Dynamic supporting and eddy current heat treatment device for laser cladding of ultra-long core rod and control method

Abstract

The invention discloses a dynamic supporting and vortex heat treatment device for ultra-long core rod laser cladding and a control method, and belongs to the technical field of laser cladding processing equipment. According to the device, the clamping mechanism drives the core rod to rotate, and the laser cladding assembly moves in the axial direction of the core rod to complete cladding machining; a multi-point supporting assembly driven by hydraulic pressure is arranged below the core rod, and deflection and rotation jumping are restrained by adjusting the position of the supporting assembly up and down and being matched with a supporting roller guide structure, so that self-adaptive supporting of the core rods with different diameters is achieved. The movable supporting trolley and the laser cladding trolley move synchronously, continuous switching and space avoiding of the supporting position along the full length of the core rod are achieved, and continuous cladding machining of the surface of the core rod is completed. The vortex heat treatment assembly performs local preheating and remelting treatment on the cladding area so as to improve the binding rate and the forming quality of the coating. The method is suitable for continuous laser cladding processing of ultra-long mandrels with different sizes, the stability of the processing process is improved, and the cladding layer is formed consistently.

Description

Technical Field

[0001] This invention relates to the field of surface strengthening and laser cladding equipment for mandrels used in the continuous rolling production of seamless steel pipes, and specifically to a device and its control method for achieving dynamic support, eddy current preheating and remelting treatment during the laser cladding process of an ultra-long mandrel. Background Technology

[0002] In the continuous rolling and diameter reduction process of seamless steel pipes, the mandrel, as an important tool for forming and controlling the dimensions of the inner surface of the steel pipe, needs to be used for a long time under high temperature, high contact pressure and strong friction load. Its surface is prone to wear and failure, which directly affects the quality of the inner surface of the steel pipe and leads to an increase in the scrap rate and the production cost of enterprises.

[0003] To improve the wear resistance and extend the service life of mandrels, a series of process technologies, including surface modification treatment of the mandrels, are proposed. Compared with traditional surface strengthening technologies such as nitriding, electroplating, physical vapor deposition, thermal spraying, and traditional welding, laser cladding has advantages such as concentrated energy input, metallurgical bonding between the cladding layer and the substrate, and controllable dilution rate and microstructure, making it more suitable for surface strengthening and remanufacturing of long shaft components such as mandrels.

[0004] However, mandrels used in continuous rolling production typically have structural characteristics such as large length, heavy weight, high slenderness ratio, and relatively insufficient overall rigidity. Compared with conventional shaft and roll parts, they are more prone to geometric changes during laser cladding. Furthermore, during long-distance continuous cladding, the deflection distribution of the mandrel under its own weight, combined with the localized high-energy heat input introduced by the cladding process, easily causes axial deflection fluctuations and radial rotational runouts at different positions. This leads to changes in the stability of the molten pool and the forming state of the cladding layer with the processing position, resulting in problems such as uneven cladding layer thickness and decreased overlap consistency during surface laser cladding of ultra-long mandrels. This increases the difficulty of achieving uniform, high-quality laser cladding across the entire mandrel surface.

[0005] A search revealed that patent document CN117070940A discloses a laser cladding machine tool for slender shaft-like workpieces. It uses a fixedly arranged support assembly and a follow-up clamping structure to support the workpiece, reducing vibration and runout during the cladding process. While this solution improves overall processing stability, the support position cannot continuously change with the processing area during cladding, making it difficult to effectively support local deflection near the cladding zone. Furthermore, spatial interference is prone to occur when the cladding path passes through the support area, typically requiring machine stoppage for adjustment or segmented cladding to avoid this. Therefore, structurally, it is difficult to achieve continuous laser cladding of ultra-long mandrels. Regarding thermal stress control, patent document CN111809179B discloses a laser cladding device using a multi-section retractable heating sleeve. This device improves the metallurgical bonding quality of the cladding layer by preheating the slender workpiece in a whole or segmented manner. However, this approach primarily relies on overall or quasi-static temperature regulation. Its heating device is structurally and operationally independent of the cladding and support processes, making it difficult to synchronously match the localized heat input and its resulting transient temperature gradient changes as the cladding zone moves axially. During the continuous cladding process of ultra-long flexible mandrels, these transient temperature gradients continuously migrate axially, easily leading to an imbalance in axial thermal stress distribution and the superimposed deflection effect of the mandrel's own weight. Consequently, it is structurally difficult to guarantee the uniformity and consistency of the cladding coating along the axial direction.

[0006] The advantage of this invention lies in addressing the problems of insufficient support responsiveness, low process coordination, and mismatch between thermal stress control and transient temperature gradient evolution in the laser cladding process of ultra-long heavy mandrels. By constructing a collaborative operation mechanism that dynamically adjusts the support according to the cladding area and synchronously integrating the local heat treatment process with the cladding process, it achieves coordinated control of geometric stability, molten pool behavior stability, and cladding layer forming consistency during the cladding process. This significantly improves the overall stability, surface strengthening quality consistency, and processing reliability of ultra-long mandrel laser cladding, better meeting the engineering application requirements of high-quality surface strengthening of mandrels in seamless steel pipe continuous rolling production. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To overcome the industry challenges of laser cladding of ultra-long mandrels, which are prone to flexural deformation and rotational runout due to their large length, heavy weight, and high slenderness ratio, under the combined effect of their own weight and local heat input, resulting in poor molten pool stability, uneven cladding layer thickness, and difficulty in ensuring axial forming consistency, as well as the insufficient responsiveness of existing support and heat treatment devices and their inability to synchronize with the axial migration of the cladding area, this invention provides a dynamic support and eddy current heat treatment device and control method for laser cladding of ultra-long mandrels.

[0009] (II) Technical Solution

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] 1. A dynamic support and eddy current heat treatment device for laser cladding of ultra-long mandrels is proposed, comprising the following:

[0012] (1) Mandrel clamping device: The device of the present invention is arranged along the axial direction of the ultra-long mandrel, and the two ends of the ultra-long mandrel are clamped by an active rotation clamping mechanism and a driven rotation clamping mechanism, respectively.

[0013] The rotary clamping mechanism consists of a rotary clamping machine tool and a machine tool chuck. Under the driving action, the active rotary clamping machine tool drives the extra-long mandrel to rotate continuously around its own axis through the machine tool chuck; the driven rotary clamping mechanism is set at the other end of the mandrel, which plays a role in following up and axial positioning of the mandrel to ensure the stability of the mandrel during the rotation process.

[0014] (2) Guide rail base device: A linear guide rail is provided along the axial direction of the mandrel. The linear guide rail is installed on the guide rail base to provide stable axial movement guidance for the laser cladding car and multiple sets of mobile support trolleys, and to ensure that each moving part can run synchronously along the axial direction of the mandrel.

[0015] (3) Laser cladding vehicle: The laser cladding assembly is set on the linear guide rail and can move axially along the guide rail direction to perform laser cladding processing on the outer surface of the ultra-long mandrel.

[0016] The laser cladding assembly includes a moving carriage, an eddy current heat treatment assembly, a laser cladding head, and a cladding lifting adjustment arm. The cladding lifting adjustment arm allows adjustment of the height of the laser cladding head relative to the outer surface of the mandrel, thereby adapting to the cladding processing requirements of ultra-long mandrels with different diameters and ensuring the stability of the laser focal point position during the cladding process.

[0017] (4) Mobile support trolley: The mobile support trolley consists of a laser ranging device, a support assembly, a hydraulic actuator, and a mobile trolley. Multiple sets of mobile support trolleys are arranged at intervals along the axial direction below the ultra-long mandrel. Each mobile support trolley is also set on the linear guide rail, and the linear guide rail and the mobile support trolley can move along the guide rail direction.

[0018] The mobile support trolley can move in coordination with the laser cladding vehicle, so that the support position changes continuously along the mandrel axis as the cladding area changes, thereby providing timely and continuous support for the mandrel in the vicinity of the cladding area.

[0019] (5) Support components: In the dynamic support system of the present invention, each mobile support trolley is equipped with a support component to provide stable support for the ultra-long mandrel during the laser cladding process, so as to reduce the bending deformation and rotational jump of the mandrel due to its own weight and heat input.

[0020] The support assembly consists of a set of support rollers and a support roller limiting shell.

[0021] The support roller is positioned below the mandrel and is arranged opposite to the outer circumferential surface of the mandrel. During the processing, it supports the mandrel, thereby suppressing the deflection and deformation of the mandrel during rotation and cladding.

[0022] In terms of structural arrangement, the support rollers are positioned and constrained by support roller limiting shells. With the center of the mandrel cross-section as the geometric reference, at least two support rollers are arranged below the center of the cross-section, forming an isosceles triangle with the center of the cross-section. This provides the mandrel with multi-point support in the radial direction, thereby improving the overall stability and vibration resistance of the support.

[0023] Furthermore, to achieve adaptive support for ultra-long mandrels of different diameters, the support rollers are mounted on a mobile support trolley via a guide groove structure.

[0024] The guide groove extends along the hypotenuse of the isosceles triangle and is used to limit the direction and range of movement of the support roller, so that the support roller always maintains a reasonable geometric relationship during the adjustment process and ensures the stability of the support state.

[0025] (6) Hydraulic actuator: The hydraulic actuator consists of a hydraulic cylinder and is connected to the moving trolley and support components.

[0026] During laser cladding, the hydraulic actuator can dynamically adjust the position of the support roller according to the geometric changes of the mandrel to maintain the stable support state of the mandrel.

[0027] Furthermore, when the equipment is being adjusted or the laser cladding vehicle or eddy current heat treatment components pass through the support area, the hydraulic actuator can drive the support rollers to move downwards or laterally to achieve an avoidance function, thereby preventing interference between the support components and the processing or heat treatment parts.

[0028] (7) Laser ranging device: In order to monitor the geometric state of the ultra-long mandrel in real time during the laser cladding process, a laser device is installed on the mobile support trolley.

[0029] The laser ranging device is used to perform non-contact detection of radial displacement, deflection changes or positional offset of the mandrel during laser cladding, so as to obtain real-time geometric state information of the mandrel relative to the mobile support trolley or the preset reference position.

[0030] The detection results of the ranging device are used to characterize the bending trend or positional change of the mandrel under its own weight and the heat input of laser cladding, and serve as the basis for adjusting the support components so that the mandrel always maintains a stable geometric state in the vicinity of the cladding area.

[0031] (8) Eddy current heat treatment assembly: The eddy current heat treatment assembly includes an eddy current preheating coil for local preheating of the mandrel before laser cladding, an eddy current remelting coil for treating the cladding layer after laser cladding, and a coil support arm.

[0032] The eddy current preheating coil is arranged in front of the laser cladding area to perform local preheating on the surface of the mandrel that is about to enter the cladding area; the eddy current remelting coil is arranged behind the cladding area to perform remelting on the formed cladding layer in order to improve the microstructure and forming quality of the cladding layer.

[0033] Furthermore, the eddy current preheating coil and the eddy current remelting coil are respectively mounted on the laser cladding vehicle through corresponding coil support arms, and move synchronously with the laser cladding vehicle along the axial direction of the mandrel.

[0034] Furthermore, the laser cladding carriage and the mobile support carriage move synchronously along the linear guide rail, so that the support position and the eddy current heat treatment position continuously migrate along the mandrel axis with the laser cladding area, thereby realizing continuous laser cladding processing of ultra-long mandrels without stopping the machine, and ensuring the coordinated matching between the support, cladding and heat treatment processes.

[0035] 2. A method for controlling laser cladding of ultra-long mandrels using the above-mentioned device, comprising the following steps:

[0036] S1. Mandrel clamping and rotation setup:

[0037] The two ends of the extra-long mandrel are respectively clamped to the active rotary clamping mechanism and the driven rotary clamping mechanism, driving the extra-long mandrel to rotate at a constant speed around its axis.

[0038] S2. Dynamic Support System Initialization:

[0039] Multiple sets of mobile support trolleys are arranged along the axial direction of the ultra-long mandrel. The support rollers are driven to approach the mandrel through hydraulic actuators to establish the initial support state.

[0040] S3. Geometric state detection and support adjustment:

[0041] During the laser cladding process, the geometric state information of the mandrel is acquired in real time by a detection device set on a mobile support trolley. Based on the detection results, the hydraulic actuators on each support trolley are coordinated and controlled so that the position of the support roller is dynamically adjusted according to the change of the mandrel state, thereby forming a continuous and stable dynamic support.

[0042] S4. Eddy current preheating treatment:

[0043] The ultra-long mandrel is locally preheated in front of the cladding area using an eddy current electromagnetic induction preheating coil.

[0044] S5. Synchronous follow-up processing:

[0045] The laser cladding carriage is controlled to move along a linear guide rail in the axial direction of the mandrel, and continuous laser cladding is performed on its outer surface while the mandrel continues to rotate. The movable support carriage moves synchronously with the laser cladding carriage along the linear guide rail, so that the support and heat treatment positions change continuously along the axial direction with the cladding area until the entire cladding process is completed.

[0046] S6, Eddy current remelting treatment:

[0047] The cladding layer is remelted behind the cladding area using an eddy current electromagnetic induction remelting coil, maintaining a certain dwell time.

[0048] S7. Processing completion and post-processing:

[0049] After the laser cladding process is completed, the laser output is stopped and the eddy current electromagnetic induction preheating coil and eddy current electromagnetic induction remelting coil are turned off. The cladding layer is then allowed to cool naturally or in a controlled manner, and necessary surface post-treatment is performed as needed.

[0050] (III) Beneficial Effects

[0051] Compared with the prior art, the present invention effectively suppresses the bending deformation and rotational jump of the ultra-long mandrel caused by its own weight and heat input during the laser cladding process by constructing a dynamic multi-point support structure that moves synchronously along the axial direction with the laser cladding area, thereby improving the geometric stability and molten pool stability during the continuous rotational cladding process.

[0052] This invention combines mandrel geometry detection with support adjustment, enabling real-time support and adaptive adjustment of adjacent positions in the cladding area. This avoids the problem of insufficient follow-up of traditional fixed support methods and improves the support consistency of different processing sections along the axial direction.

[0053] Furthermore, by integrating the eddy current preheating and remelting process with the laser cladding process, the transient temperature gradient distribution in the cladding area is effectively improved, the risk of thermal stress concentration in the cladding layer is reduced, and the forming quality of the cladding layer and the reliability of its bonding with the substrate are improved.

[0054] This invention enables continuous laser cladding of ultra-long mandrels without stopping the machine, significantly improving the stability and engineering applicability of the processing, and better meeting the application requirements of high-quality surface strengthening of mandrels in the continuous rolling production of seamless steel pipes. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a schematic diagram of the overall structure of the dynamic support and eddy current heat treatment device for laser cladding of ultra-long mandrels according to the present invention.

[0057] Figure 2 This is a schematic diagram of the working principle of laser cladding on the mandrel surface. Both the mobile support carriage 5 and the laser cladding carriage 6 move axially along the linear guide rail 402. On the laser cladding carriage 6, a preheating coil 604 is positioned in front of the cladding head 601, and a remelting coil 605 is positioned behind the cladding head 601, thus forming a continuous processing sequence of "preheating—cladding—remelting" along the mandrel axis.

[0058] Figure 3 This is a structural schematic diagram of a mobile support trolley;

[0059] Figure 4 This is a schematic diagram of the geometric distribution of the support rollers relative to the mandrel;

[0060] Figure 5 This is a structural schematic diagram of a laser cladding vehicle;

[0061] Figure 6 This is a schematic diagram of the cladding operation process of the device of the present invention;

[0062] Figure 7 The curve shows the maximum deflection of the mandrel as a function of the logarithm of the moving support trolley.

[0063] Figure 8 The curve shows the change in mandrel runout as a function of the logarithm of the moving support trolley.

[0064] Figure 9 The curve showing the deflection reduction factor as a function of the logarithm of the mobile support trolley;

[0065] Figure 10 This is a flowchart illustrating the method of the present invention.

[0066] The device shown in the figure includes:

[0067] 1. Core rod;

[0068] 2. Driven rotary clamping mechanism;

[0069] 3. Active rotary clamping mechanism; 301. Active rotary clamping machine tool; 302. Machine tool gripper plate;

[0070] 4. Base; 401. Guide rail base; 402. Linear guide rail;

[0071] 5. Mobile support trolley; 501. Support roller; 502. Laser rangefinder (Y direction); 503. Laser rangefinder (X direction); 504. Pulley; 505. Mobile trolley body; 506. Hydraulic cylinder; 507. Support roller limiting shell; 508. Mechanical self-locking device;

[0072] 6. Laser cladding vehicle; 601. Laser cladding head; 602. Cladding lifting adjustment arm; 603. Coil support arm; 604. Eddy current electromagnetic induction preheating coil; 605. Eddy current electromagnetic induction remelting coil; 606. Cladding vehicle moving trolley; 607. Pulley. Detailed Implementation

[0073] The present invention will be further described below with reference to a specific embodiment and the accompanying drawings, but the scope of protection of the present invention is not limited to the specific details described in this embodiment.

[0074] A dynamic support and eddy current heat treatment device and control method for laser cladding of ultra-long mandrels, comprising:

[0075] S1. Mandrel size selection and clamping alignment establishment

[0076] This invention relates to the surface remanufacturing of ultra-long shaft components such as seamless steel pipe continuously rolled mandrels, and the applicable mandrel parameter range is as follows:

[0077] Table 1 Applicable parameters for mandrels Parameter name Parameter Units Data value mandrel length L 8 ~ 18 m mandrel diameter D 181.3 ~ 202.8 mm mandrel quality m 2670 ~ 4104 kg Typical materials H13 / H11 / 42CrMo hot work steel, etc. elastic modulus E 180 ~ 210 GPa Poisson's ratio ν 0.28 ~ 0.30

[0078] Step 1: Select the parameters for a typical case study as follows: .

[0079] Furthermore, the length of the input mandrel ,diameter Parameters such as materials.

[0080] Step 2: Clamping and centering. The end clamping section of the mandrel 1 is clamped by the machine tool jaw disk 302, and the other end is supported and limited by the driven rotary clamping mechanism 2 to perform initial centering, so that the axis of the mandrel is parallel to the guide rail 402.

[0081] Step 3: Selection of the overall structural implementation method. For example... Figure 1As shown, the mandrel 1 is arranged horizontally, with its two ends clamped and positioned by an active rotary clamping mechanism 3 and a driven rotary clamping mechanism 2, respectively. The active rotary clamping mechanism 3 includes an active rotary clamping machine tool 301 and a machine tool chuck disk 302. The machine tool chuck disk 302 clamps the clamping section at the end of the mandrel and drives the mandrel 1 to rotate around its axis. The driven rotary clamping mechanism 2 provides follow-up support and axial limitation for the other end of the mandrel, thereby ensuring rotational coaxiality and stability.

[0082] Furthermore, a guide rail base 401 is provided on the base 4, and a linear guide rail 402 is installed on the guide rail base 401. Both the mobile support trolley 5 and the laser cladding trolley 6 cooperate with the linear guide rail 402 through pulleys (support trolley pulley 504 and cladding trolley pulley 607) to achieve synchronous or asynchronous movement along the mandrel axis.

[0083] S2. Dynamic Support System Layout and Initialization

[0084] Step 1: Arrange along the mandrel axis For the mobile support trolley 5, i.e. The set of support points, together with the clamping supports at both ends, form a An equivalent span.

[0085] If the distribution is uniform, the deflection value can be calculated using the following formula:

[0086]

[0087] The mandrel's self-weight is calculated under a uniformly distributed load:

[0088]

[0089] Moment of inertia of cross section:

[0090]

[0091] Maximum deflection without intermediate support:

[0092]

[0093] set up After considering the supporting trolley and the equivalent span, it is approximately:

[0094]

[0095] Radial runout peak-to-peak value engineering estimation:

[0096]

[0097] Maximum bending moment scales with the square of the span:

[0098]

[0099] Step 2: Select the number of supporting trolleys. The maximum deflection calculated in Step 1, with both ends simply supported, is approximately... When the number of support trolley pairs increases from 1 pair to 4 pairs, the deflection and runout decrease as shown in the table below:

[0100] Table 2. Effect of the logarithm of the support trolley on deflection and runout. Number of small cars Number of segments Span (m) Maximum deflection (mm) bounce (mm) Deflection reduction factor 0 1 13.30 57.700 115.4000 1 1 2 6.65 3.610 7.2100 16 2 3 4.43 0.7120 1.4250 81 3 4 3.33 0.2250 0.4510 256 4 5 2.66 0.0923 0.1846 625

[0101] Depend on Figures 7-9 It can be seen that when using 4 pairs of support trolleys, the maximum deflection is reduced from 57.7 mm to about 0.092 mm, and the peak-to-peak radial runout is reduced from 115.4 mm to about 0.185 mm, achieving a geometric stability improvement of about 600 times.

[0102] S3, Mandrel Geometry Detection and Support Adjustment

[0103] Step 1: Adjust the composition and apparatus. For example... Figure 5 As shown, the mobile support trolley 5 includes a mobile trolley body 505, with pulleys 504 at the bottom to cooperate with the linear guide rail 402 to achieve low-resistance linear movement. A hydraulic cylinder 506 is installed on the trolley body 505, and the telescopic end of the hydraulic cylinder 506 is connected to the support roller limiting shell 507. The support roller 501 is installed on the support roller limiting shell 507 and rolls in contact with the outer circle of the mandrel 1.

[0104] Step 2: To suppress radial drift or runout of the mandrel during rotation and heating, two sets of laser ranging devices with X and Y bidirectional ranging feedback are installed on the trolley:

[0105] 502: Measure the displacement of the mandrel in the Y direction (vertical or normal).

[0106] 503: Measure the displacement of the mandrel in the X direction (lateral or transverse).

[0107] The ranging values ​​are denoted as y(t) and x(t) respectively, relative to the target trajectory or calibration center. The error is:

[0108]

[0109] Step 3: Adaptive setting of support roller center distance. For example... Figure 4 As shown, the geometric distribution of the support roller 501 relative to the mandrel 1 satisfies the "diameter-adaptive" property. When the mandrel diameter is... At that time, the distance from the center of the support roller to the axis of the mandrel is defined as Center of mandrel cross section The apex is the center of the two support rollers 501, which are respectively... , This forms an isosceles triangle geometric relationship. When the support rollers and the outer circle of the mandrel form a stable double-point support, the distance from the center of the two support rollers to the center of the mandrel is:

[0110]

[0111] Let the vertex angle of the isosceles triangle be . Then the center distance between the two support rollers satisfies:

[0112]

[0113] The distance from the center of the support roller to the axis of the mandrel satisfies:

[0114]

[0115] in:

[0116] : Support roller radius 501;

[0117] mandrel radius: ;

[0118] The preload compensation, assembly gap, and elastic compression equivalent amount are preferably 0.5 ~ 3 mm.

[0119] When the mandrel diameter is from the reference value Become During operation, the mechanical self-locking device 508 is used for self-locking and fixing, and the positions of the support rollers 501(a) and 501(b) are dynamically adjusted along the direction of the limiting slide rail groove. This can suppress the radial displacement and runout of the flexible mandrel, ensuring that mandrels of different diameters can obtain a consistent support geometry during processing, thereby avoiding support failure or local overpressure due to diameter changes.

[0120] Step 4: Closed-loop support start-up. Hydraulic cylinder 506 is used to perform Y-axis height compensation. The hydraulic control quantity can be proportional-integral control:

[0121]

[0122] The displacement of the hydraulic cylinder is:

[0123]

[0124] in This was achieved through debugging and calibration. The aforementioned closed-loop control enables the support roller 501 to provide real-time "follow-up support" to the mandrel 1, thereby suppressing radial runout and deflection fluctuations.

[0125] S4. Heat treatment parameter selection and preheating start-up

[0126] Step 1: Determine the range of heat treatment temperatures.

[0127] The preheating and remelting temperatures are set according to the material and crack sensitivity, and the implementation range is as follows:

[0128] Without preheating, the substrate surface is... Raise to the temperature near the molten pool. After preheating, the temperature difference decrease is:

[0129] Furthermore, this can be expressed as the "surface equivalent temperature gradient":

[0130]

[0131] in This refers to the thickness of the main heat-receiving layer. Preheating and remelting make... Decrease, thereby reducing .

[0132] Table 3. Range of Heat Treatment Temperatures Process symbol Temperature range Preheating temperature <![CDATA[T pre ]]> 300~600 ℃ Peak temperature of molten pool <![CDATA[T melt ]]> 1600~2000 ℃ Remelting temperature <![CDATA[T re ]]> 550~850 ℃ Ambient temperature <![CDATA[T0]]> 20~80 ℃

[0133] Step 2: Calculation and implementation of coil magnetic field and magnetic flux.

[0134] Eddy current coils 604 and 605 are toroidal coils, with the number of turns... RMS current value Equivalent magnetic circuit air gap The magnetic flux density near the workpiece surface can be approximated by the following engineering method:

[0135]

[0136] Corresponding coupling area through the workpiece Magnetic flux:

[0137]

[0138] Step 3: Determination and implementation of effective heating depth.

[0139] Effective heating depth of eddy current:

[0140]

[0141] in Resistivity , The frequency is used. In medium- and high-frequency induction heating of steel, 5 to 20 kHz can be used in engineering to achieve a heating depth in the millimeter range.

[0142] Calculations show that the eddy current preheating coil 604 and remelting coil 605 of the present invention can achieve efficient heating of the mandrel surface in the range of about 2 to 6 mm thickness. This thickness matches the requirements of the cladding layer / heat affected zone, thereby avoiding ineffective heating of the entire cross section of the mandrel and energy waste caused by full-section heating.

[0143] Step 4: The preheating coil 604 and the remelting coil 605 are fixed on the cladding car 6 by the coil support arm 603 and are located axially back and forth on the cladding head 601, so as to achieve synchronous follow-up of "preheating-cladding-remelting" when the cladding car moves.

[0144] Furthermore, the eddy current preheating coil 604 is activated to raise the surface temperature of the area in front of the cladding to 300-600°C. Preheating length Take a depth of 0.2 to 1.0 m.

[0145] S5. Specific Implementation of Segmented Continuous Cladding

[0146] Step 1: Laser cladding vehicle adjustment. (e.g., ...) Figure 3 As shown, the laser cladding vehicle 6 includes: a laser cladding head 601, a cladding lifting adjustment arm 602, a coil support arm 603, an eddy current preheating coil 604, an eddy current remelting coil 605, a cladding vehicle moving trolley 606, and a pulley 607.

[0147] Furthermore, the cladding car moving trolley 606 cooperates with the linear guide rail 402 via pulley 607 to achieve axial movement along the mandrel; the cladding lifting adjustment arm 602 is used to adjust the height of the cladding head 601, thereby keeping the focal position constant.

[0148] Step 2: Calculation and implementation of segmented cladding process. For example... Figure 2 As shown, to ensure heat input and geometric stability, this embodiment employs "segmented continuous cladding". Let the number of segments be... Then the length of a single segment is:

[0149]

[0150]

[0151] The angular velocity of the mandrel rotation is (rad / s), rotational speed (r / min), we have:

[0152]

[0153] Spiral lap cladding is used, and the axial step distance per turn is denoted as . Then the spiral relationship is:

[0154]

[0155] Let the effective width of the melt channel be ,but:

[0156]

[0157] Therefore, the rotational speed can be obtained:

[0158]

[0159] Step 3: As Figure 6 As shown, the support roller avoidance and support point conversion are coordinated to implement segmented cladding. In order to achieve coordinated movement between the support structure and the laser cladding vehicle during the segmented continuous cladding process, this embodiment introduces the control logic of "support roller avoidance - support point conversion - re-support" during the segmented cladding process.

[0160] Furthermore, as the laser cladding carriage 6 advances along the linear guide rail 402 in the axial direction of the mandrel, the next set of mobile support carriages 5, which are in a yielding state, simultaneously move along the linear guide rail 402. When the support carriage reaches the target axial position, its hydraulic cylinder 506 switches from the yielding state to the support working state, and proceeds according to the... The relationship control mechanism 508 drives the support roller 501 to move upward, so that the support roller 501 re-contacts the outer surface of the mandrel, forming a new support point at the next segment position.

[0161] At the same time, the mobile support trolley 5 corresponding to the previous segment switches from the support working state to the avoidance state. Its hydraulic cylinder 506 drives the support roller 501 to move down and separate from the outer circle surface of the mandrel, thereby releasing the support position of the segment and realizing the continuous conversion of the support point along the axial direction of the mandrel.

[0162] Through the above-mentioned avoidance and support point conversion process, it can be ensured that during the segmented cladding process, the mandrel is always supported by at least one or more sets of support trolleys, avoiding unsupported areas, and at the same time, the fixed position of the support roller will not cause contact space obstacles that affect the continuous operation of the laser cladding vehicle.

[0163] S6, Remelting Follow-up Heat Treatment

[0164] Step 1: The eddy current remelting coil 605 behind the cladding car 6 heats the cladding area to 550 ~ 850 ℃ and maintains it for a certain period of time.

[0165] Step 2: Monitor the preheating temperature and cladding heat input in real time, so that:

[0166]

[0167] And by adjusting Speed Remelting power achieves a smooth thermal history, thereby reducing the risk of cracking.

[0168] S7, Completion and Cooling

[0169] After the laser cladding process is completed, the laser output is stopped and the eddy current electromagnetic induction preheating coil and eddy current electromagnetic induction remelting coil are turned off. The cladding layer is then allowed to cool naturally or in a controlled manner, and necessary surface post-treatment is performed as needed.

[0170] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A dynamic support and eddy current heat treatment device for laser cladding of ultra-long mandrels, characterized in that, include: (1) An active rotary clamping mechanism and a driven rotary clamping mechanism are respectively disposed at both ends of the mandrel, for clamping the mandrel and driving the mandrel to rotate around its axis; the rotary clamping mechanism includes a rotary clamping machine tool and a machine tool jaw disk; (2) A linear guide rail arranged along the axial direction of the mandrel, the linear guide rail being mounted on a guide rail base, and a laser cladding assembly and at least two sets of movable support trolleys being slidably arranged on the linear guide rail; (3) The laser cladding vehicle includes a laser cladding head, a lifting adjustment arm connected to the laser cladding head, a moving trolley, and an eddy current heat treatment assembly. The lifting adjustment arm is used to adjust the height position of the laser cladding head relative to the outer surface of the mandrel so as to realize the laser cladding process on the outer surface of the mandrel. (4) Each of the mobile support trolleys is provided with a support assembly, the support assembly including at least one set of support rollers driven by a hydraulic actuator and a support roller limiting shell, the support rollers are used to provide dynamic support to the underside of the mandrel to suppress the deflection deformation of the mandrel during rotation and cladding process; (5) The eddy current heat treatment assembly includes an eddy current preheating coil for preheating the mandrel before laser cladding, an eddy current remelting coil for treating the cladding layer after laser cladding, and a coil support arm. The mobile support trolley and the laser cladding assembly move synchronously along the linear guide rail, so that the mandrel can complete the continuous laser cladding and corresponding eddy current heat treatment process along the axial direction while rotating continuously without stopping the machine.

2. The apparatus according to claim 1, characterized in that, The support rollers are arranged with the center of the mandrel cross-section as the vertex, and the center points of at least two support rollers are located below the center of the mandrel cross-section, forming an isosceles triangle with the center of the mandrel cross-section, which is used to form a stable radial constraint on the mandrel.

3. The apparatus according to claim 2, characterized in that, The support roller is mounted on the support roller limiting shell through a guide groove structure. The guide groove limits the range of change of the central axis of the support roller along the hypotenuse of an isosceles triangle to adapt to the dynamic support requirements of mandrels of different diameters.

4. The apparatus according to any one of claims 1 to 3, characterized in that, The hydraulic actuator is used to drive the support roller to move closer to or away from the mandrel, so as to establish and release the support state.

5. The apparatus according to claim 1, characterized in that, Multiple sets of the aforementioned mobile support trolleys are arranged at intervals along the mandrel axis to divide the mandrel processing area into multiple support sections, thereby achieving segmented dynamic support.

6. The apparatus according to claim 1, characterized in that, Both the eddy current electromagnetic induction preheating coil and the eddy current electromagnetic induction remelting coil adopt a fully enclosed ring structure and are respectively mounted on the mobile support trolley via coil support arms, so that when the mobile support trolley moves downward, the eddy current coil can move away from the mandrel side and exit the processing area.

7. The apparatus according to claim 1, characterized in that, The mobile support trolley is equipped with a laser ranging device (including X-axis and Y-axis laser ranging). The laser ranging device is used to detect the relative positional relationship between adjacent mobile support trolleys and the positional state of the mandrel. Based on the detection results, it realizes dynamic coordination and spacing maintenance between each mobile support trolley to form a stable multi-point support state. The bottom of the mobile support trolley is equipped with pulleys, which cooperate with linear guide rails to achieve low-resistance linear movement.

8. A method for controlling laser cladding of an ultra-long mandrel using the device described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: The two ends of the extra-long mandrel are respectively clamped in the active rotary clamping mechanism and the driven rotary clamping mechanism, and the extra-long mandrel is driven to rotate at a constant speed around its axis; S2: Multiple sets of mobile support trolleys are arranged along the axial direction of the ultra-long mandrel, and the support rollers are driven to approach the ultra-long mandrel through hydraulic actuators to establish the initial support state; S3: The detection device installed on the mobile support trolley acquires the geometric state information of the ultra-long mandrel in real time, and coordinates the hydraulic actuators on each mobile support trolley according to the detection results, so that the position of the support roller is dynamically adjusted according to the geometric state of the ultra-long mandrel. S4: During the laser cladding process, the mandrel is locally preheated in front of the cladding area by an eddy current electromagnetic induction preheating coil. S5: Make the mobile support trolley and the laser cladding trolley move synchronously along the linear guide rail, so that the support and heat treatment positions change continuously along the axial direction with the cladding area until the entire cladding process is completed. S6: The cladding layer is remelted behind the cladding area using an eddy current electromagnetic induction remelting coil; S7: Allow the cladding layer to cool naturally or in a controlled manner, and perform necessary post-surface treatments.

9. The control method according to claim 8, characterized in that, Steps S1 to S5 are performed synchronously while the mandrel continues to rotate and the laser cladding is uninterrupted.

10. The control method according to claim 8 or 9, characterized in that, Through the coordinated control of multiple sets of mobile support trolleys, continuous support and control of the mandrel in different processing sections along the axial direction can be achieved.

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