A laser shock treatment method for silicon steel used in high-speed motor rotors

Abstract

This invention belongs to the field of silicon steel processing technology for rotors, specifically relating to a laser shock treatment method for silicon steel used in high-speed motor rotors. The method involves placing a punched, non-oriented silicon steel rotor sheet at a laser shock station; covering the surface of the silicon steel sheet with an absorption layer, which is either a finished insulating coating of silicon steel or a combination of one or more of the following: a finished insulating coating of silicon steel and black tape, black paint, or aluminum foil; turning on a stream of clean water to cover the surface of the silicon steel sheet, or covering the surface with a layer of transparent tempered glass to form a constraint layer; using single-sided, alternating single-sided, or simultaneous double-sided laser shock processing on areas prone to stress concentration, such as the rotor magnetic bridge; cleaning the surface of the silicon steel sheet after the shock processing, ensuring that the dimensional change in the thickness direction of the silicon steel sheet does not exceed 0.5%, and increasing the yield strength by 35-250 MPa. This invention employs localized laser shock processing on the surface of non-oriented silicon steel used in high-speed motor rotors, significantly improving the yield strength without changing the silicon steel composition or manufacturing process.

Description

Technical Field

[0001] This invention belongs to the field of silicon steel processing technology for rotors, specifically relating to a laser shock treatment method for silicon steel used in high-speed motor rotors. It is particularly suitable for local strengthening of non-oriented silicon steel in high-speed motor rotors for new energy vehicles, high-end home appliances, and low-altitude aircraft, which can improve local mechanical properties while ensuring magnetic properties. Background Technology

[0002] Laser shock peening technology is a high-tech method that uses plasma shock waves generated by a strong laser beam to improve the fatigue resistance, wear resistance and corrosion resistance of metallic materials. It has outstanding advantages such as non-contact operation, no heat-affected zone, strong controllability and significant strengthening effect.

[0003] High-power-density short-pulse lasers irradiate the surface of a material (typically covered by an absorbing layer and a confinement layer), instantly vaporizing the absorbing layer and forming a high-temperature, high-pressure plasma. Under the influence of the confinement layer, the plasma expands rapidly, generating a strong shock wave that propagates into the material's interior. This strong shock wave causes plastic deformation of the material's surface, forming a residual compressive stress layer with a depth of 1-2 mm, while simultaneously refining the surface grains, thus effectively suppressing crack initiation and propagation. Compared to traditional shot peening, this method generates deeper and more uniform residual compressive stress, resulting in a more durable strengthening effect. It can precisely strengthen complex geometries or localized areas, has minimal impact on surface roughness, and requires no extensive subsequent grinding. It is widely used in aerospace (e.g., engine blades, turbine disks), nuclear power, and automotive fields to improve the reliability and service life of critical load-bearing components. Patent CN119824211A proposes a laser-induced shock-based surface treatment method that utilizes laser-induced shock wave loads to simultaneously introduce surface strengthening and patterning effects, enhancing the wear resistance and durability of metal sample surfaces.

[0004] High-speed motors are the "heart" of advanced equipment such as new energy vehicles, high-end home appliances, and low-altitude aircraft, and their performance improvement closely depends on the advancement of their core material—non-oriented silicon steel. Currently, high-speed motors are developing towards ultra-high speeds, high power densities, and system integration. As the speed increases, the centrifugal stress on the rotor components also increases, placing stringent requirements on non-oriented silicon steel in terms of low iron loss, high magnetic flux density, high strength, and thin profiles. However, magnetic and mechanical properties are considered to be contradictory, and most strengthening mechanisms have a negative impact on magnetic properties. Current research mainly focuses on using solid solution strengthening, precipitation strengthening, and dislocation strengthening mechanisms on high-grade non-oriented silicon steel, but the strengthening effect is limited and increases material manufacturing costs. In fact, when non-oriented silicon steel is used as a motor rotor, stress concentration only occurs in localized areas such as the magnetic bridge and outer circumference, and laser shock peening provides a feasible technical means for surface treatment of these localized areas.

[0005] Patent CN117737578A discloses a surface treatment method for high-silicon steel used in motor rotors and stators. It reduces iron loss by adding trace amounts of composite materials during the smelting process, and combines this with surface treatment to form an excellent alloy coating, thereby improving the material's magnetic properties and corrosion resistance. This method primarily improves performance through composition control. Laser shock annealing is a monolithic process that does not distinguish between localized stress and non-stressed areas of the rotor, making it impossible to avoid magnetic property loss in non-stressed areas. It requires additional surface treatment and lacks subsequent dimensional accuracy control design, making it difficult to meet the lamination coefficient requirements of high-speed motor rotors. Patent CN120683348A discloses a high-strength non-oriented silicon steel based on laser shock annealing, its preparation method, and its application. It involves laser shock annealing of cold-rolled non-oriented silicon steel sheets or uncoated non-oriented silicon steel commercial sheets, followed by annealing, to obtain high-strength non-oriented silicon steel based on laser shock annealing. Because of the use of integral laser shock, the magnetic properties of non-stressed areas are easily damaged. In particular, annealing (holding at 550~850℃ for 1~4h) must be performed after laser shock to eliminate the residual stress introduced during the laser strengthening process. However, annealing may weaken the laser shock strengthening effect. In addition, it is necessary to remove the coating in the finished non-oriented silicon steel, which will lead to complicated processes. Summary of the Invention

[0006] The purpose of this invention is to provide a laser shock treatment method for silicon steel used in high-speed motor rotors. This method aims to improve the local strength of non-oriented silicon steel rotors and ensure rotor dimensional accuracy and surface shape, thereby improving the speed, operational stability, and reliability of high-speed motors. It also overcomes the shortcomings of existing high-strength non-oriented silicon steel preparation processes, such as the addition of alloys, complex annealing processes, and unsatisfactory performance improvements.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0008] A laser shock treatment method for silicon steel used in high-speed motor rotors includes the following steps:

[0009] (1) Place the punched non-oriented silicon steel rotor sheet at the laser impact station;

[0010] (2) Cover the surface of the silicon steel sheet with an absorbent layer, wherein the absorbent layer is an insulating coating of finished silicon steel, or a combination of one or more of the following: finished silicon steel insulating coating and black tape, black paint, and aluminum foil;

[0011] (3) Turn on the clean water flow to cover the surface of the silicon steel sheet, or cover the surface of the silicon steel sheet with a transparent tempered glass layer to form a constraint layer;

[0012] (4) Move the laser emitter to the surface of the silicon steel sheet and adjust the laser parameters according to the thickness of the silicon steel sheet. The laser parameters are: laser energy of 0.1~6J, pulse width of 8~30ns, and spot diameter of 0.1~3mm. Single-sided laser shock processing, single-sided alternating laser shock processing, or simultaneous laser shock processing on both sides are used. The laser shock processing is applied to the local area where stress concentration is easily generated in the non-oriented silicon steel rotor.

[0013] (5) After impact processing, clean the surface of the silicon steel sheet. The thickness dimension of the silicon steel sheet does not change by more than 0.5%, and the yield strength is increased by 35~250MPa.

[0014] In the laser shock treatment method for silicon steel rotors of high-speed motors, in step (1), the non-oriented silicon steel rotor sheet is non-oriented silicon steel with an insulating coating, and the thickness of the non-oriented silicon steel rotor sheet is 0.10~0.65mm.

[0015] In the laser shock treatment method for silicon steel rotor of high-speed motor, in step (2), when the absorption layer is a finished silicon steel insulating coating, carbon black to improve the laser absorption rate is added to the finished silicon steel insulating coating liquid, and the carbon black content in the finished silicon steel insulating coating liquid is 0.5~5wt%.

[0016] In the laser shock treatment method for silicon steel rotor of high-speed motor, in step (2), the thickness of the insulating coating, black tape, black paint and aluminum foil of the finished silicon steel product is 0.4~200μm.

[0017] In the laser shock treatment method for silicon steel used in high-speed motor rotors, the thickness of the constraint layer in step (3) is 0.5~3mm.

[0018] In the laser shock treatment method for silicon steel rotors of high-speed motors, in step (4), when the thickness of the non-oriented silicon steel rotor sheet is 0.1~0.35mm, the laser parameters are: laser energy of 0.1~3J, pulse width of 8~20ns, and spot diameter of 1~3mm; when the thickness of the non-oriented silicon steel rotor sheet is 0.35~0.65mm, the laser parameters are: laser energy of 3~6J, pulse width of 10~30ns, and spot diameter of 0.1~1mm.

[0019] In the laser shock treatment method for silicon steel rotor of high-speed motor, in step (4), the local area includes the magnetic bridge, the area where stress concentration is easily generated on the outer circle, and the interface area between the local area and the non-processed area. The transition processing form is adopted by reducing the laser shock wave energy, reducing the pulse width or increasing the spot diameter.

[0020] In the laser shock treatment method for silicon steel rotors of high-speed motors, in step (4), the single-sided alternating laser shock processing is achieved by changing the surface of the non-oriented silicon steel rotor sheet using a robotic arm.

[0021] In the laser shock treatment method for silicon steel rotors of high-speed motors, in step (4), the simultaneous laser shock processing on both sides uses two pulsed lasers to process both sides of the non-oriented silicon steel rotor sheet with the same laser parameters.

[0022] In the laser shock treatment method for silicon steel used in high-speed motor rotors, step (4) involves single-point laser processing or multi-point array laser processing.

[0023] The design concept of this invention is:

[0024] Existing technologies require changes to smelting and hot rolling processes, and integral laser shock can damage the magnetic properties of non-stressed areas. This invention addresses the service characteristics of non-oriented silicon steel rotors for high-speed motors (stress concentration in the magnetic bridge and outer circumference at high speeds, requiring magnetic conductivity in non-stressed areas). It applies laser shock only to stress-concentrated areas such as the rotor's magnetic bridge and outer circumference, preserving the original magnetic properties of non-stressed areas, thus avoiding the damage to magnetic properties caused by integral strengthening. This invention adjusts laser parameters according to the silicon steel thickness (0.1~0.65mm): for thinner specifications (0.1~0.35mm), low energy (0.1~3J), small pulse width (8~20ns), and large spot size (1~3mm) are used; for thicker specifications (0.35~0.65mm), high energy (3~6J), large pulse width (10~30ns), and small spot size (0.1~1mm) are used. By optimizing parameters (such as low energy and large spot size), residual stress distribution is controlled, eliminating the need for subsequent annealing and achieving localized strengthening while maintaining both magnetic properties and dimensional accuracy. In addition, the interface between the processing area and the non-processing area is processed by reducing laser energy, decreasing pulse width or increasing spot size. This protects the magnetic properties of the non-processing area and avoids loss of magnetic permeability. It also optimizes the microstructure of the interface and improves the integrity of the rotor structure.

[0025] The advantages and beneficial effects of this invention are:

[0026] 1) The technical means of this invention only performs laser shock strengthening in a local area of ​​the non-oriented silicon steel rotor. It can improve the mechanical properties of the local area of ​​the rotor (yield strength increased by 35~250MPa) without changing the previous processes such as smelting, hot rolling, cold rolling and annealing, while hardly affecting the magnetic properties. The process is simple and feasible.

[0027] 2) Based on the rotor design requirements and actual service conditions, laser shock treatment is only applied to areas prone to stress concentration, such as the rotor magnetic bridge and outer circle, and does not need to be applied to the entire non-oriented silicon steel. This ensures that the magnetic conduction effect is fully utilized in non-stress concentration areas, while resisting the stress concentration caused by high speed in stress concentration areas, thus maximizing the material utilization effect.

[0028] 3) In this invention, the interface between the local area of ​​laser shock processing and the non-processed area is processed by means of reducing the laser shock wave energy, reducing the pulse width or increasing the spot diameter, so as to avoid performance abrupt changes or stress concentration at the interface.

[0029] 4) This invention can utilize the insulating coating in the finished non-oriented silicon steel product as a laser shock strengthening absorption layer, without the need to remove the insulating coating of the finished non-oriented silicon steel product, and can also eliminate the need to cover the surface of the non-oriented silicon steel rotor with an absorption layer such as black glue. Compared with conventional laser shock strengthening treatment, the process is significantly simplified.

[0030] 5) When performing laser shock processing on non-oriented silicon steel rotors, this invention employs single-sided processing, alternating single-sided processing, or simultaneous processing on both sides. Furthermore, the thinner the non-oriented silicon steel, the lower the laser shock wave energy, the smaller the pulse width, and the larger the spot diameter. The dimensional change in the thickness direction of the non-oriented silicon steel after laser shock treatment does not exceed five per thousand, thereby reducing the impact of laser shock strengthening on the rotor shape and lamination coefficient, and also making it applicable to a wider range of non-oriented silicon steel rotor thicknesses.

[0031] 6) The laser shock treatment of the present invention can be carried out by single-point laser processing or multi-point array laser processing of sample surface, which can improve processing efficiency while taking into account the strengthening effect.

[0032] 7) Compared to the patent published under CN120683348A, the laser shock processing of this invention operates on localized areas of the non-oriented silicon steel rotor where stress concentration is likely to occur (such as magnetic bridges and outer circles), while non-stressed areas (such as magnetically conductive areas) remain completely untouched by the laser, ensuring that the magnetic induction intensity and iron loss in non-stressed areas remain stable. This invention uses the insulating coating (including carbon black modification) of the finished silicon steel as an absorption layer, eliminating the need for subsequent annealing and saving on processes such as coating removal and annealing. Due to the simplified process and reduced energy consumption, it is more suitable for industrial mass production. Furthermore, the overlapping area of ​​the laser spot in the integral shock process is prone to uneven local stress, leading to warping of the silicon steel sheet and a risk of crack propagation under long-term high-speed operation. This invention dynamically adjusts laser parameters and processing methods based on the thickness of silicon steel (e.g., large spot size of 1~3mm and low energy of 0.1~3J for thin materials, and small spot size of 0.1~1mm and high energy of 3~6J for thick materials). After impact, the thickness change of the silicon steel surface is ≤0.5%, and the lamination coefficient is ≥95%, which fully meets the clearance requirements for rotor assembly. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a laser shock treatment method for silicon steel used in high-speed motor rotors according to the present invention. In the figure, 1 is a non-oriented silicon steel rotor plate, and 2 is a laser emitter. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention.

[0035] Example 1 (0.35mm thick non-oriented silicon steel rotor lamination)

[0036] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0037] The 0.35mm thick non-oriented silicon steel rotor plate 1, punched out, is placed at the laser impact station. Using the finished silicon steel insulating coating as the absorption layer (0.5μm thick), 5wt% carbon black (by weight percentage: epoxy resin 25%, aluminum dihydrogen phosphate 30%, zinc chromate 5%, zinc molybdate 5%, silica 14%, boric acid 3%, magnesium oxide 8%, titanate coupling agent 2%, carbon black 5%, deionized water balance) is added to the finished silicon steel insulating coating solution. Clean water is then used to cover the surface of the non-oriented silicon steel rotor plate, forming a constraint layer (1mm thick water film). The laser emitter 2 is moved to the surface of the silicon steel plate, and the laser parameters are set as follows: laser energy 3J, pulse width 20ns, and spot diameter 1mm. A transition processing method with 2J energy, 15ns pulse width, and 2mm spot diameter is used at the interface between the processed and unprocessed areas. Single-point laser processing is used to process localized areas such as the rotor's magnetic bridge. After the first layer on one side is processed, a robotic arm is used to flip the rotor laminations until both sides are fully processed. After laser impact processing, the surface of the silicon steel laminations is cleaned. The dimensional variation in the thickness direction of the rotor laminations does not exceed four per thousand, and the yield strength is increased from 420 MPa to 540 MPa (an increase of 120 MPa). The magnetic induction intensity in the non-stress area (B... 50 1.68T, iron loss (P) 1.0 / 400 The value remained unchanged at 16.8 W / kg.

[0038] Example 2 (0.2mm thick non-oriented silicon steel rotor lamination)

[0039] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0040] The 0.2mm thick non-oriented silicon steel rotor plate 1 is placed in the laser impact station. A layer of black tape is applied to the insulating coating of the finished silicon steel as an absorption layer (insulating coating thickness is 0.5μm, black tape thickness is 100μm). Clean water is then applied to the surface of the non-oriented silicon steel rotor plate to form a constraint layer (water film thickness is 1mm). Two laser emitters 2 are moved to both sides of the silicon steel plate, and the laser parameters are set as follows: laser energy is 1J, pulse width is 10ns, and spot diameter is 2mm. A transition processing with an energy of 0.5J, a pulse width of 8ns, and a spot diameter of 3mm is used at the interface between the processed and unprocessed areas. Local areas such as the rotor magnetic bridge are processed simultaneously using lasers from both sides. After the laser impact processing is completed, the black tape and water on the surface of the silicon steel plate are cleaned. The dimensional change in the thickness direction of the rotor plate does not exceed 0.5%, the yield strength is increased from 405MPa to 465MPa (an increase of 60MPa), and the magnetic induction intensity (B) in the non-stress area is... 50 1.64T, iron loss (P) 1.0 / 400 The value remained unchanged at 11 W / kg.

[0041] Example 3 (0.1mm thick non-oriented silicon steel rotor lamination)

[0042] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0043] The 0.1mm thick non-oriented silicon steel rotor plate 1 is placed in the laser impact station. Using the finished silicon steel insulating coating as the absorption layer (0.4μm thick), 3wt% carbon black (by weight percentage: epoxy resin 25%, aluminum dihydrogen phosphate 30%, zinc chromate 5%, zinc molybdate 5%, silicon dioxide 16%, boric acid 3%, magnesium oxide 8%, titanate coupling agent 2%, carbon black 3%, deionized water balance) is added to the finished silicon steel insulating coating solution. A layer of transparent tempered glass (2mm thick) is then placed on the surface as a constraint layer. Two laser emitters 2 are moved to both sides of the silicon steel plate, and the laser parameters are set as follows: laser energy 0.1J, pulse width 8ns, and spot diameter 3mm. Local areas such as the rotor magnetic bridge are processed synchronously using the laser arrays on both sides. After laser impact processing, the surface of the silicon steel plate is cleaned. The dimensional variation in the thickness direction of the rotor plate does not exceed 0.5%, the yield strength is increased from 400MPa to 435MPa (an increase of 35MPa), and the magnetic induction intensity in the non-stress area (B... 50 1.60T, iron loss (P) 1.0 / 400 The value remained unchanged at 10.2 W / kg.

[0044] Example 4 (0.27mm thick non-oriented silicon steel rotor lamination)

[0045] like Figure 1As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0046] The 0.27mm thick non-oriented silicon steel rotor plate 1 is placed in the laser impact station. A layer of black tape is applied to the insulating coating of the finished silicon steel as an absorption layer (insulating coating thickness is 0.5μm, black tape thickness is 100μm). Clean water is then applied to the surface of the non-oriented silicon steel rotor plate to form a constraint layer (water film thickness is 1mm). The laser emitter 2 is moved to the surface of the silicon steel plate, and the laser parameters are set as follows: laser energy is 2J, pulse width is 20ns, and spot diameter is 2mm. A transition processing with an energy of 1J, a pulse width of 15ns, and a spot diameter of 3mm is used at the interface between the processed and non-processed areas. Single-point laser processing is used to process local areas such as the rotor magnetic bridge. After the first layer of processing on one side is completed, a robot arm is used to flip the rotor plate until both sides are fully processed. After the laser impact processing is completed, the surface of the silicon steel plate is cleaned. The dimensional change in the thickness direction of the rotor plate does not exceed 0.5%, the yield strength is increased from 420MPa to 520MPa (an increase of 100MPa), and the magnetic induction intensity in the non-stress area (B 50 1.66T, iron loss (P) 1.0 / 400 The value remained unchanged at 12.8 W / kg.

[0047] Example 5 (0.5mm thick non-oriented silicon steel rotor lamination)

[0048] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0049] The 0.5mm thick non-oriented silicon steel rotor plate 1 is placed in the laser impact station. An aluminum foil layer is placed over the insulating coating of the finished silicon steel as an absorption layer (insulating coating thickness 0.6μm, aluminum foil thickness 200μm). Clean water is then applied to the surface of the non-oriented silicon steel rotor plate to form a constraint layer (water film thickness 1mm). The laser emitter 2 is moved to the surface of the silicon steel plate, and the laser parameters are set as follows: laser energy 4J, pulse width 25ns, and spot diameter 1mm. A transition processing method with 3J energy, 20ns pulse width, and 2mm spot diameter is used at the interface between the processed and unprocessed areas. Single-sided, single-point laser processing is used to process local areas such as the rotor's magnetic isolation bridge. After laser impact processing, the surface of the silicon steel plate is cleaned. The dimensional variation in the thickness direction of the rotor plate does not exceed 0.5%, the yield strength is increased from 450MPa to 610MPa (an increase of 160MPa), and the magnetic induction intensity in the non-stressed area (B... 50 1.60T, iron loss (P) 1.5 / 50 The value remained unchanged at 2.5 W / kg.

[0050] Example 6 (0.65mm thick non-oriented silicon steel rotor lamination)

[0051] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0052] The 0.65mm thick non-oriented silicon steel rotor plate 1 is placed in the laser impact station. A layer of black tape is covered on the insulating coating of the finished silicon steel as an absorption layer (the insulating coating thickness is 2μm, and the black tape thickness is 100μm), and a layer of transparent tempered glass is covered on the surface as a constraint layer (the tempered glass thickness is 3mm). The laser emitter 2 is moved to the surface of the silicon steel plate, and the laser parameters are set as follows: laser energy of 6J, pulse width of 30ns, and spot diameter of 0.1mm. For the interface between the processed area and the non-processed area, a transition processing is performed with an energy of 4J, a pulse width of 24ns, and a spot diameter of 0.3mm. Single-point laser processing is used to process local areas such as the rotor magnetic bridge. After the first layer of processing on one side is completed, the rotor plate is flipped using a robot until both sides are fully processed. After the laser impact processing is completed, the surface of the silicon steel plate is cleaned. The dimensional change in the thickness direction of the rotor plate does not exceed 0.4%, the yield strength is increased from 480MPa to 730MPa (an increase of 250MPa), and the magnetic induction intensity (B) in the non-stress area is... 50 1.7T, iron loss (P) 1.5 / 50 The value remained unchanged at 4.55 W / kg.

[0053] Example 7 (0.20mm thick non-oriented silicon steel rotor lamination)

[0054] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0055] The 0.20mm thick non-oriented silicon steel rotor sheet 1, punched out, is placed at the laser impact station. An aluminum foil layer is applied as an absorption layer to the insulating coating of the finished silicon steel (insulating coating thickness 0.5μm, aluminum foil thickness 100μm). 0.5wt% carbon black (by weight percentage: epoxy resin 25%, aluminum dihydrogen phosphate 30%, zinc chromate 5%, zinc molybdate 5%, silica 18%, boric acid 3%, magnesium oxide 8%, titanate coupling agent 2%, carbon black 0.5%, deionized water balance) is added to the finished silicon steel insulating coating solution. A layer of transparent tempered glass (tempered glass thickness 2mm) is then applied as a constraint layer. The laser emitter 2 is moved to the surface of the silicon steel sheet, and the laser parameters are set as follows: laser energy 2J, pulse width 10ns, and spot diameter 1mm. A transition processing method with an energy of 1J, a pulse width of 8ns, and a spot diameter of 2mm is used at the interface between the processed and unprocessed areas. Single-point laser processing is used to process localized areas such as the rotor's magnetic bridge. After the first layer on one side is processed, a robotic arm is used to flip the rotor laminations until both sides are fully processed. After laser impact processing, the surface of the silicon steel laminations is cleaned. The dimensional variation in the thickness direction of the rotor laminations does not exceed 0.5%, the yield strength is increased from 410MPa to 510MPa (an increase of 100MPa), and the magnetic induction intensity in the non-stress area (B... 50 1.64T, iron loss (P) 1.0 / 400 The value remained unchanged at 11 W / kg.

[0056] Example 8 (0.15mm thick non-oriented silicon steel rotor lamination)

[0057] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0058] The 0.15mm thick non-oriented silicon steel rotor sheet 1 is placed in the laser impact station. An aluminum foil layer (0.4μm thick insulation coating, 100μm thick aluminum foil) is placed over the insulating coating of the finished silicon steel as an absorption layer, and a layer of transparent tempered glass (2mm thick) is placed over the surface as a constraint layer. Two laser emitters 2 are moved to both sides of the silicon steel sheet, and the laser parameters are set as follows: laser energy 0.5J, pulse width 10ns, and spot diameter 3mm. A transition processing method with 0.3J energy, 8ns pulse width, and 3mm spot diameter is used at the interface between the processed and unprocessed areas. Local areas such as the rotor magnetic bridge are processed synchronously using laser arrays on both sides. After laser impact processing, the surface of the silicon steel sheet is cleaned. The dimensional variation in the thickness direction of the rotor sheet does not exceed 0.5%, the yield strength is increased from 400MPa to 450MPa (an increase of 50MPa), and the magnetic induction intensity (B) in the non-stressed area is... 50 1.64T, iron loss (P) 1.0 / 400 The value remained unchanged at 11.0 W / kg.

[0059] Example 9 (0.3mm thick non-oriented silicon steel rotor lamination)

[0060] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0061] The 0.3mm thick non-oriented silicon steel rotor plate 1, after being punched, is placed at the laser impact station. Using the finished silicon steel insulating coating as the absorption layer (0.5μm thick), 4wt% carbon black (by weight percentage: epoxy resin 25%, aluminum dihydrogen phosphate 30%, zinc chromate 5%, zinc molybdate 5%, silica 15%, boric acid 3%, magnesium oxide 8%, titanate coupling agent 2%, carbon black 4%, deionized water balance) is added to the finished silicon steel insulating coating solution. Clean water is then used to cover the surface of the non-oriented silicon steel rotor plate to form a constraint layer (water film thickness 1mm). The laser emitter 2 is moved to the surface of the silicon steel plate, and the laser parameters are set as follows: laser energy 2.5J, pulse width 20ns, and spot diameter 2.5mm. A transition processing method with an energy of 2.0J, a pulse width of 16ns, and a spot diameter of 3mm is used at the interface between the processed and unprocessed areas. Single-point laser processing is used to process localized areas such as the rotor's magnetic bridge. After the first layer on one side is processed, a robotic arm is used to flip the rotor laminations until both sides are fully processed. After laser impact processing, the surface of the silicon steel laminations is cleaned. The dimensional variation in the thickness direction of the rotor laminations does not exceed 0.5%, and the yield strength is increased from 430MPa to 570MPa (an increase of 140MPa). The magnetic induction intensity in the non-stress area (B... 50 1.68T, iron loss (P) 1.0 / 400 The value remained unchanged at 13.7 W / kg.

[0062] Example 10 (0.5mm thick non-oriented silicon steel rotor lamination)

[0063] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0064] The 0.5mm thick non-oriented silicon steel rotor plate 1 is placed in the laser impact station. A layer of black paint is applied to the insulating coating of the finished silicon steel as an absorption layer (the insulating coating thickness is 1μm, and the black tape thickness is 200μm). Clean water is then applied to the surface of the non-oriented silicon steel rotor plate to form a constraint layer (the water film thickness is 1mm). The laser emitter 2 is moved to the surface of the silicon steel plate, and the laser parameters are set as follows: laser energy of 5.5J, pulse width of 30ns, and spot diameter of 0.5mm. For the interface between the processed and non-processed areas, a transition processing is performed with an energy of 4J, a pulse width of 27ns, and a spot diameter of 1mm. Single-point laser processing is used to process local areas such as the rotor magnetic bridge. After the first layer of processing on one side is completed, a robotic arm is used to flip the rotor plate until both sides are fully processed. After the laser impact processing is completed, the surface of the silicon steel plate is cleaned. The dimensional change in the thickness direction of the rotor plate does not exceed 0.4%, the yield strength is increased from 450MPa to 650MPa (an increase of 200MPa), and the magnetic induction intensity (B) in the non-stress area is... 50 1.62T, iron loss (P) 1.5 / 50 The value remained unchanged at 2.3 W / kg.

[0065] Example 11 (0.25mm thick non-oriented silicon steel rotor lamination)

[0066] like Figure 1 As shown, a laser shock treatment method for silicon steel used in high-speed motor rotors includes:

[0067] The 0.25mm thick non-oriented silicon steel rotor plate 1 is placed in the laser impact station. A layer of black tape is applied as an absorption layer to the insulating coating of the finished silicon steel (insulating coating thickness is 0.5μm, black tape thickness is 100μm), and a layer of transparent tempered glass is applied as a constraint layer (tempered glass thickness is 2mm). The laser emitter 2 is moved to the surface of the silicon steel plate, and the laser parameters are set as follows: laser energy is 1.5J, pulse width is 10ns, and spot diameter is 3mm. For the interface between the processed and unprocessed areas, a transition processing is performed with an energy of 1.0J, a pulse width of 8ns, and a spot diameter of 3mm. Local areas such as the rotor magnetic bridge are processed synchronously using a laser array. After the first layer of processing on one side is completed, the rotor plate is flipped using a robotic arm until both sides are fully processed. After the laser impact processing is completed, the surface of the silicon steel plate is cleaned. The dimensional change in the thickness direction of the rotor plate does not exceed 0.5%, the yield strength is increased from 425MPa to 505MPa (an increase of 80MPa), and the magnetic induction intensity in the non-stressed area (B 50 1.66T, iron loss (P) 1.0 / 400 The value remained unchanged at 12.1 W / kg.

[0068] The results show that the present invention significantly improves the yield strength of non-oriented silicon steel rotors by using laser shock processing on the surface without changing the silicon steel composition or manufacturing process. In Examples 1-11, the yield strength of the non-oriented silicon steel rotor laminations increased from 400-480 MPa to 435-730 MPa, with an increase of 35-250 MPa; simultaneously, the magnetic induction intensity (B) in the non-stress region... 50 Iron loss (P) 1.0 / 400 Iron loss (P) 1.5 / 50 B remains unchanged. 50 =1.60~1.70T, P 1.0 / 400 =10.2~16.8W / kg, P 1.5 / 50 =2.3~4.55W / kg. This invention uses an insulating coating as the absorption layer, or a combination of an insulating coating and one or more of black glue, black paint, and aluminum foil as the absorption layer, and employs laser shock peening to strengthen localized areas such as the rotor magnetic bridge. The thinner the non-oriented silicon steel, the lower the laser shock wave energy, the smaller the pulse width, and the larger the spot diameter. Simultaneously, the laser processing of the non-oriented silicon steel rotor employs single-sided processing, alternating side processing, or simultaneous processing of both sides. This invention features a simple process, low cost, and can significantly improve the yield strength of localized areas of the non-oriented silicon steel rotor, thereby increasing the drive motor speed.

Claims

1. A method of laser shock processing of silicon steel for high speed motor rotors, characterized in that, The method comprises the following steps: (1) placing a punch-formed non-oriented silicon steel rotor sheet in a laser impact station, the non-oriented silicon steel rotor sheet being a non-oriented silicon steel with an insulating coating, and the thickness of the non-oriented silicon steel rotor sheet being 0.10-0.65 mm; (2) covering an absorbing layer on the surface of the silicon steel sheet, the absorbing layer being a silicon steel finished product insulating coating, and when the absorbing layer is a silicon steel finished product insulating coating, adding carbon black for improving laser absorption in a silicon steel insulating layer finished product coating liquid, and the content of the carbon black in the silicon steel insulating layer finished product coating liquid being 0.5-5 wt%; (3) opening a clean water flow to cover the surface of the silicon steel sheet, or covering a transparent tempered glass layer on the surface of the silicon steel sheet to form a constraint layer; (4) moving a laser emitter to the surface of the silicon steel sheet, adjusting laser parameters according to the thickness of the silicon steel sheet, when the thickness of the non-oriented silicon steel rotor sheet is 0.1-0.35 mm, the laser parameters being: laser energy being 0.1-3 J, pulse width being 8-20 ns, and spot diameter being 1-3 mm; when the thickness of the non-oriented silicon steel rotor sheet is 0.35-0.65 mm, the laser parameters being: laser energy being 3-6 J, pulse width being 10-30 ns, and spot diameter being 0.1-1 mm; and using single-sided laser impact machining, single-sided alternating face laser impact machining, or two-sided simultaneous laser impact machining, the laser impact machining being used in local areas of the non-oriented silicon steel rotor where stress concentration is prone to occur; (5) after the impact machining is completed, cleaning the surface of the silicon steel sheet, and the thickness direction dimensional change of the silicon steel sheet being not more than 5 parts per thousand, and the yield strength being increased by 35-250 MPa.

2. The method for laser shock processing of silicon steel for high-speed motor rotors according to claim 1, characterized in that, In step (2), the thickness of the silicon steel finished product insulating coating is 0.4-200 μm.

3. The method of claim 1, wherein the laser shock processing of the silicon steel for high speed motor rotors is characterized by, In step (3), the thickness of the constraint layer is 0.5-3 mm.

4. The method of laser shock processing of silicon steel for high speed motor rotors as defined in claim 1, wherein, In step (4), the local areas include a magnetic bridge, an outer circle where stress concentration is prone to occur, and an interface area between the local areas and non-machining areas, and a transition machining form of reducing laser impact wave energy, reducing pulse width, or increasing spot diameter is used.

5. The method of laser shock processing of silicon steel for high speed motor rotors as defined in claim 1, wherein, In step (4), the single-sided alternating face laser impact machining is realized by changing the face of the non-oriented silicon steel rotor sheet by a mechanical hand.

6. The method for laser shock processing of silicon steel for high speed motor rotors as claimed in claim 1, characterized in that, In step (4), the two-sided simultaneous laser impact machining uses two pulse lasers to simultaneously machine both sides of the non-oriented silicon steel rotor sheet with the same laser parameters.

7. The method of laser shock processing of silicon steel for high speed motor rotors as defined in claim 1, wherein, In step (4), the laser impact machining uses single-point laser machining or multi-point array laser machining.

Images