Device and process method for in-situ pulse current assisted laser cladding of fiber reinforced composite coating

Abstract

The invention relates to a device and process method for in-situ pulse current assisted laser cladding of a fiber reinforced composite coating, the device comprises a base body, a plurality of refractory metal wires, a refractory metal wire clamp, a laser cladding structure and a pulse current structure, the base body is a metal part needing surface strengthening, and insulating parts with thicknesses are arranged at the two transverse ends of the base body; a plurality of refractory metal wires are used for coating the surface of a fiber-reinforced matrix and transversely laid on the matrix to be reinforced in parallel, and the two ends of the refractory metal wires extend out of the upper surface of the matrix; the refractory metal wire clamp is used for fixing a plurality of refractory metal wires; the laser cladding structure is used for conducting laser cladding on the base body and the multiple refractory metal wires. The pulse current structure is used for synchronously conveying pulse current to the base body and the multiple refractory metal wires. According to the method, the refractory metal wire is used as a pulse current conductor, most current is introduced into a molten pool in the laser cladding process, and the low-defect and high-performance fiber reinforced composite coating can be prepared while the utilization rate of pulse current is increased.

Description

Technical Field

[0001] The invention relates to the technical field of laser surface engineering, and in particular to a device and a process method for in-situ pulse current assisted laser cladding of a fiber-reinforced composite coating. Background Art

[0002] The laser cladding technology is used to prepare coatings to meet the requirements of parts under different working conditions, which is of great significance to extend the service life of parts. The process characteristics of local heating and rapid melting of laser cladding make the coating have high thermal stress and residual stress levels, and it is easy to crack. This phenomenon is more prominent in the process of laser cladding high-hardness coating. In order to improve the quality of laser cladding process, induction heating, ultrasonic vibration, electromagnetic induction and other technologies are combined with laser cladding technology. The physical and chemical processes of heat and mass transfer in the molten pool in laser cladding are regulated by thermal field, force field and electromagnetic field to achieve the purpose of reducing the thermal stress of laser cladding, reducing the crack sensitivity of coating, eliminating defects such as pores and shrinkage, and refining grains, thereby improving the comprehensive performance of laser cladding coatings. Among them, electric pulse metal treatment technology is to directly treat metal materials or metal materials in the process of solidification with pulse current. Passing pulse current to solidified or unsolidified metal materials can promote crack healing, atomic diffusion and recrystallization, refine the microstructure of the material, and reduce the residual stress generated during laser cladding.

[0003] Normally, electric pulse technology processing requires a higher pulse current density (the size of the pulse current passing through a unit area) to achieve microstructure regulation and crack self-healing effects. For example, the Chinese invention patent with the announcement number CN 103602977 B discloses a device for realizing a method for pulse current refinement of the solidification structure of laser cladding metal coatings. The electrode is directly applied to the workpiece to be clad for pulse-assisted laser cladding. Since the cross-sectional area of ​​the workpiece is larger than the coating area, most of the current does not pass through the coating back to the negative electrode, and the requirements for the pulse current generating device are too high, and the size of the workpiece to be clad is also limited. At the same time, since the pulse current is applied to the entire cladding workpiece, the pulse current density passing through the cladding layer is also low, resulting in poor effects of the pulse current in terms of grain refinement, crack healing, and stress release, and the current utilization rate is very low. Summary of the invention

[0004] Technical problem to be solved: In view of the defects caused by low pulse current density and low current utilization in the prior art, the present invention provides a device and process method for in-situ pulse current assisted laser cladding fiber reinforced composite coating, which can improve the utilization rate of pulse current and prepare low-defect and high-performance fiber reinforced composite coatings.

[0005] Technical solution: An in-situ pulse current assisted laser cladding fiber reinforced composite coating device, including a substrate, a plurality of refractory metal wires, a refractory metal wire fixture, a laser cladding structure and a pulse current structure.

[0006] The substrate is a metal part that needs to be surface-strengthened, and insulating parts with a certain thickness (0.5-1mm) are provided at both ends of the substrate;

[0007] A plurality of refractory metal wires are used for coating the surface of the fiber-reinforced substrate, are laid transversely and parallelly on the substrate to be reinforced and have both ends extending from the upper surface of the substrate;

[0008] The refractory metal wire clamp is used to fix a plurality of refractory metal wires, respectively connect the two ends of the plurality of refractory metal wires and tighten them, the refractory metal wire clamp comprises a clamp body, a limiting structure, a clamping structure and a fixing structure, wherein the clamp body is an "I"-shaped frame suspended at the bottom of the middle connecting beam, the limiting structure is arranged at one end of the clamp body close to the base, the clamping structure is arranged at the middle connecting beam, the fixing structure is arranged at the other end of the clamp body, the clamping structure is height-adjustable, and the bottom end is lower than the limiting structure, a plurality of refractory metal wires sequentially pass through the limiting structure, the bottom of the clamping structure and the top of the fixing structure, are limited by the limiting structure, fixed by the fixing structure, and compressed by the clamping structure;

[0009] The laser cladding structure is used to perform laser cladding on a substrate and a plurality of refractory metal wires, and includes a fixing seat disposed above the substrate, a laser head connected to the fixing seat, and a coaxial powder feeding head disposed at the bottom of the laser head;

[0010] The pulse current structure is used to synchronously transmit pulse current to a substrate and a plurality of refractory metal wires, and includes a pulse power supply and a pulse current connecting device, wherein the pulse current connecting device includes a fixed arm, two lateral moving devices, two positive / negative electrodes and two electrode blocks, wherein the fixed arm is horizontally sleeved on the outside of the laser head, the two lateral moving devices are respectively arranged at both ends of the fixed arm and can move horizontally, the two positive / negative electrodes are respectively movably connected to the bottom ends of the two lateral moving devices, the two electrode blocks are respectively movably connected to the bottom ends of the two positive / negative electrodes, and the bottom surfaces of the electrode blocks are arranged on a plurality of refractory metal wires, and the two positive / negative poles of the pulse power supply are respectively connected to the two positive / negative electrodes through electric wires; the non-electrically connected parts of the refractory metal wire clamp and the pulse current structure are insulated.

[0011] Preferably, the limiting structure is a refractory metal wire limiting plate, and a plurality of circular hole-shaped limiting grooves are horizontally opened in the middle of the refractory metal wire limiting plate, and the diameter of the limiting grooves is larger than the diameter of the refractory metal wire. The refractory metal wire limiting plate is used for limiting to avoid uneven coating structure caused by non-parallel arrangement of molybdenum wires during cladding.

[0012] Preferably, the two side surfaces of the clamp body near the substrate are symmetrically and vertically provided with a plurality of threaded holes, and the two side ends of the refractory metal wire limiting plate are movably connected to any one of the threaded holes on the two side surfaces of the clamp body near the substrate through bolts. In this way, the position of the refractory metal wire limiting plate can be moved up and down to meet the needs of laser cladding on substrates at different heights.

[0013] Preferably, the clamping structure includes a tightening bolt, a through hole is provided in the center of the middle connecting beam of the clamp body, a thread corresponding to the tightening bolt is provided on the inner side of the through hole, and the height of the tightening bolt is higher than the thickness of the through hole. When tightening is not required, the tightening bolt is screwed out upward, and the bottom does not contact the plurality of refractory metal wires; when tightening is required, the tightening bolt is tightened downward, and the bottom extends out of the through hole to tighten the plurality of refractory metal wires; a handle is provided on the top of the tightening bolt for easy rotation.

[0014] Preferably, the clamping structure includes a tightening bolt and a tensioning device connected to the bottom of the tightening bolt, the tensioning device includes sliding grooves on both sides and a clamping block that can slide in the sliding grooves, a through hole is provided in the center of the middle connecting beam of the clamp body, a thread corresponding to the tightening bolt is provided on the inner side of the through hole, the sliding grooves on both sides are provided on the side walls of the clamp body and the bottom of the middle connecting beam, the top of the clamping block is movably connected to the bottom of the tightening bolt, when tightening is not needed, the tightening bolt is screwed out upward, and the clamping block moves upward as the tightening bolt rotates, when tightening is needed, the tightening bolt is tightened downward, and the clamping block moves downward as the tightening bolt rotates, thereby achieving the tightening of several refractory metal wires; a handle is provided on the top of the tightening bolt for easy rotation.

[0015] Furthermore, a plurality of evenly distributed grooves are provided below the pressing block for fixing the refractory metal wire, and the refractory metal wire is pressed into the pressing cavity, thereby tightening the refractory metal wire.

[0016] Preferably, the fixing structure includes a base, fixing bolts and a refractory metal wire connector, the refractory metal wire connector is rotatably connected to the base via the fixing bolts, and the connecting end is connected to the ends of several refractory metal wires, and when the refractory metal wire connector is rotated, the several refractory metal wires are tightened.

[0017] Preferably, the lateral moving device includes a spring, and the positive / negative electrode includes an internal spring. The spring is arranged inside the lateral moving device, one end of which is connected to the top of the lateral moving device, and the other end is connected to the positive / negative electrode. The internal spring is arranged inside the positive / negative electrode, one end of which is connected to the top of the positive / negative electrode, and the other end is connected to the top of the electrode block. The top of the electrode block extends into the positive / negative electrode, and the bottom is embedded in the outside of the positive / negative electrode. When the electrode block is in a suspended state, the internal spring is in a stretched state. When the electrode block contacts the upper surface of the refractory metal wire, the internal spring is in a compressed state. When the bottom of the electrode block is under pressure, the internal spring is further tightened. The fixed arm includes two semicircular hoops, bolts and nuts corresponding to the bolts. Bolt holes corresponding to the bolts are provided on both sides of the semicircular hoops. The two semicircular hoops are movably connected to the outside of the laser head through bolts and nuts.

[0018] Furthermore, the substrate needs to be polished and cleaned before cladding to remove the surface oxide layer.

[0019] Based on the above-mentioned in-situ pulse current assisted laser cladding fiber reinforced composite coating device, the process steps are as follows:

[0020] Step 1: Use a refractory metal wire clamp to fix both ends of a plurality of refractory metal wires. First, fix one end of the plurality of refractory metal wires to a fixed structure on one side, then straighten them and pass through a limiting structure on one side, lay them in parallel on the substrate to be reinforced, and extend both ends from the upper surface of the substrate. Due to the presence of the insulating member on the upper surface of the substrate, a gap is left between the plurality of refractory metal wires and the upper surface of the substrate to ensure that the refractory metal wires do not contact the substrate and increase the pulse current density. Then, pass through the limiting structure on the other side, and fix the other ends of the plurality of refractory metal wires to the fixed structure on the other side.

[0021] Step 2: After fixing a plurality of refractory metal wires, use the compression structures on both sides to compress them;

[0022] Step 3: Adjust the positions of the laser cladding structure, the pulse current structure and the substrate to be reinforced, so that the bottom surface of the electrode block of the pulse current structure contacts the upper surfaces of the plurality of refractory metal wires, and the molten pool and the coaxial powder feeding head of the laser cladding structure are located on the upper surfaces of the plurality of refractory metal wires;

[0023] Step 4: setting laser cladding process parameters and pulse current process parameters, and starting the pulse power supply, and preheating a plurality of refractory metal wires and the substrate after power is turned on;

[0024] Step 5: Start the power supply and perform pulse current assisted laser cladding operation on the sample to obtain the product.

[0025] Preferably, the refractory metal wire is a molybdenum wire with a diameter of 0.2-0.6 mm, and the powder of the coaxial powder feeding head is a high entropy alloy CoCrFeMnNi with a particle size of 75-105 μm.

[0026] Preferably, the laser cladding process parameters in step 4 are: spot diameter is 2 mm; laser power is 1400-1600 W; scanning speed is 3 mm / s; powder feeding rate is 20 g / min; argon gas is used for gas protection of the molten pool, and the carrier gas volume is 5 L / min; the process parameters of the pulse current are: the pulse current is a unidirectional square wave, the peak current is 300 A, the pulse frequency is 500 Hz, the pulse width is 1000 μs, and the duty cycle is 50%.

[0027] The process method of the present invention is to use refractory metal wire as a conductor of pulse current, and introduce most of the current into the molten pool during the laser cladding process. While improving the current utilization rate, the refractory metal wire can also play a fiber reinforcement effect. The principle of the present invention is: the molding quality and performance improvement of the composite coating in the present invention are achieved by the introduction of refractory metal wire reinforcement and the electrothermal effect of pulse current. Since the refractory metal wire has a high melting point and laser cladding has the characteristics of rapid cooling, the refractory metal wire remains in an incompletely melted state during the laser cladding process, so that it exists in a filamentous structure in the solidified structure, achieving the effect of fiber reinforcement. While laser cladding, a pulse current is applied through the refractory metal wire, and the current is also conducted into the molten pool, so that during the solidification process, the pulse current will play a role in disturbing the molten pool and achieving grain refinement. For microcracks generated during solidification, due to the presence of the interface resistance of the microcracks, the pulse current bypasses the crack tip, thereby generating a large local thermal effect. The local melting and thermal stress at the crack tip will inhibit the growth of the crack and even heal the microcrack. Compared with regulating the microstructure of the material, crack healing mainly relies on the heat generated by the pulse current at the crack, and the required pulse current density is relatively large. The present invention introduces the current into the molten pool through the molybdenum wire. Compared with directly adding the current to the substrate, the pulse current has a higher current utilization rate and can achieve crack healing in the coating.

[0028] Beneficial effects:

[0029] 1. The refractory metal wire in the present invention can play a fiber reinforcement effect on the coating. After the laser cladding is completed, the coating contains refractory metal wires that are not completely melted throughout the entire coating, which is beneficial to improving the impact resistance and bending resistance of the coating. In a high temperature environment, the metal fiber will also provide additional support to reduce the internal stress caused by temperature changes.

[0030] 2. The refractory metal wire through which the pulse current is passed in the present invention utilizes the electrothermal effect of the current to suppress and heal the microcracks generated in the coating due to thermal stress, thereby improving the molding quality of the coating and reducing the scrap rate.

[0031] 3. The molten pool disturbance effect of the pulse current in the present invention achieves grain refinement of the coating.

[0032] 4. After the current is turned on, the refractory metal wire heats up due to the current passing through it. During laser cladding, the surface melting degree of the refractory metal wire increases, making it easier to form a metallurgical bond with the coating and difficult to separate from the coating. At the same time, the refractory metal elements are dissolved into the coating, which will improve the wear resistance of the coating.

[0033] 5. The processing flexibility of the present invention is high and can meet the requirements of different working conditions. The electric pulse assisted laser cladding process can flexibly control the coating thickness, shape and distribution of metal wires in the coating. The pulse current connection device moves synchronously with the laser head, and can freely adjust the position on the X / Y axis, and also has a certain stroke in the Z axis direction, which makes it able to adapt to the cladding coating operation requirements of the surface of three-dimensional parts.

[0034] 6. In the design of the present invention, a pulse current is applied to a molybdenum wire with a very small diameter through a pulse current connecting device. Compared with directly applying the pulse current to both ends of the substrate, this method significantly improves the pulse current density in the molten pool during the cladding process, thereby greatly improving the utilization efficiency of the pulse current. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The target device structure assembly diagram of the present invention, (a) front view; (b) top view;

[0036] Figure 2 Schematic diagram of the refractory metal wire clamp used in the present invention, (a) AA sectional view; (b) left side view; (c) top view; (d) three-dimensional view Figure 1 ; (e) is three-dimensional Figure 2 ; (f) is a cross-sectional view of a portion of (c) along the AA direction;

[0037] Figure 3 Schematic diagram of the pulse current connection device used in the present invention, (a) BB cross-sectional view; (b) left side view; (c) top view.

[0038] In the figure, the reference numerals are:

[0039] 1-refractory metal wire fixture, 2-laser head, 3-coaxial powder feeding head, 4-refractory metal wire, 5-substrate, 6-pulse current connecting device, 7-rubber block, 8-handle, 9-refractory metal wire limit plate, 10-clamp body, 11-tensioning device, 12-refractory metal wire connector, 13-lateral moving device, 14-spring, 15-fixed arm, 16-positive / negative electrode, 17-internal spring, 18-electrode block, 19-bolt, 20-nut. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] In the embodiment of this specification, the refractory metal wire 4 is a molybdenum wire with a diameter of 0.2-0.6 mm (the diameter of the molybdenum wire in this embodiment is 0.6 mm), and the number of molybdenum wires is 50. The powder of the coaxial powder feeding head 3 is a high entropy alloy CoCrFeMnNi with a particle size of 75-105 μm.

[0042] During laser cladding, an SMD-500 pulse power supply is used to provide pulse current.

[0043] Example 1

[0044] An apparatus for in-situ pulse current assisted laser cladding of fiber reinforced composite coatings, such as Figure 1 As shown, it includes a substrate 5, a plurality of refractory metal wires 4, a refractory metal wire fixture 1, a laser cladding structure and a pulse current structure. The substrate 5 is a metal part that needs to be surface-strengthened, and insulating members 7 with a thickness of 0.5-1 mm are provided at both ends of the substrate 5 to prevent the molybdenum wire from contacting the substrate 5 during the laser cladding process. In this embodiment, the insulating member 7 is a rubber sheet with a thickness of 0.5 mm.

[0045] The refractory metal wire 4 is used for coating the surface of the fiber-reinforced matrix 5 , is laid transversely and parallelly on the matrix 5 to be reinforced, and has two ends extending from the upper surface of the matrix 5 .

[0046] The refractory metal wire clamp 1 is used to fix a plurality of refractory metal wires 4, and to connect two ends of the plurality of refractory metal wires 4 respectively and tighten them.

[0047] See also Figure 2 The refractory metal wire clamp 1 includes a clamp body 10, a limiting structure, a clamping structure and a fixing structure, wherein the clamp body 10 is an "I"-shaped frame suspended at the bottom of the middle connecting beam, the limiting structure is arranged at one end of the clamp body 10 close to the base 5, the clamping structure is arranged at the middle connecting beam, and the fixing structure is arranged at the other end of the clamp body 10. The clamping structure is height-adjustable, and the bottom end is lower than the limiting structure. A plurality of refractory metal wires 4 pass through the limiting structure, the bottom of the clamping structure and the top of the fixing structure in turn, and are limited by the limiting structure, fixed by the fixing structure, and clamped by the clamping structure.

[0048] Specifically, the limiting structure is a refractory metal wire limiting plate 9, and 50 circular hole-shaped limiting grooves with an aperture of 0.6 mm are horizontally opened in the middle of the refractory metal wire limiting plate 9, and the interval between two limiting grooves is 1 mm (the distance between the centers of the two limiting grooves).

[0049] The two side surfaces of the clamp body 10 near the substrate 5 are symmetrically and vertically provided with a plurality of groups of threaded holes, and the two side ends of the refractory metal wire limiting plate 9 are movably connected to any group of threaded holes on the two side surfaces of the clamp body 10 near the substrate 5 by bolts. In this way, the position of the refractory metal wire limiting plate 9 can be moved up and down to meet the needs of laser cladding on substrates at different heights.

[0050] The clamping structure includes a tightening bolt and a tensioning device connected to the bottom of the tightening bolt, the tensioning device includes sliding grooves on both sides and a clamping block that can slide in the sliding grooves. A through hole is provided in the center of the middle connecting beam of the clamp body 10, and a thread corresponding to the tightening bolt is provided on the inner side of the through hole. The sliding grooves on both sides are provided on the side walls of the clamp body 10 and the bottom of the middle connecting beam. The top of the clamping block is movably connected to the bottom of the tightening bolt (when the tightening bolt is rotated, the clamping block does not rotate with it, but moves up with the tightening bolt). When tightening is not needed, the tightening bolt is screwed out upward, and the clamping block moves up during the rotation of the tightening bolt. When tightening is needed, the tightening bolt is tightened downward, and the clamping block moves downward during the rotation of the tightening bolt, thereby achieving the tightening of several refractory metal wires 4; a handle 8 is provided on the top of the tightening bolt for easy rotation.

[0051] The fixing structure includes a base, fixing bolts and a refractory metal wire connector 12. The refractory metal wire connector 12 is rotatably connected to the base via the fixing bolts, and the connecting end is connected to the ends of a plurality of refractory metal wires 4. When the refractory metal wire connector 12 is rotated, the plurality of refractory metal wires 4 are tightened.

[0052] See also Figure 1 The laser cladding structure is used to laser clad a substrate 5 and a plurality of refractory metal wires 4, and includes a fixing seat arranged above the substrate 5, a laser head 2 connected to the fixing seat, and a coaxial powder feeding head 3 arranged at the bottom of the laser head 2.

[0053] The pulse current structure is used to synchronously transmit pulse current to the substrate 5 and the plurality of refractory metal wires 4, and includes a pulse power supply and a pulse current connecting device 11, wherein, see Figure 3 The pulse current connection device 11 includes a fixed arm 15, two lateral moving devices 13, two positive / negative electrodes 16 and two electrode blocks 18, wherein the fixed arm 15 is horizontally sleeved on the outside of the laser head 2, the two lateral moving devices 13 are respectively arranged at both ends of the fixed arm 15 and can move horizontally (slide grooves for moving the lateral moving devices are provided on both sides of the fixed arm), the two positive / negative electrodes 16 are respectively movably connected to the bottom ends of the two lateral moving devices 13, the two electrode blocks 18 are respectively movably connected to the bottom ends of the two positive / negative electrodes 16, and the bottom surfaces of the electrode blocks 18 are arranged on a plurality of refractory metal wires 4, and the two positive / negative poles of the pulse power supply are respectively connected to the two positive / negative electrodes 16 through wires; the refractory metal wire clamp 1 and the non-electrically connected parts of the pulse current structure are insulated.

[0054] Furthermore, the lateral moving device 13 includes a spring 14, and the positive / negative electrode 16 includes an internal spring 17. The spring 14 is arranged inside the lateral moving device 13, one end of which is connected to the top of the lateral moving device 13, and the other end is connected to the positive / negative electrode 16. The internal spring 17 is arranged inside the positive / negative electrode 16, one end of which is connected to the top of the positive / negative electrode 16, and the other end of which is connected to the top of the electrode block 18. The top of the electrode block 18 extends into the inside of the positive / negative electrode 16, and the bottom is embedded in the outside of the positive / negative electrode 16. When the electrode block 1 8 is in a suspended state, the deadweight of the electrode block 18 pulls the internal spring 17 into a stretched state, when the electrode block 18 contacts the upper surface of the refractory metal wire 4, the internal spring 17 is in a compressed state, and when the bottom of the electrode block 18 is under pressure, the internal spring 17 is further tightened; the fixed arm 15 includes two semicircular hoops, bolts 19 and nuts 20 corresponding to the bolts, and bolt holes corresponding to the bolts 19 are provided on both sides of the semicircular hoops, and the two semicircular hoops are movably connected to the outside of the laser head 2 through the bolts 19 and the nuts.

[0055] When the internal spring 17 is in a compressed state, it drives the positive / negative electrodes 16 to further compress the spring 14 to ensure that the laser head can move freely to perform a complex path cladding process.

[0056] When the laser head moves up and down, the positive and negative electrodes can compress / stretch the spring, thereby achieving coordinated movement with the laser head on the Z axis. The spring 17 inside the positive and negative electrodes is in a compressed state, exerting a certain pressure on the electrode block 18 to ensure that the bottom surface of the electrode block (10mm*10mm) is always in contact with the molybdenum wire during the laser cladding process.

[0057] Based on the above-mentioned in-situ pulse current assisted laser cladding fiber reinforced composite coating device, the process steps are as follows:

[0058] Step 1: Before cladding, the surface of the substrate 5 is first polished and cleaned to remove the surface oxide layer; a refractory metal wire fixture 1 is used to fix the two ends of several refractory metal wires 4. First, one end of several refractory metal wires 4 is fixed to the fixed structure on one side, and then they are straightened and passed through the limiting structure on one side, and laid in parallel on the substrate 5 to be strengthened, and the two ends extend from the upper surface of the substrate 5. Due to the presence of the insulating part on the upper surface of the substrate 5, a gap of 0.5 mm is left between the several refractory metal wires 4 and the upper surface of the substrate 5 to ensure that the refractory metal wires do not contact the substrate and increase the pulse current density. Then, the limiting structure on the other side is passed through, and the other ends of several refractory metal wires 4 are fixed to the fixed structure on the other side. Before laser cladding, the molybdenum wire is passed through the refractory metal wire limiting plate 9 for limiting, so as to avoid uneven coating structure caused by non-parallel arrangement of the molybdenum wires during cladding;

[0059] Step 2: After fixing a plurality of refractory metal wires 4, use the compression structures on both sides to compress them;

[0060] Step 3: Adjust the positions of the laser cladding structure, the pulse current structure and the substrate 5 to be reinforced, so that the bottom surface of the electrode block 18 of the pulse current structure contacts the upper surfaces of the plurality of refractory metal wires 4, and the molten pool of the laser cladding structure and the coaxial powder feeding head 3 are located on the upper surfaces of the plurality of refractory metal wires 4;

[0061] Step 4: Set the laser cladding process parameters and pulse current process parameters. The laser cladding process parameters are: spot diameter is 2 mm; laser power is 1500 W; scanning speed is 3 mm / s; powder feeding rate is 20 g / min; argon gas is used to protect the molten pool, and the carrier gas volume is 5 L / min; the process parameters of the pulse current are: the pulse current is a unidirectional square wave, the peak current is 300 A, the pulse frequency is 500 Hz, the pulse width is 1000 μs, the duty cycle is 50%, and the pulse power supply is started. After power is turned on, several refractory metal wires 4 and the substrate 5 are preheated for 30 minutes to prevent cracks from occurring during the cladding process. At the same time, the molybdenum wire 4 is deformed under the action of tension to have a certain wire texture, which can better enhance the coating performance;

[0062] Step 5: After preheating for 30 minutes, the sample is subjected to pulse current-assisted laser cladding operation to obtain a coating with a thickness of 2 mm.

[0063] The pulse current process parameters of the present invention are: the pulse current is a unidirectional square wave, the peak current is 300A, the pulse frequency is 500Hz, the pulse width is 1000μs, and the duty cycle is 50%. For the present invention, the bottom surface of the electrode block is 10mm*10mm, and it contacts 10 molybdenum wires at a time. The diameter of each molybdenum wire is 0.6mm, and the cross-sectional area of ​​the 10 molybdenum wires is 2.826mm. 2 , the peak current density is 106.16A / mm 2 , average current: 150A, average pulse current density: 53.08A / mm 2 However, if the positive / negative electrodes are in direct contact with the metal substrate, the peak current density is 5A / mm 2 Therefore, compared with directly loading the pulse current onto the substrate, using refractory metal wire as the conductor of the pulse current can effectively improve the pulse current density and current utilization rate during the laser cladding process.

[0064] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned implementation modes, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned implementation modes can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the implementation modes of the present invention.

Claims

1. An in-situ pulse current assisted laser cladding fiber reinforced composite coating device, characterized in that: It comprises a substrate (5), a plurality of refractory metal wires (4), a refractory metal wire fixture (1), a laser cladding structure and a pulse current structure. The substrate (5) is a metal part that needs to be surface-strengthened, and insulating parts (7) with a certain thickness are provided at both lateral ends of the substrate (5); A plurality of refractory metal wires (4) are used for coating the surface of a fiber-reinforced substrate (5), are laid transversely and parallelly on the substrate (5) to be reinforced and have both ends extending from the upper surface of the substrate (5); The refractory metal wire clamp (1) is used to fix a plurality of refractory metal wires (4), and the two ends of the plurality of refractory metal wires (4) are respectively connected and tightened. The refractory metal wire clamp (1) comprises a clamp body (10), a limiting structure, a pressing structure and a fixing structure, wherein the clamp body (10) is an "I"-shaped frame suspended at the bottom of an intermediate connecting beam, the limiting structure is arranged at one end of the clamp body (10) close to the base body (5), the pressing structure is arranged at the intermediate connecting beam, and the fixing structure is arranged at the other end of the clamp body (10). The pressing structure is height-adjustable, and the bottom end is lower than the limiting structure. The plurality of refractory metal wires (4) pass through the limiting structure, the bottom of the pressing structure and the top of the fixing structure in sequence, and are limited by the limiting structure, fixed by the fixing structure, and pressed by the pressing structure. The laser cladding structure is used for laser cladding a substrate (5) and a plurality of refractory metal wires (4), and comprises a fixing seat arranged above the substrate (5), a laser head (2) connected to the fixing seat, and a coaxial powder feeding head (3) arranged at the bottom of the laser head (2); The pulse current structure is used for synchronously transmitting pulse current to a substrate (5) and a plurality of refractory metal wires (4), and comprises a pulse power supply and a pulse current connecting device (11), wherein the pulse current connecting device (11) comprises a fixed arm (15), two lateral moving devices (13), two positive / negative electrodes (16) and two electrode blocks (18), wherein the fixed arm (15) is horizontally sleeved on the outside of a laser head (2), the two lateral moving devices (13) are respectively arranged at both ends of the fixed arm (15) and can move horizontally, the two positive / negative electrodes (16) are respectively movably connected to the bottom ends of the two lateral moving devices (13), the two electrode blocks (18) are respectively movably connected to the bottom ends of the two positive / negative electrodes (16), and the bottom surface of the electrode block (18) is arranged on the plurality of refractory metal wires (4), and the two positive / negative electrodes of the pulse power supply are respectively connected to the two positive / negative electrodes (16) through electric wires; the non-electrically connected parts of the refractory metal wire clamp (1) and the pulse current structure are insulated.

2. The device for in-situ pulse current assisted laser cladding of fiber reinforced composite coating according to claim 1, characterized in that: The limiting structure is a refractory metal wire limiting plate (9), and a plurality of circular hole-shaped limiting grooves are transversely provided in the middle of the refractory metal wire limiting plate (9), and the diameter of the limiting grooves is not less than the diameter of the refractory metal wire (4).

3. The device for in-situ pulse current assisted laser cladding of fiber reinforced composite coating according to claim 2, characterized in that: The two side surfaces of the clamp body (10) close to the base (5) are symmetrically and vertically provided with a plurality of groups of threaded holes, and the two side ends of the refractory metal wire limiting plate (9) are movably connected to any one group of threaded holes on the two side surfaces of the clamp body (10) close to the base (5) through bolts.

4. The device for in-situ pulse current assisted laser cladding of fiber reinforced composite coating according to claim 1, characterized in that: The clamping structure comprises a tightening bolt. A through hole is provided at the center of the middle connecting beam of the clamp body (10). A thread corresponding to the tightening bolt is provided on the inner side of the through hole. The height of the tightening bolt is higher than the thickness of the through hole. When tightening is not required, the tightening bolt is screwed out upwards and the bottom does not contact the plurality of refractory metal wires. When tightening is required, the tightening bolt is screwed down and the bottom extends out of the through hole to tighten the plurality of refractory metal wires (4). A handle (8) is provided on the top of the tightening bolt to facilitate rotation.

5. The device for in-situ pulse current assisted laser cladding of fiber reinforced composite coating according to claim 1, characterized in that: The clamping structure comprises a tightening bolt and a tensioning device connected to the bottom of the tightening bolt, the tensioning device comprises sliding grooves on both sides and a clamping block that can slide in the sliding grooves, a through hole is provided at the center of the middle connecting beam of the clamp body (10), a thread corresponding to the tightening bolt is provided on the inner side of the through hole, the sliding grooves on both sides are provided on the side walls of the clamp body (10) and the bottom of the middle connecting beam, the top of the clamping block is movably connected to the bottom of the tightening bolt, when tightening is not needed, the tightening bolt is screwed out upward, and the clamping block moves upward as the tightening bolt rotates, when tightening is needed, the tightening bolt is screwed down, and the clamping block moves downward as the tightening bolt rotates, thereby achieving the tightening of a plurality of refractory metal wires (4); a handle (8) is provided on the top of the tightening bolt for easy rotation.

6. The device for in-situ pulse current assisted laser cladding of fiber reinforced composite coating according to claim 1, characterized in that: The fixing structure comprises a base, fixing bolts and a refractory metal wire connector (12); the refractory metal wire connector (12) is rotatably connected to the base via the fixing bolts, and the connecting end is connected to the ends of a plurality of refractory metal wires (4); when the refractory metal wire connector (12) is rotated, the plurality of refractory metal wires (4) are tightened.

7. The device for in-situ pulse current assisted laser cladding of fiber reinforced composite coating according to claim 1, characterized in that: The lateral moving device (13) comprises a spring (14), and the positive / negative electrode (16) comprises an internal spring (17). The spring (14) is arranged inside the lateral moving device (13), one end of which is connected to the top of the lateral moving device (13), and the other end is connected to the positive / negative electrode (16). The internal spring (17) is arranged inside the positive / negative electrode (16), one end of which is connected to the top of the positive / negative electrode (16), and the other end of which is connected to the top of the electrode block (18). The top of the electrode block (18) extends into the inside of the positive / negative electrode (16), and the bottom is embedded in the outside of the positive / negative electrode (16). When the electrode block (18) is in a suspended state, the internal spring (17) is in a stretched state; when the electrode block (18) contacts the upper surface of the refractory metal wire (4), the internal spring (17) is in a compressed state; when the bottom of the electrode block (18) is under pressure, the internal spring (17) is further compressed; the fixed arm (15) comprises two semicircular hoops, bolts (19) and nuts (20) corresponding to the bolts; bolt holes corresponding to the bolts (19) are provided on both sides of the semicircular hoops; the two semicircular hoops are movably connected to the outer side of the laser head (2) through the bolts (19) and the nuts.

8. A process method for an in-situ pulse current assisted laser cladding fiber reinforced composite coating device according to claim 1, characterized in that: Here are the steps: Step 1: Use a refractory metal wire clamp (1) to fix the two ends of a plurality of refractory metal wires (4). First, fix one end of the plurality of refractory metal wires (4) to a fixed structure on one side, then straighten them and pass through a limiting structure on one side, lay them in parallel on a substrate (5) to be reinforced, and extend the two ends from the upper surface of the substrate (5). Due to the presence of an insulating member on the upper surface of the substrate (5), a gap is left between the plurality of refractory metal wires (4) and the upper surface of the substrate (5) to ensure that the refractory metal wires do not contact the substrate and increase the pulse current density. Then, pass through the limiting structure on the other side, and fix the other ends of the plurality of refractory metal wires (4) to the fixed structure on the other side. Step 2: After fixing a plurality of refractory metal wires (4), they are compressed by using compression structures on both sides; Step 3: adjusting the positions of the laser cladding structure, the pulse current structure and the substrate to be reinforced (5), so that the bottom surface of the electrode block (18) of the pulse current structure contacts the upper surface of the plurality of refractory metal wires (4), and the molten pool of the laser cladding structure and the coaxial powder feeding head (3) are located on the upper surface of the plurality of refractory metal wires (4); Step 4: setting laser cladding process parameters and pulse current process parameters, and starting the pulse power supply, and preheating the plurality of refractory metal wires (4) and the substrate (5) after power is turned on; Step 5: Start the power supply and perform pulse current assisted laser cladding operation on the sample to obtain the product.

9. The process method of the device for in-situ pulse current assisted laser cladding of fiber reinforced composite coating according to claim 8 is characterized in that: The refractory metal wire (4) is a molybdenum wire with a diameter of 0.2-0.6 mm, and the powder of the coaxial powder feeding head (3) is a high entropy alloy CoCrFeMnNi with a particle size of 75-105 μm.

10. The process method of the device for in-situ pulse current assisted laser cladding of fiber reinforced composite coating according to claim 8, characterized in that: The laser cladding process parameters in step 4 are: spot diameter is 2mm; laser power is 1400-1600W; scanning speed is 3mm / s; powder feeding rate is 20g / min; argon gas is used for gas protection of the molten pool, and the carrier gas volume is 5L / min; the process parameters of the pulse current are: the pulse current is a unidirectional square wave, the peak current is 300A, the pulse frequency is 500Hz, the pulse width is 1000μs, and the duty cycle is 50%.

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