A Method for Optimizing the Injection Rate of Cutting Fluid Based on High-Performance Modeling and Simulation

Abstract

The present invention discloses a method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation. The method comprises the following steps: S1. Construct a thermo-fluid coupling cutting simulation model including a tool, a workpiece, and an Euler domain; S2. Submit the operation and analysis under the condition that the injection speed of the cutting fluid is zero; S3. Use the cutting simulation model obtained in steps S1 and S2 as a pre-simulation model; copy a pre-simulation model as a secondary simulation model; perform a restart setting on the secondary simulation model, and use the simulation result of the pre-simulation model as the initial state of the secondary simulation model; S4. Set multiple different injection speeds of the cutting fluid, and respectively submit the secondary simulation model for operation and analysis to obtain simulation results corresponding to different injection speeds of the cutting fluid. The present invention can observe the effects of different injection speeds of the cutting fluid on chip breaking and temperature conditions by changing the injection speed of the cutting fluid, and realizes the optimization of the injection speed of the cutting fluid.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal processing, and particularly relates to a method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation. Background Art

[0002] Metal cutting fluids are widely used in various cutting operations, such as turning, drilling, grinding, milling, planing, broaching, etc. During the machining process, friction between the cutting tool and the workpiece generates heat and wear. The use of cutting fluid can carry away heat to play a cooling role and can carry away chips during the cutting process to achieve the chip breaking function. However, different injection speeds of the cutting fluid have different effects on the realization of the heat transfer and chip breaking functions. Therefore, it is necessary to optimize the injection speed of the cutting fluid in order to improve the quality of various cutting operations. However, it is difficult, costly, and inefficient to optimize the injection speed of the cutting fluid only by using traditional experimental means, and it is difficult to capture the changes in various parameters during the cutting dynamic process.

[0003] Although the current cutting fluids for metal processing have many advantages, the injection speed of the cutting fluid still needs to be further optimized to accelerate the development of the metal processing field. To achieve this goal, more in-depth research needs to be carried out on the optimization of the injection speed of the cutting fluid. At present, there is little research on cutting simulation with the addition of cutting fluid, and the injection speed of the cutting fluid used in the simulation is single, so that it is impossible to accurately show the influence of different injection speeds of the cutting fluid on cutting during the cutting simulation process, and there is no way to complete the optimization of the injection speed of the cutting fluid. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation for problems such as difficulty in optimizing the injection speed of cutting fluid for metal processing and difficulty in real-time monitoring of the influence of cutting fluid on cutting. The present invention is a method that first performs dry cutting and then adds cutting fluid for cutting simulation; it is a method based on cutting simulation that couples Euler and Lagrange to handle large deformations; it is a method that uses restart analysis to reduce the amount of calculation; it is a method that uses thermal-fluid coupling for cutting simulation; it is a method that observes the chip breaking and temperature conditions under different injection speeds of the cutting fluid by changing the injection speed of the cutting fluid, so as to obtain the optimal injection speed of the cutting fluid for this metal processing.

[0005] A method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation includes the following steps:

[0006] Step S1, construct a thermal-fluid coupling cutting simulation model including a cutting tool, a workpiece, and an Euler domain, and perform mesh division, assembly positioning, allocation of Euler material regions, and parameter setting.

[0007] Step S2: Under the condition that the cutting fluid injection speed is zero, submit the thermo-fluid coupled cutting simulation model for operation analysis to obtain the simulation results. If the simulation results do not converge, adjust the parameters of the thermo-fluid coupled cutting simulation model and then resubmit for operation analysis until the simulation results converge.

[0008] Step S3: Use the cutting simulation model obtained in Steps S1 and S2 as the pre-simulation model; copy a pre-simulation model as the secondary simulation model; perform a restart setting on the secondary simulation model, and use the simulation results of the pre-simulation model as the initial state of the secondary simulation model. Reset the constraint parameters of the cutting fluid in the secondary simulation model; the constraint parameters of the cutting fluid are that while the cutting fluid moves with the tool, it sprays towards the contact area between the tool and the workpiece at the set injection speed.

[0009] Step S4: Set multiple different cutting fluid injection speeds, and submit the secondary simulation model for operation analysis respectively to obtain the simulation results corresponding to different cutting fluid injection speeds. According to the differences in the simulation results, evaluate the influence of the cutting fluid injection speed on the metal processing performance, and select the cutting fluid injection speed used in processing.

[0010] Preferably, in Step S1, the parameters of the thermo-coupled cutting simulation model include the range of the Euler domain, material properties, mesh generation, assembly positioning, analysis steps and output variables, the tool, the contact constraints between the workpiece, the cutting fluid, the motion characteristics of the tool and the cutting fluid, and the load.

[0011] Preferably, in Step S1, the established Euler domain is divided into a cutting fluid area and an empty area.

[0012] Preferably, in Step S2, only the process of the tool cutting into the workpiece is analyzed.

[0013] Preferably, the output interval of the analysis step parameters of the pre-simulation model is set to 1, so that when the pre-simulation model ends, the secondary simulation model can be used to continue the simulation.

[0014] Preferably, in Step S1, the range of the Euler domain is taken as the maximum range that the cutting fluid can reach during the simulation.

[0015] Preferably, in the mesh generation described in Step S1, a fine mesh is used for the contact area between the workpiece and the tool and the area with a preset width around it; a coarse mesh is used for other areas on the tool and the workpiece; a homogeneous mesh is used for the Euler domain.

[0016] Preferably, in Step S3, under the condition that the cutting fluid injection speed is positive, submit the secondary simulation model for operation analysis to obtain the simulation results. If the simulation results do not converge, redefine the boundary conditions of the secondary simulation model and then resubmit for operation analysis until the simulation results converge.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The present invention constructs two identical cutting simulation models. Based on finite element analysis software, first, the first cutting simulation model is used to perform dry cutting simulation on the process of the tool cutting into the workpiece. Then, using restart analysis, the simulation results of the first cutting simulation model are used as the initial state of the second cutting simulation model to perform cutting simulation with the cutting fluid injection speed. If the traditional simulation method is used, different cutting fluid working conditions need to be set for each model and the overall operation is required to obtain the calculation results. However, in this method, only the cutting fluid working conditions in the secondary simulation model need to be modified, and the simulation is carried out based on the first simulation model, reducing the calculation amount of the cutting simulation considering the cutting fluid. In addition, the present invention can observe the effects of different cutting fluid injection speeds on chip breaking and temperature conditions by changing the cutting fluid injection speed, realizing the optimization of the cutting fluid injection speed.

[0019] 2. The present invention uses finite element analysis software. Based on the cutting with added cutting fluid, the heat transfer and chip breaking functions of the cutting fluid are simulated. Data that are difficult to obtain in experiments can be obtained, and the entire machining process can be predicted, which also has high guiding value for practice.

[0020] 3. The present invention performs cutting simulation based on the coupled Eulerian-Lagrangian method, truly presenting the data of the cutting simulation with added cutting fluid, so that the injection speed of the cutting fluid can be optimized through simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flowchart of the present invention.

[0022] Figure 2 is a schematic diagram of the simulation model of the present invention.

[0023] Reference Signs: Figure 1 In the figure, 1 - tool model; 2 - workpiece model; 3 - cutting fluid. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0025] As Figure 1 shown, a method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation includes the following steps:

[0026] Step S1. Pretreat the cutting simulation model: For the tool, workpiece, and cutting fluid, construct a thermo-fluid-solid coupling cutting simulation model and define parameters; the parameters of the thermo-fluid-solid coupling cutting simulation model include the range of the Euler domain, material properties, mesh division, assembly positioning, creation of analysis steps and output variables, setting of contact constraints between the tool, workpiece, and cutting fluid, setting of motion characteristics and application of loads to the tool and cutting fluid.

[0027] As Figure 2 shown, establish a cutting simulation model with cutting fluid; the simulation model includes a tool model 1, a workpiece model 2, and an Euler domain 4; the Euler domain 4 is divided into a cutting fluid region 3 and an empty region. The tool, workpiece, Euler domain, and cutting fluid are modeled and divided in the simulation software.

[0028] The modeling process of the cutting fluid is as follows: First, divide the region where the cutting fluid is located in the established Euler domain, then assign material properties to the cutting fluid, and finally divide the cutting fluid material region, and thus the cutting fluid is established. In this embodiment, the unit of length is selected as mm, and the units of the remaining parameters are all of the same dimension. After the three-dimensional models of the tool, workpiece, Euler domain, and cutting fluid are completely established, define the material properties of the above three-dimensional models in the simulation software respectively for the simulation analysis of physical quantities.

[0029] Considering the performance of the tool, the tool is made of T15 powder metallurgy high-speed steel, the workpiece is selected as GH 4169, and the cutting fluid is selected as carbon nanotube-soybean oil nanofluid. The material parameters of the tool model, workpiece model, and cutting fluid in this embodiment are shown in Tables 1-3:

[0030] Table 1 Tool material parameters

[0031]

[0032] Table 2 Workpiece material parameters

[0033]

[0034] Table 3 Cutting fluid material parameters

[0035]

[0036] Use the Johnson-Cook (J-C) model to describe the stress-strain relationship of GH 4169 steel. The J-C model is shown as the following two equations:

[0037]

[0038]

[0039] where, σ JCThe thermoviscoelastic-plastic flow stress of the material obtained by the traditional thermoviscoelastic-plastic J-C constitutive equation; ε is the strain; is the strain rate; is the reference strain rate; T0 is the reference temperature; T melt is the melting temperature of the workpiece material; A, B, C, n, m are all constants; represents the dimensionless plastic strain rate; T * =(T - T r ) / (T m - T), represents the dimensionless temperature; represents the stress triaxiality, σ m is the spherical stress, is the Mises equivalent stress.

[0040] The specific parameters of its J-C model are shown in Table 4 and Table 5:

[0041] Table 4 J-C constitutive model parameters of GH 4169 steel

[0042]

[0043] Table 5 J-C damage model parameters of GH 4169 steel

[0044]

[0045] A fine mesh is used in the area where the tool model and the workpiece model are in contact, while a coarse mesh is used in the areas of the tool and the workpiece that are far from the contact area; a homogeneous mesh is used in the Euler domain. Then, the meshed tool model, workpiece model, and Euler domain are assembled and positioned. According to the cutting motion characteristics, a realistic analysis step is selected, and the output interval of the analysis step parameters is set to 1; in addition, the cutting force during the turning process is defined in the history variables, and the displacement, stress, strain, and temperature are defined in the field variables. Then, the friction and its constraints between the two are defined according to the contact characteristics between the tool, workpiece, and cutting fluid. Since the present invention mainly focuses on the heat transfer between the tool and the cutting fluid during the cutting process and the chip breaking situation, the tool is set as a rigid body, which can not only reduce the analysis calculation time but also improve the accuracy of the calculation results. According to the contact state between the tool and the workpiece after cutting the workpiece, the modified Coulomb friction law is applied to define the friction characteristics between the two, and the friction coefficient f = 0.24. Then, the boundary conditions of the six-direction constraints of the ground are applied to the workpiece model; the tool movement is controlled, and a displacement constraint is applied in the X direction; the Euler domain allocates the area where the cutting fluid is located and controls its co-movement with the tool; in addition, the cutting force during the cutting process defined in the history variables, and the output of the history variables only targets the tool reference point; the displacement, stress, strain, and temperature are defined in the field variables, and the output of the field variables targets the entire three-dimensional model.

[0046] Step S2: Under the condition that the cutting fluid injection speed is zero, submit the thermo-fluid coupled cutting simulation model to the simulation software solver for operation and analysis based on the coupled Eulerian-Lagrangian method to obtain the simulation results. Only operate and analyze the process of one analysis step from the moment the tool model 1 cuts into the workpiece model 2, without operating the process when the tool model 1 cuts out of the workpiece model 2.

[0047] The simulation results include cutting force, stress, strain, and temperature. If the simulation results do not converge, re-enter Step S1 to adjust the parameters of the thermo-fluid coupled cutting simulation model, specifically by changing the simulation model and finding the most suitable combination of cutting process parameters through fine meshing, cutting force, material breakage, and temperature.

[0048] In this embodiment, fine meshing is used for the contact area between the tool and the workpiece during simulation, as well as the preset range around the contact area, and coarse meshing is used for the remaining parts of the tool and the workpiece; the Euler domain is divided using homogeneous meshing. During the cutting process, the workpiece model is clamped on the machine tool by a fixture, so the bottom surface of the workpiece model is regarded as completely fixed, and full constraint boundary conditions are applied to the bottom surface of the workpiece model during finite element simulation.

[0049] Use simulation software to simulate the process of adding cutting fluid in metal processing. It is necessary to pay attention to the temperature of the tool, the temperature of the workpiece, and the chip breaking situation. To reduce the calculation amount, the simulation steps are divided into two steps. Only by changing the cutting fluid injection speed in the model of the second step can the cutting fluid injection speed be optimized.

[0050] Step S3: Use the cutting simulation model obtained in Steps S1 and S2 as the pre-simulation model; copy a pre-simulation model as the secondary simulation model; perform a restart setting on the secondary simulation model, and use the simulation results of the pre-simulation model as the initial state of the secondary simulation model. Re-set the constraint parameters of the cutting fluid in the secondary simulation model; the constraint parameters of the cutting fluid are that while the cutting fluid moves with the tool, it sprays towards the contact area between the tool and the workpiece at a set injection speed, so as to achieve the purpose of chip breaking and heat transfer.

[0051] Step S4: Submit the secondary simulation model to the simulation software solver, starting from the end point of the pre-simulation model, and perform operation and analysis based on the coupled Eulerian-Lagrangian method to obtain simulation results including cutting force, stress, strain, and temperature. Analyze and evaluate the simulation results; if the simulation results do not converge, return to Steps S1 to S3 to adjust the cutting simulation model. Since the cutting simulation model has been subjected to a convergence check in Step S2; therefore, the secondary simulation model that only adjusts the cutting fluid injection speed is likely to converge.

[0052] By setting different cutting fluid injection speeds in the secondary simulation model, the influence of different cutting fluid injection speeds on the cutting quality is obtained, so as to select the optimal cutting fluid injection speed for the specified working conditions.

[0053] The simulation method of the present invention is different from the conventional simulation which has a large amount of calculation and is rough. It only needs to divide the simulation steps into two steps. In the first step, a simulation model is created, and various parameters of the Euler domain, workpiece and tool, as well as the thermo-hydro-mechanical coupling model of the constraints are set, and the cutting fluid injection speed is set to zero; then in the second step, by setting different cutting fluid injection speeds, a restart analysis is carried out, and the second step starts based on the first step, so as to realize reducing the amount of calculation by using the restart analysis, processing the cutting simulation of large deformation based on the coupled Euler-Lagrange method, and carrying out the cutting simulation by using the thermo-hydro-mechanical coupling, so as to realize the optimization of the cutting fluid injection speed.

[0054] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation of the present invention itself. Various changes can be made in its form and details without departing from the spirit and scope of the present invention defined by the appended claims.

Claims

1. A method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation, characterized in that: Including the following steps: Step S1: Construct a thermo-fluid-solid coupling cutting simulation model including a cutting tool, a workpiece, and an Euler domain, and perform mesh generation, assembly positioning, allocation of Euler material regions, and parameter setting; Step S2: Under the condition that the cutting fluid injection velocity is zero, submit the thermo-fluid-solid coupling cutting simulation model for operation analysis to obtain simulation results; if the simulation results do not converge, adjust the parameters of the thermo-fluid-solid coupling cutting simulation model and resubmit for operation analysis until the simulation results converge; Step S3: Use the cutting simulation model obtained in Steps S1 and S2 as a pre-simulation model; copy a pre-simulation model as a secondary simulation model; perform a restart setting on the secondary simulation model, and use the simulation results of the pre-simulation model as the initial state of the secondary simulation model; reset the constraint parameters of the cutting fluid in the secondary simulation model; the constraint parameters of the cutting fluid are that while the cutting fluid moves with the cutting tool, it sprays towards the contact area between the cutting tool and the workpiece at a set injection velocity; Step S4: Set multiple different cutting fluid injection velocities, and submit the secondary simulation model for operation analysis respectively to obtain simulation results corresponding to different cutting fluid injection velocities. According to the differences in the simulation results, evaluate the influence of the cutting fluid injection velocity on the metal processing performance, and select the cutting fluid injection velocity used in processing.

2. The method for optimizing the injection rate of cutting fluid based on high-performance modeling and simulation according to claim 1, wherein: In Step S1, the established Euler domain is divided into a cutting fluid region and an empty region.

3. The method for optimizing the injection rate of cutting fluid based on high-performance modeling and simulation according to claim 1, wherein: In Step S2, only the process of the cutting tool cutting into the workpiece is analyzed by operation.

4. A method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation according to claim 1, characterized in that: The output interval of the analysis step parameters of the pre-simulation model is set to 1, so that after the pre-simulation model ends, the secondary simulation model can continue the simulation.

5. A method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation according to claim 1, characterized in that: In Step S1, the Euler domain range is taken as the maximum range that the cutting fluid can reach during the simulation process.

6. The method for optimizing the injection rate of cutting fluid based on high-performance modeling and simulation according to claim 1, wherein: In the mesh generation described in Step S1, a fine mesh is used for the contact area between the workpiece and the cutting tool and the area with a preset width around it; a coarse mesh is used for other areas on the cutting tool and the workpiece; a homogeneous mesh is used for the Euler domain.

7. A method for optimizing the injection speed of cutting fluid based on high-performance modeling and simulation according to claim 1, characterized in that: In Step S3, under the condition that the cutting fluid injection velocity is positive, submit the secondary simulation model for operation analysis to obtain simulation results; If the simulation results do not converge, redefine the boundary conditions of the secondary simulation model and resubmit for operation analysis until the simulation results converge.

Images