A trolley-type furnace bottom plate obtained based on finite element simulation method

Abstract

The present invention provides a trolley type furnace bottom plate obtained based on a finite element simulation method, comprising the following steps: S1, establishing a trolley type furnace bottom plate entity model; S2, establishing an analysis system through Ansys Workbench software; S3, importing the trolley type furnace bottom plate entity model; S4, defining material properties; S4.1, entering a material setting system through an A2 Engineering Date component module; S4.2, setting a Poisson's ratio to 0.3 and a thermal expansion coefficient to 1.6E-5C ‑1 ; S5. Mesh the solid model of the trolley furnace bottom plate; S6. Add loads and constraints; S7. Get the simulation results. Select the menu Solution, right-click and insert TotalDeformation to get the deformation cloud map. Make the trolley furnace bottom plate alloy reach the degree of deformation, and increase the ability to effectively resist over time, so that the trolley furnace bottom plate can maintain a stable shape and size under high temperature or long-term stress conditions.

Description

Technical Field

[0001] The invention relates to the technical field of intelligent equipment manufacturing, and in particular to a trolley type furnace bottom plate obtained based on a finite element simulation method. Background Art

[0002] The trolley-type furnace bottom plate is a new type of integrated tooling required for the trolley-type resistance furnace and is a load-bearing component in the heat treatment process of forgings.

[0003] The maximum operating temperature of the trolley furnace heat treatment tooling is designed to be 1100℃, and the design load is 5T; the use environment is: raise the temperature of the trolley furnace to 1100℃, keep the temperature of the tooling and the workpiece at about 1100℃, and cool it naturally by air after keeping it warm for several hours; however, the cooling process will cause large internal stress inside the tooling, which is easy to cause deformation and cracking of the tooling. Therefore, the trolley-type resistance furnace has the following technical requirements for the trolley-type furnace bottom plate: First, it is necessary to ensure that the designed tooling can reach the load capacity of 5T workpieces under the temperature of 1100℃; second, it is necessary to meet the dissipation of thermal stress during the cooling process of the workpiece, and ensure that the tooling will not produce deformation and cracking that affects the use effect; therefore, how to design a trolley-type furnace bottom plate that can reach the load capacity of 5T workpieces under the temperature of 1100℃, and meet the dissipation of thermal stress during the cooling process of the workpiece, and ensure that the tooling will not produce deformation and cracking that affects the use effect, has become a problem that plagues trolley-type furnace bottom plate manufacturing companies. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a trolley-type furnace bottom plate obtained based on a finite element simulation method, which simulates in advance the degree of deformation of the trolley-type furnace bottom plate alloy and can effectively resist the deformation over time, thereby enabling the trolley-type furnace bottom plate to maintain a stable shape and size under high temperature or long-term stress conditions.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A trolley-type furnace bottom plate obtained based on a finite element simulation method, wherein the structure of the trolley-type furnace bottom plate comprises an upper layer, a middle layer and a lower layer, wherein the upper layer is a circular hole receiving surface structure, the middle layer is a grid frame structure, and the lower layer is a flat plate;

[0007] The circular hole receiving surface is in the shape of a round pancake with a through hole in the middle; the grid frame is formed by N cross arrays connected to each other, the cross includes cross-connected horizontal plates and vertical plates, the circular hole receiving surface is connected to the upper end of the intersection of the cross, and the flat plate is arranged at the lower end of the cross.

[0008] The trolley-type furnace bottom plate includes a base plate and a receiving frame, the receiving frame includes a plurality of first mesh plates and a plurality of second mesh plates, the first mesh plates and the second mesh plates are arranged crosswise with each other, a cylinder is arranged at the intersection of the first mesh plates and the second mesh plates, a circular hole-shaped receiving surface is arranged on the upper end surface of the cylinder, the first mesh plates and the second mesh plates are both provided with first through holes, and the first mesh plates and the second mesh plates are both arranged on the base plate.

[0009] Four side plates are arranged on the base plate, and the side plates are distributed around the receiving frame. The side plates are arranged with a second through hole and a third through hole, the second through hole corresponds to the first through hole, and the third through hole corresponds to the cylinder.

[0010] A clamping plate is arranged on the outer side surface of the side plate, and a clamping groove is arranged between the clamping plate and the side plate.

[0011] The trolley-type furnace bottom plate comprises a top layer and a bottom layer, wherein the top layer is a hexagonal hole receiving surface structure, and the bottom layer is a flat plate structure;

[0012] The finite element simulation method comprises the following steps:

[0013] S1. Establish a solid model of the trolley type furnace bottom plate;

[0014] Use solideworks software to model the trolley-type furnace bottom plate and design a solid model of the trolley-type furnace bottom plate;

[0015] S2. Establish analysis module through Ansys Workbench software;

[0016] Use Ansys Workbench software to solve and analyze through the structural statics module, drag Static Strutural into the blank space, and establish an analysis module;

[0017] S3. Import the solid model of the trolley type furnace bottom plate;

[0018] Importing the entity model into the analysis model established in step S2;

[0019] S4. Define material properties;

[0020] S4.1. Enter the material setting system through the A2 Engineering Date component module and open the Isotropic Elastic, Cofficient of Thermal Expansion window in the material properties window;

[0021] S4.2. Set the elastic modulus to 2E11, the Poisson's ratio to 0.3, and the thermal expansion coefficient to 1.6E-5C through the material properties of ZGCr25Ni20Si2. -1 ;

[0022] S5. Meshing the solid model of the trolley type furnace bottom plate;

[0023] Use hexahedral mesh, mesh type is C3D8R, and set the mesh size to 10mm;

[0024] S6. Add loads and constraints;

[0025] S6.1, add a small area load of 0.2T to a linear load of 0.5T;

[0026] S6.2. Select the menu Static Structural and right-click to insert ThermalCondition, set the ambient temperature to 1100℃, and right-click to insert Force; the uniform load on the surface is 2000N, right-click to insert Force, set the load in the online area to 5000N, right-click to insert FrictionlessSupport, and constrain the bottom surface;

[0027] S7, obtain simulation results;

[0028] By selecting Solution from the menu, right-click and insert TotalDeformation to obtain the deformation cloud map.

[0029] In step S6.2, the load includes three forms: 1. temperature load, the design temperature is 1100°C; 2. surface area load, the design load value is 0.2T and the force bearing area is 300mm*300mm; 3. linear load, the design load value is 0.5T and the load length is 700mm;

[0030] The composition contents of the trolley furnace bottom plate are as follows by mass: chromium Cr: 24-27%, nickel Ni: 19-22%, tungsten W: 2.5-3.5%, cobalt Co: 1.0-2.0%, niobium Nb: 0.5-1.0%, and C: 0.1-0.2%.

[0031] In step S2, the structural statics module performs solution analysis including the following steps:

[0032] K1. Divide the continuum into many continuous units and take the displacement of several nodes of each unit as the unknown quantity, that is, {δ} e =[u i ,v i ,w i ,...] T, the displacement of any point in the unit cell is {f}=[u,v,w] T ; The displacement function N(x, y, z) is introduced to represent the distribution form and change law of the field variable in the unit, so that the value of the field variable at the node can be used to describe the field variable at any point in the unit; the appropriate model established in the unit is:

[0033] {f}=[N]{δ} e (one)

[0034] In formula (1), [N] = [IN1, IN2, IN3, ...]; I is the unit matrix;

[0035] K2. According to the characteristics of isoparametric elements, the local coordinates (ξ,η,ζ) are transformed into global coordinates (x,y,z). The coordinate transformation is performed by an expression similar to displacement interpolation. A mapping relationship is established between the child unit after the coordinate change and the parent unit (regular unit under local coordinates). Regardless of whether the internal unit or the unit near the boundary can select the same displacement function, the method of establishing the unit characteristic matrix for them is the same.

[0036] K3. Solve the expression of the relationship between the unit node force and the node displacement through geometric equations, constitutive equations, virtual work principle or potential variation equation, that is, the unit stiffness matrix, as follows:

[0037] {ε}=(ε x ,ε y ,ε z ,γ xy ,γ yz ,γ zx )

[0038] (ε)=[B]{δ} e (two)

[0039] In formula (2), [B] = [B1, B2, B3, ...];

[0040] K4. For small deformation linear elastic problems, the stress matrix within the unit is established according to the physical equation as follows:

[0041] (σ)=[D]{ε}=[D][B]{δ} e (three)

[0042] In formula (3), [B] is the geometric matrix, [D] is the elastic matrix, [S] is the stress matrix, and [S] = [D][B];

[0043] K5. Calculate the nodal force {F} in the unit according to the principle of virtual work e ,as follows:

[0044] {F} e=[k]{δ} e (Four)

[0045] In formula (4), [k] is the stiffness matrix of the unit,

[0046] K6. For any point i on the overall structure, establish the equilibrium equation as follows:

[0047]

[0048] In formula (5), {R i} is the external load on node i, and the above formula indicates that {R i} is balanced with the sum of the nodal forces of all elements surrounding point i at point i.

[0049] The beneficial effects of the present invention are:

[0050] 1. Through software simulation, it can be seen that the maximum deformation of the trolley-type furnace bottom plate structure under high temperature and heavy load is 13.07mm, and the maximum stress under high temperature and heavy load is 7.2935MPa. The yield strength of the material ZGCr25Ni20Si2 is 205MPa, and 7.2935MPa is much smaller than 205MPa. Therefore, the strength of the trolley-type furnace bottom plate structure under high temperature and heavy load meets the requirements, which can ensure that the trolley-type furnace bottom plate structure will not crack when the designed tooling can reach the load capacity of 5T workpiece at a temperature of 1100℃.

[0051] 2. Through the analysis of the software pre-processing module, analysis calculation module and post-processing module, including structural analysis (linear analysis, nonlinear analysis and highly nonlinear analysis), fluid dynamics analysis, electromagnetic field analysis, acoustic field analysis, piezoelectric analysis and multi-physical field coupling analysis, it can simulate the interaction of various physical media, and has sensitivity analysis and optimization analysis. The post-processing module can display the calculation results in the form of color contour lines, gradient display, vector display, particle flow trace display, etc., and can also display or output the calculation results in the form of charts and curves.

[0052] 3. The bottom plate of the trolley-type furnace carries items at high temperatures, and the items carried at high temperatures remain unchanged. When the load remains unchanged, the creep resistance of the high-melting-point alloy formed by tungsten and niobium enables the trolley-type furnace bottom plate alloy to achieve effective resistance when the deformation degree increases with time, so that the trolley-type furnace bottom plate can maintain a stable shape and size under high temperature or long-term stress conditions, avoiding the problem of items stuck in the trolley-type resistance furnace being unable to be removed due to deformation of the trolley-type furnace bottom plate, or items on the trolley-type resistance furnace falling off.

[0053] 4. When conducting finite element simulation analysis on the trolley-type furnace bottom plate, the continuous solution area with infinite degrees of freedom is discretized into discrete bodies (units) with finite degrees of freedom and connected to each other in a certain way (nodes), that is, the continuum is hypothetically divided into a finite number of discrete units, and the units are only connected to each other at a finite number of specified points, and the original continuum is replaced by a collection of discrete units. In general, the finite element equation is a set of linear equations with node displacements as unknown quantities. Solving the set of equations can obtain the displacements of a finite number of nodes on the continuum, and then the stress distribution law on each unit can be obtained, thereby evaluating the performance of the above-mentioned trolley-type furnace bottom plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a mesh subdivision diagram of the simulation model of the present invention;

[0055] Figure 2 This is the loading diagram of the bottom plate of the round hole trolley type furnace;

[0056] Figure 3 This is the load diagram of the bottom plate of the round hole trolley furnace (Force: 2000N, temperature 1100 degrees Celsius);

[0057] Figure 4 This is the load diagram of the bottom plate of the round hole trolley furnace (Force: 5000N, temperature 1100 degrees Celsius);

[0058] Figure 5 Deformation cloud diagram of circular hole structure;

[0059] Figure 6 Stress cloud diagram of circular hole structure;

[0060] Figure 7 Deformation cloud diagram of hexagonal hole structure;

[0061] Figure 8 Stress cloud diagram of hexagonal hole structure;

[0062] Fig. 9 It is a round hole trolley type furnace bottom plate;

[0063] Fig.10 It is a hexagonal hole trolley type furnace bottom plate;

[0064] Fig.11 It is a structural schematic diagram of one of the plates in the bottom plate of the trolley type furnace;

[0065] Fig.12 for Fig.11 A top view of

[0066] Fig.13 for Fig.11 A partial enlarged view of part A;

[0067] Fig.14 for Fig.11 Section view of the middle plate along the BB direction;

[0068] Fig.15 This is a schematic diagram of the connection between two adjacent plates on the bottom plate of a trolley-type furnace.

[0069] As shown in the figure: 10-base plate, 20-supporting frame, 21-first grid plate, 22-second grid plate, 23-cylinder, 24-first through hole, 201-circular hole-shaped supporting surface, 30-side plate, 31-second through hole, 32-third through hole, 40-card slot, 41-card plate. DETAILED DESCRIPTION

[0070] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0071] Example 1

[0072] A trolley type furnace bottom plate obtained based on a finite element simulation method, the finite element simulation method comprising the following steps:

[0073] S1. Establish a solid model of the trolley type furnace bottom plate;

[0074] Use solideworks software to model the trolley-type furnace bottom plate and design a solid model of the trolley-type furnace bottom plate;

[0075] S2. Establish analysis module through Ansys Workbench software;

[0076] Use Ansys Workbench software to solve and analyze through the structural statics module, drag Static Strutural into the blank space, and establish an analysis module;

[0077] S3. Import the solid model of the trolley type furnace bottom plate;

[0078] Importing the entity model into the analysis system established in step S2;

[0079] S4. Define material properties;

[0080] S4.1. Enter the material setting system through the A2 Engineering Date component module and open the Isotropic Elastic, Cofficient of Thermal Expansion window in the material properties window;

[0081] S4.2. Set the elastic modulus to 2E11, the Poisson's ratio to 0.3, and the thermal expansion coefficient to 1.6E-5C through the material properties of ZGCr25Ni20Si2. -1 ;

[0082] S5, such as Figure 1 As shown, meshing is performed on the solid model of the trolley type furnace bottom plate;

[0083] Use hexahedral mesh, mesh type is C3D8R, and set the mesh size (ElementSize) to 10mm;

[0084] S6. Add loads and constraints;

[0085] S6.1, add a small area load of 0.2T to a linear load of 0.5T;

[0086] S6.2. Select Static Structural from the menu, right-click and insert ThermalCondition, set the ambient temperature to 1100℃, and right-click and insert Force; the uniform load on the surface is 2000N (that is, 0.2t), right-click and insert Force, set the load in the online area to 5000N (that is, 0.5t), right-click and insert FrictionlessSupport to constrain the bottom surface; the effect of applying the load is shown in the figure below. Figure 2-4 As shown, the circular hole design is taken as an example.

[0087] S7, obtain simulation results;

[0088] By selecting Solution from the menu, right-click and insert TotalDeformation to obtain the deformation cloud map.

[0089] from Figures 5 to 8 From the deformation cloud diagram, it can be seen that the maximum deformation of the structure under high temperature and heavy load is 13.07mm; from the stress cloud diagram, it can be seen that the maximum stress generated by the structure under high temperature and heavy load is 7.2935MPa; the yield strength of ZG30Cr25Ni20Si2 is 205MPa, and 7.2935MPa is much smaller than 205MPa. Therefore, the strength of the structure under high temperature and heavy load meets the requirements and can be used normally.

[0090] S8, performing a comparative analysis on the obtained simulation results to obtain an analysis result;

[0091] According to the deformation cloud map obtained in step S7, the simulation results are compared and analyzed to obtain the optimal solution, as shown in Table 1 below:

[0092]

[0093] Table 1 is a comparative analysis of the simulation results.

[0094] Fig. 9As shown, the trolley-type furnace bottom plate includes an upper layer, a middle layer and a lower layer, the upper layer is a round hole receiving surface structure, the middle layer is a grid frame structure, and the lower layer is a flat plate;

[0095] The circular hole receiving surface is in the shape of a round pancake with a through hole in the middle; the grid frame is formed by N cross arrays connected to each other, the cross includes cross-connected horizontal plates and vertical plates, the circular hole receiving surface is connected to the upper end of the intersection of the cross, and the flat plate is arranged at the lower end of the cross.

[0096] like Fig.10 As shown, the structure of the trolley-type furnace bottom plate includes a top layer and a bottom layer, the top layer is a hexagonal hole receiving surface structure, and the bottom layer is a flat plate structure.

[0097] Since the workpiece on the tooling is handled through small-area contact and linear contact, the weight of the heat-treated workpiece is about 5 tons, and the tooling is assembled from 25 pieces, with an average load of 0.2 tons per piece. Considering the particularity of the heat-treated workpiece, the simulation uses a small-area load of 0.2 tons to accumulate to a linear load of 0.5 tons.

[0098] In step S6.2, the load includes three forms: 1. Temperature load, the design temperature is 1100°C; 2. Surface area load, the design load value is 0.2T and the load area is 300mm*300mm; 3. Linear load, the design load value is 0.5T and the load length is 700mm.

[0099] The composition content of the trolley furnace bottom plate material is as follows by mass: chromium Cr: 24-27%, nickel Ni: 19-22%, tungsten W: 2.5-3.5%, cobalt Co: 1.0-2.0%, and niobium Nb: 0.5-1.0%, C: 0.1-0.2%, S: ≤0.035%, P: ≤0.035%, and the rest is Fe and unavoidable impurities.

[0100] In step S2, the structural statics module performs solution analysis including the following steps:

[0101] K1. Divide the continuum into many continuous units and take the displacement of several nodes of each unit as the unknown quantity, that is, {δ} e =[u i ,v i ,w i ,...] T , the displacement of any point in the unit cell is {f}=[u,v,w] T ; The displacement function N(x, y, z) is introduced to represent the distribution form and change law of the field variable in the unit, so that the value of the field variable at the node can be used to describe the field variable at any point in the unit; the appropriate model established in the unit is:

[0102] {f}=[N]{δ} e (one)

[0103] In formula (1), [N] = [IN1, IN2, IN3, ...]; I is the unit matrix;

[0104] K2. According to the characteristics of isoparametric elements, the local coordinates (ξ,η,ζ) are transformed into global coordinates (x,y,z). The coordinate transformation is performed by an expression similar to displacement interpolation. A mapping relationship is established between the child unit after the coordinate change and the parent unit (regular unit under local coordinates). Regardless of whether the internal unit or the unit near the boundary can select the same displacement function, the method of establishing the unit characteristic matrix for them is the same.

[0105] K3. Solve the expression of the relationship between the unit node force and the node displacement through geometric equations, constitutive equations, virtual work principle or potential variation equation, that is, the unit stiffness matrix, as follows:

[0106] {ε}=(ε x ,ε y ,ε z ,γ xy ,γ yz ,γ zx )

[0107] (ε)=[B]{δ} e (two)

[0108] In formula (2), [B] = [B1, B2, B3, ...];

[0109] K4. For small deformation linear elastic problems, the stress matrix within the unit is established according to the physical equation as follows:

[0110] (σ)=[D]{ε}=[D][B]{δ} e (three)

[0111] In formula (3), [B] is the geometric matrix, [D] is the elastic matrix, [S] is the stress matrix, and [S] = [D][B];

[0112] K5. Calculate the nodal force {F} in the unit according to the principle of virtual work e ,as follows:

[0113] {F} e =[k]{δ} e (Four)

[0114] In formula (4), [k] is the stiffness matrix of the unit,

[0115] K6. For any point i on the overall structure, establish the equilibrium equation as follows:

[0116]

[0117] In formula (5), {R i} is the external load on node i, and the above formula indicates that {R i} is balanced with the sum of the nodal forces of all elements surrounding point i at point i.

[0118] The safety of the material structure of the trolley-type furnace bottom plate is determined by three factors: equivalent stress, equivalent plastic strain and total deformation.

[0119] The equivalent stress [σ v The calculation formula of ] is as follows:

[0120]

[0121] In formula (6), σ1, σ2, σ3 refer to the first, second, and third principal stresses respectively, [σ s ] is the allowable yield stress of the material, σ s is the material yield limit, n s is the safety factor;

[0122] The equivalent plastic strain ε v The calculation formula is as follows:

[0123]

[0124] In formula (VII), v is Poisson's ratio; ε1 is principal strain 1; ε2 is principal strain 2; ε3 is principal strain 3;

[0125] The total deformation U total The calculation formula is as follows:

[0126]

[0127] In formula (8), U x , U y and U z They are the deformation components in the three directions of coordinates x, y, and z.

[0128] The main elements of the trolley furnace bottom plate are chromium Cr and nickel Ni metal.

[0129] The trolley-type furnace bottom plate adopts Cr, which is used to increase the hardenability of steel and make it have a secondary hardening effect, improve the hardness and wear resistance of carbon steel without making the steel brittle, and make the steel have better comprehensive mechanical properties after quenching and tempering.

[0130] Adjusting the Cr content makes it have the effects of high temperature oxidation resistance and oxidation corrosion resistance, while increasing the thermal strength of the steel to form chromium-containing carbides, thereby improving the wear resistance of the material surface.

[0131] The bottom plate of the trolley furnace uses nickel to strengthen ferrite and refine pearlescence, increasing the strength of the steel without significantly reducing its toughness.

[0132] Increasing Ni by 1% can increase the strength by about 29.4Pa. At the same time, the yield strength of steel increases faster than the tensile strength, and the damage to the toughness, plasticity and other process properties of steel is less than the impact of other alloying elements.

[0133] The bottom plate of the trolley type furnace adopts Ni to improve the fatigue resistance of steel and reduce the sensitivity of steel to notches.

[0134] The trace elements of the bottom plate of the trolley furnace are: metal elements tungsten W, cobalt Co and niobium Nb.

[0135] The bottom plate of the trolley-type furnace adopts W element, which is used to dissolve in liquid iron in a small amount, forming special carbides with carbon, promoting the transformation of austenite into martensite to enhance hardness, improve wear resistance and abrasion resistance.

[0136] The trolley-type furnace bottom plate uses Co element to promote martensitic transformation and increase toughness and strength.

[0137] The bottom plate of the trolley-type furnace uses Nb element to refine the grains, increase the thermal strength of the tooling, and resist the ability to resist rapid cooling and thermal stress. It is also used to prevent excessive penetration of C element during heat treatment and avoid product cracking.

[0138] A high melting point alloy formed by tungsten and niobium, which has excellent strength and creep resistance at high temperatures.

[0139] The bottom plate of the trolley-type furnace carries items at high temperatures, and the items carried at high temperatures remain unchanged. Under the condition that the load remains unchanged, the creep resistance of the high-melting-point alloy formed by tungsten and niobium enables the alloy of the bottom plate of the trolley-type furnace to effectively resist the phenomenon that the degree of deformation increases with time, so that the bottom plate of the trolley-type furnace can maintain a stable shape and size under high temperature or long-term stress conditions, avoiding the problem of items stuck in the trolley-type resistance furnace being unable to be removed due to deformation of the bottom plate of the trolley-type furnace, or items on the trolley-type resistance furnace falling off.

[0140] Cobalt itself is a hard element that can improve the alloy's wear resistance and deformation resistance, while niobium, due to its high melting point and high strength, can also significantly improve the alloy's mechanical properties. When they are combined together, they can form a strong and tough alloy structure that enables the alloy to withstand higher pressures and more harsh working environments.

[0141] The bottom plate of the trolley type furnace adopts carbon C to improve the strength: carbon is a strong austenite forming element, which significantly improves the strength of austenitic stainless steel through solid solution strengthening, and is also used to stabilize the austenite structure: carbon can make the austenite area expand strongly and stabilize the austenite structure, and its effect is about 30 times that of nickel.

[0142] 1. The round hole receiving surface can prevent the workpiece from getting stuck in the workpiece hole;

[0143] 2. Able to solve the problem of temperature uniformity: During the heat treatment process, temperature control is crucial. The central through-hole design of the round cake helps to achieve a more uniform temperature distribution, which helps to reduce the temperature difference between the inside and outside of the workpiece, thereby avoiding thermal stress and phase change stress caused by temperature difference and reducing the risk of cracking.

[0144] 3. Cooling rate control: The center through hole can act as a cooling channel, allowing the quenching medium to pass more quickly and evenly cool the workpiece. This helps control the cooling rate and avoid the problem of substandard performance due to too fast or too slow cooling.

[0145] 4. Reduce residual stress: During the heat treatment process, residual stress may be generated inside the workpiece due to the unevenness of heating and cooling. The design of the center through hole can reduce this stress to a certain extent, thereby improving the stability and service life of the workpiece.

[0146] 5. Reduce deformation: During heat treatment, the workpiece may be deformed due to the influence of organizational structure and phase change. By optimizing the design of the center through hole and the heat treatment process, the deformation of the workpiece can be reduced and the dimensional stability can be improved.

[0147] 6. Improved energy efficiency: The central through hole allows the quenching medium to flow more smoothly, thereby improving the energy efficiency of the quenching process. This helps to reduce production costs and reduce energy consumption.

[0148] The functions of the grid structure are as follows:

[0149] (1) Uniform temperature distribution: Due to the structural characteristics of the grid plate, the cross arrangement makes the heat more evenly distributed on the plate surface. This helps to reduce thermal stress and inconsistency of material properties caused by uneven temperature.

[0150] (2) Optimize heat conduction: The cross grid design increases the surface area of ​​the plate, thereby enhancing the heat conduction effect. This can accelerate the heating and cooling speed during the heat treatment process and improve work efficiency.

[0151] (3) Reduce deformation: The grid structure provides better support and stability, making the grid plate less likely to deform during heat treatment. This helps maintain the dimensional accuracy and shape stability of the workpiece.

[0152] (3) Improved stress distribution: The cross grid can effectively disperse and balance the stress generated during heat treatment. This helps to reduce cracks or fractures caused by stress concentration.

[0153] (4) Improved energy efficiency: The grid structure helps the quenching medium pass through the workpiece more evenly, improving the energy efficiency of the quenching process. This helps reduce production costs while reducing environmental impact.

[0154] The perforated round cakes are set on a cross-shaped grid plate, which can solve the following technical problems during the heat treatment process:

[0155] Improve heating efficiency: The perforated round cake design can increase its surface area and improve heat conduction efficiency. When placed on a grid plate for heat treatment, heat can be conducted to the inside of the round cake more quickly, thereby shortening the heating time.

[0156] Uniform heating and cooling: The cross grid plate can provide uniform support, so that the round cake is evenly stressed during the heating and cooling process, avoiding deformation and cracking caused by thermal stress concentration or uneven cooling.

[0157] Optimize heat medium flow: The hole design on the disc facilitates the flow and penetration of the heat treatment medium, ensuring that the heat can be evenly distributed in all parts of the disc. This helps to eliminate temperature gradients and improve the uniformity of heat treatment.

[0158] Prevent deformation caused by thermal expansion: The cross grid plate can provide certain constraints on the round cake, reducing its deformation due to thermal expansion during the heat treatment process. The structural design of the grid plate can optimize the support method of the round cake to avoid unnecessary displacement or deformation.

[0159] Easy to operate and handle: The perforated round cake design can also facilitate clamping and positioning during heat treatment, improving the convenience and accuracy of operation. At the same time, the presence of the grid plate also facilitates the handling and movement of the workpiece.

[0160] The upper layer is a hexagonal hole supporting surface; the lower layer is a flat plate structure; the hexagonal hole has good anti-cracking properties and can produce slight deformation with structural stress, thereby reducing the risk of product cracking.

[0161] In summary, the perforated round cakes are set on a grid plate composed of a cross, which can improve heating efficiency, uniform heating and cooling, optimize the flow of heat medium, prevent deformation, and facilitate operation and processing during the heat treatment process, which helps to improve the quality, efficiency and stability of the heat treatment.

[0162] Based on the preparation method of adopting multiple accessories to fuse into an integral furnace bottom plate, the material of the furnace bottom plate is designed. By adjusting the alloy elements of the furnace bottom plate material, heat-resistant alloy steel with Cr and Ni as main elements is selected, and the rare metal elements W, Co and Nb are added in the design. The W element promotes the transformation of austenite into martensite to enhance hardness, improve wear resistance and abrasion resistance, the Co element promotes martensite transformation, increases toughness and strength, and the Nb element refines the grains to increase the thermal strength of the material tray and the ability to resist rapid cooling, i.e., thermal stress, while effectively preventing excessive penetration of the C element during the heat treatment process to avoid product cracking. The above-mentioned element ratio ensures that the material frame material of the present invention has a lower thermal expansion coefficient, the ability to resist rapid cooling and thermal stress, avoids product cracking, improves the thermal mechanical strength of the material frame, and increases the number of recycling times of the material frame, thereby saving production and operation costs.

[0163] A conventional heat treatment tool is constructed by placing a shim on a furnace plate and stacking a material tray. Since the material tray is placed on the upper surface of the shim, the shim is often dragged and displaced during the heat treatment of the part, making it impossible to ensure that the center of gravity of the material tray falls on the shim during the heat treatment process; due to the unreasonable force structure of the material tray, cracks are formed on the material tray during the heat treatment process. During use, the cracks gradually deepen, causing the material tray to break, which requires replacement of the material tray, resulting in high cost losses. Since the heat treatment tooling must be heated together with the parts, the prior art tooling includes a furnace bottom plate, shims and a material tray. Sometimes the heat taken away by the tooling is equal to or greater than the heat of the workpiece, accounting for about 30-35% of the total heat, increasing the production cost of the heat treatment.

[0164] By designing the structure of the tooling, the weight and heat permeability of the furnace plate are reduced while ensuring the bearing capacity, further reducing the heat energy loss of ineffective heating, effectively saving energy and reducing costs; the problem of the tray components in the prior art of the heat treatment process of parts being easily deformed after heating and easily broken due to insufficient bearing capacity is solved, and the safety problem of workers' regular placement caused by the displacement of tooling during the parts processing process is solved, while the problem of the overall self-weight and high heat loss of the furnace bottom plate, shim and tray tooling is solved; an integrated furnace bottom plate with strong bearing capacity under high temperature and long thermomechanical fatigue life is provided, which can be used alone (no shim and tray are needed), greatly reducing the cost of use and increasing the service life.

[0165] In the finite element simulation method, the analysis is judged by three factors: equivalent stress, equivalent plastic strain and total deformation. Before making a prototype, stress can be found in any part of the computer-aided design model. Therefore, you can predict which areas may fail first and which areas may fail under higher loads. By correctly applying finite element analysis, you can effectively perform design iterations on simulation models instead of physical prototypes; things that cannot be seen can be displayed along the construction and testing route. For example, if a certain part of the furnace plate is concentratedly loaded, the deformation may not be obvious before it suddenly cracks or breaks. Now, if you want to make it harder in a certain direction, it is difficult to measure such a small deflection on the test bench. Through finite element analysis, the deflection is easy to see, which helps you understand the load path and strengthen the structure in the most effective way.

[0166] Improved performance of new and existing products, Reduced design and manufacturing costs, Reduced number of physical testing trials required, Faster time to market, Alternative designs and materials can be evaluated and optimized, Quick analysis of variations of basic solutions, Better product design due to clear understanding of the design intent of components, Reduced material waste, Topology and weight optimization of structures without compromising performance and safety, Better design decisions can be made due to complete information, Final product design of required quality can be reached faster, Easily meet various product standards and contractual requirements, Improved product safety, Determine product behavior under real-world conditions by applying appropriate boundary conditions on the model, FEA can be performed even on affordable workstations and desktop personal computers, CAE software is now a must-have tool for most first-class companies, Determine the service life of products and determine warranty and repair plans.

[0167] On the other hand, finite element simulation analysis is used to verify the performance of the furnace bottom plate. Finite element simulation analysis has no restrictions on size or weight, and the analysis cost is low. Among them, the weight of the furnace bottom plate is generally about 11 tons. If a simulated load experiment is used, it will cost a lot of manpower and material resources. To obtain accurate data, destructive tests are required, and the cost is also relatively expensive. Finite element simulation analysis can solve this problem well.

[0168] By performing finite element simulation analysis on the trolley-type furnace bottom plate, the continuous solution area with infinite degrees of freedom is discretized into discrete bodies (units) with finite degrees of freedom and connected to each other in a certain way (nodes), that is, the continuum is hypothetically divided into a finite number of discrete units, and the units are only connected to each other at a finite number of specified points, and the original continuum is replaced by a collection of discrete units. In general, the finite element equation is a set of linear equations with node displacements as unknown quantities. Solving the set of equations can obtain the displacements of a finite number of nodes on the continuum, and then the stress distribution law on each unit can be obtained, thereby evaluating the performance of the above-mentioned trolley-type furnace bottom plate.

[0169] At present, the furnace bottom plate is generally assembled by stacking furnace plate, pad iron and material tray in sequence, and the material tray carries the forging. However, the pad iron often drags and displaces during the heat treatment of the workpiece, which makes it impossible to ensure that the center of gravity of the material tray falls on the pad iron during the heat treatment process; due to the unreasonable force structure of the material tray, cracks are formed in the material tray during the heat treatment process. The cracks gradually deepen during use, causing the material tray to break, so that the material tray needs to be replaced, which has a high cost loss; in addition, since the heat treatment tooling must be heated together with the workpiece, the heat taken away by the existing furnace bottom plate is equal to or greater than the heat of the workpiece, accounting for about 30-35% of the total heat, which increases the production cost of heat treatment; therefore, the traditional furnace bottom plate has problems such as overall structural instability, easy displacement, and high energy consumption; and, during the cooling process, a large internal stress will be generated inside the material tray, which is easy to cause its deformation and cracking, so the structure of the trolley furnace bottom plate is as follows:

[0170] The trolley-type furnace bottom plate includes a base plate 10 and a receiving frame 20, the receiving frame 20 includes a plurality of first grid plates 21 and a plurality of second grid plates 22, the first grid plates 21 and the second grid plates 22 are arranged crosswise with each other, a cylinder 23 is arranged at the intersection of the first grid plate 21 and the second grid plate 22, the upper end surface of the cylinder 23 is provided with a circular hole-shaped receiving surface 201, the first grid plate 21 and the second grid plate 22 are both provided with a first through hole 24, and the first grid plate 21 and the second grid plate 22 are both arranged on the base plate 10.

[0171] Four side plates 30 are arranged on the base plate 10 , and the side plates 30 are distributed around the receiving frame 20 . The side plates 30 are provided with a second through hole 31 and a third through hole 32 . The second through hole 31 corresponds to the first through hole 24 , and the third through hole 32 corresponds to the cylinder 23 .

[0172] A clamping plate 41 is disposed on the outer side surface of the side plate 30 , and a clamping slot 40 is disposed between the clamping plate 41 and the side plate 30 .

[0173] The use of an integrated plate improves the stability of the overall structure and the flatness of the furnace bottom plate; and while ensuring the load-bearing capacity, it reduces the weight and heat permeability of the furnace bottom plate itself, further reduces the heat energy loss caused by ineffective heating, effectively saves energy and reduces costs, and realizes the lightweighting of the furnace bottom plate.

[0174] The design of the circular hole-shaped receiving surface 201 is beneficial to the uniform distribution of temperature during the heat treatment process, which helps to reduce the temperature difference between the inside and outside of the furnace bottom plate, thereby avoiding thermal stress and phase change stress caused by temperature difference and reducing the risk of cracking.

[0175] By setting circular hole-shaped receiving surfaces 201 at each intersection of the cross grid, four rib confluences are dispersed into three rib confluences, thereby reducing shrinkage and preventing the grid plate from being too long and forming cracks due to shrinkage tension during the cooling process. In addition, the heating efficiency can be improved, heating and cooling can be uniform, the flow of heat medium can be optimized, deformation can be prevented, and operation and processing can be facilitated, which helps to improve the quality, efficiency and stability of heat treatment of workpieces.

[0176] The stability of the overall structure and the flatness of the furnace bottom plate are improved, and the furnace bottom plate is lightweight. A circular hole-shaped receiving surface 201 distributed in an array is arranged on the furnace bottom plate. The design of the central through hole of the circular hole-shaped receiving surface 201 is conducive to the uniform distribution of temperature during the heat treatment process, and helps to reduce the temperature difference between the inside and outside of the furnace bottom plate, thereby avoiding thermal stress and phase change stress caused by the temperature difference and reducing the risk of cracking; and the design of the central through hole of the circular hole-shaped receiving surface 201 can optimize the flow of heat medium, help the flow and penetration of the heat treatment medium, and ensure that the heat can be evenly distributed in various parts of the cylinder, which helps to eliminate temperature gradients and improve the uniformity of heat treatment.

[0177] The design of the circular hole-shaped receiving surface 201 is also beneficial to improving the performance of the heat-treated workpiece treated by the trolley-type resistance furnace. First, the central through hole of the circular hole-shaped receiving surface 201 can be used as a cooling channel, allowing the quenching medium to pass through more quickly and evenly cool the heat-treated workpiece, which helps to control the cooling rate and avoid the problem of substandard workpiece performance caused by too fast or too slow cooling; at the same time, the central through hole allows the quenching medium to flow more smoothly, thereby improving the energy efficiency of the quenching process, helping to reduce production costs and reduce energy consumption; secondly, during the heat treatment process, due to the unevenness of heating and cooling, residual stress may be generated inside the workpiece. The design of the circular hole-shaped receiving surface 201 can reduce this residual stress to a certain extent, thereby improving the stability and service life of the workpiece. In addition, during heat treatment, due to the influence of organizational structure and phase change, the workpiece may be deformed. The design of the circular hole-shaped receiving surface 201 can reduce the deformation of the workpiece and improve dimensional stability.

[0178] By setting a cylinder 23 at the intersection of the first mesh plate 21 and the second mesh plate 22, the intersection of the four ribs can be dispersed into multiple groups of three ribs, thereby reducing shrinkage; and, during the cooling process of the workpiece, the first mesh plate 21 and the second mesh plate 22 are divided into multiple sections by the cylinder 23, which can prevent the mesh plate from being too long and forming cracks due to shrinkage tension during the cooling process. Compared with square holes, the connection structure of the circular hole has high strength and small deformation. In addition, the circular hole-shaped receiving surface density set at each intersection is high, which can prevent the workpiece from getting stuck in the hole.

[0179] By providing circular hole-shaped receiving surfaces 201 at each intersection of the grid layers, the surface area of ​​the receiving frame 20 can be increased and the heat conduction efficiency can be improved; when the workpiece is placed on the furnace bottom plate for heat treatment, the heat can be conducted to the inside of the cylinder 23 more quickly, thereby shortening the heating time; secondly, the grid layer can provide uniform support for the cylinder 23, so that the cylinder 23 is evenly stressed during the heating and cooling process, avoiding deformation and cracking caused by thermal stress concentration or uneven cooling; the first grid plate 21 and the second grid plate 22 can provide certain constraints on the cylinder 23, reducing its deformation due to thermal expansion during the heat treatment process; and the structural design of the grid layer can optimize the support method of the cylinder 23 to avoid unnecessary displacement or deformation.

[0180] The design of the circular hole-shaped receiving surface 201 can also facilitate the clamping and positioning of the workpiece during the heat treatment process, thereby improving the convenience and accuracy of the operation. At the same time, the existence of the grid layer also facilitates the processing and movement of the workpiece.

[0181] The first grid plate 21 and the second grid plate 22 form a cross grid shape. The use of the cross grid has the following effects: (1) Due to the structural characteristics of the grid plate, the cross arrangement makes the heat more evenly distributed on the furnace bottom plate, which helps to reduce the thermal stress and inconsistency of material properties caused by uneven temperature; (2) The design of the cross grid increases the surface area of ​​the plate, thereby enhancing the heat conduction effect, which can accelerate the heating and cooling speed during the heat treatment process and improve work efficiency; (3) The grid structure provides better support and stability, making it less likely for the support frame to deform during the heat treatment process, which helps to maintain the dimensional accuracy and shape stability of the workpiece; (4) The cross grid can effectively disperse and balance the stress generated during the heat treatment process, which helps to reduce cracks or fractures caused by stress concentration; (5) The cross grid helps the quenching medium to pass through the heat-treated workpiece more evenly, improves the energy efficiency of the quenching process, helps to reduce production costs, and reduces the impact on the environment.

[0182] During the heat treatment process, the furnace bottom plate can improve heating efficiency, uniformly heat and cool, optimize the flow of heat medium, prevent deformation, and facilitate operation and handling, which helps to improve the quality, efficiency and stability of the workpiece heat treatment.

[0183] By providing the first through holes 24, air convection between the square grooves in the grid layer can be accelerated, which is beneficial to hot air circulation and improves heating uniformity and heating efficiency during the heat treatment process.

[0184] It also includes at least two card slots 40, which are arranged on at least two sides of the receiving frame 20, and the openings of the card slots 40 face the top or bottom of the receiving frame 20. Among the multiple plates, each adjacent two plates are positioned and connected by two card slots 40 with openings facing opposite directions, thereby avoiding displacement between the plates and improving the stability of the furnace bottom plate.

[0185] The clamping plate 41 is fixedly connected to the base plate 10 to form a clamping slot 40 opening toward the top of the receiving frame 20; or, the clamping plate 41 is fixedly connected to the top surface of the receiving frame 20 to form a clamping slot 40 opening toward the bottom of the receiving frame 20.

[0186] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A trolley type furnace bottom plate obtained based on finite element simulation method, characterized in that: The structure of the trolley-type furnace bottom plate includes an upper layer, a middle layer and a lower layer, wherein the upper layer is a circular hole receiving surface structure, the middle layer is a grid frame structure, and the lower layer is a flat plate; The circular hole receiving surface is in the shape of a round pancake with a through hole in the middle; the grid frame is formed by N cross arrays connected to each other, the cross includes cross-connected horizontal plates and vertical plates, the circular hole receiving surface is connected to the upper end of the intersection of the cross, and the flat plate is arranged at the lower end of the cross; The trolley-type furnace bottom plate comprises a base plate (10) and a receiving frame (20), the receiving frame (20) comprises a plurality of first grid plates (21) and a plurality of second grid plates (22), the first grid plates (21) and the second grid plates (22) are arranged crosswise with each other, a cylinder (23) is arranged at the intersection of the first grid plates (21) and the second grid plates (22), a circular hole-shaped receiving surface (201) is arranged on the upper end surface of the cylinder (23), the first grid plates (21) and the second grid plates (22) are both provided with first through holes (24), and the first grid plates (21) and the second grid plates (22) are both arranged on the base plate (10); Four side plates (30) are arranged on the base plate (10), and the side plates (30) are distributed around the receiving frame (20). A second through hole (31) and a third through hole (32) are arranged on the side plates (30), and the second through hole (31) corresponds to the first through hole (24), and the third through hole (32) corresponds to the cylinder (23); A clamping plate (41) is provided on the outer side surface of the side plate (30), and a clamping groove (40) is provided between the clamping plate (41) and the side plate (30); The trolley-type furnace bottom plate comprises a top layer and a bottom layer, wherein the top layer is a hexagonal hole receiving surface structure, and the bottom layer is a flat plate structure; The finite element simulation method comprises the following steps: S1. Establish a solid model of the trolley type furnace bottom plate; Use solideworks software to model the trolley-type furnace bottom plate and design a solid model of the trolley-type furnace bottom plate; S2. Establish analysis module through Ansys Workbench software; Use Ansys Workbench software to solve and analyze through the structural statics module, drag Static Strutural into the blank space, and establish an analysis module; S3. Import the solid model of the trolley type furnace bottom plate; Importing the entity model into the analysis module established in step S2; S4. Define material properties; S4.

1. Enter the material setting system through the A2 Engineering Date component module and open the Isotropic Elastic, Cofficient of Thermal Expansion window in the material properties window; S4.

2. Set the elastic modulus to 2E11, the Poisson's ratio to 0.3, and the thermal expansion coefficient to 1.6E-5C through the material properties of ZGCr25Ni20Si2. -1 ; S5. Meshing the solid model of the trolley type furnace bottom plate; Use hexahedral mesh, mesh type is C3D8R, and set the mesh size to 10mm; S6. Add loads and constraints; S6.1, add a small area load of 0.2T to a linear load of 0.5T; S6.

2. Select the menu Static Structural and right-click to insert ThermalCondition, set the ambient temperature to 1100℃, and right-click to insert Force; the uniform load on the surface is 2000N, right-click to insert Force, set the load in the online area to 5000N, right-click to insert FrictionlessSupport, and constrain the bottom surface; S7, obtain simulation results; Select Solution from the menu, right-click and insert TotalDeformation to get the deformation cloud map; In step S6.2, the load includes three forms:

1. temperature load, the design temperature is 1100°C; 2. surface area load, the design load value is 0.2T and the force bearing area is 300mm*300mm; 3. linear load, the design load value is 0.5T and the load length is 700mm; The safety of the material structure of the trolley-type furnace bottom plate is determined by three factors: equivalent stress, equivalent plastic strain and total deformation.

2. The trolley type furnace bottom plate obtained based on the finite element simulation method according to claim 1, characterized in that: The composition contents of the trolley furnace bottom plate are as follows by mass: chromium Cr: 24-27%, nickel Ni: 19-22%, tungsten W: 2.5-3.5%, cobalt Co: 1.0-2.0%, niobium Nb: 0.5-1.0%, and C: 0.1-0.2%.

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