used for identifying the defect characteristics of the welded steel pipe 100 and feeding the defect characteristics back to the first controller 7b, and the first controller 7b is used for receiving the defect characteristics fed back by the eddy current sensor 7a and uploading the defect signal to the control module 6. When the welded steel pipe 100 with the defect passes through the probe of the eddy current sensor 7a, eddy current is generated, the probe measures the variation of the eddy current to obtain the defect of the welded steel pipe 100 and uploads the defect to the first controller 7b, and the first controller 7b uploads a defect signal to the control module 6 after receiving the defect characteristics.
And the control module 6 is used for receiving the defect signal uploaded by the identification module 7 and sending an identification signal to the identification module 8. The identification module 8 is used for receiving the identification signal sent by the control module 6 and spraying an identification to the defect part, and comprises a second controller 8a, a defect identifier 8b and an identification liquid storage device 8c, wherein the second controller 8a is used for receiving the identification signal sent by the control module 6 and sending a first working signal to the defect identifier 8 b; a defect marker 8b for receiving the first working signal sent by the second controller 8a and spraying a mark to the defect part, and a marking liquid storage device 8c for supplying a marking liquid to the defect marker 8 b. The marking liquid storage device 8c stores the marking liquid, and the marking liquid is pressurized and fed to the defect marker 8b, and the defect marker 8b ejects the marking to the defect portion.
The control module 6 is further configured to send an execution signal to the execution module 9. The execution module 9 is used for receiving the execution signal sent by the control module 6 and cutting off and sorting the bad pipe body of the welded steel pipe 100 with the mark, and comprises a third controller 9a, a defect cutting device 9b and a sorting device 9c, wherein the third controller 9a is used for receiving the execution signal sent by the control module 6, sending a second working signal to the defect cutting device 9b and sending a third working signal to the sorting device 9 c; the defect removing device 9b is used for receiving a second working signal sent by the third controller 9a and removing a poor pipe body of the welded steel pipe 100 with the mark; and the sorting device 9c is used for receiving a third working signal sent by the third controller 9a and sorting out the defective pipe bodies cut by the defect cutting device 9 b.
Here, the defect removing device 9b is the same as the normal removing device of the welded steel pipe 100, and when no defect is found, the removing device cuts the welded steel pipe 100 normally and discharges the material, and when a defect is found, the third controller 9a sends a third operation signal to the sorting device 9c, and the sorting device 9c sorts the cut pipe body with the defect to a designated position. Here, sorting device 9c is the cylinder top pushes away the structure, pushes away the body of taking the defect to bad pipe collecting box through the flexible of cylinder.
(6) Radial and axial sizing: and (3) respectively carrying out radial shaping and axial shaping on the good steel pipes obtained in the step (5) by using a shaping mold 10, wherein the shaping molds 10 are distributed circumferentially around the good steel pipes, the shaping molds 10 distributed circumferentially form a mold set, and the mold set is provided with a plurality of groups and is arranged at intervals along the length direction of the good steel pipes. Here, the sizing die 10 can move in the circumferential direction of the welded steel pipe 100 to achieve all-directional sizing.
In this example, a tensile test and a hardness test were performed on the welded steel pipe produced by the above-described process, and it was found that the welded steel pipe had a yield strength of 827MPa, a tensile strength of 896MPa, and an elongation after fracture of 15.5%, a vickers hardness HV1 of the welded steel pipe mother pipe was 301.7, and a vickers hardness HV1 of the weld was 295.6, and the welded steel pipe was subjected to a crushing test, and was crushed in the whole pipe in a crushing direction perpendicular to the weld by 90 degrees, and in a compression dimension of 2/3 outer diameters or more, and no crack occurred in both the weld and the mother pipe after the test. And finally, performing a flaring test on the welded steel pipe, wherein the top center taper is 45, the flaring rate is more than or equal to 6%, and when the outer diameter is expanded by 6mm, cracks do not appear on the welded seam of the sample and the flared end of the mother pipe.
The welded steel pipe manufactured by the method has the following advantages:
1. using welded steel tubes as safety members instead of seamless steel tubes: the invention uses the flat rolled steel plate to manufacture the welded steel pipe to replace the seamless steel pipe manufactured by punching the round bar, fills the blank that the welded steel pipe is zero in the application field of the global crawler crane chord web arm, has high cost performance and greatly improves the production efficiency, particularly changes the seamless steel pipe manufactured by a plurality of processes into the welded steel pipe with simplified integration and less hot processing flow, and has obvious energy-saving and environmental protection effects.
2. The material has strong pertinence of chemical components and high comprehensive performance: the steel ingot material is a new steel ingot material developed according to the requirements of hoisting load improvement, energy conservation, emission reduction, light weight and the like in the crane industry, trace alloy elements are proportioned to effectively guarantee the strength of steel and improve weldability and plasticity indexes, prevent coarse and refined grain sizes of crystal grains and improve the mechanical property of the steel, Cr and Cu improve the corrosion resistance and wear resistance of the steel, and the steel plate is subjected to quenching and tempering heat treatment to ensure that the tensile strength Rm is more than or equal to 820MPa, the yield strength ReH is more than or equal to 780MPa, As is more than or equal to 20 percent, and the hoisting load is improved by more than one time.
3. Uniform wall thickness and strong anti-damage capability: the invention adopts the flat rolled steel plate to manufacture the welded steel pipe, realizes the uniform and high precision of the radial wall thickness of the steel pipe, has constant anti-collision capability in all directions of the steel pipe, and achieves the excellent effect of strong anti-damage capability.
4. The surface is flawless, is anticorrosive and has no omission, and the surface adhesion is strong: the surface of the product has no defects of pits, warping, and the like, the corrosion resistance does not leak, the enrichment effect of the Si element is fully exerted by controlling the content of the Si element and the like, and the Si element and the C, W element generate corresponding compounds, so that the effect of strong spraying adhesion is achieved, and the product has excellent corrosion resistance.
5. The buffer rescue is guaranteed when the arm support fails: according to the invention, when materials, processes and manufacturing methods are researched, unexpected failure of the chord web arm of the crawler crane is taken as an important index, high strength and plasticity coexist by controlling the steel pipe to have good impact toughness and plasticity indexes, the situation that the workpiece failure buffer time of the seamless steel pipe is zero is changed, and the product has failure and has a certain buffer time to provide guarantee for rescue.
6. The invention adopts a self-developed double-W rolling die forming mode: according to the invention, the traditional C-shaped bending forming design is changed into W-shaped bending forming through a rolling die, so that the two longitudinal edges are longitudinally straight and have no difference in height after the steel plate is bent, the stability during welding is achieved, and the problem of unstable welding caused by overlarge steel plate resilience due to C-shaped bending in the prior art is solved.
7. The invention adopts a self-developed welding defect recognition device: in order to prevent the quality insufficiency or the defects in the manufacturing process of the welded steel pipe, the invention develops equipment which can automatically identify, automatically mark, automatically sort and cut the defects and the defects generated in the welding process of the steel pipe within the speed of 90 m/min, thereby effectively ensuring the safety and the reliability of the product.
8. The invention adopts a novel fine shaping device: the invention changes the traditional radial or axial shaping mode of the welded steel pipe into a radial and axial omnibearing shaping device which can be wholly or locally adjusted, thereby not only improving the geometric precision, but also improving the straightness and the planeness of the whole steel pipe.
The above-mentioned embodiments are merely illustrative of the technical idea and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered in the scope of the present invention.
Claims (1)
1. A manufacturing method of a welded steel pipe for a chord web arm of a crawler crane is characterized by comprising the following steps: the manufacturing method comprises the following steps:
(1) preparing a steel plate: the smelted steel ingot is flat rolled into a steel plate with uniform thickness, and the steel plate is subjected to quenching and tempering heat treatment;
(2) bending and forming: bending the steel plate subjected to quenching and tempering heat treatment in the step (1) into a W shape gradually according to a certain decreasing coefficient, and finally closing and forming the steel plate;
(3) high-frequency welding: performing high-frequency welding on the joint of the steel plates formed in the closed mode in the step (2) to obtain a required welded steel pipe;
(4) intermediate frequency annealing: performing intermediate frequency annealing on the welded steel pipe obtained in the step (3), and keeping the temperature for 2 minutes, wherein the annealing temperature is 850 +/-20 ℃;
(5) defect identification: flaw detection is carried out on the welded steel pipe annealed in the step (4), defects on the welded steel pipe are identified, defective steel pipes with the defects are cut off and sorted out, and good steel pipes are obtained;
(6) radial and axial sizing: respectively carrying out radial shaping and axial shaping on the good product steel pipes obtained in the step (5) by using shaping molds, wherein the shaping molds are provided with a plurality of groups and are circumferentially distributed around the circumference of the good product steel pipes, the shaping molds which are circumferentially distributed form a mold group, and the mold group is provided with a plurality of groups and is arranged at intervals along the length direction of the good product steel pipes;
in the step (1), the steel ingot comprises the following components in percentage by mass: 0.04-0.20% of C, 0.08-0.70% of Si, 1.0-1.90% of Mn, 0.4-1.20% of Cr, 0.2-1.0% of Ni, 0.1-0.9% of Cu, 0.001-0.04% of V, 0.03-0.06% of Nb0.05-0.18% of Ti, 0.01-0.06% of Al and the balance of Fe; the quenching and tempering heat treatment of the steel plate comprises the following steps:
a. heating the steel plate to 930-950 ℃ at a heating speed of 16-21 ℃/s, and preserving heat for 40-45 minutes;
b. rapidly cooling the steel plate subjected to heat preservation in the step a to below 300 ℃ at the speed of 210-230 ℃/s, and then naturally cooling to room temperature, wherein the rapidly cooled cooling medium is water;
c. b, heating the steel plate naturally cooled in the step b to 300-350 ℃ at a heating speed of 15-20 ℃/s, preserving the temperature for 70-80 minutes, and naturally cooling to room temperature;
in the step (2), the steel plate is rolled into a W shape through a rolling die, wherein the rolling die comprises an upper die and a lower die, the surface of one side, close to each other, of the upper die and the lower die is W-shaped, and the upper die and the lower die can be matched to roll the steel plate into the W shape; and synchronously injecting a lubricant into the steel plate when the steel plate is bent and formed.
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Denomination of invention: A manufacturing method for welded steel pipes used for the chord arm of crawler cranes Effective date of registration: 20240102 Granted publication date: 20210330 Pledgee: China Construction Bank Zhangjiagang branch Pledgor: Jiangsu Huacheng Industry Pipe Making Corp. Registration number: Y2024980000045 |
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