Test Method for Ultrasonic Roller Burnishing of Metal Material Surface Strengthening

Abstract

The present invention discloses a test method for ultrasonic rolling processing of metal material surface strengthening, including: Step 10, determining test factors and levels of each test factor according to the metal material to be surface-strengthened; Step 20, referring to the orthogonal table, designing an orthogonal test table according to the determined test factors and levels of each test factor; Step 30, calculating the equivalent energy factor G of each test according to the levels of each test factor in each test in the orthogonal test table; Step 40, determining a similar test group including tests with similar equivalent energy factor G, deleting at least one test and retaining at least one test in the similar test group; Step 50, updating the orthogonal test table and conducting tests according to the updated orthogonal test table. Applying this test method can optimize and reduce the number of tests.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic rolling processing for surface strengthening of metal materials, and particularly relates to a test method for ultrasonic rolling processing for surface strengthening of metal materials. Background Art

[0002] Ultrasonic rolling processing is a good surface strengthening means, and can also be used for secondary repair of such components that have been put into use on the surface of damaged workpieces, such as aircraft engine blades, to extend the service life cycle, and is of great significance to the surface integrity of metal materials in terms of surface roughness, introduced residual compressive stress, microhardness, and microcrystalline grain scale.

[0003] Ultrasonic rolling processing is a working method that combines ultrasonic impact energy and static load rolling, and is a more efficient processing method. Among the existing processing tool heads that combine ultrasonic and rolling, one is to fix the rolling tool on a rotating frame to process the axial and radial surfaces; the other is to combine the force-applying component with a rolling cylindrical working head to process the flat surface. For example, the Chinese patent application with the application number 201610823005.3 provides a method for ultrasonic rolling process. The method of applying ultrasonic rolling to strengthen the surface of metal materials has important economic and practical value and broad application prospects.

[0004] The ultrasonic rolling process is currently carrying out application verification work on key components of aeroengines. The process parameters that affect surface integrity include static pressure, rolling speed, rolling pitch, number of rolling passes, ball amplitude, ultrasonic frequency, etc. There are many process control parameters for ultrasonic rolling processing, and the prior art requires multiple tests during the process verification, which is time-consuming and laborious. Summary of the Invention

[0005] The purpose of the present invention is to provide a test method for ultrasonic rolling processing for surface strengthening of metal materials. Using this test method can optimize and reduce the number of tests.

[0006] The present invention discloses a test method for ultrasonic rolling processing for surface strengthening of metal materials, including:

[0007] Step 10: Determine the test factors and the levels of each test factor according to the metal material to be surface-strengthened;

[0008] Step 20: Refer to the orthogonal table and design an orthogonal test table according to the determined test factors and the levels of each test factor;

[0009] Step 30: Calculate the equivalent energy factor G of each test by combining the levels of each test factor in each test in the orthogonal test table;

[0010] Step 40, determine similar test groups including tests with similar equivalent energy factor G, and delete at least one test and retain at least one test in the similar test groups;

[0011] Step 50, update the orthogonal test table, and conduct tests according to the updated orthogonal test table.

[0012] In some embodiments, the equivalent energy factor G is calculated according to the following formula:

[0013] G = k·F·A·f·t

[0014] where F is the static pressure of ultrasonic rolling, A is the amplitude of the rolling ball in ultrasonic rolling, f is the ultrasonic frequency, t is the processing time of single test ultrasonic rolling, k is a coefficient. When the test method includes single-sided ultrasonic rolling processing of the metal material, k = 1; when the test method includes double-sided impact ultrasonic rolling processing of the metal material, k = 2.

[0015] In some embodiments, the test method includes that when conducting each test, the number of rolling passes of the rolling ball in ultrasonic rolling on the surface of the metal material is n; in each rolling pass, the rolling of the rolling ball adopts a reciprocating linear motion with a "rectangular wave" trajectory. The length L of the main motion of the reciprocating linear motion of the rolling ball defines the length of the processing area, the width of the feed motion of the reciprocating linear motion of the rolling ball is d, the feed motion defines the width direction of the processing area, the width size of the processing area is W, and the rolling speed of the rolling ball on the surface of the metal material is v; wherein, the equivalent energy factor G is calculated according to the following formula:

[0016] G = k·F·A·f·(FLOOR(W / d)+1)·L·n / v

[0017] where FLOOR() is the floor function.

[0018] In some embodiments, the test factors include the static pressure of ultrasonic rolling, the rolling speed of the rolling ball on the surface of the metal material, the width of the feed motion of the reciprocating linear motion of the rolling ball, and the number of rolling passes of the rolling ball in ultrasonic rolling on the surface of the metal material.

[0019] In some embodiments, determining the similar test groups including tests with similar equivalent energy factor G includes: calculating the relative deviation degree between each pair of the equivalent energy factors G of each test, and determining each test with the relative deviation degree values calculated between any two equivalent energy factors G all within the first threshold range as a similar test group.

[0020] In some embodiments, the first threshold range is determined according to the surface properties of the metal material.

[0021] In some embodiments, the metal material includes a TiB2 particle-reinforced aluminum matrix composite material.

[0022] In some embodiments, determining similar test groups including tests with similar equivalent energy factor G includes: calculating the relative deviation degrees between each pair of the equivalent energy factor G of each test, and determining each test for which the values of the relative deviation degrees calculated for any two equivalent energy factor G are both within the first threshold range as a similar test group, where the first threshold range is (-10%, +10%).

[0023] Based on the test method for ultrasonic rolling processing of metal material surface strengthening provided by the present invention, by designing an orthogonal test according to the determined test factors and levels, when verifying parameters affecting surface integrity such as residual compressive stress and microhardness, the number of tests can be optimized and reduced. At the same time, for the initially designed orthogonal test table, by calculating the equivalent energy factor G and deleting the tests with similar equivalent energy factor G in the orthogonal test table, the tests in the orthogonal test table can be further optimized and reduced.

[0024] Through the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, other features and advantages of the present invention will become clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of this application. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0026] Figure 1 is a flowchart of the test method for ultrasonic rolling processing of metal material surface strengthening according to an embodiment of the present invention;

[0027] Figure 2 is the surface of the metal material when the ball is rolling once in the test method for ultrasonic rolling processing of metal material surface strengthening according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0029] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0030] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper" etc. may be used here to describe the spatial positional relationship of one device or feature shown in the figure with other devices or features. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is inverted, the device described as "above" or "over" other devices or structures will then be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations are made for the spatial relative descriptions used here.

[0031] As Figure 1 shown, the test method for ultrasonic roller burnishing processing of the surface strengthening of the metal material in this embodiment includes:

[0032] Step 10, determining the test factors and the levels of each test factor according to the metal material to be surface strengthened.

[0033] The metal material to be surface strengthened can be materials such as pure metal materials, metal matrix composites, etc. First, according to the material property requirements of the surface strengthening to be carried out, determine the test factors (i.e., the process parameters of ultrasonic roller burnishing, such as the static pressure of the ball, the rolling speed of the ball, etc.) that need to be verified for their influence on the surface integrity (such as microhardness, residual compressive stress, etc.) and the levels corresponding to each test factor. When determining the levels of the test factors, first determine the value range of each test factor, and then take several levels to be verified (i.e., several specific numerical values) for each factor within the value range.

[0034] Step 20: Refer to the orthogonal array and design an orthogonal test table based on the determined test factors and the levels of each test factor.

[0035] After determining the test factors to be verified and the levels of each test factor, refer to the orthogonal array template, select a suitable orthogonal array, and design an orthogonal test table for the process parameters of ultrasonic rolling.

[0036] Step 30: Calculate the equivalent energy factor G for each test based on the levels of each test factor in each test in the orthogonal test table.

[0037] In the designed orthogonal test table, there are multiple tests to be carried out. Each test is a combination of the levels of each test factor, that is, each test factor has a value under each test. At this time, combining the values of each test factor and other process parameters, the equivalent energy factor G of each test can be calculated.

[0038] Step 40: Determine the similar test groups including tests with similar equivalent energy factors G. At least one test should be deleted and at least one test should be retained in the similar test groups.

[0039] After calculating the equivalent energy factor G for each test, group the tests with similar equivalent energy factors G into a similar test group. Then, the equivalent energy factors G of the tests in the same similar test group are all similar. The effects of the tests with similar equivalent energy factors in the orthogonal test table on the surface integrity of ultrasonic rolling surface strengthening of metal materials are approximately the same. To improve the test efficiency, some tests can be deleted to optimize the number of tests.

[0040] Step 50: Update the orthogonal test table and conduct tests according to the updated orthogonal test table.

[0041] After deleting some tests in the orthogonal test table using the equivalent energy factor, update the orthogonal test table, and then conduct relevant tests according to the orthogonal test table.

[0042] The test method for ultrasonic rolling of metal material surface strengthening in this embodiment can optimize and reduce the number of tests when verifying the parameters affecting the surface integrity such as residual compressive stress and microhardness by designing an orthogonal test according to the determined test factors and levels. At the same time, for the initially designed orthogonal test table, by calculating the equivalent energy factor G, for some tests with similar equivalent energy factors in the orthogonal test table, their effects on the surface integrity such as microhardness, residual compressive stress, and surface roughness are similar. To improve the test efficiency, tests with similar equivalent energy factors G can be deleted in the orthogonal test table to further optimize and reduce the tests in the orthogonal test table.

[0043] In some embodiments, the equivalent energy factor G is calculated according to the following formula:

[0044] G = k·F·A·f·t

[0045] Wherein, F is the static pressure of the ball on the surface of the metal material during ultrasonic rolling processing, A is the amplitude of the ball in ultrasonic rolling, f is the ultrasonic frequency, t is the processing time of ultrasonic rolling in a single test, that is, the time when the surface of the metal material is subjected to ultrasonic rolling action, k is a coefficient. When the test method includes single-sided ultrasonic rolling processing of the metal material, k = 1; when the test method includes double-sided impact ultrasonic rolling processing of the metal material, k = 2.

[0046] Single-sided ultrasonic rolling processing means that only one surface of the metal material is subjected to ultrasonic rolling processing in one test. Double-sided impact ultrasonic rolling processing means that in one test, two balls are used to simultaneously perform ultrasonic rolling on the opposite sides of the surface of the metal material. The static pressure, ball amplitude, ultrasonic frequency, etc. are the same during ultrasonic rolling, which can reduce the deformation caused by the processing of the metal material, and has good processing effect and high efficiency.

[0047] In some embodiments, the test method includes that during each test, the number of rolling passes of the ball in ultrasonic rolling on the surface of the metal material is n, that is, in one test, the same surface of the metal material is rolled multiple times; in each rolling pass, the rolling of the ball adopts a reciprocating linear motion with a "rectangular wave" trajectory. The length L of the main motion of the reciprocating linear motion of the ball defines the length of the processing area, the width of the feed motion of the reciprocating linear motion of the ball is d, the feed motion defines the width direction of the processing area, the width size of the processing area is W, and the rolling speed of the ball on the surface of the metal material is v. That is, as Figure 2 shown, in each rolling pass, the rolling path of the ball is a "rectangular wave" path. The main motion of the ball rolling is a linear rolling motion along the length L direction. After the ball rolls from the first side to the second side along the length direction, it moves d along the width direction, and then rolls from the second side in the length direction back to the first side along the length direction. The length L is much larger than the width d of the feed motion, and the time of the ball in the feed motion is less and can be ignored. The equivalent energy factor G is calculated according to the following formula:

[0048] G = k·F·A·f·(FLOOR(W / d)+1)·L·n / v

[0049] Wherein, FLOOR() is a floor function for calculating the largest integer not greater than the given value. For example, FLOOR(0.9) is equal to 0, and FLOOR(2.2) is equal to 2.

[0050] In some embodiments, the test factors include the static pressure of the ball in ultrasonic rolling, the rolling speed of the ball on the surface of the metal material, the width of the feed motion of the reciprocating linear motion of the ball, and the number of rolling passes of the ball in ultrasonic rolling on the surface of the metal material.

[0051] In some embodiments, determining a similar test group including tests with similar equivalent energy factors G includes calculating relative deviations between the equivalent energy factors G of each test, and determining as a similar test group any tests for which the calculated relative deviations of any two equivalent energy factors G are within a first threshold range. The first threshold range is determined based on the surface properties of the metal material. The relative deviations are calculated using the following formula:

[0052] (G x -G y ) / G x or (G x -G y ) / G y , where G x , G y Represents the equivalent energy factors of any two different tests, that is, calculate the relative deviation of the equivalent energy factors of the two tests, make the difference between the equivalent energy factors of the two tests and then divide it by the equivalent energy factor of any one of the two tests.

[0053] The present invention is illustrated below with a specific embodiment.

[0054] Step 10: Determine the test factors and the levels of each test factor according to the metal material to be surface strengthened.

[0055] In this example, the metal material to be surface-strengthened by ultrasonic rolling is a TiB2 particle-reinforced aluminum-based composite material (hardness 120 HV, yield strength 460 MPa), and single-sided ultrasonic rolling is used. The test factors to be determined are static pressure, rolling speed, the width of the ball's reciprocating linear motion feed, and the number of rolling passes. The levels of each test factor are shown in the following table:

[0056] Table 1 Process parameters of ultrasonic rolling test of TiB2 particle reinforced aluminum matrix composites

[0057]

[0058] Step 20, referring to the orthogonal table, designing an orthogonal test table according to the determined test factors and the levels of each test factor.

[0059] Based on orthogonality, some representative points are selected from the comprehensive test for testing. These representative points have the characteristics of "uniform dispersion, neatness and comparability". It is a highly efficient, fast and economical experimental design method. Combined with other process parameters of actual ultrasonic rolling (ultrasonic frequency is 20000Hz, ball amplitude is 7um), according to the four experimental factors selected in the above table, each experimental factor has three levels. Since this is a four-factor three-level multi-index problem, if a comprehensive experimental design is required, three4 = 81 tests, while only 9 tests are required using the orthogonal experimental design L9(3 4 ). The designed orthogonal experimental table is as follows:

[0060] Table 2 Initial orthogonal experimental table for ultrasonic rolling tests of TiB2 particle-reinforced aluminum matrix composites

[0061]

[0062] Step 30, calculate the equivalent energy factor G for each test factor level of each test in the orthogonal experimental table.

[0063] Calculate the equivalent energy factor G for each numbered test. The results are as follows:

[0064] Table 3 Equivalent energy factor for ultrasonic rolling tests of TiB2 particle-reinforced aluminum matrix composites

[0065]

[0066] Step 40, determine the similar test groups including tests with similar equivalent energy factor G. At least one test should be deleted and at least one test should be retained in the similar test groups.

[0067] For the second threshold range of TiB2 particle-reinforced aluminum matrix composites, it is (-10%, +10%). Calculate the relative deviation degree for any two of the equivalent energy factor G of each test. The tests for which the relative deviation degree of any two equivalent energy factor G calculated according to Table 3 is within (-10%, +10%) mainly include the test numbered 9 and the test numbered 1, and the test numbered 3 and the test numbered 5. Group the test numbered 9 and the test numbered 1 as similar test group 1, and group the test numbered 3 and the test numbered 5 as similar test group 2. Delete the test numbered 9 within similar test group 1, and delete the test numbered 5 within similar test group 2.

[0068] Step 50, update the orthogonal experimental table and conduct tests according to the updated orthogonal experimental table.

[0069] The updated orthogonal experimental table is as follows:

[0070] Table 4 Final orthogonal experimental table for ultrasonic rolling tests of TiB2 particle-reinforced aluminum matrix composites

[0071]

[0072] Conduct tests according to the updated orthogonal experimental table.

[0073] To verify the effectiveness of the method of optimizing the number of tests using the equivalent energy factor, in this embodiment, in addition to conducting tests according to the above table, we also conducted tests on the deleted numbered tests. For the test results, we measured the microhardness and residual compressive stress on the surface of the TiB2 particle-reinforced aluminum matrix composite for each test. The error of the measuring tool for microhardness is 4%, and the error of the measuring tool for residual compressive stress is 0.1σ s (σ s is the yield strength. In this test, the yield strength of the TiB2 particle-reinforced aluminum matrix composite is 460 MPa, and the error of the measuring tool for residual compressive stress is 46 MPa) The test results are as follows:

[0074] Table 5 Ultrasonic rolling test results of TiB2 particle-reinforced aluminum matrix composite

[0075]

[0076] According to Table 5, it can be seen that for the test results of the test numbered 9 deleted in the similar test group 1, the microhardness and residual compressive stress are similar to those of the test numbered 1, and the differences in the results are within the error range of the measuring tool. For the test results of the test numbered 5 deleted in the similar test group 2, the microhardness and residual compressive stress are similar to those of the test numbered 3, and the differences in the results are within the error range of the measuring tool. It can be verified that the method of optimizing the tests using the equivalent energy factor G in the orthogonal test in this embodiment is effective.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered by the scope of the technical solutions claimed by the present invention.

Claims

1. An experimental method for ultrasonic rolling processing of metal material surface strengthening, characterized in that Including: Step 10: Determine the test factors and the levels of each test factor according to the metal material to be surface strengthened; Step 20: Refer to the orthogonal array and design an orthogonal test table according to the determined test factors and the levels of each test factor; Step 30: Calculate the equivalent energy factor G of each test by combining the levels of each test factor in each test in the orthogonal test table; Step 40: Determine the similar test groups including the tests with similar equivalent energy factor G, and delete at least one test and retain at least one test in the similar test groups; Step 50: Update the orthogonal test table and conduct tests according to the updated orthogonal test table; Among them, the equivalent energy factor G is calculated according to the following formula: G = k·F·A·f·t Where, F is the static pressure of ultrasonic rolling, A is the amplitude of the rolling ball in ultrasonic rolling, f is the ultrasonic frequency, t is the processing time of ultrasonic rolling for a single test, and k is a coefficient. When the test method includes single-sided ultrasonic rolling processing of the metal material, k = 1; when the test method includes double-sided impact ultrasonic rolling processing of the metal material, k = 2.

2. The test method for ultrasonic rolling strengthening of the metal material surface according to claim 1, characterized in that, The test method includes that when conducting each test, the number of rolling passes of the rolling ball in ultrasonic rolling on the surface of the metal material is n; in each rolling pass, the rolling of the rolling ball adopts a reciprocating linear motion with a "rectangular wave" trajectory. The length L of the main motion of the reciprocating linear motion of the rolling ball defines the length of the processing area, the width of the feed motion of the reciprocating linear motion of the rolling ball is d, the feed motion defines the width direction of the processing area, the width size of the processing area is W, and the rolling speed of the rolling ball on the surface of the metal material is v; among them, the equivalent energy factor G is calculated according to the following formula: G = k·F·A·f·(FLOOR(W / d)+1)·L·n / v Where, FLOOR() is the floor function.

3. The test method for ultrasonic rolling strengthening of metal material surfaces as described in claim 2, wherein, The test factors include the static pressure of ultrasonic rolling, the rolling speed of the rolling ball on the surface of the metal material, the width of the feed motion of the reciprocating linear motion of the rolling ball, and the number of rolling passes of the rolling ball in ultrasonic rolling on the surface of the metal material.

4. The test method for ultrasonic rolling strengthening of the metal material surface according to claim 1, wherein Determining the similar test groups including the tests with similar equivalent energy factor G includes: calculating the relative deviation degree between each pair of the equivalent energy factors G of each test, and determining each test with the relative deviation degree values calculated from any two equivalent energy factors G all within the first threshold range as a similar test group.

5. The test method for ultrasonic rolling strengthening of metal material surface as described in claim 4, characterized in that, Determine the first threshold range according to the surface properties of the metal material.

6. The test method for ultrasonic rolling strengthening of metal material surface according to any one of claims 1 to 5, characterized in that, The metal material includes TiB2 particle-reinforced aluminum matrix composite material.

7. The test method for ultrasonic roller burnishing of metal material surface strengthening according to claim 6, characterized in that Determining the similar test groups including the tests with similar equivalent energy factor G includes: calculating the relative deviation degree between each pair of the equivalent energy factors G of each test, and determining each test with the relative deviation degree values calculated from any two equivalent energy factors G all within the first threshold range as a similar test group, where the first threshold range is (-10%, +10%).

Images