An apparatus and method for tilt correction in indentation and scratch testing

Abstract

This invention relates to a device and method for tilt correction in indentation scratch testing, belonging to the field of precision testing. The tilt correction device mainly consists of a stage (1), piezoelectric precision positioning units a (2-a), b (2-b), c (2-c), and a base plate (3). The piezoelectric precision positioning units a (2-a), b (2-b), and c (2-c) are completely identical. The correction method involves using an indentation scratch tester to apply a small load indentation to the three vertices of an isosceles right triangle, measuring the z-coordinates of the three points, and calculating the deflection angles of the sample around the x and y axes. Then, the tilt angle of the sample is corrected using the tilt correction device. The advantages of this invention are: it can accurately measure the tilt angle of the sample; the three sets of flexible mechanisms arranged in an equilateral triangle can reduce the size of the device; and the flexible mechanisms using a two-stage amplification can improve the correction range.

Description

Technical Field

[0001] This invention relates to the field of precision testing, and in particular to a device and method for tilt correction in indentation and scratch testing. It combines indentation and scratch testing technology with precision drive technology, has high correction accuracy and small external size, and can correct the tilt angle of the sample during the indentation and scratch process. Background Technology

[0002] The ultimate failure of engineering materials and their products often stems from minute deformation damage and defects; therefore, the study of the micro- and nano-mechanical properties of materials has become a current hot topic. Indentation scratch testing, as a method that can accurately characterize the surface hardness, micro-friction and wear properties, machinability, and adhesion characteristics of materials, has attracted widespread attention.

[0003] Machining and assembly errors in indentation instruments, as well as sample clamping errors, often result in the sample not being perpendicular to the indenter axis. This leads to a lower contact area in indentation testing, resulting in higher calculated hardness and elastic modulus values. In scratch testing, besides affecting the contact area, it also causes the z-axis adjustment range of the indenter to exceed its limits, causing the scratch to gradually deepen or become shallower. A 2011 study by MS Kashani et al. in Acta Materialia (883-895) showed that a 5° sample tilt produces a 12% error in hardness testing. Therefore, researching devices and methods for correcting sample tilt during indentation is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide an apparatus and method for tilt correction in indentation and scratch testing, solving the aforementioned problems existing in the prior art. This invention possesses high correction accuracy and small external dimensions, and can correct the tilt angle of the sample during the indentation and scratch testing process.

[0005] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0006] A device for tilt correction in pressure scratch testing is characterized in that: the tilt correction device mainly consists of a stage (1), a piezoelectric precision positioning unit a (2-a), a piezoelectric precision positioning unit b (2-b), a piezoelectric precision positioning unit c (2-c) and a base plate (3), wherein the piezoelectric precision positioning unit a (2-a), the piezoelectric precision positioning unit b (2-b) and the piezoelectric precision positioning unit c (2-c) are fixed to the base plate (3) by screws, and the stage (1) is fixed to the piezoelectric precision positioning unit a (2-a), the piezoelectric precision positioning unit b (2-b) and the piezoelectric precision positioning unit c (2-c) by screws;

[0007] The piezoelectric precision positioning units a (2-a), b (2-b), and c (2-c) are completely identical. The piezoelectric precision positioning unit a (2-a) is composed of a flexible mechanism a (201-a), a piezoelectric stack a (202-a), and a wedge block assembly a (203-a). The piezoelectric stack a (202-a) is installed in the square groove of the flexible mechanism a (201-a) and pre-tightened by the wedge block assembly a (203-a). The structures of the piezoelectric precision positioning units b (2-b) and c (2-c) are completely identical to those of the piezoelectric precision positioning unit a (2-a).

[0008] The flexible mechanism a (201-a) includes a first-stage lever amplification mechanism and a second-stage half-bridge amplification mechanism. The amplification mechanism uses an arc-shaped hinge, and the rotation part uses arc-shaped hinges in both the x and y directions.

[0009] The device for tilt correction in pressure scratch testing is characterized in that: the piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), piezoelectric precision positioning unit c (2-c) and base plate (3) are arranged in a centrally symmetrical structure, and the centers of the three rotating hinges form an equilateral triangle.

[0010] A method for tilt correction according to the aforementioned device for tilt correction in indentation testing is characterized by using an indentation tester to apply a small load indentation to the three vertices of an isosceles right triangle, measuring the z-coordinates of the three points, calculating the deflection angles of the sample around the x and y axes, and correcting the tilt angle of the sample using the tilt correction device. The method specifically includes the following steps:

[0011] Step 1: Install the tilt correction device into the indentation scratch tester, and clamp the pre-cleaned test piece onto the tilt correction device. Control the indentation scratch tester to press the piece into the three vertices of the isosceles right triangle with the same load.

[0012] Step 2: Read the z-coordinate values ​​of the three points respectively, and calculate the tilt angles around the x-axis and y-axis using the following formulas;

[0013] (1)

[0014] (2)

[0015] In the formula, , For the tilt angles corresponding to the x-axis and y-axis, The z-coordinate of the right-angle vertex. , This represents the z-coordinate value of the corresponding vertex on the x-axis or y-axis. Let be the length of the right-angled side of the isosceles right triangle;

[0016] Step 3: Calculate the required elongation of piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), and piezoelectric precision positioning unit c (2-c):

[0017] (3)

[0018] (4)

[0019] (5)

[0020] In the formula, Let the side length of the equilateral triangle be . , and These represent the elongation of the three piezoelectric precision positioning units;

[0021] Step 4: Control the piezoelectric precision positioning units a (2-a), b (2-b), and c (2-c) of the tilt correction device to extend or shorten to the corresponding lengths. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate the invention and are used to explain it, but do not constitute an undue limitation of the invention.

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 This is a schematic diagram of the piezoelectric precision positioning unit a (2-a) of the present invention;

[0025] Figure 3 This is a schematic diagram of the piezoelectric precision positioning unit b (2-b) of the present invention;

[0026] Figure 4 This is a schematic diagram of the piezoelectric precision positioning unit c (2-c) of the present invention;

[0027] Figure 5 This is a schematic diagram of the tilt angle measurement method of the present invention;

[0028] Figure 6 This is a diagram showing the rotation center distribution of piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), and piezoelectric precision positioning unit c (2-c) of the present invention;

[0029] In the figure: 1. Stage; 2-a. Piezoelectric precision positioning unit a; 2-b. Piezoelectric precision positioning unit b; 2-c. Piezoelectric precision positioning unit c; 201-a. Flexible mechanism a; 202-a. Piezoelectric stack a; 203-b. Wedge block a; 201-a. Flexible mechanism b; 202-b. Piezoelectric stack b; 203-b. Wedge block b; 201-c. Flexible mechanism c; 202-c. Piezoelectric stack c; 203-c. Wedge block c; 3. Base plate. Detailed Implementation

[0030] The following description, in conjunction with the accompanying drawings, further illustrates the detailed content of the present invention and its specific embodiments.

[0031] See Figure 1 As shown, a device for tilt correction in pressure scratch testing is characterized in that: the tilt correction device mainly consists of a stage (1), a piezoelectric precision positioning unit a (2-a), a piezoelectric precision positioning unit b (2-b), a piezoelectric precision positioning unit c (2-c) and a base plate (3). The piezoelectric precision positioning units a (2-a), b (2-b) and c (2-c) are fixed to the base plate (3) by screws, and the stage (1) is fixed to the piezoelectric precision positioning units a (2-a), b (2-b) and c (2-c) by screws.

[0032] See Figures 2 to 4 The piezoelectric precision positioning units a (2-a), b (2-b), and c (2-c) are completely identical. The piezoelectric precision positioning unit a (2-a) is composed of a flexible mechanism a (201-a), a piezoelectric stack a (202-a), and a wedge block assembly a (203-a). The piezoelectric stack a (202-a) is installed in the square groove of the flexible mechanism a (201-a) and pre-tightened by the wedge block assembly a (203-a). The structures of the piezoelectric precision positioning units b (2-b) and c (2-c) are completely identical to those of the piezoelectric precision positioning unit a (2-a).

[0033] The flexible mechanism a (201-a) includes a first-stage lever amplification mechanism and a second-stage half-bridge amplification mechanism. The amplification mechanism uses an arc-shaped hinge, and the rotation part uses arc-shaped hinges in both the x and y directions.

[0034] The device for tilt correction in pressure scratch testing is characterized in that: the piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), piezoelectric precision positioning unit c (2-c) and base plate (3) are arranged in a centrally symmetrical structure, and the centers of the three rotating hinges form an equilateral triangle.

[0035] A method for tilt correction according to the aforementioned device for tilt correction in indentation testing is characterized by using an indentation tester to apply a small load indentation to the three vertices of an isosceles right triangle, measuring the z-coordinates of the three points, calculating the deflection angles of the sample around the x and y axes, and correcting the tilt angle of the sample using the tilt correction device. The method specifically includes the following steps:

[0036] Step 1: Install the tilt correction device into the indentation scratch tester, and clamp the pre-cleaned test piece onto the tilt correction device. Control the indentation scratch tester to press the piece into the isosceles right triangle with the same load at each of the three vertices. See [link to relevant documentation]. Figure 5 ;

[0037] Step 2: Read the z-coordinate values ​​of the three points respectively, and calculate the tilt angles around the x-axis and y-axis using the following formulas;

[0038] (1)

[0039] (2)

[0040] In the formula, , For the tilt angles corresponding to the x-axis and y-axis, The z-coordinate of the right-angle vertex. , This represents the z-coordinate value of the corresponding vertex on the x-axis or y-axis. Let be the length of the right-angled side of the isosceles right triangle;

[0041] Step 3, see Figure 6 The required elongation of piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), and piezoelectric precision positioning unit c (2-c) was calculated.

[0042] (3)

[0043] (4)

[0044] (5)

[0045] In the formula, Let the side length of the equilateral triangle be . , and These represent the elongation of the three piezoelectric precision positioning units;

[0046] Step 4: Control the piezoelectric precision positioning units a (2-a), b (2-b), and c (2-c) of the tilt correction device to extend or shorten to the corresponding lengths.

[0047] Example:

[0048] This invention proposes an apparatus and method for tilt correction in indentation and scratch testing, which corrects the tilt of the sample. The following examples further illustrate the implementation process and beneficial effects of this invention.

[0049] The tilt correction device is connected to the scratch indenter with screws, and then the sample is cured with paraffin and attached to the tilt correction device. See also Figure 5 With l set to 50 μm, the coordinates of the three points were determined to be (0, 0), (50, 0), and (0, 50). A 1 mN indentation was applied at each of the three points, and the z-direction displacements during indentation were obtained as 2.863 μm, 3.975 μm, and 3.264 μm, respectively. The values ​​were calculated using equations (1) and (2). 1.27° It is 0.52°. It is designed to be [specific value] during the manufacturing process. The value is 15mm, calculated using equations (3), (4), and (5). 0, 332.5μm, The value is 284.1 μm. The three sets of piezoelectric precision positioning units are controlled to extend to the specified length to complete the sample tilt correction.

[0050] The results from the examples show that a device and method for tilt correction in indentation and scratch testing can be used to correct the tilt of the sample during the indentation and scratch process. It has the advantages of simple structure, easy operation and high correction accuracy.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made to the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for tilt correction in indentation and scratch testing, characterized in that: A device for tilt correction in pressure scratch testing is used to perform tilt correction. The device mainly consists of a stage (1), piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), piezoelectric precision positioning unit c (2-c), and a base plate (3). The piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), and piezoelectric precision positioning unit c (2-c) are fixed to the base plate (3) with screws. The stage (1) is fixed to the piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), and piezoelectric precision positioning unit c (2-c) with screws. The piezoelectric precision positioning units a (2-a), b (2-b), and c (2-c) are completely identical. The piezoelectric precision positioning unit a (2-a) is composed of a flexible mechanism a (201-a), a piezoelectric stack a (202-a), and a wedge block assembly a (203-a). The piezoelectric stack a (202-a) is installed in the square groove of the flexible mechanism a (201-a) and pre-tightened by the wedge block assembly a (203-a). The structures of the piezoelectric precision positioning units b (2-b) and c (2-c) are completely identical to those of the piezoelectric precision positioning unit a (2-a). The flexible mechanism a (201-a) includes a first-stage lever amplification mechanism and a second-stage half-bridge amplification mechanism. The amplification mechanism uses an arc-shaped hinge, and the rotation part uses arc-shaped hinges in both the x and y directions. The piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), piezoelectric precision positioning unit c (2-c) and base plate (3) are arranged in a centrally symmetrical structure, and the centers of their three rotating hinges form an equilateral triangle; Using an indentation tester, small load indentations are made at the three vertices of an isosceles right triangle. The z-coordinates of the three points are measured, and the deflection angles of the sample around the x and y axes are calculated. The tilt angle of the sample is then corrected using a tilt correction device. The specific steps include: Step 1: Install the tilt correction device into the indentation scratch tester, and clamp the pre-cleaned test piece onto the tilt correction device. Control the indentation scratch tester to press the piece into the three vertices of the isosceles right triangle with the same load. Step 2: Read the z-coordinate values ​​of the three points respectively, and calculate the tilt angles around the x-axis and y-axis using the following formulas; （1） （2） In the formula, , For the tilt angles corresponding to the x-axis and y-axis, The z-coordinate of the right-angle vertex. , This represents the z-coordinate value of the corresponding vertex on the x-axis or y-axis. Let be the length of the right-angled side of the isosceles right triangle; Step 3: Calculate the required elongation of piezoelectric precision positioning unit a (2-a), piezoelectric precision positioning unit b (2-b), and piezoelectric precision positioning unit c (2-c): （3） （4） （5） In the formula, Let the side length of the equilateral triangle be . , and These represent the elongation of the three piezoelectric precision positioning units; Step 4: Control the piezoelectric precision positioning units a (2-a), b (2-b), and c (2-c) of the tilt correction device to extend or shorten to the corresponding lengths.

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