A large-size complex curved surface part multi-point laser shock forming device and method

Abstract

The present application relates to a large size complex curved surface part multi-point laser impact forming device and method, belongs to the plastic processing technical field. To solve the problem that the existing method is low in efficiency, it is difficult to accurately form complex components, and it is impossible to form components with positive and negative curvature, the device mainly includes a control system, a laser, a plurality of mechanical arms, a gantry, a chuck, a CCD camera, a plurality of laser heads, an optical cable, a signal transmission line, a laser control line and a ranging laser, and the main steps are: 1, laser parameter and deformation relationship determination, 2, model processing, 3, path planning, 4, blank preparation, 5, impact forming, 6, iteration optimization, 7, taking and post-processing. The present application can realize accurate, flexible and effective control of multi-laser forming parameters, and can efficiently and accurately manufacture large size complex curved surface parts by using a small number of lasers.

Description

TECHNICAL FIELD

[0001] The application relates to a large-size complex curved surface part multi-point laser impact forming device and method, and belongs to the technical field of plastic processing. BACKGROUND

[0002] At present, the main forming methods of titanium alloy complex curved surface parts are cold stamping forming, hot forming and superplastic forming. The precise forming of the sheet is realized through the cooperation of punch movement or other loads and the die, but it has the problems of high die cost and long production cycle. The additive manufacturing technology which has developed rapidly in recent years can realize moldless rapid manufacturing, but it is difficult to be applied to thin-walled and weak rigid complex curved surface parts. The shot forming technology can realize moldless manufacturing of large thin-walled curved surface components, but its forming capacity is limited, and only components with large curvature radius can be formed, and many craters are formed on the surface of the components during the forming process, which affects the surface quality of the components.

[0003] In recent years, a laser shot forming method, also known as laser impact forming, has been extended from mechanical shot peening technology. Laser impact forming is a new forming technology which uses the force effect of laser-induced high-amplitude shock wave to make the sheet produce plastic deformation, and has the characteristics of high processing flexibility, accurate control, little or no springback, good performance of the formed parts and no pollution, etc. It is a new moldless and flexible forming technology, and the surface of the sheet after impact forming forms very deep high-amplitude residual compressive stress, which can significantly improve the fatigue life. Patent ZL01134063.0 proposes a laser impact precision forming method and device, which directly uses a strong pulsed laser beam to impact the surface of a workpiece to generate an impact wave pressure exceeding the yield strength of the sheet, and then makes the sheet produce plastic deformation. Due to the small deformation amount generated by single impact, the efficiency is low when facing large-size part forming, and the in-plane stress transmission to the surrounding area may cause the sheet to warp in other areas when single-point impact forming in a certain area, which increases the difficulty of re-impact and makes it difficult to realize precise forming of complex components. For parts with positive and negative curvatures, single-point laser impact forming makes the sheet bend in a certain direction, and the section bending resistance coefficient increases sharply, so it will be difficult to form the opposite curvature shape in the perpendicular direction. Patent ZL201911300078.4 proposes a multi-point laser impact forming device and forming method, in which multiple pulsed lasers are arranged in a two-dimensional plane, and a workpiece clamping system is used to fix the workpiece and rotate the sheet to accept laser action. Since multiple pulsed lasers are arranged closely, the power of the lasers is limited by space, and they are only suitable for forming sheet with small thickness. Since the lasers are fixed and the sheet is rotated, the deformation of the sheet will inevitably cause the lasers to be unable to be along the normal direction of the deformed sheet, which introduces an uncertain factor, and the actual effective forming parameters of the lasers acting on the sheet cannot be accurately and cooperatively controlled, thereby affecting the forming effect. For large-size parts, a large number of lasers are needed, which is extremely high in cost. SUMMARY

[0004] The present application is to solve the problems of low efficiency, difficulty in precise forming of complex components, inability to form components with positive and negative curvature, and inability to form thick plates, difficulty in coordinated control of effective forming parameters, and high cost of a large number of lasers in the existing laser shock forming method. A large-size complex curved surface part multi-point laser shock forming device and method are provided, which can accurately, flexibly and effectively control the forming parameters of multiple lasers, and efficiently and accurately manufacture large-size complex curved surface parts with fewer lasers. The key technology is the development of a special device.

[0005] According to one aspect of the present application, a large-size complex curved surface part multi-point laser shock forming device is provided, which comprises a controller 2, a laser 3, a mechanical arm 4, a gantry 5, a chuck 6, a CCD camera 7, a laser head 9, an optical cable 10, a signal transmission line 11, a laser control line 12, and a ranging laser 13.

[0006] The controller 2 is connected with the laser 3 through the laser control line 12;

[0007] The controller 2 is connected with the mechanical arm 4 through the signal transmission line 11;

[0008] The controller 2 is connected with the ranging laser 13 through the signal transmission line 11;

[0009] The controller 2 is connected with the CCD camera 7 through a data line;

[0010] The chuck 6 is arranged on the gantry 5;

[0011] The laser head 9 is arranged on the mechanical arm 4;

[0012] The laser 3 is connected with the laser head 9 through the optical cable 10;

[0013] The large-size complex curved surface part multi-point laser shock forming device can clamp a plate blank 8, and through multi-point laser shock, cooperate with the movable mechanical arm, accurately process a large-size complex curved surface part according to the design;

[0014] The length and width of the plate blank 8 are at least 2 meters. The size of the overall device is adjusted according to the size of the plate blank 8.

[0015] The controller 2 has signal acquisition, data processing function and control signal output function;

[0016] The mechanical arm 4 has 6 degrees of freedom, is arranged with n, is placed on the ground through a base, and the laser head 9 is installed at the end of the mechanical arm 4. Three ranging lasers 13 are installed on each laser head 9 in a plane perpendicular to the laser light path, which is used to determine the normal of the outer surface of the processed object.

[0017] wherein n is in the range of 2, 3 or 4;

[0018] The laser 3 is a multi-channel output laser, the laser output parameters of each channel can be independently adjusted, the laser output by the laser 3 is transmitted to the laser head 9 through the optical cable 10, and is output by the laser head 9 to act on the slab; or a laser 3 can be configured for each laser head 9.

[0019] The controller 2 outputs real-time laser parameters of each channel to the laser 3 through the laser control line 12, and the laser 3 outputs laser with corresponding parameters;

[0020] The gantry 5 is composed of a gantry base 5-1, a gantry column 5-2 and a gantry beam 5-3, the gantry column 5-2 is vertically arranged, one end of which is fixedly installed on the gantry base 5-1, the gantry beam 5-3 is horizontally arranged, and the other ends of which are fixedly connected to the two gantry columns 5-2, two clamps 6 are fixedly connected below the gantry beam 5-3, the gantry 5 is placed on the ground through the gantry base 5-1, and the gantry 5 clamps the slab 8 to be laser impact formed through the clamps 6;

[0021] The mechanical arm 4 can be arranged on one side of the gantry 5, or on both sides of the gantry 5.

[0022] The mechanical arm 4 can be a mature mechanical arm product on the market.

[0023] The CCD camera 7 is used to measure the profile of the slab 8 in the laser impact forming process, and is used to compare with a theoretical numerical model to correct the laser impact forming parameters, the image collected by the CCD camera 7 is transmitted to the controller 2 through a data line, the controller 2 receives the pose signal of the mechanical arm 4 and the signal of the distance measuring laser 13 through the signal transmission line 11, and gives the pose control signal of the mechanical arm 4 according to the calculation result.

[0024] According to another aspect of the present application, a multi-point laser impact forming method for large-size complex curved surface parts is provided, which adopts the multi-point laser impact forming device for large-size complex curved surface parts described above.

[0025] The method comprises the following steps:

[0026] Step one, laser parameter and deformation relationship determination: a test piece is prepared from the slab 8 to be formed, an energy absorption layer 15 is pasted or coated on the surface of the test piece, a constraint layer 14 is covered on the energy absorption layer 15, different parameter lasers are used for impact, and then corresponding strains ε are recorded, and the laser parameter and strain relationship is obtained through multiple experiments:

[0027] ε = f (E, d, t, n) (1)

[0028] Wherein, E is the single pulse laser energy, S is the laser spot diameter, t is the slab thickness, n is the number of laser pulses;

[0029] Step two, model processing: add process section to the numerical model of the target part 1-1 to obtain the numerical model of the target part 1-2 with process section, select a face as the front face, calculate the strain required at each place when the flat slab 8 is deformed into the target part 1-2 with process section, assume that one direction in the target part 1-2 with process section is the x direction and the direction perpendicular to it is the y direction, and the strain required at each place in the x and y directions is ε x and ε y :

[0030] ε x = 0.5t / (p x - 0.5t)(2)

[0031] ε y = 0.5t / (p y - 0.5t)(3)

[0032] Wherein, p x and p y are the radii of curvature in the x and y directions, respectively, and take positive values when convex and negative values when concave;

[0033] Step three, path planning: expand the target part 1-2 with process section into a plane, correspond the strain required at each place of the target part 1-2 with process section calculated in step two to the expanded plane, divide the regions according to the positive and negative of the required strain, i.e. positive strain region, negative strain region and zero strain region, wherein the zero strain region refers to the region where the required strain value is not greater than 0.0001, determine the step length L according to the spot diameter and the overlap rate, then determine the impact points along the x and y directions with the step length L as the interval with a certain point on the expanded plane as the origin, do not set impact forming points in the zero strain region, the path direction during impact forming is from the zero strain region to the region far away from the zero strain region along the x or y direction, determine the paths according to the overlap rate, the laser beam should act on the front face during impact forming in the positive strain region, and the laser beam should act on the back face during impact forming in the negative strain region, determine the laser parameters according to the required strain at each place calculated in step two and the relationship between the laser parameters and the strain determined in step one;

[0034] Step four, blank preparation: determine the blank size according to the expanded plane in step three and cut the blank, paste or coat the energy-absorbing layer 15 on both sides of the slab 8, cover the constraint layer 14 on the energy-absorbing layer 15, and fix the prepared slab 8 to the gantry 5 through the chuck 6;

[0035] Step five, impact forming: several laser heads 9 are placed on one side or both sides of the slab 8 by the mechanical arm 4, and impact forming is carried out along the path calculated in step three, the laser parameters at different positions are determined in step three, and the controller 2 controls the laser 3 to output, the laser beam needs to be always along the normal direction of the slab 8 during laser impact forming, the negative strain area and the adjacent positive strain area need to be impact formed at the same time, the same positive strain area or negative strain area can be impact formed by multiple laser heads 9 at the same time, and the energy of single-point impact forming can be improved by using multiple laser heads 9 to act on a point at the same time;

[0036] The negative strain area and the adjacent positive strain area need to be impact formed at the same time because the negative strain area and the positive strain area are concave-convex in opposite directions, such as a saddle surface, and simultaneous impact forming can avoid the problem that the cross-sectional bending coefficient increases sharply after bending in a certain direction and it is difficult to form a shape with opposite curvature in the perpendicular direction;

[0037] Step six, iterative optimization: after one pass of impact forming according to the planned path, the formed slab 8-1 is photographed by the CCD camera 7, the measured surface model is calculated by the controller 2, the compensation strain Δε x and Δε y of the formed slab 8-1 at each position are calculated according to formulas (4) and (5), the difference is used to determine the parameters during laser impact forming, and the impact forming is performed again until the normal distance between the measured surface model of the formed slab 8-1 measured by the CCD camera 7 and the target part model 1-1 is less than the allowable value;

[0038] Δε x = 0.5t / (p x -0.5t)-0.5t / (p' x -0.5t) (4)

[0039] Δε y = 0.5t / (p y -0.5t)-0.5t / (p' y -0.5t) (5)

[0040] Wherein, p' x and p' y are the curvature radii of the measured surface model in the x and y directions, respectively, and take positive values when convex and negative values when concave;

[0041] Step seven, taking out and post-processing: the formed slab 8-1 is taken out from the gantry 5, the constraint layer 14 and the energy absorption layer 15 on the surface are removed, and the process section is cut to obtain the target part 1-1.

[0042] The laser pulse width of each channel of the laser 3 is 1ns-120ns, the energy is 0.1-50J, the spot diameter is 1-10mm, and the frequency is 0.5-5Hz.

[0043] The energy absorption layer 15 is selected from at least one of carbon black paint, black paint, aluminum foil or black tape.

[0044] The constraint layer 14 is selected from at least one of K9 glass and / or water film.

[0045] In step five, the laser beam needs to be always along the normal direction of the plate blank 8 during laser shock forming, which is achieved by three ranging lasers 13 installed on the laser head 9. The distance measured by the ranging lasers 13 is fed back to the controller 2, and the controller 2 adjusts the pose of the mechanical arm 4 to make the distance measured by the three ranging lasers 13 the same, so as to determine whether the laser beam is along the normal direction of the plate blank 8.

[0046] The material of the plate blank 8 is selected from at least one of titanium alloy, high-temperature alloy, aluminum alloy and intermetallic compound.

[0047] In step five, multiple laser heads 9 can work simultaneously in the same positive strain zone or negative strain zone. In this way, the problem of plate blank 8 warping caused by the imbalance of stress field due to the transmission of in-plane stress to the surrounding when the ratio of the maximum length to the wall thickness in the weak rigidity area is greater than 100 during single-point impact forming of the plate blank 8 can be prevented, and the forming efficiency can be improved.

[0048] In step five, multiple laser heads 9 can act on a point at the same time to improve the single-point impact forming energy, so as to solve the problem that some difficult-to-deform materials cannot be formed due to insufficient energy of a single laser head.

[0049] The beneficial effects of the present application are:

[0050] I. Compared with the moving parts, the present application adopts multiple laser heads installed on the execution end of the mechanical arm, which can have higher flexibility and can ensure that each laser head works at the same time and is perpendicular to the to-be-formed area.

[0051] II. The beams output by each laser head of the present application are always along the normal direction of the plate blank, which can make the output laser energy effectively act on the plate blank according to the set value, thereby reducing the forming error.

[0052] III. The present application simultaneously performs impact forming on adjacent concave and convex areas, which can avoid the problem that the cross-section bending coefficient increases sharply in a certain direction after bending, and it is difficult to form an opposite curvature shape in the perpendicular direction.

[0053] IV. The present application adopts multiple laser heads acting on a point at the same time to improve the single-point impact forming energy, so as to solve the problem that some difficult-to-deform materials cannot be formed due to insufficient energy of a single laser head.

[0054] Five, the present application adopts multiple laser heads to impact form in the inner concave and outer convex area at the same time, which can prevent the in-plane stress from transmitting to the surrounding when the rigid blank is single-point impact formed, and the stress field imbalance causes macroscopic deformation, which causes the warping problem of the blank 8.

[0055] Six, the present application adopts multiple laser heads to form at the same time, which greatly improves the forming efficiency and can be applied to the rapid trial production of aircraft and other equipment skin parts. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 is the axonometric view of the target part;

[0057] Figure 2 is the axonometric view of the target part with process section;

[0058] Figure 3 is the schematic diagram of the large-size complex curved surface part before forming by the multi-point laser impact forming device;

[0059] Figure 4 is the schematic diagram of the large-size complex curved surface part after forming by the multi-point laser impact forming device;

[0060] Figure 5 is the schematic diagram of the laser head;

[0061] Figure 6 is the schematic diagram of the gantry in the multi-point laser impact forming device for large-size complex curved surface parts;

[0062] Figure 7 is the schematic diagram of the blank with constraint layer and energy absorption layer;

[0063] Figure 8 is the required strain distribution diagram in the x direction when the flat plate-shaped blank in embodiment 1 is deformed into the target part with process section;

[0064] Figure 9 is the required strain distribution diagram in the y direction when the flat plate-shaped blank in embodiment 1 is deformed into the target part with process section.

[0065] Wherein, 1-1 target part, 1-2 target part with process section, 2 controller, 3 laser, 4 mechanical arm, 5 gantry, 5-1 gantry base, 5-2 gantry column, 5-3 gantry beam, 6 chuck, 7 CCD camera, 8 blank, 8-1 formed blank, 9 laser head, 10 optical cable, 11 signal transmission line, 12 laser control line, 13 distance measuring laser, 14 constraint layer, 15 energy absorption layer. DETAILED DESCRIPTION

[0066] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0067] Embodiment 1

[0068] The target part is as shown in Figure 1 The material of the part is TC4, and the thickness is 1.5 mm.

[0069] Step one, laser parameter and deformation relationship determination: a 2000 mm x 2000 mm test piece is prepared from a t = 1.5 mm thick TC4 plate, about 0.2 mm thick black tape is pasted on the surface of the test piece, 0.1 mm thick K9 glass is covered on the black tape, the test piece is impacted by laser with different single pulse laser energy E, laser spot diameter S, and laser pulse number n, and then the corresponding strain ε is recorded. Through multiple experiments, the laser parameter and strain relationship ε = f (E, d, t, n) is obtained;

[0070] Step two, model processing: as shown in Figure 1 The target part 1-1 numerical model is extended by 200 mm at one end of a near straight edge, and a plane is constructed along the x direction starting from the extended edge. A transition circular arc with a radius of 100 mm is added between the constructed plane and the extended surface, thereby obtaining the numerical model of the target part 1-2 with process section. The surface protruding in the z direction is selected as the front surface, and the strain distribution required at each position when the flat plate blank 8 is deformed into the target part 1-2 with process section is calculated according to formulas 2 and 3;

[0071] Step three, path planning: the target part 1-2 with process section is unfolded into a plane, and the required strain of the target part 1-2 with process section at each position calculated in step two is corresponded to the unfolded plane, as shown in Figure 8 and Figure 9 According to the required strain calculated in step two, the regions are divided into positive strain region, negative strain region and zero strain region, which refers to the region where the required strain value is not greater than 0.0001. The spot diameter is selected to be 5 mm, and the overlap rate is 50%. Then, the step length L is 2.5 mm. A certain point on the unfolded plane is taken as the origin, and the impact points are determined along the x and y directions at intervals of 2.5 mm. The zero strain region is not set to have impact forming points. During impact forming, the path direction is along the x or y direction starting from the zero strain region to away from the zero strain region, and the overlap rate between each path is also 50%. The laser beam should act on the front surface during impact forming in the positive strain region, and the laser beam should act on the back surface during impact forming in the negative strain region. The laser parameters and impact times at different points are determined according to the required strain at each position calculated in step two and the laser parameter and strain relationship determined in step one;

[0072] Step four, blank preparation: the blank size is determined according to the unfolded plane in step three, and the blank is cut. About 0.2 mm thick black tape is pasted on both sides of the blank, and 0.1 mm thick K9 glass is covered on the black tape. The prepared blank is fixed and installed on the gantry through the chuck 6;

[0073] Step five, impact forming: several laser heads loaded by mechanical arms are placed on both sides of the slab, and impact forming is carried out along the path calculated in step three, the laser parameters at different positions are determined in step three, and the controller controls the laser output, the laser beam needs to be always along the normal direction of the slab during laser impact forming, the negative strain area and the adjacent positive strain area need to be impact formed at the same time, the same positive strain area or negative strain area can be impact formed by multiple laser heads at the same time;

[0074] Step six, iterative optimization: after completing impact forming according to the planned path, the formed slab is photographed by a CCD camera, the measured surface model is calculated by the controller, the error between the measured surface model and the target part model is analyzed, the compensation strain Δε x and Δε y is calculated according to formula 4 and formula 5, and the laser parameters and impact times at different points are determined according to the compensation strain combined with the laser parameters and strain relationship determined in step one, and the iteration is performed for several times until the normal distance between the measured surface model of the slab and the target part model is less than the allowable value.

[0075] Step seven, taking out and post-processing: the formed slab is taken out from the gantry, the black tape and K9 glass on the surface are removed, and the process section is cut to obtain the target part.

[0076] In the description of the present application, it should be understood that the orientations and positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations and positional relationships shown in the drawings, and are only for the convenience of describing the present application or simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0077] The present application has been disclosed with the preferred embodiments as above, however, it is not intended to limit the present application, any skilled person in the art can make some changes or modifications to the above disclosed structure and technical content without departing from the scope of the technical solution of the present application, and equivalent implementation cases with equivalent changes are obtained, but any simple modification, equivalent change and modification made to the above implementation cases according to the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method for multi-point laser shock forming of large-sized complex curved surface parts, characterized in that, a multi-point laser shock forming device for large-sized complex curved surface parts is used, which is composed of a controller (2), a laser (3), a mechanical arm (4), a gantry (5), a chuck (6), a CCD camera (7), a laser head (9), an optical cable (10), a signal transmission line (11), a laser control line (12), and a ranging laser (13); the controller (2) is connected with the laser (3) through the laser control line (12); the controller (2) is connected with the mechanical arm (4) through the signal transmission line (11); the controller (2) is connected with the ranging laser (13) through the signal transmission line (11); the controller (2) is connected with the CCD camera (7) through a data line; the chuck (6) is arranged on the gantry (5); the laser head (9) is arranged on the mechanical arm (4); the laser (3) is connected with the laser head (9) through the optical cable (10); the multi-point laser shock forming device for large-sized complex curved surface parts can hold a blank (8), and through multi-point laser shock, combined with the movable mechanical arm, a large-sized complex curved surface part can be accurately processed according to the design; the length and width of the blank (8) are at least 2 meters; the method comprises the following steps: Step 1, determination of laser parameters and deformation relationship; Step 2, model processing; A process section is added to the numerical model of the target part (1-1) to obtain a numerical model of the target part (1-2) with a process section. A surface is selected as the front surface, and the strain required at each location when the flat plate blank (8) is deformed into the target part (1-2) with a process section is calculated. Assuming that one direction in the surface of the target part (1-2) with a process section is the x direction and the direction perpendicular to it is the y direction, the strain required at each location in the x direction and the y direction is ε x and ε y : ε x = 0.5t / (p x -0.5t) (2) ε y = 0.5t / (p y -0.5t) (3) wherein p x and p y are the radii of curvature in the x and y directions, respectively, taking positive values for convexity and negative values for concavity; Step 3, path planning; Step 4, blank preparation; Step 6, iterative optimization; After one-time impact forming according to the planned path, the formed blank (8-1) is photographed by the CCD camera (7), the measured profile model is calculated by the controller (2), the compensation strain ΔE of the formed blank (8-1) at each position is calculated according to formula (4) and formula (5) x and ΔE y , the parameters during laser impact forming are determined according to the difference, and the impact forming is performed again until the normal distance between the measured profile model of the formed blank (8-1) measured by the CCD camera (7) and the target part model (1-1) is less than the allowable value. Δε x = 0.5t / (p x -0.5t) - 0.5t / (p' x -0.5t) (4) Δε y = 0.5t / (p y -0.5t) - 0.5t / (p' y -0.5t) (5) wherein p'xand p'yare the measured profile model curvature radii in the x and y directions, respectively, taking positive values for convexity and negative values for concavity. x and p'xand p'yare the measured profile model curvature radii in the x and y directions, respectively, taking positive values for convexity and negative values for concavity. y wherein p'xand p'yare the measured profile model curvature radii in the x and y Step 7, taking out and post-processing. 2.The method for multi-point laser shock forming of large-sized complex curved surface parts according to claim 1, characterized in that, the controller (2) has signal acquisition, data processing, and control signal output functions. 3.The method for multi-point laser shock forming of large-sized complex curved surface parts according to claim 1, characterized in that, the mechanical arm (4) has 6 degrees of freedom, and n mechanical arms are arranged and placed on the ground through a base; wherein, n is 2, 3, or 4. 4.The method for multi-point laser shock forming of large-sized complex curved surface parts according to claim 1, characterized in that, the laser head (9) is installed at the end of the mechanical arm (4). 5.The method for multi-point laser shock forming of large-sized complex curved surface parts according to claim 1, characterized in that, 3 ranging lasers (13) are installed on each laser head (9) in a plane perpendicular to the laser light path, for determining the normal of the outer surface of the processed object. 6.The method for multi-point laser shock forming of large-sized complex curved surface parts according to claim 1, characterized in that, the laser (3) is a multi-channel output laser, and the laser output parameters of each channel can be independently adjusted. 7.The method for multi-point laser shock forming of large-sized complex curved surface parts according to claim 1, characterized in that, each laser head (9) is separately configured with a laser (3). 8.The method for multi-point laser shock forming of large-sized complex curved surface parts according to claim 1, characterized in that, the laser output by the laser (3) is transmitted to the laser head (9) through the optical cable (10), and then output by the laser head (9) to act on the blank.

9. The method of claim 1, wherein the gantry (5) is composed of a gantry base (5-1), a gantry column (5-2) and a gantry beam (5-3).

10. The method of claim 1, wherein the gantry (5) is composed of a gantry base (5-1), a gantry column (5-2) and a gantry beam (5-3).

11. The method of claim 10, wherein the gantry column (5-2) is vertically arranged, one end of which is fixedly installed on the gantry base (5-1), and the gantry beam (5-3) is horizontally arranged, two ends of which are fixedly connected to the other ends of the two gantry columns (5-2).

12. The method of claim 10, wherein two chucks (6) are fixedly connected below the gantry beam (5-3).

13. The method of claim 12, wherein the gantry (5) holds the plate blank (8) to be laser shock formed by the chucks (6).

14. The method of claim 10, wherein the gantry (5) is placed on the ground by the gantry base (5-1).

15. The method of claim 1, wherein the mechanical arm (4) can be arranged on one side of the gantry (5) or on both sides of the gantry (5).

16. The method of claim 1, wherein the CCD camera (7) is used to measure the profile of the plate blank (8) during the laser shock forming process, and the measured profile is compared with the theoretical numerical model to correct the laser shock forming parameters, and the image collected by the CCD camera (7) is transmitted to the controller (2) through a data line.

17. The method of claim 16, wherein the controller (2) receives the pose signal of the mechanical arm (4) and the signal of the distance measuring laser (13) through the signal transmission line (11), and gives the pose control signal of the mechanical arm (4) according to the calculation result.

18. The method of claim 1, wherein step one is to determine the relationship between laser parameters and deformation: a test piece is prepared from the plate blank (8) to be formed, an energy absorption layer (15) is pasted or coated on the surface of the test piece, a constraint layer (14) is covered on the energy absorption layer (15), different parameter lasers are used for laser shock, and then the corresponding strain ε is recorded, and the relationship between laser parameters and strain is obtained through multiple experiments: ε = f (E, d, t, n) (1) wherein E is the single pulse laser energy, S is the laser spot diameter, t is the plate blank thickness, and n is the laser pulse number. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 19. The multi-point laser shock forming method for large-sized complex curved surface parts according to claim 18, characterized in that, Step three, path planning: the target part (1-2) with process section is unfolded into a plane, the required strain at each position of the target part (1-2) with process section calculated in step two is corresponded to the unfolded plane, the regions are divided according to the positive and negative required strain, i.e. positive strain region, negative strain region and zero strain region, wherein the zero strain region refers to the region with required strain value not greater than 0.0001, the step length L is determined according to the spot diameter and the overlap rate, then the point positions for shock forming are determined along the x and y directions with the unfolded plane as the origin and with the step length L as the interval, no shock forming point position is set in the zero strain region, the path direction during shock forming is from the zero strain region to the region far away from the zero strain region along the x or y direction, each path is determined according to the overlap rate, the laser beam should act on the front surface during shock forming in the positive strain region, the laser beam should act on the back surface during shock forming in the negative strain region, and the laser parameters are determined according to the required strain at each position calculated in step two and the relationship between the laser parameters and the strain determined in step one.

20. The multi-point laser shock forming method for large-sized complex curved surface parts according to claim 19, characterized in that, Step four, blank preparation: the blank size is determined according to the unfolded plane in step three and the blank is cut, the energy absorption layer (15) is pasted or coated on both sides of the plate blank (8), the constraint layer (14) is covered on the energy absorption layer (15), and the prepared plate blank (8) is fixed and installed on the gantry (5) through the chuck (6).

21. The multi-point laser shock forming method for large-sized complex curved surface parts according to claim 20, characterized in that, Step five, shock forming: a plurality of laser heads (9) loaded by the mechanical arm (4) are placed on one side or both sides of the plate blank (8), and shock forming is performed along the paths calculated in step three, the laser parameters at different positions are determined in step three, and the laser parameters are output by the controller (2) to control the laser (3), the laser beam needs to always be along the normal direction of the plate blank (8) during laser shock forming, the negative strain region and the adjacent positive strain region need to be simultaneously shock formed, the same positive strain region or negative strain region can be simultaneously shock formed by multiple laser heads (9), and the mode of multiple laser heads (9) acting on a point can be used to improve the single-point shock forming energy; The negative strain region and the adjacent positive strain region need to be simultaneously shock formed because the concave-convex directions of the negative strain region and the positive strain region are opposite, and simultaneous shock forming can avoid the problem that the cross-sectional bending resistance coefficient increases sharply after bending in a certain direction, making it difficult to form the opposite curvature shape in the perpendicular direction.

22. The multi-point laser shock forming method for large-sized complex curved surface parts according to claim 21, characterized in that, Step seven, taking out and post-processing: the formed plate blank (8-1) is taken out from the gantry (5), the constraint layer (14) and the energy absorption layer (15) on the surface are removed, and the target part (1-1) is obtained by cutting off the process section.

23. The multi-point laser shock forming method for large-sized complex curved surface parts according to claim 19, characterized in that, The laser (3) each channel output laser pulse width 1ns~120ns, energy 0.1~50J, spot diameter 1~10mm, frequency is 0.5~5Hz.

24. The method of claim 18, wherein the method is a multi-point laser shock forming method for a large-size complex curved surface part. The energy-absorbing layer (15) is selected from at least one of carbon black paint, black paint, aluminum foil or black tape.

25. The method of claim 18, wherein the method is a multi-point laser shock forming method for a large-size complex curved surface part. The constraint layer (14) is selected from at least one of K9 glass and / or water film.

26. The method of claim 21, wherein the method is a multi-point laser shock forming method for a large-size complex curved surface part. In step five, the laser beam needs to be always along the normal direction of the plate blank (8) during laser shock forming, which is achieved by three ranging lasers (13) installed on the laser head (9). The distance measured by the ranging lasers (13) is fed back to the controller (2), and the controller (2) adjusts the pose of the mechanical arm (4) to make the distance measured by the three ranging lasers (13) the same to determine whether the laser beam is along the normal direction of the plate blank (8).

27. The method of claim 18, wherein the method is a multi-point laser shock forming method for a large-size complex curved surface part. The material of the plate blank (8) is selected from at least one of titanium alloy, high-temperature alloy, aluminum alloy and intermetallic compound.

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