A Method for Integral Forming of Ribbed Conical Curved Surface Components by Laser Shot Peening

Abstract

The present invention provides a laser shot peening integral forming method for a ribbed conical surface component, which realizes the integral forming of the ribbed conical surface component by laser shot peening the component, and has the advantages of good flexibility, no contact, high impact pressure, and integration of plastic forming and forming. By setting the overlap rate of the laser spot on different arcs and the laser energy on each arc, the spot scanning path of the laser shot peening is planned and programmed, so that the overlap rate of the spot on the same arc is constant, and the overlap rate on different arcs changes according to a gradient, and at the same time, the laser energy is controlled to change the residual stress distribution of the component, so as to cause the component to produce bending deformation with different arc curvatures, and realize the integral forming of the ribbed conical surface component.

Description

Technical Field

[0001] The present invention belongs to the technical field of plastic forming manufacturing, and particularly relates to a method for integral forming of ribbed conical surface components by laser peening. Background Art

[0002] The forming of ribbed conical surface components is a key core technology in the field of forming manufacturing. At present, the traditional manufacturing processes mainly include casting, mechanical milling, and extrusion forming, etc. However, the above processes have problems such as non-dense casting structures of the formed components, residual stress imbalance caused by mechanical milling, and extrusion shrinkage holes. In addition, for single-piece and small-batch production of ribbed conical surface components, the need to design and manufacture corresponding molds for different-shaped extrusion parts, and the long design and manufacturing cycle and high cost of extrusion molds also seriously limit their engineering applications. Summary of the Invention

[0003] The present invention provides a method for integral forming of ribbed conical surface components by laser peening. By controlling the overlapping mode of laser spots and the input of laser energy, the distribution of the residual stress field in the component is changed to generate different degrees of bending deformation, realizing the integration of the laser peening forming and strengthening processes of ribbed conical surface components.

[0004] The present invention provides a method for integral forming of ribbed conical surface components by laser peening. The specific steps include:

[0005] Step S1: According to the thickness of the component and the bending angle of the component during laser impact, set the thickness of the ribbed ring fan or fan-shaped component so that the direction of laser impact is opposite to the direction of component deformation and bending;

[0006] Step S2: Grind, polish, and clean the surface of the above component, and perform a drying pretreatment;

[0007] Step S3: Stick an absorption protection layer on the surface of the pretreated component;

[0008] Step S4: Place the component with the absorption protection layer as a whole on the robotic arm workbench, fix it with a special fixture, and cover it with a constraint layer;

[0009] Step S5: Set the laser peening forming process parameters: including setting the overlapping rate of laser spots and setting the laser energy of the spots,

[0010] Set the overlapping rate of the laser spot. On the ribbed ring fan or fan-shaped component, calculate the laser spot center coordinates in the plane polar coordinate system. Taking the center of the circle corresponding to the arc as the origin and the boundary where one of the arc radii is located as the polar axis, program the calculated laser spot center coordinates so that the spot overlapping mode has a constant circumferential overlapping rate for the same arc and the overlapping rate along its radial direction for different arcs increases in a gradient manner from the larger radius to the smaller radius. That is, when the ribbed conical surface is unfolded into a fan shape, the laser spot overlapping rate η i =(1 - r i / 2r1)×100%, where r i is the radius of the circle where the i-th circle of the arc of the spot scanning path on the fan is located, r1 is the radius of the circle where the outermost circle of the arc of the spot scanning path on the fan is located, and r m is the radius of the circle where the innermost circle of the arc of the spot scanning path on the fan is located, where r1 ≤ r i ≤ r m ;

[0011] Set the laser energy of the spot. In the plane rectangular coordinate system, on the ribbed ring fan or fan-shaped component, taking the center of each circumferential arc as the coordinate origin, the laser energy y follows the "symmetric arc" type change according to the formula y 2 =(l i / 2) 2 - x 2 , where y is the laser energy, l i is the arc length of the i-th circle, and x is the arc length of the spot within the arc of length l i , where 1 ≤ i ≤ m and i is an integer;

[0012] Step S6: Use the process parameters set in Step S5 to perform laser peening integral forming on the ribbed ring fan or fan-shaped component in Step S4: Control the spot scanning path of the robotic arm through the laser integrated system, and control the input of the gradient laser energy and the overlapping rate to change the residual stress distribution of the component, so that the ring fan or fan forms a conical surface workpiece.

[0013] Optionally, in Step S1, the thickness of the ribbed conical surface component is 2 - 5 mm.

[0014] Optionally, the spot scanning path in Step S6 is an overall counterclockwise "S" - shaped arc from the large arc to the small arc.

[0015] Optionally, the material of the component is a lightweight metal or lightweight alloy with strong plasticity and low hardness.

[0016] Optionally, the absorption protection layer is 100 μm black tape.

[0017] Optionally, the constraint layer is a 2 - 5 mm water layer.

[0018] Optionally, the spot diameter is 2 mm, and the gradient laser energy ranges from 1 to 10 J.

[0019] Optionally, the overlapping rate of the laser spots between any two adjacent arcs is 50%.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The present invention proposes a method for integral forming of a ribbed conical surface component by laser peening, which can realize the integration of the laser peening forming and strengthening processes of the ribbed conical surface component, that is, realize the integration of plastic forming and formability of high-performance lightweight components, and the process is simple.

[0022] 2. Starting from the laser energy and the overlapping rate of the laser spots for the distribution of the residual stress field of the conical surface component, by combining and controlling the constant / gradient overlapping mode of the laser spots and the type of gradient laser energy input, different degrees of bending deformation of the component are induced, and the integral forming of the ribbed conical surface component without a mold can be realized, with high efficiency and low cost, and it is suitable for the integral forming of components of various sizes and batches.

[0023] 3. The shock wave induced by the laser has the advantages of good flexibility, large impact pressure, non-contact, etc., and the depth of the induced residual compressive stress and the degree of bending deformation of the component are greater, and the forming effect is better. Description of the Drawings

[0024] Figure 1 It is a diagram showing the relationship between the thickness of the component and the bending angle of the component during laser shock.

[0025] Figure 2 It is a schematic diagram of a ribbed ring-sector component.

[0026] Figure 3 It is a schematic diagram showing the position of the center of the laser spot on the ribbed ring-sector component in the plane polar coordinate system.

[0027] Figure 4 It is a schematic diagram of the trajectory of the center of the laser spot on the ribbed ring-sector component in the plane polar coordinate system. Figure 1 .

[0028] Figure 5 It is a schematic diagram of the trajectory of the center of the laser spot on the ribbed ring-sector component in the plane polar coordinate system. Figure 2 .

[0029] Figure 6 It is a schematic diagram of the laser spot overlap.

[0030] Figure 7 It is a schematic diagram of the circumferential gradient overlapping rate of the laser spots between each gradient arc.

[0031] Figure 8Schematic diagram of "symmetric circular arc" type laser energy output and forming of ribbed conical surface components.

[0032] Figure 9 Stereogram of the ribbed conical surface component after overall forming. Specific implementation manners

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0034] It can be understood that for the convenience of description, only the parts related to the embodiments of the present invention are shown in the drawings of the present invention, and the parts irrelevant to the embodiments of the present invention are not shown in the drawings.

[0035] The embodiment of the present invention provides a method for laser peening overall forming of ribbed conical surface components, and the specific steps include:

[0036] Step S1: According to the thickness of the component and the bending angle of the component during laser shock, set the thickness of the ribbed ring fan or fan-shaped component so that the direction of laser shock is opposite to the direction of component deformation and bending;

[0037] Step S2: Grind, polish and clean the surface of the above component, and perform a drying pretreatment;

[0038] Step S3: Stick an absorption protection layer on the surface of the pretreated component;

[0039] Step S4: Place the component with the absorption protection layer attached as a whole on the robotic arm workbench, fix it with a special fixture, and cover a constraint layer;

[0040] Step S5: Set the laser peening forming process parameters: including setting the overlap rate of laser spots and setting the laser energy of the spots,

[0041] Set the overlap rate of laser spots. On the ribbed ring fan or fan-shaped component, calculate the center coordinates of the laser spot in the plane polar coordinate system. Taking the center of the circle corresponding to the arc as the origin and the boundary where one of the arc radii is located as the polar axis, program the calculated center coordinates of the laser spot so that the spot overlap method has a constant circumferential overlap rate for the same arc and the overlap rate along its radial direction for different arcs increases in a gradient manner from large to small according to the radius. That is, when the ribbed conical surface is unfolded into a fan shape, the overlap rate η of the laser spot on the i-th circle of the arc i =(1 - r i / 2r1)×100%, r i is the radius of the circle where the i-th circle of the arc of the spot scanning path on the fan shape is located, r1 is the radius of the circle where the outermost circle of the arc of the spot scanning path on the fan shape is located, r m is the radius of the circle where the innermost circle of the arc of the spot scanning path on the fan shape is located, where r1 ≤ ri ≤ r m ;

[0042] Set the laser energy of the light spot. In the plane rectangular coordinate system, on the ribbed ring fan or sector component, with the center of each circumferential arc as the coordinate origin, the laser energy y follows the formula y 2 =(l i / 2) 2 -x 2 for a "symmetric arc" type change, where y is the laser energy, l i is the arc length of the i-th circle, and x is the arc length within the light spot on the arc length l i , where 1 ≤ i ≤ m and i is an integer;

[0043] Step S6: Use the process parameters set in Step S5 to perform laser shock peening integral forming on the ribbed ring fan or sector component in Step S4: Control the light spot scanning path of the robotic arm through the laser integrated system, and control the input of the gradient laser energy and the overlapping rate to change the residual stress distribution of the component, so that the ring fan or sector forms a conical surface workpiece.

[0044] Specifically, in the plane polar coordinate system, with the center of the arc of the ribbed ring fan or sector component as the origin, and one of the arc radius boundaries as the polar axis θ0, the angle between it and the other boundary is θ n , the angle between adjacent light spots is △θ, the large arc boundary is r1, the small arc radius is r m , and the light spot center coordinate A ij (r i , θ j ) is located within the fan-shaped area, that is, r1 ≤ r i ≤ r m , 0 = θ0 ≤ θ j ≤ θ n = θ, the circumferential overlapping rate is constant along each arc, and the overlapping rate gradually decreases with the increase of the radius between arcs. The overlapping rate of the radial laser light spot between any two adjacent arcs along the arc is 50%, and the scanning path of the light spot is a counterclockwise "S" shaped arc from the outside to the inside.

[0045] The calculation process of the laser light spot overlapping rate on each arc within the fan-shaped area is as follows:

[0046] Draw perpendicular lines from the origin of the plane polar coordinates to the distances between the centers of the laser light spots on each circumferential gradient arc, obtaining a set of right-angled similar triangles (△1, △2, ······ △ m ), and through the properties of right-angled similar triangles:

[0047] (C1 / 2) / (C2 / 2) = r1 / r 2→ C2 = (r2 / r1)C1

[0048] (C2 / 2) / (C3 / 2) = r2 / r 3→ C3 = (r3 / r2)C2 = (r3 / r1)C1

[0049] ··········

[0050] (C m-1 / 2) / (C m / 2) = r m-1 / r m→ C m = ····· = (r m / r1)C1

[0051] It is obtained that: C m = ····· = (r m / r1)C1 = Dr m / 2r1, △θ = l m / r m ≈ C m / r m = D / 2r1

[0052] Therefore, the laser spot center coordinates A ij (r i , θ j ) in the i-th circle and the j-th △θ angle within the fan-shaped area are:

[0053] The first circle: A 10 (r1, 0), A 11 (r1, D / 2r1), ·····, A 1j (r1, jD / 2r1), ·····, A 1n (r1, nD / 2r1);

[0054] The second circle: A 20 (r2, 0), A 21 (r2, D / 2r1), ·····, A 2j (r2, jD / 2r1), ·····, A 2n (r2, nD / 2r1);

[0055] ······

[0056] The i-th circle: A i0 (r i , 0), A i1 (r i , D / 2r1), ·····, A ij (r i , jD / 2r1), ·····, A in (r i , nD / 2r1);

[0057] ·····

[0058] The m-th circle: A m0 (r m , 0), A m1 (r m , D / 2r1), ·····, A mj (r m , jD / 2r1), ·····, A mn (r m , nD / 2r1).

[0059] Also, because: η m = [2(D / 2 - C m ) + C m / D = 1 - C m / D

[0060] Substituting gives: η m = 1 - r m / 2r1

[0061] That is, the laser spot overlap ratio on the i-th circle arc is: η i = (1 - r i / 2r1) × 100%.

[0062] In the formula, (η1, η2, ···· η m ) are the laser spot overlap ratios on the circumferential gradient arcs from large to small, (r1, r2, ···· r m ) are the gradient arc radii from large to small, (C1, C2, ···· C m ) are the center distances of the laser spots on the circumferential gradient arcs from large to small, D is the laser spot diameter, 1 ≤ i ≤ m, 0 ≤ j ≤ n.

[0063] In the plane rectangular coordinate system, on the ribbed ring fan or sector component, with the center of each circumferential arc as the coordinate origin, the laser energy y changes in a "symmetric arc" shape according to the formula y 2 = (l i / 2) 2 - x 2 , that is, the laser energy has a "symmetric arc" shaped gradient laser energy that first increases and then decreases along the θ i positive direction on the circumference of the arc with a radius of r j . Among them, l1, l2, ··· l i ·· l m are the arc lengths of the gradient arcs from large to small, l i is the arc length of the i-th circle, x is the arc length within the spot on the arc length l i . Among them, 1 ≤ i ≤ m, and i is an integer.

[0064] Optionally, in step S1, the thickness of the ribbed conical surface member is 2-5 mm.

[0065] Optionally, in the light spot scanning path in step S6, the overall shape is a counterclockwise "S" shaped arc from a large arc to a small arc.

[0066] Optionally, the member material is a light metal or light alloy with strong plasticity and low hardness.

[0067] Optionally, the absorption protection layer is a 100 μm black tape.

[0068] Optionally, the constraint layer is a 2-5 mm water layer.

[0069] Optionally, the light spot diameter is 2 mm, and the gradient laser energy range is 1-10 J.

[0070] Example 1:

[0071] Step S1: Select a ribbed fan-shaped ring member of 6008-T6 aluminum alloy with a thickness of 2 mm;

[0072] Step S2: Polish, buff, and clean the surface of a 6008-T6 aluminum alloy ribbed fan-shaped ring member with component dimensions of θ = 105°, r1 = 195 mm, and r m = 79 mm, and perform a dry pretreatment;

[0073] Step S3: Stick a 100 μm black tape on the surface of the pretreated ribbed fan-shaped ring member;

[0074] Step S4: Place the ribbed fan-shaped ring member with the black tape on the KUKA robotic arm workbench, fix it with a special fixture, and cover it with a 2 mm water layer as the constraint layer;

[0075] Step S5: Set the laser process parameters: the light spot diameter is 2 mm, the lap rate of the laser light spot along the radial direction of the arc between any two adjacent arcs is 50%, △θ = 1 / 195°, m = 117, n = 20475.

[0076] It is calculated that the circumferential gradient laser light spot lap rates from large to small are 50%, 50.26%, ······, 1-r i / 2r1, ······, 79.74%. Program according to the calculated laser light spot center coordinates, and control the KUKA robotic arm through the laser integrated system to plan the light spot scanning path of laser peening forming in the plane polar coordinate system, ensuring that the light spot lap method is a constant lap in the circumferential direction of the same arc and a gradient lap in the circumferential direction of different arcs.

[0077] Control the radius r iThe circumferential direction of each arc has a "symmetric arc" - type gradient laser energy that first increases and then decreases symmetrically, and all follow the formula y 2 =(l i / 2) 2 -x 2 for the "symmetric arc" - type change, and along the positive direction of θ i it first increases from 1 J to 10 J and then decreases from 10 J to 1 J.

[0078] Step S6: Use the process parameters set in Step S5 to perform integral laser peening forming on the ribbed ring fan or fan - shaped component in Step S4: Control the spot scanning path of the robotic arm through the laser integration system, and control the input of the gradient laser energy and the overlapping rate to change the residual stress distribution of the component, so that the ring fan or fan - shaped component forms a conical - surface workpiece.

[0079] Example 2

[0080] Step S1: Select a ribbed fan - ring component of 3 - mm T2 copper alloy;

[0081] Step S2: Grind, polish, and clean the surface of the T2 copper alloy ribbed fan - ring component with component dimensions of θ = 126°, r1 = 996 mm and r m = 569 mm, and perform a dry pre - treatment.

[0082] Step S3: Stick a 100 - μm black tape on the surface of the pre - treated ribbed fan - ring component;

[0083] Step S4: Place the ribbed fan - ring component with the black tape on the KUKA robotic arm workbench, fix it with a special fixture, and cover it with a 3 - mm water layer as a constraint layer;

[0084] Step S5: Set the laser process parameters: the spot diameter is 2 mm, the overlapping rate of the laser spot along the radial direction of the arc between any two adjacent arcs is 50%, △θ = 1 / 996°, m = 428, n = 125496.

[0085] It is calculated that the circumferential gradient laser spot overlapping rates from large to small for each arc are 50%, 50.05%, ······, 1 - r i / 2r1, ······, 71.44%. Program according to the calculated laser spot center coordinates, and control the KUKA robotic arm through the laser integration system to plan the spot scanning path of laser peening forming in the plane polar coordinate system, ensuring that the spot overlapping method is constant overlapping in the circumferential direction of the same arc and gradient overlapping in the circumferential direction of different arcs.

[0086] Control the circumferential direction of each arc of radius r i to have a "symmetric arc" - type gradient laser energy that first increases and then decreases symmetrically, and all follow the formula y2 =(l i / 2) 2 -x 2 The "symmetric circular arc" type change of i increases from 2J to 9J first along the positive direction of θ and then decreases from 9J to 2J.

[0087] Step S6: Laser shock peening integral forming is carried out on the ribbed ring fan or sector component in Step S4 by using the process parameters set in Step S5: controlling the spot scanning path of the robotic arm through the laser integrated system, and controlling the input of gradient laser energy and the overlapping rate to change the residual stress distribution of the component, so that the ring fan or sector forms a conical surface workpiece.

[0088] Example 3

[0089] Step S1: Select a ribbed fan-shaped ring component of 5mm AZ31 magnesium alloy;

[0090] Step S2: Grind, polish and clean the surface of the AZ31 magnesium alloy ribbed fan-shaped ring component with the component size of θ = 45°, r1 = 605mm and r m = 405mm, and perform dry pretreatment;

[0091] Step S3: Stick 100μm black tape on the surface of the pretreated ribbed fan-shaped ring component;

[0092] Step S4: Place the ribbed fan-shaped ring component with black tape on the KUKA robotic arm workbench, fix it with a special fixture, and cover it with a 5mm water layer as the constraint layer;

[0093] Step S5: Set the laser process parameters: the spot diameter is 2mm, the overlapping rate of the laser spot along the radial direction of the circular arc between any two adjacent circular arcs is 50%, △θ = 1 / 605°, m = 201, n = 27225.

[0094] It is calculated that the circumferential gradient laser spot overlapping rates of each circular arc from large to small are 50%, 50.08%, ······, 1 - r i / 2r1, ······, 66.53%. Program according to the calculated laser spot center coordinates, and control the KUKA robotic arm to plan the spot scanning path of laser shock peening forming in the plane polar coordinate system through the laser integrated system, ensuring that the spot overlapping method is constant circumferential overlapping of the same circular arc and gradient overlapping of different circular arcs circumferentially.

[0095] Control the circumferential direction of each circular arc of radius r i to have a "symmetric circular arc" type gradient laser energy with a symmetric distribution of first increasing and then decreasing, and all follow the formula y 2 =(l i / 2) 2-x 2 The "symmetric circular arc" type change along θ i In the positive direction, it first increases from 3J to 8J and then decreases from 8J to 3J.

[0096] Step S6: Use the process parameters set in Step S5 to perform integral laser peening on the ribbed ring fan or fan-shaped component in Step S4: Control the spot scanning path of the robotic arm through the laser integration system, and control the input of gradient laser energy and the overlapping rate to change the residual stress distribution of the component, so that the ring fan or fan shape forms a conical surface workpiece.

[0097] Refer to Figure 9 , after the laser shock forming test, use a laser rangefinder to measure the deformation bending angles of 6008-T6 aluminum alloy, T2 copper alloy, and AZ31 magnesium alloy. The measurement results show that within a certain processing error range, the formed parts basically meet the forming accuracy requirements.

[0098] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A method for integral forming of a ribbed conical surface component by laser peening, characterized in that, The specific steps include: Step S1: Set the thickness of the ribbed ring fan or sector component according to the component thickness and the bending angle of the component during laser shock, so that the direction of laser shock is opposite to the direction of component deformation and bending; Step S2: Grind, polish and clean the surface of the above component, and perform a drying pretreatment; Step S3: Stick an absorption protection layer on the surface of the pretreated component; Step S4: Place the component with the absorption protection layer as a whole on the robotic arm workbench, fix it with a special fixture, and cover it with a constraint layer; Step S5: Set the laser peening forming process parameters: including setting the overlap rate of the laser spot and setting the laser energy of the spot, Set the overlapping rate of the laser spot. On the ribbed ring fan or sector member, calculate the center coordinates of the laser spot in the plane polar coordinate system. Taking the center of the circle corresponding to the arc as the origin and the boundary where one of the arc radii is located as the polar axis, program the calculated center coordinates of the laser spot so that the spot overlapping method is that the circumferential overlapping rate of the same arc is constant, and the overlapping rate of different arcs along their radial direction increases in a gradient manner from large to small. That is, when the ribbed conical surface is unfolded into a sector, the overlapping rate η of the laser spot on the i-th circle of the arc i = (1 - r i / 2r1) × 100%, r i is the radius of the circle where the i-th circle of the arc of the spot scanning path on the sector is located, r1 is the radius of the circle where the outermost circle of the arc of the spot scanning path on the sector is located, r m is the radius of the circle where the innermost circle of the arc of the spot scanning path on the sector is located, where r1 ≤ r i ≤ r m ; Set the laser energy of the light spot. In the plane rectangular coordinate system, on the ribbed ring fan or sector component, with the center of each circumferential arc as the coordinate origin, the laser energy y follows the formula y 2 = ( l i / 2) 2 - x 2 for a "symmetric arc" type change, where y is the laser energy, l i is the arc length of the i-th circle, and x is the arc length of the light spot on the arc length l i , where 1 ≤ i ≤ m and i is an integer; Step S6: Perform overall laser peening forming on the ribbed ring fan or sector component in Step S4 using the process parameters set in Step S5: Control the spot scanning path of the robotic arm through the laser integrated system, and control the input and overlap rate of the gradient laser energy to change the residual stress distribution of the component, so that the ring fan or sector forms a conical surface.

2. The laser peening integral forming method for the ribbed conical surface member according to claim 1, characterized in that, In the said Step S1, the thickness of the ribbed conical surface component is 2 - 5 mm.

3. The laser shock peening integral forming method for the ribbed conical surface member according to claim 1, characterized in that, The spot scanning path in the said Step S6 is an overall counterclockwise "S" shaped arc from a large arc to a small arc.

4. The laser peening integral forming method for the ribbed conical surface member according to claim 1, characterized in that The component material is a lightweight alloy with strong plasticity and low hardness.

5. The laser peening integral forming method of the ribbed conical surface member according to claim 1, characterized in that The absorption protection layer is black adhesive tape.

6. The method for integral forming of a ribbed conical surface member by laser peening according to claim 1, characterized in that, The constraint layer is a 2 - 5 mm water layer.

7. The method for integral forming of a ribbed conical surface member by laser peening according to claim 3, wherein The spot diameter is 2 mm, and the gradient laser energy range is 1 - 10 J.

8. The laser shock peening integral forming method for the ribbed conical surface member according to claim 1, characterized in that, The overlap rate of the laser spot along the radial direction of the arc between any two adjacent arcs is 50%.

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