Design method of negative chamfering cutter microstructure based on topological optimization

Abstract

The invention provides a topological optimization-based negative chamfering tool microstructure design method, which comprises the following steps of: performing three-dimensional orthogonal cutting thermal-mechanical coupling simulation on a negative chamfering tool to obtain positive stress distribution of a target area of the negative chamfering tool in a cutting state; wherein the target area is a V-shaped area or an inclined plane area formed at the junction of the rake face and the chamfered edge; and based on the normal stress distribution of the target area, adjusting the material density distribution of the target area by using a variable density method, and carrying out topological optimization on the material density distribution of the target area by taking the tool nose stress minimization as a target function to obtain the microstructure of the target area. Compared with a traditional micro-texture tool with a simple structure, the method can perform structural design on a stress concentration area to improve the stress condition of the tool, so that the cutting performance of the tool is improved, the service life of the tool is prolonged, and the quality of a machined surface is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of cutting tool design, and in particular relates to a design method for negative chamfer tool micro-texture based on topology optimization. Background Art

[0002] Gray cast iron, commonly used in the manufacture of brake discs and drums, is typically cut with negatively chamfered tools to protect the brittle graphite particles from breaking and extend tool life. However, negatively chamfered tools are prone to increased wear, excessive temperatures, and chip accumulation under dry cutting conditions, resulting in reduced cutting performance. Through topology optimization, microtextures with specialized geometries can be introduced onto the tool surface to improve friction and heat transfer between the tool and the workpiece.

[0003] Today's microtexture designs are primarily inspired by the remarkable adaptations of biological surfaces to their environments. Scientists have observed that natural forms, such as the tiny denticles on shark skin and the micro- and nano-scale protrusions on lotus leaves, can effectively reduce friction, resist wear, and even possess self-cleaning properties. These biological microstructures have inspired new approaches to tool design. By mimicking these natural forms, similar microtextures can be engineered onto tool surfaces, aiming to improve cutting performance and extend tool life.

[0004] Specifically, the design of bionic micro-textured tools usually involves machining micron or nanometer-scale grooves, protrusions, holes and other structures on the tool surface. These micro-textures can change the friction state of the tool-workpiece contact interface, reduce friction and cutting heat during the cutting process, and thus reduce tool wear. In addition, micro-textures can also store lubricants, improve the lubrication conditions of the cutting area, and further improve cutting efficiency. However, although bionic micro-textured tools perform well in reducing wear, their design methods still rely mainly on traditional geometric structures, lack diversity, and it is difficult to achieve major breakthroughs in micro-texture morphology. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a design method for negative chamfer tool micro-texture based on topology optimization. Compared with traditional micro-texture tools with simple structures, it can perform structural design on stress concentration areas to improve the stress condition of the tool, thereby improving the tool cutting performance, tool life and processing surface quality.

[0006] This application provides a design method for negative chamfer tool microtexture based on topology optimization, including:

[0007] A three-dimensional orthogonal cutting thermal-mechanical coupling simulation is performed on a negative chamfering tool to obtain the normal stress distribution in the target area of the negative chamfering tool during cutting; wherein the target area is the V-shaped area or the bevel area formed by the intersection of the rake face and the chamfer;

[0008] Based on the normal stress distribution of the target area, the variable density method is used to perform topological optimization on the material density distribution of the target area with tool tip stress minimization as the objective function to obtain the microtexture of the target area.

[0009] Furthermore, the three-dimensional orthogonal cutting thermal-mechanical coupling simulation for the negative chamfering tool includes:

[0010] respectively setting the geometrical dimensions and shapes of the negative chamfering tool and the workpiece to construct three-dimensional models of the negative chamfering tool and the workpiece;

[0011] respectively setting the material properties of the negative chamfering tool and the workpiece, and assembling the three-dimensional models of the negative chamfering tool and the workpiece;

[0012] A three-dimensional orthogonal cutting thermal-mechanical coupling simulation is performed on the negative chamfering tool under actual cutting conditions.

[0013] Furthermore, the actual cutting conditions include: cutting parameters and constraints of the cutting process;

[0014] The cutting parameters include: cutting depth, cutting speed, and initial temperature;

[0015] The constraint conditions are that the negative chamfering tool and the right side of the workpiece are both subject to symmetrical constraints, and the side surface of the workpiece is subject to fixed constraints.

[0016] Furthermore, the material density distribution of the target area is topologically optimized by:

[0017] The three-dimensional model of the target area of the negative chamfering tool is projected into a two-dimensional model using hyperbolic tangent projection;

[0018] Using the normal stress distribution of the target area as the body load of the two-dimensional model, setting the material properties of the target area, and limiting the volume fraction of the material;

[0019] The uniform distribution of material density is used as the initial solution, and the density variable scaling method is used to distribute each density value between 0 and 1 to obtain the material density distribution of the target area.

[0020] Furthermore, the micro-texture is symmetrically distributed as a whole, with a dendritic channel structure formed in the central area, multiple longitudinal stripe-like branches on the left and right sides, and a serrated texture on the upper boundary.

[0021] The design method of negative chamfer tool micro-texture based on topology optimization provided in this application can perform structural design on stress concentration areas to improve the stress condition of the tool, thereby improving the tool cutting performance, tool life and processing surface quality, compared with traditional micro-texture tools with simple structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart of a method for designing negative chamfer tool micro-texture based on topology optimization provided in an embodiment of the present application is shown;

[0023] Figure 2 A schematic diagram of an assembly of a three-dimensional model of a negative chamfering tool and a workpiece provided in an embodiment of the present application is shown;

[0024] Figure 3 A schematic diagram of the microtexture of the target area based on topology optimization design provided in an embodiment of the present application is shown;

[0025] Figure 4 A model diagram of a negative chamfering tool based on topology optimization provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of this technical solution more clear, the following technical solution is further described in detail in conjunction with specific implementation methods. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of this technical solution.

[0027] First, we introduce the topology optimization method used in this application. Topology optimization intelligently designs the optimal microstructure layout based on the specific operating conditions of the tool by optimizing material distribution and structural morphology. This allows the tool to effectively disperse heat, reduce friction, and improve cutting stability during the cutting process. Specifically, on negative chamfered cutting tools, the optimized microtexture not only enhances the tool's wear resistance but also improves cutting forces and surface quality during the cutting process, thereby extending the tool's life and enhancing machining accuracy.

[0028] Next, see Figure 1 The flowchart of the design method of negative chamfer tool micro texture based on topology optimization provided in the embodiment of the present application is shown. Figure 1 As shown, the method includes:

[0029] S101. Perform a three-dimensional orthogonal cutting thermal-mechanical coupling simulation on a negative chamfering tool to obtain a normal stress distribution in a target area of the negative chamfering tool under a cutting state.

[0030] The target area is a V-shaped area or a bevel area formed by the junction of the rake face and the chamfer.

[0031] Here, since the junction between the rake face and the chamfer is the core area of cutting contact and stress concentration, the microtexture of this area affects the performance of the tool. Therefore, the V-shaped area or bevel area formed by the junction of the rake face and the chamfer is determined as the target area.

[0032] In specific implementation, the following methods are used to perform three-dimensional orthogonal cutting thermal-mechanical coupling simulation on negative chamfering tools:

[0033] Step 1011: Set the geometric dimensions and shapes of the negative chamfering tool and the workpiece respectively to construct a three-dimensional model of the negative chamfering tool and the workpiece.

[0034] As an example, the workpiece geometry is set as follows: length 15mm, width 4mm, and height 8mm. The negative chamfer tool geometry is set as follows: tip radius 0.4mm, main cutting angle 80°, chamfer width 0.2mm, negative rake angle -20°, and the original length is reduced to 5mm to remove the non-cutting sections on both sides.

[0035] Step 1012: Set the material properties of the negative chamfering tool and the workpiece respectively, and assemble the three-dimensional models of the negative chamfering tool and the workpiece.

[0036] As an example, the workpiece material is gray cast iron HT250, and its material properties are shown in Table 1. The negative chamfer tool material is PCBN (polycrystalline cubic boron nitride), and its material properties are shown in Table 2. The material properties are used to characterize the plasticity and thermomechanical properties of the material.

[0037] Table 1. Material properties of gray cast iron HT250

[0038]

[0039] Table 2. Material properties of PCBN

[0040]

[0041] Here, see Figure 2 The figure shows an assembly diagram of a three-dimensional model of a negative chamfering tool and a workpiece, in which 1 represents the workpiece and 2 represents the negative chamfering tool.

[0042] Step 1013: Perform a three-dimensional orthogonal cutting thermal-mechanical coupling simulation on the negative chamfering tool under actual cutting conditions.

[0043] The actual cutting conditions include: cutting parameters and constraints of the cutting process; the cutting parameters include: cutting depth, cutting speed, initial temperature; the constraints are that the right side of the negative chamfer tool and the workpiece are both subject to symmetrical constraints, and the side of the workpiece is subject to fixed constraints. Figure 2The constraints marked in .

[0044] In this step, first, a finite element model is established in the target area of the negative chamfering tool. Then, considering multiple physical field factors including stress, heat flow, and friction contact, the real cutting position, heat flux boundary, and contact friction coefficient are loaded into the finite element model to realize three-dimensional orthogonal cutting thermal-mechanical coupling simulation.

[0045] As an example, the cutting parameters are set as follows: cutting depth is 1 mm, cutting speed is 47 m / min, and initial temperature is 20°C.

[0046] S102 , based on the normal stress distribution of the target area, using a variable density method and minimizing the tool tip stress as an objective function, topologically optimize the material density distribution of the target area to obtain the microtexture of the target area.

[0047] In this step, the variable density method is based on the SIMP interpolation model, defining the design variable as the material density. The penalty mechanism is used to reduce the existence of intermediate density values, making the optimization results clearer. The specific explanation is as follows: For each point, the value of density ρ(x) is between 0 (no material) and 1 (full material). The behavior of the material is assumed to be proportional to the density, that is, the relationship between the elastic modulus E(x) of the material and the density ρ(x) can be expressed by the following formula (1):

[0048] E(x)=E0·ρ(x) p ; (1)

[0050] Where E0 is the initial elastic modulus of the material, ρ(x) is the material density at position x, and p is a penalty factor (usually p>1). By penalizing the density, it forces the optimization results to tend to the extreme cases of full material (ρ=1) or no material (ρ=0).

[0051] In specific implementation, the material density distribution of the target area can be topologically optimized by the following methods:

[0052] Step 1021 : Project the three-dimensional model of the target area of the negative chamfering tool into a two-dimensional model using hyperbolic tangent projection.

[0053] Step 1022: Use the normal stress distribution of the target area as the body load of the two-dimensional model, set the material properties of the target area, and limit the volume fraction of the material.

[0054] The volume fraction is set to a value range of 40%-60%.

[0055] Step 1023: Using the uniform distribution of material density as the initial solution, the density variable scaling method is used to distribute each density value between 0 and 1, so as to obtain the material density distribution of the target area.

[0056] After obtaining the material density distribution of the target area, the edge tracking algorithm is used to convert the material density distribution into a vector boundary to obtain the micro texture of the target area. Figure 3 Schematic diagram of micro-texture of target area based on topology optimization design as shown; Figure 3 As shown in the figure, the central area of the microtexture forms a "branch-like" channel structure, which can guide the heat to diffuse to both sides or inside the tool, reducing heat concentration; there are multiple longitudinal striped branches on the left and right sides of the microtexture, which have the function of ventilation grooves or stress unloading channels; the overall microtexture is symmetrically distributed, maintaining a balanced path of cutting force and heat flow, which is conducive to maintaining the stability of chip morphology; the upper boundary of the microtexture presents a serrated texture, which helps to enhance local disturbance and promote the separation of cutting debris.

[0057] After obtaining the micro texture of the target area, the micro texture is integrated into the target area of the solid model of the negative chamfer tool. Specifically, on the basis of keeping the main tool tip structure unchanged, the micro texture is processed on the rake face using a laser marking machine. Here, Figure 4 The model diagram of the negative chamfer tool based on topology optimization is shown. In the figure, 2 represents the negative chamfer tool and 3 represents the micro texture of the target area.

[0058] The above content is only a preferred embodiment of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scopes based on the ideas of the present technical content. As long as these changes do not deviate from the concept of the present invention, they all fall within the scope of protection of the present invention.

Claims

1. A design method for negative chamfer tool micro-texture based on topology optimization, characterized in that: The method comprises: A three-dimensional orthogonal cutting thermal-mechanical coupling simulation is performed on a negative chamfering tool to obtain the normal stress distribution in the target area of the negative chamfering tool during cutting; wherein the target area is the V-shaped area or the bevel area formed by the intersection of the rake face and the chamfer; Based on the normal stress distribution of the target area, the variable density method is used to perform topological optimization on the material density distribution of the target area with tool tip stress minimization as the objective function to obtain the microtexture of the target area.

2. The method according to claim 1, wherein The three-dimensional orthogonal cutting thermal-mechanical coupling simulation for the negative chamfering tool includes: respectively setting the geometrical dimensions and shapes of the negative chamfering tool and the workpiece to construct three-dimensional models of the negative chamfering tool and the workpiece; respectively setting the material properties of the negative chamfering tool and the workpiece, and assembling the three-dimensional models of the negative chamfering tool and the workpiece; A three-dimensional orthogonal cutting thermal-mechanical coupling simulation is performed on the negative chamfering tool under actual cutting conditions.

3. The method according to claim 2, wherein The actual cutting conditions include: cutting parameters and constraints of the cutting process; The cutting parameters include: cutting depth, cutting speed, and initial temperature; The constraint conditions are that the negative chamfering tool and the right side of the workpiece are both subject to symmetrical constraints, and the side surface of the workpiece is subject to fixed constraints.

4. The method according to claim 1, wherein The material density distribution in the target area is topologically optimized by: The three-dimensional model of the target area of the negative chamfering tool is projected into a two-dimensional model using hyperbolic tangent projection; Using the normal stress distribution of the target area as the body load of the two-dimensional model, setting the material properties of the target area, and limiting the volume fraction of the material; The uniform distribution of material density is used as the initial solution, and the density variable scaling method is used to distribute each density value between 0 and 1 to obtain the material density distribution of the target area.

5. The method according to claim 1, wherein The micro texture is symmetrically distributed as a whole, with a dendritic channel structure formed in the central area, multiple longitudinal stripe branches on the left and right sides, and a serrated texture on the upper boundary.

Images