Laser cladding surface treatment method for mandrel used in seamless steel pipe rolling process

Abstract

The present invention relates to a laser cladding surface treatment method for a mandrel used in a seamless steel pipe rolling process. A longitudinal reciprocating unit is disposed below a base plate. The longitudinal reciprocating unit is provided with a number of stopper units, the same number as the cup holders. Driven by the longitudinal reciprocating unit, each stopper unit is capable of longitudinal reciprocating motion beneath the aligned cup holders, causing the ice cream cup at the bottom of the cup barrel to disengage and fall from the barrel during motion. The present invention has a simple overall structure, is highly convenient for installation and maintenance, and has a low vertical height, making it suitable for use in various environments. The oblique wedge-shaped front end of the stopper cooperates with the side opening of the cup holder and the air jet to rapidly disengage the bottom ice cream cup downward, ensuring the normal operation of subsequent processes.

Description

Technical Field

[0001] The invention belongs to the technical field of core rod surface treatment, in particular to a laser cladding surface treatment method for a core rod used in a seamless steel pipe rolling process. Background Art

[0002] Seamless steel pipes play a vital role in my country's economic development and are widely used in industries such as petroleum, military, and boilers. Mandrels are essential tools for setting the pipe and wall during the production process. They are also a major consumable component in continuous pipe mills, accounting for over 55% of production and maintenance costs. The lifespan of mandrels directly impacts the manufacturing cost of seamless steel pipes. According to statistics, the current mandrel consumption index for seamless pipe rolling in China is 0.9 kg / ton. In 2015, my country's total seamless steel pipe production was approximately 30 million tons, consuming 27,000 tons of mandrels. Mandrels are primarily made of quenched and tempered H13 hot-working die steel. The basic price of domestic mandrels is approximately 50,000 yuan / ton, resulting in an annual mandrel consumption value of 1.35 billion yuan. To increase the service life of the core rod, traditional technology often uses the electroplating hard chrome process. However, the environmental pollution caused by the electroplating hard chrome process on the core rod surface has attracted more and more attention from governments at all levels, and it is difficult to continue in the long term. At present, the electroplating hard chrome process has been basically eliminated abroad. Other surface treatment processes such as plasma spraying and spray welding also have various problems. In addition, the powder feeding channel in the powder feeding head is at a fixed angle when conveying alloy powder. If the powder feeding angle needs to be adjusted, it can only be replaced with a new powder feeding head with a different angle, which is very inconvenient. In addition, the existing powder feeding valve plate has defects in the dispersion and distribution of alloy powder, and the heat dissipation effect is also poor. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a laser cladding surface treatment method for a mandrel used in a seamless steel pipe rolling process, which is used to treat the surface of the mandrel by a laser cladding process, so that the surface of the mandrel has local repairability, extends the failure cycle of the mandrel surface, and increases the service life of the mandrel.

[0004] The technical solution adopted by the present invention is:

[0005] A laser cladding surface treatment method for a mandrel used in a seamless steel pipe rolling process, characterized in that it comprises the following steps:

[0006] ⑴Pre-treat the surface of the core rod;

[0007] ⑵Set the laser spot diameter, overlap rate and cladding speed;

[0008] (3) Cladding the alloy powder on the surface of the mandrel after surface pretreatment, and using inert gas for protection during the cladding process;

[0009] (4) Allow the core rod to cool naturally after cladding treatment;

[0010] ⑸ Obtain the finished product.

[0011] Furthermore, the laser spot in step (2) is a strip-shaped spot with a length of 30 mm and a width of 1-1.5 mm;

[0012] The overlap rate in step (2) is 40-60%;

[0013] The cladding speed in step (2) is 200-1000 mm / min.

[0014] Furthermore, the alloy powder in step (3) is a mixture of a nickel-based alloy and tungsten carbide, or the alloy powder in step (3) is a mixture of a cobalt-based alloy and tungsten carbide;

[0015] When the alloy powder is a mixture of nickel-based alloy and tungsten carbide:

[0016] The nickel-based alloy consists of 0.02% C, 9.2% Mo, 0.98% Fe, 0.32% Mn, 21.5% Cr, 0.40% Si, 0.07% O, 0.01% Al, 0.09% N, 3.45% Nb and the balance Ni;

[0017] The tungsten carbide is composed of 2.46% C, 33.92% Ni, 1.32% Fe, 2.75% Cr, 1.50% Si, 0.018% O, 1.48% B, 0.003% S, 0.003% P and the balance WC;

[0018] When the alloy powder is a mixture of cobalt-based alloy and tungsten carbide:

[0019] The cobalt-based alloy consists of 0.2% C, 3% Mo, 25% Cr, 1.0% Si, 2% Ni and the balance Co;

[0020] The tungsten carbide consists of 2.46% C, 33.92% Ni, 1.32% Fe, 2.75% Cr, 1.50% Si, 0.018% O, 1.48% B, 0.003% S, 0.003% P and the balance WC.

[0021] Furthermore, the structure of the alloy powder spraying device includes a base plate, a powder feeding valve plate, and a quick-release joint. An opening is provided on the side wall of the laser head, the base plate is provided on the opening, and a powder feeding valve plate capable of limited swinging is provided on the inner wall of the base plate located at the opening. The upper end of the powder feeding valve plate is connected to the quick-release joint provided on the base plate, and the lower end of the powder feeding valve plate extends from a through hole aligned with the bottom plate of the laser head. When the powder feeding valve plate is limited and swung, the angle between the lower end of the powder feeding valve plate and the vertical direction changes; a strip-shaped powder nozzle is provided on the bottom surface of the powder feeding valve plate.

[0022] The structure of the limited swing is selected from any one of the following structures (1) or (2):

[0023] (1) Two side plates spaced apart from each other are provided on the inner wall of the base plate at the opening, the powder feeding valve plate is hingedly mounted between the two side plates, a limiting screw hole is provided on the side wall on any one side or both sides of the powder feeding valve plate, an arc-shaped through groove is provided on the side wall aligned with the screw hole, a limiting bolt is slidably mounted in the arc-shaped through groove, the end of the limiting bolt can be engaged in the limiting screw hole, and when the limiting bolt is tightened in the limiting screw hole, the powder feeding valve plate and the inner wall can be in close static contact with each other;

[0024] or,

[0025] ⑵ Two side plates spaced apart from each other are provided on the inner wall of the substrate at the opening, and a hinge is provided on the side wall on any one side or both sides of the powder feeding valve plate. The powder feeding valve plate is hinged on the two side plates through the hinge, and the end of the hinge extending out of the side plate is connected to the output shaft of the stepper motor provided on the substrate through a transmission mechanism, and the signal output end of the stepper motor is connected to the host computer.

[0026] Furthermore, a baffle is provided at the front end of each side wall, and a blocking block is provided at the rear end of each side wall, the bottom surface of the blocking block is pressed against the bottom surface of the opening, and the baffle and blocking block are used to limit the swing angle of the powder feeding valve plate;

[0027] The through hole is arranged tilted, and when the lower end of the powder feeding valve plate swings forward to the limit position, it can contact the inner wall of the front end of the through hole, and when the lower end of the powder feeding valve plate swings backward to the limit position, it can contact the inner wall of the rear end of the through hole.

[0028] Furthermore, the valve plate includes an upper valve seat and a lower valve seat, a powder inlet is provided at the upper end of the upper valve seat, and a powder spraying port is provided at the lower end of the lower valve seat, the lower end of the upper valve seat and the upper end of the lower valve seat are connected to each other, and the upper channel in the upper valve seat and the lower channel in the lower valve seat together constitute a powder delivery channel after the upper valve seat and the lower valve seat are connected to each other, and a disturbance mechanism is provided in the channel in the upper valve seat, and the disturbance mechanism is located below the powder inlet provided on the upper valve seat.

[0029] Furthermore, a U-shaped air duct is provided in the lower valve seat beside the lower channel, and the U-shaped air duct is connected to the air supply interface provided on the surface of the lower valve seat, and the U-shaped air duct is integrally connected to the air supply opening provided on the bottom surface of the lower valve seat.

[0030] Furthermore, a cooling portion is integrally provided on the rear end surface of the lower valve seat. A cold water channel is provided inside the cooling portion. The cold water channel is respectively communicated with a water inlet and a water outlet provided on the surface of the cooling portion.

[0031] Furthermore, the disturbance mechanism includes a substrate and a disturbance rod, and a plurality of disturbance rods spaced apart from each other are provided on the substrate;

[0032] A slot is provided on the inner wall at the rear end of the upper channel, which is communicated with an opening provided at the bottom surface of the lower valve seat. The substrate enters the slot from the opening and is squeezed tightly in the slot after the upper valve seat and the lower valve seat are connected to each other.

[0033] Furthermore, a protrusion is provided on the bottom surface of the upper valve seat, and a depression is provided on the upper end surface of the lower valve seat. After the upper valve seat and the lower valve seat are connected to each other, the protrusion is embedded in the depression.

[0034] The advantages and positive effects of the present invention are:

[0035] In the present invention, the alloy powder is a mixture of a nickel-based alloy and tungsten carbide or a mixture of a cobalt-based alloy and tungsten carbide. The alloy powder is clad on the surface of the mandrel using a laser cladding process, forming an alloy cladding layer on the surface. Since the alloy powder contains elements or their oxides that have grain refinement and grain strengthening effects on the alloy cladding layer, the microstructure of the alloy cladding layer is characterized by grain refinement, increased dislocation density, and uniform and dense microstructure. It also has the solid solution strengthening effect of a supersaturated alloy, so it can effectively improve the mechanical properties of the mandrel surface, such as hardness, wear resistance, corrosion resistance, and fatigue resistance, and extend the service life by 2-3 times compared to traditional technologies, thereby reducing the cost of rolling. In addition, for mandrels with damaged surfaces, the laser cladding process can also be used to repair the surface, which can further reduce the rolling cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a high-magnification image of the cross-sectional structure of the sample of the present invention;

[0037] Figure 2 (a) is a low-magnification image of the cross-sectional structure of the sample of Control Example 1;

[0038] Figure 2 (b) is a high-magnification image of the cross-sectional structure of the sample of Control Example 1;

[0039] Figure 3 is the hardness indentation diagram of the sample of Control Example 1;

[0040] Figure 4 This is a high-magnification image of the cross-sectional structure of the sample of Control Example 2;

[0041] Figure 5 This is a high-magnification image of the cross-sectional structure of the sample of Control Example 3;

[0042] Figure 6 It is a cross-sectional view at the laser head;

[0043] Figure 7 yes Figure 6 An enlarged schematic diagram at the lower left corner of ;

[0044] Figure 8 yes Figure 7 Schematic diagram of the substrate moving upward;

[0045] Figure 9 yes Figure 8 Schematic diagram of the substrate moving toward the outside of the laser head;

[0046] Figure 10 This is the installation diagram of the stepper motor;

[0047] Figure 11 It is a structural diagram of the powder feeding valve plate;

[0048] Figure 12 yes Figure 11 Rear view;

[0049] Figure 13 yes Figure 11 Left view of;

[0050] Figure 14 yes Figure 12 Bottom view of

[0051] Figure 15 yes Figure 11 sectional view of ;

[0052] Figure 16 yes Figure 12 A partial cross-sectional view of the cooling portion;

[0053] Figure 17 yes Figure 13 sectional view of ;

[0054] Figure 18 It is a schematic diagram of another structure of the cooling unit. DETAILED DESCRIPTION

[0055] The present invention will be further described below with reference to the following examples. The following examples are illustrative rather than restrictive, and the scope of protection of the present invention cannot be limited by the following examples.

[0056] A laser cladding surface treatment method for a mandrel used in a seamless steel pipe rolling process, the innovation of the present invention lies in: comprising the following steps:

[0057] ⑴Pre-treat the surface of the core rod;

[0058] ⑵Set the laser spot diameter, overlap rate and cladding speed;

[0059] (3) Cladding the alloy powder on the surface of the mandrel after surface pretreatment, and using inert gas for protection during the cladding process;

[0060] (4) Allow the core rod to cool naturally after cladding treatment;

[0061] (5) The naturally cooled core rod is subjected to surface treatment;

[0062] ⑹ Obtain the finished product.

[0063] The above preprocessing includes the following steps:

[0064] (1) Remove 0.5-1.5 mm of the core rod surface by turning or grinding;

[0065] ⑵ Use cleaning agent to remove oil and impurities on the surface of the core rod;

[0066] ⑶ The surface of the core rod is dry.

[0067] The laser uses German IPG high-power laser, and the laser spot can adopt two shapes, specifically:

[0068] 1. The laser spot is circular, the diameter of the laser spot is 2-6 mm, and the cladding power is 3000-10000 watts.

[0069] 2. The laser spot is a strip spot with a length of 30 mm and a width of 1-1.5 mm, and the cladding power is 3000-4000 watts.

[0070] The overlap rate is 40-60%. The cladding speed is 200-400 mm / min. During laser cladding, the laser is used to scan the alloy powder onto the surface of the core rod one by one. The cladding layer is metallurgically bonded to the substrate, and the tungsten carbide is evenly distributed in the cladding layer without defects such as pores and cracks.

[0071] The alloy powder is a mixture of a nickel-based alloy and tungsten carbide or a mixture of a cobalt-based alloy and tungsten carbide, wherein the weight percentage of the nickel-based alloy and the tungsten carbide is , and the weight percentage of the cobalt-based alloy and the tungsten carbide is .

[0072] The nickel-based alloy consists of 0.02% C, 9.2% Mo, 0.98% Fe, 0.32% Mn, 21.5% Cr, 0.40% Si, 0.07% O, 0.01% Al, 0.09% N, 3.45% Nb, and the balance is Ni. The matching tungsten carbide consists of 2.46% C, 33.92% Ni, 1.32% Fe, 2.75% Cr, 1.50% Si, 0.018% O, 1.48% B, 0.003% S, 0.003% P, and the balance is WC.

[0073] The cobalt-based alloy consists of 0.2% C, 3% Mo, 25% Cr, 1.0% Si, 2% Ni, and the balance Co. The matching tungsten carbide consists of 2.46% C, 33.92% Ni, 1.32% Fe, 2.75% Cr, 1.50% Si, 0.018% O, 1.48% B, 0.003% S, 0.003% P, and the balance WC.

[0074] During the cladding process, 99.99% argon or helium is used to protect the molten pool to avoid burning and decomposition of tungsten carbide, with helium being preferred.

[0075] After cooling, the surface treatment is carried out, which includes the following steps:

[0076] ⑴ Remove 0.2 mm of the cladding layer by turning or grinding, and the surface roughness meets the requirement of 0.8-0.4;

[0077] ⑵ Use cleaning agent to remove oil and impurities on the surface;

[0078] ⑶The surface is dry.

[0079] Example 1

[0080] A laser cladding surface treatment method for a mandrel used in a seamless steel pipe rolling process comprises the following steps:

[0081] (1) Surface pretreatment of the core rod, the pretreatment includes the following steps:

[0082] ① Remove 0.5-1.5 mm of the core rod surface by turning or grinding;

[0083] ② Use cleaning agent to remove oil and impurities on the surface of the core rod;

[0084] ③The core rod surface is dry.

[0085] ⑵Set the laser spot diameter, overlap rate and cladding speed;

[0086] The laser uses a German IPG high-power laser. The laser spot is circular with a diameter of 2 mm and the cladding power is 10,000 watts. The overlap ratio is 40%. The cladding speed is 200 mm / min. The laser scans the alloy powder onto the surface of the core rod one by one.

[0087] (3) Cladding the alloy powder on the surface of the mandrel after surface pretreatment, and using inert gas for protection during the cladding process;

[0088] The alloy powder is a mixture of a nickel-based alloy and tungsten carbide or a mixture of a cobalt-based alloy and tungsten carbide.

[0089] The nickel-based alloy consists of 0.02% C, 9.2% Mo, 0.98% Fe, 0.32% Mn, 21.5% Cr, 0.40% Si, 0.07% O, 0.01% Al, 0.09% N, 3.45% Nb, and the balance is Ni. The matching tungsten carbide consists of 2.46% C, 33.92% Ni, 1.32% Fe, 2.75% Cr, 1.50% Si, 0.018% O, 1.48% B, 0.003% S, 0.003% P, and the balance is WC.

[0090] (4) Allow the core rod to cool naturally after cladding treatment;

[0091] (5) The naturally cooled core rod is subjected to surface treatment, which includes the following steps:

[0092] ① Remove 0.2mm of the cladding layer by turning or grinding, and the surface roughness meets the requirement of 0.8-0.4;

[0093] ② Use cleaning agent to remove oil and impurities on the surface;

[0094] ③The surface is dry.

[0095] ⑹ Obtain the finished product.

[0096] The finished product was tested, and its cross-sectional high-magnification image is as follows Figure 1 As shown, tungsten carbide is in complete granular form and evenly distributed in the cladding layer, which improves the hardness and wear resistance of the cladding layer. While improving the hardness and wear resistance, it also improves the impact resistance.

[0097] Example 2

[0098] The difference from Example 1 is that:

[0099] The laser spot diameter is 6 mm, the cladding power is 3000 W, the overlap ratio is 60%, and the cladding speed is 400 mm / min. The laser scans the alloy powder on the surface of the core rod one by one.

[0100] The shielding gas is argon. The cobalt-based alloy consists of 0.2% C, 3% Mo, 25% Cr, 1.0% Si, 2% Ni, and the balance is Co. The matching tungsten carbide consists of 2.46% C, 33.92% Ni, 1.32% Fe, 2.75% Cr, 1.50% Si, 0.018% O, 1.48% B, 0.003% S, 0.003% P, and the balance is WC.

[0101] The rest is the same as Example 1.

[0102] Example 3

[0103] The difference from Example 1 is that:

[0104] The laser spot diameter was 4 mm, the cladding power was 6000 W, the overlap ratio was 50%, and the cladding speed was 300 mm / min. The laser scanned the alloy powder onto the surface of the core rod in successive strokes.

[0105] The rest is the same as Example 1.

[0106] Example 4

[0107] The difference from Example 1 is that:

[0108] The laser spot is a strip-shaped spot 30 mm long and 1-1.5 mm wide. The cladding power is 4000 W. The overlap ratio is 50%. The cladding speed is 300 mm / min. The laser scans the alloy powder on the surface of the core rod one by one.

[0109] The rest is the same as Example 1.

[0110] Comparative Example 1

[0111] Plasma sprayed Ni+20% WC coating sample.

[0112] The low-power and high-power images of the cross-sectional structure of the sample are as follows: Figure 2 As shown in the figure, many unmelted particles can be seen. The hardness of the sample was tested and the results were as follows: Figure 3 The hardness indentation diagram shown, the hardness at this point is only HV 0.2 321 does not meet the high hardness requirements of WC particles, so no WC was found in the coating, and the WC was completely burned during processing.

[0113] Comparative Example 2

[0114] Laser remelting plasma sprayed Ni+20% WC coating sample.

[0115] The high magnification image of the cross-section of the sample is as follows Figure 4 As shown, no WC strengthening particles were found, and the average hardness was HV 0.2 210. WC has been completely burned during processing.

[0116] Comparative Example 3

[0117] Spray-welded Ni+20% WC coating sample.

[0118] The high magnification image of the interface structure of the sample is as follows Figure 5 As shown, no WC strengthening particles were found, and the average hardness was HV 0.2 208. The WC was completely burned during processing.

[0119] The alloy powder spraying structure used in the above process is: Figures 6-10As shown, the alloy powder spraying structure includes a base plate 2, a powder feed valve plate 14, and a quick-release connector 6. An opening 3 is provided on the side wall of the lower end 2 of the laser head 1. The opening is covered by a base plate secured by bolts 4 and completely covers the opening. A powder feed valve plate, capable of limited positional rotation, is provided on the inner wall of the base plate located near the opening. The upper end of the powder feed valve plate is connected to the end 8 of the quick-release connector on the base plate that extends into the opening. The end of the quick-release connector, located outside the base plate, is connected to other equipment via a pipeline 7. The lower end of the powder feed valve plate extends from a through hole 13 aligned with the laser head base plate 21. The angle between the lower end of the powder feed valve plate and the vertical direction changes as the powder feed valve plate limits its positional rotation. A strip-shaped powder nozzle is provided on the bottom surface of the powder feed valve plate, through which alloy powder is ejected and sprayed onto the laser cladding location.

[0120] In this embodiment, two side panels 16 spaced apart from each other are provided on the inner wall of the base plate at the opening, and the powder feeding valve plate is hinged between the two side panels by a hinge shaft 10 on the side wall of the powder feeding valve plate, and a limiting screw hole 18 is provided on the side wall on any one side or both sides of the powder feeding valve plate, and an arc-shaped through groove 15 is provided on the side wall corresponding to the screw hole, and a limiting bolt 9 is slidably installed in the arc-shaped through groove, and the end of the limiting bolt can engage in the limiting screw hole. When the limiting bolt is tightened in the limiting screw hole, the powder feeding valve plate and the inner wall can be in close static contact with each other. At this time, the powder feeding valve plate is fixed in this position. Preferably, the side walls on both sides of the powder feeding valve plate are fixed with limiting bolts.

[0121] Each sidewall is provided with a baffle 19 at the front end and a block 20 at the rear end. The bottom of the block presses against the bottom 22 of the opening. The baffle and block are used to limit the swing angle of the powder feed valve plate. The through-hole is tilted, so that when the lower end of the powder feed valve plate swings forward to the limit position, it contacts the inner wall at the front end of the through-hole. When the lower end of the powder feed valve plate swings backward to the limit position, it contacts the inner wall at the rear end of the through-hole. The tilt of the through-hole further limits the swing angle of the powder feed valve plate.

[0122] A powder feeding channel is provided within the powder feeding valve plate. The upper end of the channel communicates with a quick-release connector provided on the base plate via a pipeline 17. The lower end of the channel communicates with a nozzle 11 provided at the lower end of the powder feeding valve plate, which extends below the base plate of the laser head. A preferred embodiment is a quick-release head 23 provided at the upper end of the powder feeding valve plate. The upper end of the quick-release head communicates with a quick-release connector provided on the base plate via a pipeline, and the lower end of the quick-release head communicates with the upper end of the powder feeding channel. This pipeline is high-temperature resistant. Due to the small swing angle of the powder feeding valve plate, a relatively rigid, high-temperature resistant pipe can be used. For example, a heat-resistant pipe having a stainless steel outer layer with a spiral structure, a heat stabilizer-sandwiched fabric middle layer, and a coated fiber inner layer can be used.

[0123] The surface of the substrate that contacts the outer wall of the laser head near the opening is provided with a high-temperature-resistant sealing layer. This high-temperature-resistant sealing layer can use a commercially available high-temperature sealing gasket. The laser head shown in the figure is also equipped with a water cooling component and an inert gas delivery component, but these are not shown in the figure as they are not relevant to this case.

[0124] In addition to the manual adjustment and positioning method using limit bolts and arc-shaped through grooves, the above-mentioned powder feeding valve plate can also control the swing angle of the powder feeding valve plate by a motor. Specifically, two side plates spaced apart from each other are provided on the inner wall of the base plate at the opening, and a hinge shaft 10 is provided on the side wall on any one side or both sides of the powder feeding valve plate. The powder feeding valve plate is hinged on the two side plates 16 through the hinge shaft, and the end of the hinge shaft extending out of the side plate is connected to the output shaft of the stepper motor 24 provided on the base plate through a transmission mechanism, and the signal output end of the stepper motor is connected to the host computer.

[0125] like Figure 10 As shown, the stepper motor is installed on the base plate in the rear direction of the figure, and its output shaft is connected to the hinge shaft of the powder feeding valve plate through a gear pair or a similar transmission mechanism. The output shaft of the stepper motor on the front baffle can make the powder feeding valve plate fine-tune a small angle when it rotates in steps. The rotation angle and other signals output by the stepper motor are transmitted to the host computer in the control room through the signal output end, and various working status information is displayed on the display screen of the host computer.

[0126] In order to further detect the laser cladding process on site, Figure 10 A camera is set on the front side of the focusing mirror. The lens of the camera is kept at a certain distance from the entire laser head and is roughly perpendicular to capture images or videos. These images or videos are transmitted to the display screen of the host computer for the control personnel to observe the on-site working status.

[0127] An opening is provided on the laser head, and a base plate is provided on the opening. A powder feeding valve plate capable of limited swinging is hingedly mounted on the inner wall of the base plate at the opening. The lower end of the powder feeding valve plate extends into the through hole provided on the base plate of the laser head, and the nozzle provided at its lower end extends to the bottom of the base plate of the laser head. The powder feeding valve plate is connected to the quick-release joint on the base plate through a pipeline. The flowing gas transports the alloy powder to the bottom of the laser beam through the quick-release joint, pipeline, powder feeding valve plate and nozzle. The laser beam scans to melt the alloy powder onto the component. When the powder feeding angle needs to be adjusted, the base plate is removed from the laser head, and then the limit bolt is loosened. The angle of the powder feeding valve plate is adjusted, and then the limit bolt is tightened again. In this way, the powder feeding angle is adjusted. Moreover, when the powder feeding valve plate has a blockage or other fault, the limit bolt can be removed, and then the connection between the pipeline and the powder feeding valve plate can be disconnected, and another powder feeding valve plate can be replaced.

[0128] The specific structure of the powder feeding valve plate is as follows: Figures 11-18As shown, the valve plate includes an upper valve seat 28 and a lower valve seat 29. A powder inlet 27 is provided at the upper end of the upper valve seat, which is equipped with a powder feed quick-release connector 26, which is connected to the powder feed air pipe. A strip-shaped powder injection port 36 is provided at the lower end of the lower valve seat. The lower end of the upper valve seat and the upper end of the lower valve seat are interconnected. The upper channel 40 in the upper valve seat and the lower channel in the lower valve seat, after the upper and lower valve seats are interconnected, together form a powder feed channel. A disturbance mechanism is provided within the channel in the upper valve seat, located below the powder inlet provided on the upper valve seat.

[0129] A U-shaped air duct 43 with a U-shaped cross section is provided within the lower valve seat, adjacent to the lower passage. This U-shaped air duct communicates with an air supply port 45 provided on the surface of the lower valve seat. A quick-release air supply connector 34 is installed within the air supply port, which connects to an inert gas source. The U-shaped air duct is integrally connected to an air supply opening 35 provided on the bottom surface of the lower valve seat.

[0130] A cooling portion 32 is integrally provided on the rear end surface of the lower valve seat. A cold water channel is provided inside the cooling portion. The cold water channel is connected to the water inlet and water outlet provided on the surface of the cooling portion. A water inlet quick-release connector 31 and a water outlet quick-release connector 30 are installed at the water inlet and water outlet, respectively. The cold water channel includes a horizontal channel 48 and a vertical channel 47. Multiple horizontal channels ( Figure 16 There are four in the middle), one side of all cross passages ( Figure 16 left side) and the other side ( Figure 16 The uppermost horizontal channel has an opening on the surface of the cooling portion as a water outlet 30, the lowermost horizontal channel has an opening on the surface of the cooling portion as a water inlet 31, and the vertical channels and other horizontal channels are provided with blocking covers 33 in the openings on the surface of the cooling portion.

[0131] The disturbance mechanism includes a base plate 38 and disturbance rods 39, with multiple spaced-apart disturbance rods disposed on the base plate. A slot 49 is provided on the rear end inner wall 37 of the upper channel, communicating with an opening 41 provided on the bottom surface of the lower valve seat. The base plate slides into the slot through the opening. When the upper valve seat is connected to the lower valve seat via bolts 25, the inner wall of the slot presses against the outer surface of the upper portion of the base plate, while the upper end surface of the lower valve seat at the opening presses against the bottom surface of the lower end 46 of the base plate. As a result, the base plate is squeezed into the slot after the upper and lower valve seats are connected. The transverse cross-section of the disturbance rods can be circular, elliptical, triangular, or diamond-shaped.

[0132] In order to achieve a tighter connection, a protrusion 50 is provided on the bottom surface of the upper valve seat, and a recess 51 is provided on the upper end surface of the lower valve seat. After the upper valve seat and the lower valve seat are connected to each other, the protrusion is embedded in the recess.

[0133] The upper channel is a rectangular parallelepiped shape from top to bottom, and the lower channel is an inverted quadrangular pyramid shape 42 and a rectangular parallelepiped shape 44 connected as one piece from top to bottom; the bottom surface of the rectangular parallelepiped shape has the same area as the upper end surface of the inverted quadrangular pyramid shape, and the bottom surface of the inverted quadrangular pyramid shape has the same area as the upper end surface of the rectangular parallelepiped shape 44 located below it.

[0134] like Figure 18 As shown, the cooling part extends from one side of the lower valve seat to the other side in the horizontal direction, and the air supply quick release connector is set on the side of the lower valve seat. Figure 6-10 in the structure.

[0135] The use process of the present invention is:

[0136] When installing

[0137] 1. Select a disturbance mechanism with a circular cross-section, slide it into the slot, then buckle the upper and lower valve seats and tighten the bolts.

[0138] 2. Install the fastening bolts through the mounting holes of the upper valve seat and the lower valve seat (the left and right sides of the upper valve seat, the left side of the cooling part, and the right side of the lower valve seat, not shown in the figure), and install the entire valve plate on the side wall of the laser head.

[0139] 3. Connect the powder delivery air pipe to the powder delivery quick-release joint, connect the inert gas source to the air supply quick-release joint through the air pipe, and connect the cold water source to the water inlet quick-release joint and the water outlet quick-release joint respectively.

[0140] 4. After adjusting the powder feeding gas flow rate, cooling water flow rate, inert gas flow rate and valve plate angle, start the laser cladding process.

[0141] In the present invention, the valve plate is divided into a detachable upper valve seat and a lower valve seat, which are stacked vertically and fixed to each other by bolts. The upper channel in the upper valve seat and the lower channel in the lower valve seat are connected to each other and form a powder feeding channel. The upper end of the powder feeding channel is connected to the powder feeding quick-release joint installed at the powder feeding port at the upper end of the upper valve seat, and the lower end of the powder feeding channel is connected to the powder injection port at the lower end of the lower valve seat. A U-shaped air duct is provided in the lower valve seat beside the lower channel, and a powder injection port is provided inside the opening of the U-shaped air duct at the bottom surface of the lower valve seat. When the powder injection port sprays alloy powder, the U-shaped air duct sprays The inert gas released can not only protect the laser cladding working area, but also form an air curtain to avoid the large-scale scattering of alloy powder. The disturbance mechanism is slidably embedded in the inner wall of the rear end of the upper channel, and the installation and disassembly are very simple. The disturbance mechanism with different cross-sectional shapes can be replaced according to actual work requirements, and the lower valve seat with different widths of the lower channel can also be selected. Through the above-mentioned convenient disassembly and assembly disturbance mechanism and the replaceable lower valve seat, the uniformity of alloy powder transportation and the different density distribution and different speeds of the sprayed alloy powder are achieved.

Claims

1. A laser cladding surface treatment method for a mandrel used in a seamless steel tube rolling process, characterized in that: The following steps are involved: ⑴Pre-treat the surface of the core rod; ⑵Set the laser spot diameter, overlap rate and cladding speed; (3) Cladding the alloy powder on the surface of the mandrel after surface pretreatment, and using inert gas for protection during the cladding process; (4) Allow the core rod to cool naturally after cladding treatment; (5) Obtaining the finished product; The alloy powder spraying structure comprises a base plate, a powder feeding valve plate and a quick-release joint. An opening is provided on the side wall of the laser head, the base plate being provided on the opening. A powder feeding valve plate capable of limited positional rotation is provided on the inner wall of the base plate located at the opening. The upper end of the powder feeding valve plate is connected to the quick-release joint provided on the base plate. The lower end of the powder feeding valve plate extends from a through hole aligned with the bottom plate of the laser head. When the powder feeding valve plate is limitedly swung, the angle between the lower end of the powder feeding valve plate and the vertical direction changes. A strip-shaped powder nozzle is provided on the bottom surface of the powder feeding valve plate. The structure of the limited swing is selected from any one of the following structures (1) or (2): (1) Two side plates spaced apart from each other are provided on the inner wall of the base plate at the opening, the powder feeding valve plate is hingedly mounted between the two side plates, a limiting screw hole is provided on the side wall on any one side or both sides of the powder feeding valve plate, an arc-shaped through groove is provided on the side wall aligned with the screw hole, a limiting bolt is slidably mounted in the arc-shaped through groove, the end of the limiting bolt can be engaged in the limiting screw hole, and when the limiting bolt is tightened in the limiting screw hole, the powder feeding valve plate and the inner wall can be in close static contact with each other; or, ⑵ Two side plates spaced apart from each other are provided on the inner wall of the substrate at the opening, and a hinge is provided on the side wall on any one side or both sides of the powder feeding valve plate. The powder feeding valve plate is hinged on the two side plates through the hinge, and the end of the hinge extending out of the side plate is connected to the output shaft of the stepper motor provided on the substrate through a transmission mechanism, and the signal output end of the stepper motor is connected to the host computer.

2. The laser cladding surface treatment method for a mandrel for a seamless steel pipe rolling process according to claim 1, characterized in that: The laser spot in step (2) is a strip-shaped spot with a length of 30 mm and a width of 1-1.5 mm; The overlap rate in step (2) is 40-60%; The cladding speed in step (2) is 200-1000 mm / min.

3. The laser cladding surface treatment method for a mandrel for a seamless steel tube rolling process according to claim 1 or 2, characterized in that: The alloy powder in step (3) is a mixture of a nickel-based alloy and tungsten carbide, or the alloy powder in step (3) is a mixture of a cobalt-based alloy and tungsten carbide; When the alloy powder is a mixture of nickel-based alloy and tungsten carbide: The nickel-based alloy consists of 0.02% C, 9.2% Mo, 0.98% Fe, 0.32% Mn, 21.5% Cr, 0.40% Si, 0.07% O, 0.01% Al, 0.09% N, 3.45% Nb and the balance Ni; The tungsten carbide is composed of 2.46% C, 33.92% Ni, 1.32% Fe, 2.75% Cr, 1.50% Si, 0.018% O, 1.48% B, 0.003% S, 0.003% P and the balance WC; When the alloy powder is a mixture of cobalt-based alloy and tungsten carbide: The cobalt-based alloy consists of 0.2% C, 3% Mo, 25% Cr, 1.0% Si, 2% Ni and the balance Co; The tungsten carbide consists of 2.46% C, 33.92% Ni, 1.32% Fe, 2.75% Cr, 1.50% Si, 0.018% O, 1.48% B, 0.003% S, 0.003% P and the balance WC.

4. The laser cladding surface treatment method for a mandrel for a seamless steel pipe rolling process according to claim 3, characterized in that: A baffle is provided at the front end of each side wall, and a blocking block is provided at the rear end of each side wall, the bottom surface of the blocking block is pressed against the bottom surface of the opening, and the baffle and blocking block are used to limit the swing angle of the powder feeding valve plate; The through hole is arranged tilted, and when the lower end of the powder feeding valve plate swings forward to the limit position, it can contact the inner wall of the front end of the through hole, and when the lower end of the powder feeding valve plate swings backward to the limit position, it can contact the inner wall of the rear end of the through hole.

5. The laser cladding surface treatment method for a mandrel for a seamless steel pipe rolling process according to claim 4, characterized in that: The valve plate includes an upper valve seat and a lower valve seat, a powder inlet is provided at the upper end of the upper valve seat, and a powder spraying port is provided at the lower end of the lower valve seat, the lower end of the upper valve seat and the upper end of the lower valve seat are connected to each other, and the upper channel in the upper valve seat and the lower channel in the lower valve seat jointly constitute a powder feeding channel after the upper valve seat and the lower valve seat are connected to each other, and a disturbance mechanism is provided in the channel in the upper valve seat, and the disturbance mechanism is located below the powder inlet provided on the upper valve seat.

6. The laser cladding surface treatment method for a mandrel for a seamless steel pipe rolling process according to claim 5, characterized in that: A U-shaped air duct is provided in the lower valve seat beside the lower channel, and the U-shaped air duct is connected to the air supply interface provided on the surface of the lower valve seat, and the U-shaped air duct is connected to the air supply opening provided on the bottom surface of the lower valve seat.

7. The laser cladding surface treatment method for a mandrel for a seamless steel pipe rolling process according to claim 6, characterized in that: A cooling portion is integrally provided on the rear end surface of the lower valve seat. A cold water channel is provided inside the cooling portion. The cold water channel is respectively communicated with a water inlet and a water outlet provided on the surface of the cooling portion.

8. The laser cladding surface treatment method for a mandrel for a seamless steel tube rolling process according to claim 6 or 7, characterized in that: The disturbance mechanism includes a substrate and a disturbance rod, and a plurality of disturbance rods spaced apart from each other are arranged on the substrate; A slot is provided on the inner wall at the rear end of the upper channel, which is communicated with an opening provided at the bottom surface of the lower valve seat. The substrate enters the slot from the opening and is squeezed tightly in the slot after the upper valve seat and the lower valve seat are connected to each other.

9. The laser cladding surface treatment method for a mandrel for a seamless steel pipe rolling process according to claim 8, characterized in that: The bottom surface of the upper valve seat is provided with a protrusion, and the upper end surface of the lower valve seat is provided with a recess. After the upper valve seat and the lower valve seat are connected to each other, the protrusion is embedded in the recess.

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