Ultrasonic roll bonding parameter normalization method

Abstract

The application provides a normalization method of ultrasonic rolling parameters, comprising the following steps: determining a processing area of a sample; designing a plurality of ultrasonic rolling strengthening experiments by using four processing parameters at different levels in a working range of the processing parameters; establishing a model of processing time of the processing area with a unit size; establishing a model of total energy obtained by the processing area with a unit size in the ultrasonic rolling process; determining the total energy G corresponding to each ultrasonic rolling strengthening experiment as a G factor; obtaining the hardness, roughness and residual stress values of the sample processed by each ultrasonic rolling strengthening equipment under different G factors; and drawing the roughness-G factor, hardness-G factor and residual stress-G factor interaction diagram of the material of the processed sample. The application can well normalize the processing parameters of different ultrasonic rolling equipment, and effectively compare the horizontal processing effects.

Description

Technical Field

[0001] This invention relates to the field of surface strengthening technology, and specifically to a method for normalizing ultrasonic rolling strengthening parameters. Background Technology

[0002] Surface mechanical treatment improves the fatigue life of materials by introducing deformation on the material surface, forming a surface hardened layer and residual stress field. Introducing residual compressive stress reduces the effective tensile stress and increases the crack propagation threshold, thereby improving fatigue strength. Simultaneously, ultrasonic surface strengthening technology can increase the surface hardness of mechanical components, reduce surface roughness, and improve the surface microstructure, thus improving the fatigue performance and wear resistance of mechanical components and broadening the application range of materials. Surface mechanical treatment includes many types, commonly including shot peening, laser shock peening, and ultrasonic surface strengthening. Shot peening uses a shot peening medium to impact the material surface at high speed, causing plastic deformation of the metal and improving the material's mechanical properties. However, shot peening often increases surface roughness, which may lead to a significant reduction in lifespan in some cases. Laser shock peening uses the interaction between a laser and a target to form a shock wave, deforming the material surface to achieve surface strengthening. However, its high cost and complex process limit its application.

[0003] Ultrasonic surface strengthening is a dynamic strengthening technique that combines static pressure and ultrasonic impact energy to strengthen metal surfaces during processing. While utilizing ultrasonic vibration to generate a powerful impact, ultrasonic surface strengthening also avoids the pitting defects caused by traditional shot peening by using tungsten carbide balls rolling on the material surface. Ultrasonic surface strengthening devices can be installed on traditional lathes and milling machines, as well as advanced CNC robotic arms, thus having a wide range of applications. By adjusting parameters such as ultrasonic vibration frequency and amplitude, the surface strengthening effect can be controlled, allowing for free adjustment of residual stress, hardening degree, and strengthened layer depth, resulting in good process controllability. Compared to laser shock peening, ultrasonic surface strengthening equipment is simpler, easier to operate, and has lower maintenance costs. Due to its many advantages, surface strengthening technology is widely used in the domestic and international aerospace manufacturing and maintenance industries, becoming a necessary process specified in aircraft manufacturing standards and manuals. Currently, surface strengthening technology is also increasingly being applied to blade manufacturing.

[0004] Ultrasonic surface strengthening equipment mainly consists of an ultrasonic generator, transducer, amplitude transformer, and processing head. The ultrasonic generator emits a high-frequency ultrasonic sinusoidal electrical signal. The transducer converts this high-frequency ultrasonic sinusoidal electrical signal into a displacement signal through a piezoelectric ceramic plate (specifically, the piezoelectric ceramic deforms due to the current signal, converting the electrical signal into a displacement signal with the same frequency). The amplitude transformer amplifies the displacement signal and transmits it to the processing head for processing. To date, ultrasonic surface strengthening equipment has evolved into various forms of ultrasonic amplitude transformers and processing heads, with significant differences in ultrasonic frequency and amplitude. Therefore, even using the same processing parameters (processing interval, feed rate, downward pressure, and number of rolling passes), different ultrasonic surface strengthening equipment can produce vastly different processing results. This inability to guarantee consistent processing results under the same parameters limits the optimization and development of this process and hinders the accumulation of experimental data on ultrasonic rolling strengthening process parameters.

[0005] Based on this, the present invention proposes a parameter normalization method, which aims to normalize the parameters of different types of ultrasonic enhancement equipment. By introducing the G factor, different processing parameters are quantitatively described, thereby achieving a horizontal comparison between the processing effects of different equipment. Summary of the Invention

[0006] To address the shortcomings of the above methods, this invention provides a parameter normalization method that can normalize different processing parameters, thereby enabling a horizontal comparison of the processing effects of different ultrasonic rolling equipment.

[0007] To achieve the above objectives, the present invention provides a method for normalizing ultrasonic rolling strengthening parameters, which includes the following steps:

[0008] S0: Determine the processing area of ​​the sample;

[0009] S1: Within the working range of the four processing parameters of static pressure F, rolling gap d, feed speed v, and number of rolling passes n of each ultrasonic rolling strengthening equipment, multiple ultrasonic rolling strengthening experiments are designed using these four processing parameters at different levels.

[0010] S2: Establish a model for the processing time t of a processing area per unit size;

[0011] S3: Using the model of processing time t for a unit-size processing area, a model of the total energy G obtained by a unit-size processing area during ultrasonic rolling is further established;

[0012] S4: Substitute the processing parameters of the ultrasonic rolling strengthening experiment in S1 into the model of total energy G established in S3 to determine the total energy G corresponding to each ultrasonic rolling strengthening experiment designed in S1, as the G factor.

[0013] S5: Perform the ultrasonic rolling strengthening experiment designed in S1 to process the specimens using different ultrasonic rolling strengthening equipment, and obtain the hardness, roughness and residual stress values ​​of the specimens processed by each ultrasonic rolling strengthening equipment under different G factors.

[0014] S6: Plot the interaction diagram of the roughness-G factor, hardness-G factor, and residual stress-G factor of the material of the processed sample.

[0015] It also includes S7: Based on the interaction diagram of roughness-G factor, hardness-G factor and residual stress-G factor of each ultrasonic rolling strengthening device, the evolution law of roughness, hardness and residual stress of the material of the sample processed by the ultrasonic rolling strengthening device with the G factor is obtained, and the selection limit of the G factor of the ultrasonic rolling strengthening device for the material of the sample is given.

[0016] In S1, the ultrasonic rolling strengthening experiment is an orthogonal experiment; for the four processing parameters, namely static pressure F, rolling gap d, feed speed v and number of rolling passes n, multiple values ​​at different levels are selected for each processing parameter, and multiple ultrasonic rolling strengthening experiments are designed to be carried out using different combinations of processing parameters at different levels within the working range of each ultrasonic rolling device and its processing parameters.

[0017] The ultrasonic rolling equipment includes a single-sided sequential strengthening device and a double-sided impact strengthening device. The sample is an aluminum-based material sample. Three different levels of values ​​are selected for each processing parameter.

[0018] In S2, the processing time t for a unit size processing area is:

[0019]

[0020] Where d is the rolling gap, v is the feed speed, and n is the number of rolling passes.

[0021] In S3, the total energy G obtained per unit size of the processed area during ultrasonic rolling is:

[0022]

[0023] Where f is the ultrasonic vibration frequency, d is the rolling gap, v is the feed speed, n is the number of rolling passes; A is the amplitude of the ultrasonic rolling equipment; k() is the dynamic force F. d The functional relationship between A and the static force F, where F is the static force and A is the amplitude of the ultrasonic rolling device.

[0024] In step S5, the ultrasonic rolling strengthening device performs rolling strengthening in a zigzag path within the processing area to process and obtain a sample.

[0025] In S5, the hardness, roughness, and residual stress values ​​of each sample are obtained using characterization experiments.

[0026] The ultrasonic rolling strengthening parameter normalization method of the present invention introduces the G factor as an indicator factor to normalize the processing parameters of different ultrasonic rolling strengthening equipment, thereby enabling horizontal comparison of different ultrasonic rolling strengthening equipment, breaking down the barrier that it is difficult to learn from the experimental parameters of different equipment, thus effectively accumulating experimental data and effectively improving the efficiency of process optimization. Attached Figure Description

[0027] Figure 1 This is a flowchart of the ultrasonic rolling strengthening parameter normalization method of the present invention.

[0028] Figure 2 This is a graph showing the relationship between the energy absorbed by the material, G, and its roughness.

[0029] Figure 3 This is a graph showing the relationship between the energy absorbed by the material (G) and its hardness.

[0030] Figure 4 This is a graph showing the relationship between the energy absorbed by the material, G, and the residual stress. Detailed Implementation

[0031] The embodiments of the present invention are given below and described in detail.

[0032] like Figure 1 The diagram illustrates the ultrasonic rolling strengthening parameter normalization method of the present invention, which can normalize different processing parameters, thereby enabling a horizontal comparison of the processing effects of different ultrasonic rolling equipment. It should be noted that the ultrasonic rolling strengthening parameter normalization method of the present invention is not limited to a specific type of equipment or a single strengthening parameter. The two strengthening methods described in detail below (i.e., the single-sided sequential strengthening device and the double-sided impact strengthening device) are merely examples used for verification and comparison.

[0033] like Figure 1 As shown, the ultrasonic rolling strengthening parameter normalization method of the present invention includes the following steps:

[0034] Step S0: Determine the processing area of ​​the sample; wherein, step S0 is an optional step, and in some embodiments this step may be omitted.

[0035] The processing area can be rectangular, trapezoidal, or circular. In this embodiment, since most samples are flat, a rectangle is convenient for processing, so a rectangle is used as the shape of the processing area.

[0036] Step S0 may further include determining the dimensions of the processing area. The dimensions of the processing area include d1 and d2, where d1 represents the width of the processing area of ​​the sample and d2 represents the length of the processing area of ​​the sample. In other embodiments, the step of determining the dimensions of the processing area may be omitted, and the actual dimensions of the processing area may be replaced by unit area or unit dimension.

[0037] Step S1: Within the working range of the four processing parameters of static pressure F, rolling gap d, feed speed v and number of rolling passes n of each ultrasonic rolling strengthening equipment, multiple ultrasonic rolling strengthening experiments are designed using these four processing parameters at different levels, so as to perform ultrasonic surface strengthening on the sample in the subsequent step S5.

[0038] In this embodiment, the ultrasonic rolling strengthening experiment is designed as an orthogonal experiment. For the four processing parameters—static pressure F, rolling gap d, feed speed v, and number of rolling passes n—multiple values ​​at different levels are selected for each parameter. Furthermore, the multiple ultrasonic rolling strengthening experiments are designed to utilize different combinations of processing parameters at different levels within the working range of each ultrasonic rolling device. These processing parameters are controlled by the operator, meaning that different surface properties can be obtained by adjusting the processing parameters.

[0039] In this embodiment, the ultrasonic rolling equipment includes a single-sided sequential strengthening device and a double-sided impact strengthening device, and the sample is an aluminum-based material sample. According to the different working ranges of the single-sided sequential strengthening device and the double-sided impact strengthening device and the material properties of the aluminum-based material sample, three different levels of values ​​are selected for each processing parameter. For example, the static pressure value is selected as three values: F1, F2, and F3. Each different ultrasonic strengthening device performs multiple strengthening experiments under the condition of using the static pressure values ​​of F1, F2, and F3.

[0040] Step S2: Establish a model for the processing time t of a processing area per unit size;

[0041] Based on the model of processing time t per unit size of processing area, the processing time t per unit size of processing area is:

[0042]

[0043] Where d is the rolling gap, v is the feed speed, and n is the number of rolling passes.

[0044] Step S3: Using the model of the processing time t of a unit-size processing area, further establish a model of the total energy G obtained by the unit-size processing area during ultrasonic rolling.

[0045] The total energy G (i.e., G-factor) obtained per unit size of the processed area during ultrasonic rolling is a normalized result obtained by unifying the four processing parameters based on their physical meaning. By establishing a model and defining the relationship between the G-factor and surface properties, a bridge can be built between processing parameters and surface properties.

[0046] The total energy G gained per unit size of the processed area during ultrasonic rolling is the number of ultrasonic impacts multiplied by the energy of a single impact. The number of ultrasonic impacts is the ultrasonic vibration frequency f of the ultrasonic rolling equipment multiplied by the processing time t per unit size of the processed area, and the energy gained from a single impact is the dynamic force F. d Multiply by the amplitude A of the corresponding ultrasonic rolling equipment.

[0047] Therefore, based on the model of the total energy G obtained per unit size of the processed area during ultrasonic rolling, the total energy G obtained per unit size of the processed area during ultrasonic rolling is:

[0048]

[0049] Where f is the ultrasonic vibration frequency of the ultrasonic rolling equipment, t is the processing time per unit size of the processing area, d is the rolling gap, v is the feed speed, and n is the number of rolling passes; F d The dynamic force is represented by A, and the amplitude of the ultrasonic rolling equipment is represented by A. Both the ultrasonic vibration frequency f and the amplitude A of the ultrasonic rolling equipment are inherent properties of the equipment, and the manufacturer will provide the corresponding amplitude information.

[0050] Dynamic force F d The relationship between F and the static force F is functional, i.e., F d = k(F), where k() represents a functional relationship between the two, which can be obtained through calibration. Therefore, equation (2) can be rewritten as:

[0051]

[0052] Where f is the ultrasonic vibration frequency of the ultrasonic rolling equipment, t is the processing time per unit size of the processing area, d is the rolling gap, v is the feed speed, n is the number of rolling passes, and k() is the dynamic force F. d The functional relationship between A and the static force F, where F is the static force and A is the amplitude of the ultrasonic rolling device.

[0053] Step S4: Substitute the processing parameters of the ultrasonic rolling strengthening experiment in step S1 into the model of the total energy G obtained by the processing area per unit size during the ultrasonic rolling process established in step S3 (i.e. formula (3)) to determine the total energy G corresponding to each ultrasonic rolling strengthening experiment designed in step S1, as the G factor.

[0054] Step S5: Perform the ultrasonic rolling strengthening experiment designed in step S1 to process the specimens using different ultrasonic rolling strengthening equipment, and perform characterization experiments on the processed specimens to obtain the hardness, roughness and residual stress values ​​of the specimens processed by each ultrasonic rolling strengthening equipment under different G factors.

[0055] The ultrasonic rolling strengthening equipment performs rolling strengthening in a zigzag path within the processing area to obtain the sample.

[0056] The hardness, roughness, and residual stress values ​​of each sample were obtained using corresponding characterization experiments. The ultrasonic rolling strengthening experiment and the corresponding characterization experiments both adopted the existing experimental methods. The ultrasonic rolling method can be described in reference [1], while the hardness, roughness, and residual stress tests were measured in accordance with national standards [2]-[5]. No qualitative description is given here. Among them, reference [1] is [S.Yao,X.Cao,S.Liu,C.Gong,K.Zhang,C.Zhang,X.Zhang,Two-sidedultrasonic surface rolling process of aeroengine blades based on on-machinenoncontact measurement,Frontiers of Mechanical Engineering 15(2)(2020)240-255], reference [2] is [GB / T 4342-1991 (Metallic Micro Vickers Hardness Test Method)], reference [3] is [GB / T4340.1-1999 (Metallic Vickers Hardness Test Part 1: Test Method)], reference [4] is [GB / T 7704-2008 (Standard for X-ray Diffraction Determination of Residual Stress)], and reference [5] is [GB / T 7220-1987 (Standard for Surface Roughness Parameter Measurement)].

[0057] Step S6: Plot the interaction diagrams of the roughness-G factor, hardness-G factor, and residual stress-G factor of the processed sample material to compare the processing effects of different ultrasonic rolling strengthening equipment.

[0058] By using the interaction diagrams of roughness-G factor, hardness-G factor, and residual stress-G factor, the processing effects of different ultrasonic rolling strengthening equipment can be compared horizontally, and the superior machine can be selected. Secondly, for the new level of processing parameters, there is no need to conduct tedious experiments to investigate whether they will damage the sample surface.

[0059] Step S7: Based on the interaction diagram of roughness-G factor, hardness-G factor and residual stress-G factor of each ultrasonic rolling strengthening device, obtain the evolution law of roughness, hardness and residual stress of the material of the sample processed by the ultrasonic rolling strengthening device with the G factor, and give the selection limit of the G factor of the ultrasonic rolling strengthening device for the sample material, so as to guide the selection of new processing parameters.

[0060] Therefore, this invention normalizes the processing parameters by introducing the total energy G (i.e., G factor) obtained per unit size of the processing area during ultrasonic rolling. This indicator factor (i.e., G factor) allows for a horizontal comparison of the processing effects of different ultrasonic rolling strengthening equipment, breaking down the barriers to experimental data exploration of ultrasonic rolling strengthening parameters.

[0061] Experimental results:

[0062] The degree of plastic deformation of a material is related to processing parameters such as static pressure, feed rate, processing spacing, and number of processing passes. Theoretically, the more processing passes, the greater the static pressure, the smaller the spacing, and the slower the speed, the more energy the material absorbs. The more energy absorbed, the greater the degree of plastic deformation, the higher the surface residual compressive stress, the thicker the residual compressive stress layer, and the better the fatigue resistance. However, in actual processing, more processing passes, greater static pressure, and smaller spacing do not necessarily lead to better strengthening effects. When the degree of processing exceeds a certain limit, increasing the number of passes or increasing the static pressure will not further increase the depth of the plastic deformation layer. The following uses the ultrasonic rolling strengthening parameter normalization method of this invention to examine the processing effects of two devices, named a single-sided sequential strengthening device and a double-sided impact strengthening device, respectively.

[0063] According to step S5, the material is ultrasonically rolled and strengthened using these two devices (i.e., single-sided sequential strengthening device and double-sided impact strengthening device). The results of the hardness, roughness and residual stress of the strengthened material are shown below:

[0064] Table 1. Orthogonal experimental parameters for single-sided sequential strengthening process

[0065]

[0066] Table 2. Orthogonal experimental parameters for the double-sided punching strengthening process.

[0067]

[0068] In step S4 of this invention, parameter normalization is performed on the two devices. The parameter normalization method is as described in the specific embodiment. The processing parameters of the two ultrasonic enhancement devices are normalized according to the formula. The calculated G-factors are shown in Tables 3 and 4 below:

[0069] Table 3. G-factor parameters of the single-sided sequential strengthening device

[0070]

[0071] Table 4. G-factor parameters of the two-sided counter-shock strengthening device

[0072]

[0073] According to step S6, a graph was plotted with G-factor as the x-axis and roughness, hardness, and residual stress as the y-axis. The result is as follows: Figures 1-3 As shown in the attached figure, data that originally exhibited significant differences in processing parameters due to variations in equipment can be uniformly compared using the G-factor, thereby effectively determining the process range. For example, when the material is used under non-cyclic loading conditions, requiring a high surface roughness of less than 0.5 μm, then according to... Figure 1 The G factor should be less than 150J. Therefore, the G factor corresponding to the new processing parameters calculated is applicable if the G factor is less than 150J.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various modifications can be made to the above embodiments of the present invention. For example, the laser sensor used in the present invention can be replaced by an ultrasonic sensor or other structure, and the model of the color difference measurement device can be changed, etc. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the scope of protection of the claims of this invention. Any aspects not described in detail in this invention are conventional technical content.

Claims

1. A method of normalizing ultrasonic roll bonding parameters, comprising: The method comprises the following steps: S1: in the working range of the four processing parameters of static pressure F, rolling distance d, feeding speed v and rolling number n of each ultrasonic rolling strengthening device, a plurality of ultrasonic rolling strengthening experiments are designed by using different levels of the four processing parameters respectively; S2: a model of processing time t of a unit size processing area is established; In the S2, the processing time t of the unit size processing area is: Wherein, d is the rolling distance, v is the feeding speed, and n is the rolling number; S3: a model of total energy G obtained by a unit size processing area in the ultrasonic rolling process is further established by using the model of processing time t of the unit size processing area; In the S3, the total energy G obtained by the unit size processing area in the ultrasonic rolling process is: wherein f is the ultrasonic vibration frequency, d is the rolling distance, v is the feed speed, n is the rolling number; A is the amplitude of the ultrasonic rolling equipment; k() is the function relationship between the dynamic force F d and the static force F, F is the static force, and A is the amplitude of the ultrasonic rolling equipment; S4: the processing parameters of the ultrasonic rolling strengthening experiment of S1 are substituted into the model of total energy G established in S3 to determine the total energy G corresponding to each ultrasonic rolling strengthening experiment designed in S1 as a G factor; S5: the ultrasonic rolling strengthening experiments designed in S1 are performed to process samples by using different ultrasonic rolling strengthening devices to obtain the hardness, roughness and residual stress values of each sample processed by each ultrasonic rolling strengthening device under different G factors; S6: the roughness-G factor, hardness-G factor and residual stress-G factor interaction diagram of the processed sample material is drawn.

2. The ultrasonic roll bonding parameter normalization method of claim 1, wherein, Further comprising S7: according to the roughness-G factor, hardness-G factor and residual stress-G factor interaction diagram of each ultrasonic rolling strengthening device, the evolution law of the roughness, hardness and residual stress of the sample material processed by the ultrasonic rolling strengthening device with the G factor is obtained, and the selection limit of the G factor of the ultrasonic rolling strengthening device for the sample material is given.

3. The ultrasonic roll bonding parameter normalization method of claim 1 wherein, Before performing the S1, further comprising S0: determining the processing area of the sample.

4. The ultrasonic roll bonding parameter normalization method of claim 1 wherein, In the S1, the ultrasonic rolling strengthening experiment is an orthogonal experiment; for the four processing parameters of static pressure F, rolling distance d, feeding speed v and rolling number n, a plurality of different levels of values are selected for each processing parameter, and a plurality of ultrasonic rolling strengthening experiments are designed to be performed by using different combinations of different levels of processing parameters in the working range of each ultrasonic rolling device and its processing parameters.

5. The ultrasonic roll bonding parameter normalization method of claim 4, wherein, The ultrasonic rolling device comprises a single-face sequential strengthening device and a double-face opposite impact strengthening device, and the sample is an aluminum-based material sample; each processing parameter selects 3 different levels of values.

6. The ultrasonic roll bonding parameter normalization method of claim 1 wherein, In the S5, the ultrasonic rolling strengthening device reciprocates in a zigzag path within the range of the processing area to process the sample.

7. The ultrasonic roll bonding parameter normalization method of claim 1 wherein, In the S5, the hardness, roughness and residual stress values of each sample are obtained by a characterization experiment.

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