A method and apparatus for preheating a ceramic material for laser welding

Abstract

The application discloses a method and equipment for prefabricating thermal auxiliary laser welding ceramic materials, and the method comprises the following steps: S1, clamping and splicing the parts to be welded of the ceramic materials together, positioning the ceramic materials, and applying 2-8N pre-pressure to the ceramic materials; S2, preheating the ceramic materials, so that the ceramic materials reach a preheating temperature, and the preheating temperature is 20-250 DEG C; and S3, after the preheating of the ceramic materials is completed, laser welding is performed on the parts to be welded of the ceramic materials. The ceramic materials are preheated at a temperature of 20-250 DEG C, the obtained welding seam has an attractive appearance, the welding seam crack length is reduced, and the welding seam bending strength is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser welding of ceramic materials, and particularly to a method and equipment for pre-prepared thermal auxiliary laser welding of ceramic materials. BACKGROUND

[0002] Ceramics and their composites have become the preferred materials for the cooling system of hypersonic vehicles due to their strong heat / corrosion resistance and high-temperature mechanical properties. In particular, alumina ceramics have become the most widely used ceramic material due to their simple manufacturing process and excellent overall performance. Currently, the connection of alumina ceramics is mostly achieved by methods such as microwave welding, brazing, and laser welding, among which laser welding is the most promising technology for ceramic welding.

[0003] Laser welding technology is a high-efficiency welding method that uses a high-energy-density laser beam as a heat source. Compared with traditional welding methods such as electric arc welding, gas welding, and resistance welding, which are widely used at present, laser welding has the advantages of fast welding speed, small deformation, and high welding quality.

[0004] In the processing process, the ceramic is directly welded by laser, and the ceramic is a brittle material, which leads to the generation of cracks and reduces the strength of the connected joint.

[0005] Patent No. CN107790882B discloses a laser welding method for molybdenum and molybdenum alloy based on thermal cycle regulation, which includes the following steps: 1) pretreating the molybdenum and molybdenum alloy workpieces to be welded; 2) clamping the molybdenum and molybdenum alloy workpieces to be welded, then placing them in an inert gas atmosphere, and then adjusting the laser welding head so that the axis of the laser beam emitted by the laser welding head forms an angle of 0°-10° with the vertical direction; 3) gradually preheating the areas to be welded of the molybdenum and molybdenum alloy workpieces to be welded by the laser beam emitted by the laser welding head, then welding the molybdenum and molybdenum alloy workpieces to be welded by the laser beam emitted by the laser welding head, and then gradually heat-insulating the areas to be welded of the molybdenum and molybdenum alloy workpieces to be welded by the laser beam emitted by the laser welding head, obtaining the welded workpieces. This welding method can effectively reduce the thermal stress generated during the welding of molybdenum and molybdenum alloy. In the current welding process, the main factors affecting the welding stress include material factors, manufacturing factors, and structural factors, among which the manufacturing factors can be regulated by preheating or slow cooling. Although the patent No. CN107790882B discloses a method of gradually preheating the molybdenum and molybdenum alloy workpieces to be welded, which can effectively reduce the thermal stress generated during the welding of molybdenum and molybdenum alloy, it is not clear whether this method can solve the problem of cracks in the process of laser welding of ceramics. SUMMARY

[0006] The technical problem solved by the present application is to provide a method and equipment for pre-heat assisted laser welding of ceramic materials to solve the problem of cracks in the ceramic laser welding process.

[0007] To solve the above technical problems, the technical solution adopted by the present application is: a method for pre-heat assisted laser welding of ceramic materials, comprising the following steps:

[0008] S1, clamping and splicing the parts to be welded of the ceramic material together to position the ceramic material and apply a pre-pressure of 2-4N to the ceramic material;

[0009] S2, preheating the ceramic material to make the ceramic material reach a preheating temperature of 20-250℃;

[0010] S3, after the preheating of the ceramic material is completed, laser welding is performed on the parts to be welded of the ceramic material.

[0011] In the prior art, during the direct laser welding process, due to the high energy density of the laser, a large temperature gradient is easily generated, and ceramic is a brittle material, so a large thermal stress is generated during the direct laser welding of ceramic, which leads to the generation of cracks and reduces the strength of the joint. In the present application, a preheating temperature of 20-250℃ and a pre-pressure of 2-8N are used, which can obtain a beautiful weld appearance, reduce the weld crack length, and improve the weld bending strength.

[0012] Preferably, the preheating temperature in S2 is 100-250℃. Further preferably, the preheating temperature in S2 is 200℃≤T<250℃. In this preheating temperature range, the cracks of the ceramic base material can be reduced, the weld crack length is reduced, and the weld bending strength is improved. When the preheating temperature is lower than 100℃, the improvement of the weld crack is small, and when the preheating temperature is too high, the weld appears overburning phenomenon and the bending strength decreases.

[0013] The preheating in S2 uses a preheating laser head.

[0014] The preheating laser beam before welding is used to preheat the ceramic plate, and then another welding laser beam is used to irradiate the workpiece surface to complete the ceramic welding, thereby reducing the temperature gradient generated during the welding process.

[0015] The laser process parameters in S2 and S3 are: welding laser power 400-500W, minimum spot diameter 0.2-0.5mm, welding speed 15-40mm / s, defocusing amount +2~+4mm, laser beam and workpiece surface angle 0°, nozzle and workpiece distance 0.5-2mm, angle 30-60°, auxiliary gas pressure 10-20bar, and welding length 30-50mm.

[0016] In S1, the welding fixture simultaneously applies pressure to the ceramic material, the pressure range is 0<F≤50N, and the pressure direction is perpendicular to the ceramic material and the welding direction.

[0017] The welding direction refers to the direction in which the ceramic material does not move and the welding laser moves, or the direction in which the welding laser does not move and the ceramic material moves.

[0018] In the prior art, a certain pressure can also be applied to the metal material during welding, and the main purpose is to eliminate the gap between the welded parts. In the present application, a certain pressure is applied during the welding of ceramic materials, which not only has the effect of eliminating the gap between the welded parts, but also can improve the toughness of the ceramic material. Because ceramics have obvious brittleness, the toughness of ceramic materials is currently improved mainly from the following aspects: 1. reducing defects in the ceramic material; 2. forming a certain compressive stress on the surface of the ceramic; 3. eliminating microcracks on the surface of the ceramic. For example, the pre-compressive stress on the surface can reduce the tensile stress generated during work, and make the ceramic "unbreakable". In the study of the cracking mechanism of the ceramic under pre-compressive stress, the application of a pre-compressive stress of appropriate size can effectively reduce the damage inside the material and limit the expansion of the median radial crack; the existence of the pre-compressive stress has little effect on the tangential force of the scratch, that is, the pre-compressive stress does not bring additional difficulty to the processing and removal of the material.

[0019] In the welding of alumina ceramic experiments, it is found that it is not the greater the pre-compressive stress, the better, but for different ceramic materials and different sizes of welded parts, a reasonable range of pre-compressive stress should be applied. For this experiment, the sensor range of 0-50N can fully meet the requirements, and the application of a smaller pre-compressive stress can eliminate the un-fused phenomenon of the weld, and the application of a too large pre-compressive stress will cause the whole ceramic plate to break.

[0020] The pressure range applied by the welding fixture to the ceramic material is 2N-4N. When no pressure is applied to the ceramic material, the center of the ceramic material weld appears a fused crack, and when the pre-compressive stress is 2N-4N, the un-fused crack appearing in the center of the weld disappears.

[0021] The ceramic material is an alumina ceramic plate. The present application is suitable for widely used alumina ceramic plates, and because ceramic materials are all brittle, the present application is also suitable for other brittle ceramic materials.

[0022] The present application also discloses a pre-prepared thermal auxiliary laser welding equipment, which comprises a pre-heating laser head, a welding laser head and a welding fixture, the pre-heating laser head and the welding laser head are arranged side by side, the welding fixture is arranged directly below the pre-heating laser head and the welding laser head, and the welding fixture is a pressurized welding fixture.

[0023] The preheating laser head is used for preheating the ceramic plate, and then another welding laser is used for welding, so that the temperature gradient generated in the welding process is reduced, and the crack is reduced; the pressurized welding clamp is used for applying surface pressure perpendicular to the welding direction before welding, so that the gap between the welded parts is small enough, and the pressure of 0-50N can be maintained to promote the molten pool flow and the stability of the welding process; the welding clamp is used for clamping the ceramic plate and fixing the pre-welding pressurizing device. When the laser welding is performed, the preheating laser beam is in front of the welding laser beam, the ceramic plate is preheated by the preheating laser beam, the required temperature is reached, and a certain preheating area is formed on the ceramic plate, meanwhile, the pre-welding pressurizing device applies the required pressure perpendicular to the welding direction, the preheating and pressurizing before welding are completed, and then the welding laser beam and the preheating laser beam are welded together under the control of the controller.

[0024] The welding clamp comprises a base, two supports mounted on the base and opposite to each other, vertical clamping pieces arranged at the upper ends of the supports, pressure sensors mounted on the inner surfaces of the supports, first stoppers respectively mounted on the inner surfaces of the pressure sensors, and horizontal clamping pieces mounted at the two ends of the supports.

[0025] The vertical clamping pieces are used for pressing the ceramic materials on the base, and the base can be provided with a support plate, and the ceramic materials can be pressed on the support plate. Meanwhile, the horizontal clamping pieces are used for clamping the two ceramic materials in the horizontal direction, for clamping and positioning the ceramic welded parts, and for applying the pre-pressure perpendicular to the welding direction, and the screw pressing device, the pressure sensor and the display device are matched, and the size of the pre-pressure is controlled.

[0026] The principle of the present application is as follows: the reasonable preheating temperature is used for reducing the temperature gradient in the welding process, thereby reducing the welding stress and the cracks on the base material, and obviously reducing the unmelted cracking generated in the welding process; the reasonable pre-pressure is used for promoting the molten pool flow and eliminating the unmelted cracking generated in the welding process; under the joint action of the two methods, the cracks on the ceramic base material are reduced, the unmelted cracking generated in the welding process is eliminated, and the ceramic welding is completed.

[0027] Compared with the prior art, the present application has the following beneficial effects: (1) the present application adds a laser beam for preheating before welding for the laser welding ceramic process and equipment, which greatly reduces the temperature gradient generated in the laser welding ceramic process, and the ceramic will generate a certain plasticity at high temperature, for example, the alumina ceramic will generate a certain plasticity at 1237℃, and the titanium oxide ceramic will generate a certain plasticity at 1038℃, the present application preheats the ceramic material, so that the ceramic material is closer to the plasticity temperature, thereby reducing the stress generated in the laser welding ceramic process and reducing the cracks generated in the welding process.

[0028] (2) The application uses laser beam preheating before welding. In laser ceramic welding, common preheating methods include high-temperature furnace preheating, heating platform preheating and flame preheating. However, these methods have the disadvantages of difficult clamping of workpieces, inability to quickly raise temperature, inaccurate temperature control, energy waste caused by overall heating of clamps and workpieces, etc. Laser beams can make the local ceramic welding part quickly reach the preheating condition without affecting the sensors in the clamp and pre-welding pressure device due to the large energy density, easy adjustment of focal length, power and speed and other parameters.

[0029] (3) The application uses pre-welding pressure welding. The gap between the welding parts will seriously affect the quality of laser welding, and the dynamic viscosity coefficient of ceramic is much lower than that of metal, resulting in poor fluidity of the molten pool. The use of pre-welding pressure ensures that the welding parts are closely attached and have a certain pressure during welding, promoting the flow of the molten pool and making the welding process more stable.

[0030] (4) The pre-welding pressure device in the application includes a screw tightening mechanism, a pressure sensor and a pressure display, which can control the size of the pre-pressure.

[0031] (5) The application completes the preheating power welding without moving the ceramic welding parts, which not only reduces the problem of difficult clamping after preheating of the welding parts, but also simplifies the process flow of ceramic laser welding without affecting the sensors in the clamp and pre-welding pressure device during local preheating. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The ceramic weld joint photo welded by the method described in Example 1 of the application.

[0033] Figure 2 The ceramic weld joint photo welded by the method described in Comparative Example 1 of the application.

[0034] Figure 3 The ceramic weld joint photo welded by the method described in Comparative Example 2 of the application.

[0035] Figure 4 The ceramic weld joint photo welded by the method described in Comparative Example 3 of the application.

[0036] Figure 5 The ceramic weld joint photo welded by the method described in Comparative Example 4 of the application.

[0037] Figure 6 The ceramic weld joint photo welded by the method described in Comparative Example 5 of the application.

[0038] Figure 7 The ceramic weld joint photo welded by the method described in Example 2 of the application.

[0039] Figure 8is a schematic diagram of the prefabricated thermal auxiliary laser welding equipment of the present application.

[0040] Figure 9 is a schematic diagram of the prefabricated thermal auxiliary laser welding method.

[0041] Figure 10 is a schematic diagram of the pre-welding preheating device.

[0042] Figure 11 is a schematic diagram of the laser welding fixture.

[0043] Figure 12 is a schematic diagram of the pre-welding pressure device.

[0044] Figure 1. Pre-welding preheating device, 2. Welding fixture, 3. Pre-welding pressure device, 4. Preheating laser processor, 5. Welding laser processor, 6. Controller, 7. Motion controller, 8. Temperature controller, 9. Temperature monitoring device, 10. First flange, 11. Preheating laser head, 12. Second flange, 13. Welding laser head, 14. Base, 15. Pressure sensor, 16. First stop block, 17. Compression screw, 18. Ceramic plate, 19. Second stop block, 20. Clamping screw, 21. Preheating laser beam, 22. Welding laser beam, 23. Preheating area, 24. Pressure value display device, 25. Support. DETAILED DESCRIPTION

[0045] Example 1

[0046] The workpiece of this example is two pieces of 95 alumina ceramic plate, the size is 40x40x1mm, the processing requirement is to connect the two pieces of ceramic plate together by butt welding method.

[0047] The welding process parameters used in this example are: welding laser power 450W, minimum spot diameter 0.3mm, welding speed 25mm / s, defocusing amount +3mm, laser beam and workpiece surface angle 0°, nozzle and workpiece distance 1mm, angle 45°, auxiliary gas pressure 15bar, welding length 40mm. The preheating temperature range is 200-250℃.

[0048] The two pieces of ceramic plate are clamped together by the welding fixture, the ceramic plate is positioned and clamped, the screw clamping mechanism is used to apply a surface force of 4N to the ceramic plate, then the preheating laser head is used to preheat the ceramic plate, the required preheating temperature is completed by the temperature controller, and finally the controller controls the welding laser head to weld. In the whole welding process, the ceramic plate is not moved, and the prefabricated thermal auxiliary laser welding ceramic is completed. In the laser welding process, the ceramic material is heated by laser to form a weld, so that the adjacent ceramic materials are welded together.

[0049] Compared with traditional laser direct welding, high-temperature furnace preheating welding, brazing and other processing methods, the prefabricated heat-assisted laser welding ceramic material process and equipment provided by the application has the following advantages: (1) high processing quality; (2) fast processing speed; (3) no need to move the welding part during preheating, and no need to replace the tooling, which can greatly improve the production efficiency; (4) high-temperature resistance of the welded joint.

[0050] As shown in Figure 1 , the weld morphology obtained under the combined action of applying 4N pre-pressure and preheating at 200-250 DEG C is shown below, and there is no un-fused cracking in the center of the weld, and the cracks on the base material are reduced.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that the ceramic plate is not preheated, and no pressure is applied to the ceramic plate.

[0053] As shown in Figure 2 , (a), (b) and (c) are respectively the views of the ceramic weld photos obtained by the process described in Comparative Example 1 from different angles, and when there is no preheating and no pressure is applied, the ceramic directly cracks in large pieces during laser welding to form Figure 2 a gap on both sides of the weld, and a clear un-fused cracking is formed in the center of the weld.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 1 is that no pressure is applied to the ceramic plate, and the preheating temperature is 20 DEG C, 50 DEG C, 100 DEG C, 200 DEG C and 250 DEG C, respectively.

[0056] As shown in Figure 3 , (a1) and (a2) are respectively the photos of the ceramic weld photos obtained by preheating at 20 DEG C, (b1) and (b2) are respectively the photos of the ceramic weld photos obtained by preheating at 50 DEG C, (c1) and (c2) are respectively the photos of the ceramic weld photos obtained by preheating at 100 DEG C, (d1) and (d2) are respectively the photos of the ceramic weld photos obtained by preheating at 200 DEG C, and (e1) and (e2) are respectively the photos of the ceramic weld photos obtained by preheating at 250 DEG C.

[0057] When the preheating temperature is lower than 100 DEG C, the improvement effect on the weld cracking is small. When the preheating temperature is increased, the weld morphology is beautiful, the weld crack length is reduced, and the weld bending strength is increased; but when the preheating temperature is too high (250 DEG C), the weld appears overburning phenomenon, and the bending strength is reduced; among them, when the preheating temperature is 100 DEG C, the bending strength is 9.3 MPa, which is increased by 272% compared with the normal temperature.

[0058] Comparative Example 3

[0059] The difference between the present comparative example and Example 1 is that the ceramic plate is not preheated, and the pressure applied is 0N, 2N, 4N, 6N, and 8N, respectively.

[0060] As shown in Figure 4 , (a) is a photo of the front of the ceramic weld seam when the pressure is 0N; (f) is a photo of the back of the ceramic weld seam when the pressure is 0N; (b) is a photo of the front of the ceramic weld seam when the pressure is 2N; (g) is a photo of the back of the ceramic weld seam when the pressure is 2N; (c) is a photo of the front of the ceramic weld seam when the pressure is 4N; (h) is a photo of the back of the ceramic weld seam when the pressure is 4N; (d) is a photo of the front of the ceramic weld seam when the pressure is 6N; (k) is a photo of the back of the ceramic weld seam when the pressure is 6N; (e) is a photo of the front of the ceramic weld seam when the pressure is 8N; and (l) is a photo of the back of the ceramic weld seam when the pressure is 8N. With the application of clamping force, the weld seam cracks transition from the center of the weld seam to the base material, and the length of the cracks on the base material gradually increases. Between 2N and 4N, no cracks appear in the center of the weld seam, and there are relatively few cracks on the base material.

[0061] Comparative Example 4

[0062] The difference between the present comparative example and Example 1 is that the ceramic plate is not preheated, and no pressure is applied to the ceramic plate. As shown in Figure 5 , when no pressure is applied, fusion cracking appears in the center of the weld seam.

[0063] Comparative Example 5

[0064] The difference between the present comparative example and Example 1 is that the ceramic plate is not preheated, and the pressure applied to the ceramic plate is 4N.

[0065] As shown in Figure 6 , when the pre-pressure is 4N, the un-fusion cracking that appears in the center of the weld seam disappears, and there are cracks in the ceramic base material on the lower side of the weld seam.

[0066] Example 2

[0067] The difference between the present example and Example 1 is that a defocus amount of +20 mm is used, and a pre-pressure of 2-4N and a preheating temperature of 200°C are applied.

[0068] As shown in Figure 7 , the weld seam cracks are reduced, and no cracks appear on the base material, but the penetration depth becomes shallower.

[0069] The combination of pre-pressure and preheating in the present application enables laser welding of ceramics. Without moving the ceramic welding piece, local preheating and pre-pressure can be applied to promote molten pool flow, reduce the temperature gradient during laser welding of ceramics, and complete the laser welding of ceramics. This effectively solves the technical problems of previous ceramic preheating, such as the need to repeatedly disassemble the welding piece, the difficulty of clamping the high-temperature welding piece, the difficulty of connecting the welded joint, the time-consuming and labor-intensive process, thereby simplifying the process flow, greatly improving the quality of ceramic welding, production efficiency, and the scope of application of the laser welding process.

[0070] As shown in Figure 8 , the present application provides a pre-heat auxiliary laser welding ceramic material equipment, comprising pre-welding preheating device 1, pre-welding pressure device 3, welding fixture 2, preheating laser processor 4, welding laser processor 5, controller 6, motion controller 7, temperature controller 8. Pre-welding preheating device 1 and temperature controller 8 cooperate for preheating ceramic plate to the required temperature, then using another welding laser for welding, reducing the temperature gradient generated during welding, reducing the generation of cracks; pre-welding pressure device 3 before welding, perpendicular to the welding direction, the surface force is applied to ensure that the gap between the welding parts is small enough and can maintain 0-50N pressure, promote the flow of molten pool and the stability of the welding process; welding fixture 2 is used for clamping ceramic plate and fixing pre-welding pressure device; preheating laser processor 4 and welding laser processor 5 are used for providing energy for preheating and welding; controller 6 and motion controller 7 are connected for controlling the speed and direction of welding. Figure 7 Preheating laser processor 4, welding laser processor 5, controller 6, motion controller 7, temperature controller 8 are installed in the control panel, and are integrally installed in the pre-welding preheating device 1.

[0071] When laser welding is carried out, as shown in Figure 9 , the preheating laser beam 21 is in front and the welding laser beam 22 is in back, first by the preheating laser beam 21 to preheat the ceramic plate, after reaching the required temperature, a certain preheating area 23 is formed on the ceramic plate, at the same time the pre-welding pressure device applies the required pre-pressure perpendicular to the welding direction, the specific direction is shown by the arrow in the figure, at this time the preheating and pressure before welding are completed, then the welding laser beam 22 and the preheating laser beam 21 together are welded under the control of the controller.

[0072] As shown in Figure 10 , the pre-welding preheating device 1 comprises a welding laser head 13, a preheating laser head 11 and a temperature monitoring device 9. The welding laser head 13 is connected with the welding laser processor 5, and the preheating laser head 11 is connected with the preheating laser processor 4; the preheating laser head 11 is installed on the second flange 12, the second flange 12 is installed on the welding laser head 13, the welding laser head 13 is installed on the controller 6, the preheating laser head 11 emits laser to scan on the ceramic welding part 18, the ceramic material interacts with the preheating laser beam to make it warm up, the temperature monitoring device 9 is installed on the first flange 10, the first flange 10 is installed on the preheating laser head 11, and whether the preheating reaches the required temperature is monitored, if not, the output parameters of the preheating laser processor 4 are changed by the temperature controller 8, the preheating temperature is adjusted, and the welding speed, defocusing amount and welding position of the welding laser head are controlled by the motion controller 7.

[0073] As shown in Figures 11-12As shown, the vertical clamping member uses a vertical pressing screw 17, and the horizontal clamping member uses a horizontal pressing screw 20. The welding fixture 2 comprises a base 14, a vertical pressing screw 17, a first stopper 16, a second stopper 19, and a pressure sensor 15. The bottom surface of the base 14, in combination with the first stopper 16 and the second stopper 19, limits the 5 degrees of freedom of the ceramic plate 18, and the movement freedom in the welding direction is not limited.

[0074] The horizontal pressing screw 20 rotates clockwise to press the ceramic plate 18, and the pressure sensor 15 is fixed on the base 14, which ensures the positioning and clamping of the ceramic plate during welding.

[0075] In the design of the welding fixture 2, the movement freedom in the welding direction is not limited, because in machining, the volume and weight of the workpiece will decrease after machining compared to before machining, and in welding, the volume and weight of the workpiece will increase after machining compared to before machining. Therefore, in the design of the welding fixture, one degree of freedom can be allowed to be unrestricted, which is intended to facilitate the installation and removal of the welding parts.

[0076] The pre-welding pressing device 3 comprises a screw 20, a first stopper 16, a second stopper 19, a pressure sensor 15, and a pressure value display device 24. By rotating the clamping screw 20 clockwise, the second stopper 19 is fed 0-10mm, and a dead point is formed between the threads, so that the clamping screw 20 cannot be rotated counterclockwise by moving the second stopper 19. Rotating the screw clockwise applies a surface force of 0-50N to the ceramic plate 18, which is transmitted to the pressure sensor 15 through the first stopper 16, and the pressure sensor 15 outputs the pressure number, which is connected to the pressure value display device 24 to read the pre-pressure value. The welding fixture is provided with a groove on the bottom side, and the pressure sensor 15 can be fixed on the welding fixture, and can clamp two ceramic plates with a size of 40x40x1mm to 50x40x5mm for butt welding.

[0077] The application discloses a method and equipment for preheating and assisting laser welding of ceramic materials, which comprises a preheating device, a pre-pressure device and a welding fixture, wherein the preheating laser beam is used for preheating the ceramic plate, and then another welding laser beam is used for irradiating the workpiece surface to complete the ceramic welding, so that the temperature gradient generated in the welding process is reduced; the pre-pressure device is used for applying pre-pressure perpendicular to the welding direction before welding, and is provided with a screw pressing device, a pressure sensor and a display device to control the size of the pre-pressure; and the welding fixture is used for clamping and positioning the ceramic welding piece and fixing the pre-pressure device. The equipment can realize that the ceramic welding piece locally and rapidly reaches the preheating condition, and does not affect the clamp and the sensor in the pre-pressure device. The pre-pressure device is used to ensure that the welding piece is closely attached and has a certain pre-pressure during the welding process, promote the flow of the molten pool, make the welding process more stable, reduce the thermal stress generated in the welding process and reduce the generation of welding cracks. The specific implementation steps of the method are as follows: 1. The ceramic plate is polished smooth around, the color around is the same as that of the base material, there is no cutting trace and micro crack, the whole plate is cleaned with alcohol, and the ceramic plate is ensured to be clean and dry; 2. The ceramic plate is clamped by using the welding fixture, and the pre-pressure device applies a certain pre-pressure to the ceramic plate; 3. The preheating laser beam in the preheating device scans the ceramic plate to reach the softening temperature of the ceramic material, forms a certain preheating area, and then the welding laser beam is welded under the driving of the controller, and the preheating and assisting is used to complete the ceramic welding.

Claims

1. A method for prefabricating thermo-assisted laser welding ceramic materials, characterized in that... Includes the following steps: S1. Clamp and splice the ceramic materials to be welded together to position the ceramic materials and apply a pre-pressure of 2N-4N to the ceramic materials; S2. Preheat the ceramic material to a temperature of 200℃≤T<250℃. S3. After the ceramic material is preheated, laser welding is performed on the parts of the ceramic material to be welded. The ceramic material is an alumina ceramic plate; S2 uses a preheating laser head for preheating; The laser process parameters for S2 and S3 are as follows: welding laser power 400-500W, minimum spot diameter 0.2-0.5mm, welding speed 15-40mm / s, defocusing amount +2~+4mm, laser beam angle with workpiece surface 0°, nozzle distance with workpiece 0.5-2mm, angle 30-60°, auxiliary gas pressure 10-20bar, and welding length 30-50mm.

2. The method for prefabricated thermo-assisted laser welding of ceramic materials according to claim 1, characterized in that, In S1, the welding fixture simultaneously applies pressure to the ceramic material, with the pressure direction perpendicular to both the ceramic material and the welding direction.

3. The method for prefabricated thermo-assisted laser welding of ceramic materials according to claim 1, characterized in that, The equipment used for preheating-assisted laser welding includes a preheating laser head (11), a welding laser head (13), and a welding fixture (2). The preheating laser head (11) and the welding laser head (13) are arranged side by side, and the welding fixture (2) is located directly below the preheating laser head (11) and the welding laser head (13). The welding fixture (2) is a pressure welding fixture.

4. The method for prefabricated thermo-assisted laser welding of ceramic materials according to claim 3, characterized in that, The welding fixture (2) includes a base (14) and two supports (25) mounted on the base (14) and installed opposite to each other. The upper end of the support (25) is provided with a vertical clamping member. A pressure sensor (15) is installed on the inner surface of the support (25). A first stop (16) is installed on the inner surface of the pressure sensor (15). The workpiece to be welded is clamped between the two first stops (16). Horizontal clamping members are installed at both ends of the support (25).

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