A single crystal diamond circular arc cutter index blade grinding direction optimization method

Abstract

A method for optimizing the grinding direction of a single-crystal diamond circular arc tool includes three steps: determining the tool grinding trajectory model, constructing the tool grinding direction deviation function, and optimizing the tool grinding direction. This method targets the mechanical indexing grinding process of single-crystal diamond circular arc tools. Taking the single-crystal diamond circular arc tool as the research object, it compares the deviation between the actual grinding direction and the expected easy-to-grind direction, processes this difference to obtain a squared error loss value, and determines the magnitude of the gap between the current tool grinding direction and the expected easy-to-grind direction. Based on the grinding trajectory model, a variable-step search method is used to adjust the controller output, causing the actuator (the X and Y axis motors of the machine tool) to move the tool, changing the tool's grinding position on the grinding wheel, so that the tool grinding direction reaches or approaches the easy-to-grind direction. This invention uses a variable-step search method to achieve online optimization of the tool grinding direction, eliminating the time required for offline diamond crystal orientation, making it more automated and intelligent, and effectively improving tool grinding efficiency and grinding level.

Description

Technical Field

[0001] This invention relates to the field of ultra-precision machining technology, and in particular to a method for optimizing the indexing and grinding direction of a single-crystal diamond circular arc cutting tool. Background Technology

[0002] For ultra-precision machining processes, achieving high precision in part shape and size and ultra-smooth machined surfaces requires not only ultra-precision machine tools, high-resolution testing instruments, and ultra-stable machining environments, but also high-precision diamond cutting tools. With the continuous development of ultra-precision machining technology, the requirements for ultra-precision cutting tools are also increasing, especially when dealing with various difficult-to-machine composite materials, engineering ceramics, and hard and brittle non-metallic materials, where the need for ultra-precision cutting tools becomes even more urgent. Single-crystal diamond possesses excellent physical properties such as high hardness, good wear resistance, high strength, and good thermal conductivity, as well as excellent corrosion resistance and chemical stability. During cutting, it is not prone to sticking or building up edge, and can be ground to produce extremely sharp cutting edges. These characteristics make single-crystal diamond tools irreplaceable in the field of modern cutting and machining, and it is hailed as one of the most promising tool materials of our time. However, the high hardness, wear resistance, difficulty in welding, and anisotropy of single-crystal diamond crystals themselves bring great challenges to tool processing. Both grinding efficiency and grinding accuracy must be considered. Therefore, when using mechanical grinding to process arc-shaped tools, an indexing grinding method is adopted, using a multi-face combination for small-scale grinding to create a flank face that is approximately arc-shaped. Current technology involves determining the easy-grinding direction of each indexed grinding surface offline during the grinding process to improve the grinding efficiency of arc-shaped tools. This method mainly relies on manual or instrumental judgment, which requires a high level of experience and is time-consuming. To further improve tool grinding efficiency, this invention, based on the online identification of grinding direction for single-crystal diamond tools, studies an online optimization method for the grinding direction of single-crystal diamond tools, thereby improving the grinding efficiency of arc-shaped tools and ultimately improving the grinding quality of tools. Summary of the Invention

[0003] The purpose of this invention is to provide a method for optimizing the grinding direction of single-crystal diamond circular arc tools. This method focuses on the mechanical indexing grinding process of single-crystal diamond circular arc tools. Taking the single-crystal diamond circular arc tool as the research object, it compares the deviation between the actual grinding direction and the expected easy-grinding direction, processes this difference to obtain the squared error loss value, and judges the size of the gap between the current tool grinding direction and the expected easy-grinding direction. Based on the grinding trajectory model, a step search method with variable step size is adopted to adjust the controller output, so that the actuator (the X and Y axis motors of the machine tool) moves the tool, changes the grinding position of the tool on the grinding wheel, and makes the tool grinding direction reach or approach the easy-grinding direction. The step search method with variable step size can realize online optimization of the tool grinding direction.

[0004] A method for optimizing the grinding direction of a single-crystal diamond circular arc cutting tool includes the following steps:

[0005] Step 1: Determining the tool grinding trajectory model

[0006] When sharpening a single-crystal diamond circular arc tool, the crystal orientation of the first face is generally selected at the grinding contact point A, which is located in the middle of the grinding disk radius. This ensures that the sharpening speed is appropriate and that the tool is not affected by vibration during sharpening, thus preventing a decrease in tool quality. The back face is indexed and sharpened to form a circular arc. After each index face is sharpened, the tool is rotated by one index angle to sharpen the next index face. Due to the anisotropy of diamond crystals, the sharpening efficiency of different crystal orientations on different crystal faces is different. Usually, based on the hardness distribution curves of the three typical crystal faces of diamond crystals, namely (100), (110), and (111), the easy-to-grind direction on the index face is found on the single-crystal diamond tool by instrument measurement. If the machining of the circular arc tool requires sharpening five index faces in sequence, according to experimental analysis, the easy-to-grind position point of each index face can be determined in advance by measurement method to form a sharpening trajectory. During actual sharpening, after reaching the sharpening trajectory point, the identification model determines whether the sharpening direction of the current indexing surface is the easy-to-sharpen direction. If there is a deviation, the tool position is moved near the trajectory point according to the direction optimization method, so that the tool is sharpened in the easy-to-sharpen direction.

[0007] Step 2: Construction of the tool grinding direction deviation function

[0008] To better optimize the tool's grinding direction, it is necessary to understand the deviation between the current grinding direction and the expected grinding direction. This requires constructing a "deviation function," where the deviation function value represents the magnitude of the deviation. The variable parameters in the deviation function are the displacements of the tool position on the x and y axes, ∆x and ∆y. By gradually adjusting the parameters of the deviation function, the deviation function gradually decreases until it reaches its minimum value, i.e., the parameters are gradually optimized to the optimal level, thereby obtaining the most suitable position parameters so that the tool's grinding surface is closest to the grinding direction. This invention compares the deviation between the actual grinding direction and the expected grinding direction, processes this deviation to obtain the squared error loss value, and constructs the deviation function as shown in equation (1).

[0009] (1)

[0010] In the formula: z This indicates the deviation of the current tool sharpening direction from the expected easy-to-sharpen direction. a i For the target category vector, b i This is the current identified category vector. k iThese are the weighting coefficients.

[0011] Weight coefficients k i The determination depends on the specific experimental conditions and requires continuous experimentation. k i The optimal value is (1.6, 1.2, 1).

[0012] Step 3: Optimization method for tool sharpening direction.

[0013] The position of the cutting tool on the grinding wheel ( x , y The change in these two variables will affect the magnitude of the deviation function value. There are various implementation methods for optimization systems with these two variables. This invention is based on the step-by-step search method in automatic search optimization control to control the change in tool position. Based on an understanding of the characteristics of the grinding machine tool, the search range of the coordinate parameters can be roughly determined, and a definite starting point can be found. x 0, y 0). After giving a starting point, first follow along x Increase the positive axis by one step ∆ x i , ∆ x i This is called the step size. The change in the deviation function value ∆ is then calculated. z i = z i - z i-1 If ∆ z i <0, meaning the deviation function value decreases, indicates that the tool is moving towards the easier-to-grind direction, and the optimization direction is correct. The next step is to continue increasing ∆ along the positive x-axis according to formula (2). x i+1 Step distance ∆ x i+1 Size and ∆ z i Related. If ∆ z i >0, meaning the deviation function value increases, indicates that the tool is moving away from the easy-to-grind direction, and the optimization direction is incorrect. Therefore, according to formula (2), along x The coordinate axis increases negatively in the next step ∆ x i+1 During the movement along the x-axis, if the deviation function value continuously decreases until it increases after taking one step forward, then the movement is reversed by half a step. This is considered a reversal at this point. x The position coordinates on the coordinate axis have reached the optimal value and will remain unchanged during subsequent tool movements.

[0014] (2)

[0015] (3)

[0016] Then along y The coordinate axis increases in the positive direction in the next step ∆ y i Its next step ∆ y i+1 Move according to formula (3). The subsequent movement follows the same pattern as above. x The same applies to the coordinate axes. When the optimal position coordinate on the y-axis is found, the search for both axes has been successful, and the optimization can be confirmed as complete. The current position can then be determined as the easy-grinding direction of the indexing grinding surface of the single-crystal diamond tool. After grinding for a period of time, the tool rotates to the next indexing surface, and the search for the easy-grinding direction of the current grinding surface continues according to the above optimization method until the single-crystal diamond arc tool is fully ground.

[0017] The beneficial effects of this invention are:

[0018] This invention employs a step search method with variable step size to achieve online optimization of the tool's grinding direction. It eliminates the time required for offline diamond crystal orientation, making it more automated and intelligent, and effectively improving the tool's grinding efficiency. Attached Figure Description

[0019] Figure 1 This is a block diagram of the online optimization control of the tool grinding direction according to the present invention;

[0020] Figure 2 This is a diagram of the tool grinding trajectory of the present invention;

[0021] Figure 3 This is a schematic diagram of the search process of the present invention. Detailed Implementation

[0022] Please see Figure 1 , Figure 2 and Figure 3 The image shown is an embodiment of the present invention.

[0023] A method for optimizing the grinding direction of a single-crystal diamond circular arc cutting tool includes the following steps:

[0024] Step 1: Determine the tool sharpening trajectory model

[0025] When sharpening a single-crystal diamond circular arc tool, the crystal orientation of the first face is generally selected at the grinding contact point A, which is located in the middle of the grinding disk radius. This ensures that the sharpening speed is appropriate and that the tool is not affected by vibration during sharpening, thus preventing a decrease in tool quality. The back face is indexed and sharpened to form a circular arc. After each index face is sharpened, the tool is rotated by one index angle to sharpen the next index face. Due to the anisotropy of diamond crystals, the sharpening efficiency of different crystal orientations on different crystal faces is different. Usually, based on the hardness distribution curves of the three typical crystal faces of diamond crystals, namely (100), (110), and (111), the easy-to-sharpen direction on the index face is found on the single-crystal diamond tool by instrument measurement. If the machining of the circular arc tool requires sharpening five index faces in sequence, according to experimental analysis, the easy-to-sharpen position point of each index face can be determined in advance by visual inspection or measurement methods to form a sharpening trajectory. During actual sharpening, after reaching the sharpening trajectory point, the identification model determines whether the sharpening direction of the current indexing surface is the easy-to-sharpen direction. If there is a deviation, the tool position is moved near the trajectory point according to the direction optimization method, so that the tool is sharpened in the easy-to-sharpen direction.

[0026] Step 2: Construction of the tool grinding direction deviation function

[0027] To better optimize the tool's grinding direction, it is necessary to understand the deviation between the current grinding direction and the expected grinding direction. This requires constructing a "deviation function," where the deviation function value represents the magnitude of the deviation. The variable parameters in the deviation function are the displacements of the tool position on the x and y axes, ∆x and ∆y. By gradually adjusting the parameters of the deviation function, the deviation function gradually decreases until it reaches its minimum value, i.e., the parameters are gradually optimized to the best, thereby obtaining the most suitable position parameters so that the tool's grinding surface is closest to the grinding direction. In this embodiment, the deviation function is constructed by comparing the deviation between the actual grinding direction and the expected grinding direction, and processing this deviation to obtain the squared error loss value, as shown in equation (1).

[0028] (1)

[0029] In the formula: z This indicates the deviation of the current tool sharpening direction from the expected easy-to-sharpen direction. a i For the target category vector, b i This is the current identified category vector. k i These are the weighting coefficients.

[0030] Weight coefficients k i The determination depends on the specific experimental conditions and requires continuous experimentation. ki The optimal value is (1.6, 1.2, 1).

[0031] Step 3: Optimization Method for Tool Grinding Direction

[0032] The position of the cutting tool on the grinding wheel ( x , y The change in these two variables will affect the magnitude of the deviation function value. There are various implementation methods for optimization systems with these two variables. This invention is based on the step-by-step search method in automatic search optimization control to control the change in tool position. Based on an understanding of the characteristics of the grinding machine tool, the search range of the coordinate parameters can be roughly determined, and a definite starting point can be found. x 0, y 0). After giving a starting point, first follow along x Increase the positive axis by one step ∆ x i , ∆ x i This is called the step size. The change in the deviation function value ∆ is then calculated. z i = z i - z i-1 If ∆ z i <0, meaning the deviation function value decreases, indicates that the tool is moving towards the easier-to-grind direction, and the optimization direction is correct. The next step is to continue increasing ∆ along the positive x-axis according to formula (2). x i+1 Step distance ∆ x i+1 Size and ∆ z i Related. If ∆ z i >0, meaning the deviation function value increases, indicates that the tool is moving away from the easy-to-grind direction, and the optimization direction is incorrect. Therefore, according to formula (2), along x The coordinate axis increases negatively in the next step ∆ x i+1 During the movement along the x-axis, if the deviation function value continuously decreases until it increases after taking one step forward, then the movement is reversed by half a step. This is considered a reversal at this point. x The position coordinates on the coordinate axis have reached the optimal value and will remain unchanged during subsequent tool movements.

[0033] (2) (3)

[0034] Then along y The coordinate axis increases in the positive direction in the next step ∆ yi Its next step ∆ y i+1 Move according to formula (3). The subsequent movement follows the same pattern as above. x The same applies to the coordinate axes. When the optimal position coordinate on the y-axis is found, the search for both axes has been successful, and the optimization can be confirmed as complete. The current position can then be determined as the easy-grinding direction of the indexing grinding surface of the single-crystal diamond tool. After grinding for a period of time, the tool rotates to the next indexing surface, and the search for the easy-grinding direction of the current grinding surface continues according to the above optimization method until the single-crystal diamond arc tool is fully ground.

Claims

1. A method for optimizing the indexing edge grinding direction of a single crystal diamond torus cutter, the method comprising: Includes the following steps: ​ Step 1: Determining the tool grinding trajectory model When sharpening a single-crystal diamond circular arc tool, the crystal orientation of the first face is generally selected at the middle position of the grinding contact point A, which is located at the center of the grinding disk radius. The back face is then indexed and ground to form an arc shape. After each index face is finished, the tool is rotated by one index angle to grind the next index face. The easy-grinding position point of each index face can be determined in advance according to the measurement method to form a grinding trajectory. During actual grinding, after reaching the grinding trajectory point, the recognition model is used to determine whether the current index face grinding direction is the easy-grinding direction. If there is a deviation, the tool position is moved near the trajectory point according to the direction optimization method, so that the tool is ground in the easy-grinding direction. Step 2: Construction of the tool grinding direction deviation function The deviation function value represents the magnitude of the deviation. The variable parameters in the deviation function are the displacements of the tool position on the x and y axes, ∆x and ∆y. By gradually adjusting the parameters of the deviation function, the deviation function gradually decreases and reaches its minimum value, that is, the parameters are gradually optimized to the best, so as to obtain the most suitable position parameters, so that the tool grinding surface is closest to the easy grinding direction. By comparing the deviation between the actual grinding direction and the expected easy grinding direction, and processing this deviation to obtain the squared error loss value, the constructed deviation function is shown in equation (1): （1）； In the formula: z This indicates the deviation of the current tool sharpening direction from the expected easy-to-sharpen direction. a i For the target category vector, b i This is the current identified category vector. k i These are the weighting coefficients; Step 3: Optimization Method for Tool Grinding Direction The position of the cutting tool on the grinding wheel ( x , y Changes in these parameters will affect the magnitude of the deviation function value; based on an understanding of the characteristics of the grinding machine, the search range for the coordinate parameters is roughly determined, and a specific starting point is found. x 0, y 0), after giving a starting point, first along x Increase the positive axis by one step ∆ x i , ∆ x i This is called the step size, and the change in the deviation function value ∆ is calculated at this point. z i = z i - z i-1 If ∆ z i <0, meaning the deviation function value decreases, indicates that the tool is moving towards the easier-to-grind direction, and the optimization direction is correct; the next step is to continue increasing ∆ along the positive x-axis according to formula (2). x i+1 Step distance ∆ x i+1 Size and ∆ z i Related; if ∆ z i >0, meaning the deviation function value increases, indicates that the tool is moving away from the easy-to-grind direction, and the optimization direction is incorrect. Therefore, according to formula (2), along x The coordinate axis increases negatively in the next step ∆ x i+1 During the movement along the x-axis, if the deviation function value continuously decreases until it increases after taking one step forward, then the movement is reversed by half a step. This is considered a reversal at this point. x The position coordinates on the coordinate axis have reached the optimal value and will remain unchanged during the subsequent tool movement; （2） （3） Then along y The coordinate axis increases in the positive direction in the next step ∆ y i Its next step ∆ y i+1 Move according to formula (3); the subsequent movement pattern is the same as above. x When the optimal position coordinate on the y-axis is found, the search for both axes has been successful, and the optimization can be confirmed to be complete. The current position can be determined as the easy-grinding direction of the indexing grinding surface of the single crystal diamond tool. After grinding for a period of time, the tool moves to the next indexing surface, and the search for the easy-grinding direction of the grinding surface at this time is continued according to the above optimization method until the grinding of the single crystal diamond arc tool is completed.

2. The method of claim 1, wherein the method is characterized by: The weight coefficient in step two k i = (1.6, 1.2, 1).

3. The method of claim 1, wherein the method is characterized by: In step two, the automatic search optimization control method uses a step search method to control the change of tool position.

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