Method for solving the temperature field of external cylindrical grinding with epicycloid heat source as process parameters vary

Abstract

The present invention relates to a method for solving the temperature field of cylindrical grinding with an epicycloidal heat source that changes with process parameters, and belongs to the field of grinding temperature control. The method solves the Reynolds equation by an iterative method to obtain the grinding fluid pressure and average flow rate, determines the convection heat transfer coefficient of the workpiece and the grinding fluid, determines the mapping relationship between the motion trajectory of the grinding wheel abrasive particles and the grinding process parameters and the grinding wheel type based on the posture coordinate change method, determines the shape of the epicycloidal heat source of cylindrical grinding that changes with process parameters, and solves the grinding temperature using a moving heat source method. The method provided by the present invention can take into account the influence of the grinding process parameters on the surface morphology and temperature of the cylindrical grinding, thereby more accurately analyzing the temperature field distribution during the grinding process, and providing theoretical guidance for process optimization design and cylindrical grinding temperature control in engineering practice.

Description

Technical Field

[0001] The invention belongs to the field of grinding temperature control and relates to a method for solving the temperature field of outer cylindrical grinding of an epicycloidal heat source that changes with process parameters. Background Art

[0002] As an important finishing method, cylindrical grinding plays an important role in ensuring the dimensional accuracy and surface roughness of the workpiece. The grinding process often generates a lot of heat, which causes the surface temperature of the workpiece to concentrate and cause grinding burns, seriously affecting the workpiece yield. Therefore, it is very necessary to accurately simulate and analyze the grinding temperature field.

[0003] Traditional methods for calculating the temperature field of grinding processing include commercial finite element software calculation or classical grinding temperature field numerical analysis model. Due to the large difference in the order of magnitude between the grinding depth and the size of the grinding wheel abrasive grains, the finite element method usually calculates the grinding temperature field by establishing a grinding model of the abrasive grains and the workpiece, which makes it difficult to accurately and truly simulate the temperature field distribution under actual grinding conditions. The classical grinding temperature field numerical analysis model uses the moving heat source method to solve the grinding temperature field based on traditional heat source models such as uniformly distributed heat source, triangular heat source, and quadratic curve heat source. When the grinding process parameters change significantly, the shape of the heat source will not adjust accordingly, resulting in a large error between the solved temperature field and the actual measurement results.

[0004] In view of the shortcomings of the above research, the present invention proposes a method for solving the temperature field of cylindrical grinding that can be adaptively changed according to process parameters. Based on this method, researchers can determine the heat flow distribution state and heat distribution coefficient according to the grinding process parameters, thereby more accurately calculating the grinding temperature field and determining the optimal working condition parameters that match the optimal processing efficiency of the workpiece. In view of this, the present invention is conducive to improving the level of cylindrical grinding process design and analysis, and provides a theoretical reference for predicting grinding burns. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for solving the temperature field of cylindrical grinding with an epicycloidal heat source that varies with process parameters.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for solving the temperature field of cylindrical grinding with epicycloidal heat source that varies with process parameters, the method comprising the following steps:

[0008] S1: Calculate the grinding force of the grinding wheel, the center of the workpiece is O1 and the radius is r w , the speed is ω w ; The center of the grinding wheel is O2 and the radius is r w , the speed is ω sThe angle between two adjacent abrasive grains a and b is γ, and the grinding depth is defined as a. p ; The part between the tracks of adjacent abrasive grains during grinding is the undeformed chip; Assuming that the abrasive grains are evenly distributed on the grinding wheel surface, the semi-apex angle of the conical abrasive grains is θ, and the grinding wheel grain size M is given, the spacing between any two abrasive grains is ω and the number of abrasive grains per unit time N is calculated, that is,

[0009]

[0010]

[0011] At the same time, the force analysis of a single abrasive particle is carried out according to the flow stress theory, assuming that the radius is r s The grinding wheel rotates at a speed n s Grinding radius is r w The workpiece with grinding depth a p When the abrasive tangential grinding force F ti and normal grinding force F ni It is expressed as:

[0012]

[0013] Further obtain the total tangential grinding force F during cylindrical grinding t and normal grinding force F n ,Right now

[0014]

[0015] S2: According to the grinding process parameters and grinding wheel parameters, the grinding trajectory (x, y) of the grinding wheel abrasive is calculated, and the abrasive phase difference γ is solved according to the abrasive particle spacing, so as to obtain the undeformed chip thickness F(x), and perform normalization processing, and determine the shape of the epicycloidal heat source according to the proportional relationship between the heat source size and the undeformed chip thickness;

[0016] S3: Calculate the actual grinding contact arc length l according to the motion state of the abrasive particles and the elastic-plastic principle c ;

[0017]

[0018] In the formula, F n is the unit normal grinding force, R r is the roughness factor, B represents the grinding wheel width, E s 、E w are Young's modulus of the grinding wheel and workpiece, μ s , μ w are the Poisson's ratios of the grinding wheel and the workpiece respectively; calculate the workpiece convection heat transfer coefficient h w ,

[0019]

[0020] Among them, β w is the thermal characteristic coefficient of the workpiece, where λ w is the workpiece heat transfer coefficient, ρ w is the workpiece density, v w represents the linear velocity of the workpiece, and v w =2πn w , C1 is related to the size of the Peclet number, and when Pe<0.2, C1=0.76; when 0.2≤Pe≤10, When Pe≥10, C1=1.06;

[0021] S4: According to the rotation speed of the grinding wheel and the workpiece, the linear iteration method is used to solve the Reynolds equation to obtain the grinding fluid pressure distribution p in the grinding contact area. After meeting the convergence condition, the finite difference method is used to solve the average flow velocity u of the grinding fluid, and then the workpiece convection heat transfer coefficient h is obtained. w ;

[0022] S5: Determine the heat flow distribution ratio of the grinding contact arc area, and determine the Reynolds number Re according to the average flow velocity u of the grinding fluid.

[0023]

[0024] ρ l Indicates the grinding fluid density, h l Re represents the characteristic thickness of the grinding fluid, η represents the viscosity coefficient of the grinding fluid; the flow state of the grinding fluid is determined according to Re, when Re>2300, it is determined to be a turbulent state, when Re>2300, it is determined to be a laminar state, and the convective heat transfer coefficient of the grinding fluid h is calculated. f ;

[0025]

[0026] S6: Solve the energy distribution ratios of workpiece-grinding wheel and workpiece-grinding chips respectively, and then obtain the energy distribution ratio R entering the workpiece w ;

[0027]

[0028] In the formula, r0 and k g represents the effective contact radius and thermal conductivity of the abrasive particles, v s represents the grinding wheel linear speed, and v s =2πn s , α w is the thermal diffusivity of the workpiece, and Among them, λ w is the workpiece heat transfer coefficient, ρ w Indicates the workpiece density, c wIndicates the specific heat capacity of the workpiece; shear strain Maximum undeformed wear chip thickness a gmax Expressed as

[0029]

[0030] S7: Solve for the total heat source intensity q m , calculate the heat flux distribution state q(ξ) of the epicycloidal heat source according to the grinding wheel abrasive trajectory;

[0031] S8: Based on the heat flux distribution state q(ξ) of the epicycloid heat source and the heat distribution ratio coefficient R w And the actual length of the grinding contact arc l c , the moving heat source method is used to solve the temperature field of cylindrical grinding. The temperature rise T(x,z) at any point on the workpiece is expressed as

[0032]

[0033] Optionally, in S2, the wear particle trajectory equation is solved as follows:

[0034] S201: According to the grinding process parameters and the grinding wheel parameters, the grinding track (x, y) of the grinding wheel abrasive is calculated, and the abrasive phase difference γ is solved according to the abrasive spacing. In the workpiece coordinate system, the parameterized equation of the abrasive track is expressed as

[0035] x=(r s +r w -a p )cos(ω w t)+r s cos[±ω s t-(n-1)γ] (11a)

[0036] y=(r s +r w -a p )sin(ω w t)+r s sin[±ω s t-(n-1)γ] (11b)

[0037]

[0038] In the formula, for abrasive particle a, n=1, for abrasive particle b, n=2, t represents the movement time, ω w and ω s denote the angular velocity of the workpiece and the grinding wheel respectively. According to the parameterized equation, the above parameterized equation is expressed in the form of y=f(x);

[0039] S202: According to the adjacent abrasive particle trajectory equation, the shape equation of the undeformed chip is written as:

[0040] F(x)=f(x)-f γ (x) (12)

[0041] Where f(x) is the equation of the ideal trajectory a, f γ (x) is the equation of the adjacent ideal trajectory b; and F(x) is related to the grinding depth a p , grinding wheel linear speed v s , workpiece linear speed v w and the parameters between adjacent trajectories;

[0042] S203: Normalize the heat source curve coordinates and the heat flow in the grinding contact arc area

[0043]

[0044]

[0045] S204: Determine the shape of the epicycloidal heat source according to the proportional relationship between the size of the heat source and the thickness of the undeformed wear chips.

[0046] Optionally, in S4, the workpiece convection heat transfer coefficient h w The solution process is as follows:

[0047] S401: Solve the Reynolds equation by linear iteration method to obtain the grinding fluid pressure distribution p in the grinding contact area

[0048]

[0049] The boundary pressure of the lubricated contact domain meets the condition

[0050] p l (x s ,y)=p l (x e ,y)=p l (x,y s )=p l (x,y e )=0 (15)

[0051] In the formula, x s and x e They represent the inlet and outlet coordinates of the bearing raceway outer cylindrical grinding lubrication calculation domain along the grinding fluid inlet direction (x direction), and y s and e They respectively represent the inlet and outlet coordinates of the bearing raceway external cylindrical grinding lubrication calculation domain along the grinding wheel width direction (y direction);

[0052] S402: Determine whether the calculated pressure iteration meets the convergence condition

[0053]

[0054] In the formula, and are the grinding fluid pressures calculated for the previous iteration and the current iteration, ε lp is the pressure convergence accuracy, which is defined as ε lp =1.0×10 -4 , when the convergence condition is met, the solution is completed, otherwise the grinding fluid pressure is corrected and the solution is returned to step S401;

[0055]

[0056] In the formula, k p is the grinding fluid pressure factor, k p =0.05;

[0057] S403: Use the finite difference method to solve the average flow velocity u of the grinding fluid:

[0058]

[0059] S404: Obtaining the workpiece convection heat transfer coefficient h w ;

[0060]

[0061] Among them, β w is the thermal characteristic coefficient of the workpiece, where λ w is the workpiece heat transfer coefficient, ρ w is the workpiece density, v w represents the linear velocity of the workpiece, and v w =2πn w , C1 is related to the size of the Peclet number, and when Pe<0.2, C1=0.76; when 0.2≤Pe≤10, When Pe≥10, C1=1.06.

[0062] Optionally, in S7, the heat source distribution state solving process is as follows:

[0063] S701: First calculate the total grinding heat source intensity q m

[0064] q m =F t v s (20)

[0065] According to the heat source distribution ratio, the equivalent cycloidal heat source intensity acting on the workpiece is q w =R w q m ;

[0066] S702: Calculate the heat flux intensity distribution state in the grinding contact arc area:

[0067]

[0068]

[0069] Where ξ is the actual position of the contact arc, q(ξ) is the actual heat flux intensity, and A w is the heat source shape coefficient introduced, which is used to determine the maximum position of the heat source and the heat source distribution state, and is obtained by integration;

[0070]

[0071] S703: Calculate the total heat flow into the workpiece

[0072]

[0073] The beneficial effect of the present invention is that the method can accurately solve the cylindrical grinding temperature field according to different grinding wheel types and grinding process parameter conditions, which is beneficial to improving the grinding surface quality and enhancing the processing efficiency.

[0074] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0076] Figure 1 It is a schematic diagram of the external cylindrical grinding machining trajectory;

[0077] Figure 2 It is the heat source shape and the relative error diagram of the maximum temperature;

[0078] Figure 3 Schematic diagram of the process flow for solving the temperature of cylindrical grinding with epicycloidal heat source. DETAILED DESCRIPTION

[0079] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0080] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0081] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0082] Typical external cylindrical grinding machining path diagram Figure 1 As shown, the center of the workpiece is O1 and the radius is r w , the speed is ω w ; The grinding wheel has a center of O2 and a radius of r w , the speed is ω s And the angle between two adjacent abrasive grains a and b is opposite to the workpiece rotation direction, and the grinding depth is defined as a p ; The part between the tracks of adjacent abrasive particles during the grinding process is the undeformed chips. Figure 2 The shapes of the uniform heat source (Uniform), right-triangular heat source (Right-triangular), quadratic heat source (Quadratic) and epitrochoid heat source (Epitrochoid) are shown respectively, as well as the comparison between the theoretical maximum temperature and the experimental maximum temperature calculated using different models, to illustrate the reliability of the epitrochoid heat source.

[0083] A method for solving the temperature field of cylindrical grinding with epicycloidal heat source that varies with process parameters, the method comprising the following steps:

[0084] S1: Calculate the grinding force of the grinding wheel. Assume that the abrasive grains are evenly distributed on the surface of the grinding wheel, the semi-apex angle of the conical abrasive grains is θ, and the grinding wheel grain size M is given. Based on this, calculate the distance between any two abrasive grains as ω and the number of abrasive grains per unit time N, that is,

[0085]

[0086]

[0087] At the same time, the force analysis of a single abrasive particle is carried out according to the flow stress theory, assuming that the radius is r s The grinding wheel rotates at a speed n s Grinding radius is r w The workpiece with grinding depth a p When the abrasive tangential grinding force F ti and normal grinding force F ni It can be expressed as:

[0088]

[0089] Further obtain the total tangential grinding force F during cylindrical grinding t and normal grinding force F n ,Right now

[0090]

[0091] S2: According to the grinding process parameters and grinding wheel parameters, the grinding trajectory (x, y) of the grinding wheel abrasive is calculated, and the abrasive phase difference γ is solved according to the abrasive particle spacing, so as to obtain the undeformed chip thickness F(x), and perform normalization processing, and determine the shape of the epicycloidal heat source according to the proportional relationship between the heat source size and the undeformed chip thickness;

[0092] S3: Calculate the actual grinding contact arc length l according to the motion state of the abrasive particles and the elastic-plastic principle c ;

[0093]

[0094] In the formula, F n is the unit normal grinding force, R r is the roughness factor, B represents the grinding wheel width, E s 、E w are Young's modulus of the grinding wheel and workpiece, μ s , μ w are the Poisson's ratios of the grinding wheel and the workpiece, respectively. On this basis, the workpiece convection heat transfer coefficient h is calculated w ,

[0095]

[0096] Among them, β w is the thermal characteristic coefficient of the workpiece, where λ w is the workpiece heat transfer coefficient, ρ w is the workpiece density, v w represents the linear velocity of the workpiece, and v w =2πn w , C1 is related to the size of the Peclet number, and when Pe<0.2, C1=0.76; when 0.2≤Pe≤10, When Pe≥10, C1=1.06.

[0097] S4: According to the rotation speed of the grinding wheel and the workpiece, the linear iteration method is used to solve the Reynolds equation to obtain the grinding fluid pressure distribution p in the grinding contact area. After meeting the convergence condition, the finite difference method is used to solve the average flow velocity u of the grinding fluid, and then the workpiece convection heat transfer coefficient h is obtained. w ;

[0098] S5: Determine the heat flow distribution ratio of the grinding contact arc area, and determine the Reynolds number Re according to the average flow velocity u of the grinding fluid.

[0099]

[0100] ρ l Indicates the grinding fluid density, h l Re represents the characteristic thickness of the grinding fluid, and η represents the viscosity coefficient of the grinding fluid. The flow state of the grinding fluid is determined according to Re. When Re>2300, it is determined to be a turbulent state (Turbulent flow), and when Re>2300, it is determined to be a laminar state (Laminar flow). The convection heat transfer coefficient of the grinding fluid h is calculated. f ;

[0101]

[0102] S6: Solve the energy distribution ratios of workpiece-grinding wheel and workpiece-grinding chips respectively, and then obtain the energy distribution ratio R entering the workpiece w ;

[0103]

[0104] In the formula, r0 and k g represents the effective contact radius and thermal conductivity of the abrasive particles, v s represents the grinding wheel linear speed, and v s =2πn s , α w is the thermal diffusivity of the workpiece, and Among them, λw is the workpiece heat transfer coefficient, ρ w Indicates the workpiece density, c w Indicates the specific heat capacity of the workpiece. Shear strain Maximum undeformed wear chip thickness a gmax It can be expressed as

[0105]

[0106] S7: Solve for the total heat source intensity q m , calculate the heat flux distribution state q(ξ) of the epicycloidal heat source according to the grinding wheel abrasive trajectory;

[0107] S8: Based on the heat flux distribution state q(ξ) of the epicycloid heat source and the heat distribution ratio coefficient R w And the actual length of the grinding contact arc l c , the moving heat source method is used to solve the temperature field of cylindrical grinding. The temperature rise T(x,z) at any point on the workpiece can be expressed as

[0108]

[0109] The above process can be used Figure 3 The schematic diagram of the temperature solution process for cylindrical grinding using an epicycloidal heat source is shown.

[0110] In step S2, the wear particle trajectory equation is solved as follows:

[0111] S201: According to the grinding process parameters and the grinding wheel parameters, the grinding track (x, y) of the grinding wheel abrasive is calculated. At the same time, the abrasive phase difference γ is solved according to the abrasive spacing. In the workpiece coordinate system, the parameterized equation of the abrasive track can be expressed as

[0112] x=(r s +r w -a p )cos(ω w t)+r s cos[±ω s t-(n-1)γ] (11a)

[0113] y=(r s +r w -a p )sin(ω w t)+r s sin[±ω s t-(n-1)γ] (11b)

[0114]

[0115] In the formula, for abrasive particle a, n=1, for abrasive particle b, n=2, t represents the movement time, ωw and ω s represent the angular velocity of the workpiece and the grinding wheel respectively. According to the parameterized equation, the above parameterized equation can be expressed in the form of y=f(x).

[0116] S202: According to the adjacent abrasive particle trajectory equation, the shape equation of the undeformed chip is written as

[0117] F(x)=f(x)-f γ (x) (12)

[0118] Where f(x) is the equation of the ideal trajectory a, f γ (x) is the equation of the adjacent ideal trajectory b. And F(x) is related to the grinding depth a p , grinding wheel linear speed v s , workpiece linear speed v w And the parameters between adjacent trajectories.

[0119] S203: Normalize the heat source curve coordinates and the heat flow in the grinding contact arc area

[0120]

[0121]

[0122] S204: Determine the shape of the epicycloidal heat source according to the proportional relationship between the size of the heat source and the thickness of the undeformed wear chips.

[0123] In step S4, the workpiece convection heat transfer coefficient h w The solution process is as follows:

[0124] S401: Solve the Reynolds equation by linear iteration method to obtain the grinding fluid pressure distribution p in the grinding contact area

[0125]

[0126] The boundary pressure of the lubricated contact domain meets the condition

[0127] p l (x s ,y)=p l (x e ,y)=p l (x,y s )=p l (x,y e )=0 (15)

[0128] In the formula, x s and x e They represent the inlet and outlet coordinates of the bearing raceway outer cylindrical grinding lubrication calculation domain along the grinding fluid inlet direction (x direction), and ys and e They respectively represent the inlet and outlet coordinates of the bearing raceway external cylindrical grinding lubrication calculation domain along the grinding wheel width direction (y direction).

[0129] S402: Determine whether the calculated pressure iteration meets the convergence condition

[0130]

[0131] In the formula, and are the grinding fluid pressures calculated for the previous iteration and the current iteration, ε lp is the pressure convergence accuracy, which can be defined as ε in the present invention. lp =1.0×10 -4 , when the convergence condition is met, the solution is completed, otherwise the grinding fluid pressure is corrected and the solution is returned to step S401.

[0132]

[0133] In the formula, k p is the grinding fluid pressure factor, which is set to k in the present invention. p =0.05.

[0134] S403: Use the finite difference method to solve the average flow velocity u of the grinding fluid:

[0135]

[0136] S404: Obtaining the workpiece convection heat transfer coefficient h w ;

[0137]

[0138] Among them, β w is the thermal characteristic coefficient of the workpiece, where λ w is the workpiece heat transfer coefficient, ρ w is the workpiece density, v w represents the linear velocity of the workpiece, and v w =2πn w , C1 is related to the size of the Peclet number, and when Pe<0.2, C1=0.76; when 0.2≤Pe≤10, When Pe≥10, C1=1.06.

[0139] In step S7, the heat source distribution state solution process is as follows:

[0140] S701: First calculate the total grinding heat source intensity q m

[0141] q m=F t v s (20)

[0142] According to the heat source distribution ratio, the cycloidal heat source intensity acting on the workpiece is equivalent to q w =R w q m .

[0143] S702: Calculate the heat flux intensity distribution state in the grinding contact arc area

[0144]

[0145]

[0146] Where ξ is the actual position of the contact arc, q(ξ) is the actual heat flux intensity, and A w It is the introduced heat source shape coefficient, which is used to determine the maximum position of the heat source and the heat source distribution state, and can be obtained by integration.

[0147]

[0148] S703: Calculate the total heat flow into the workpiece

[0149]

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for solving the temperature field of cylindrical grinding with epicycloidal heat source that varies with process parameters, characterized by: The method comprises the following steps: S1: Calculate the grinding force of the grinding wheel, the center of the workpiece is O1 and the radius is r w , the speed is ω w ; The center of the grinding wheel is O2 and the radius is r w , the speed is ω s The angle between two adjacent abrasive grains a and b is γ, and the grinding depth is defined as a. p ; The part between the tracks of adjacent abrasive grains during grinding is the undeformed chip; Assuming that the abrasive grains are evenly distributed on the grinding wheel surface, the semi-apex angle of the conical abrasive grains is θ, and the grinding wheel grain size M is given, the spacing between any two abrasive grains is ω and the number of abrasive grains per unit time N is calculated, that is, At the same time, the force analysis of a single abrasive particle is carried out according to the flow stress theory, assuming that the radius is r s The grinding wheel rotates at a speed n s Grinding radius is r w The workpiece with grinding depth a p When the abrasive tangential grinding force F ti and normal grinding force F ni It is expressed as: Further obtain the total tangential grinding force F during cylindrical grinding t and normal grinding force F n ,Right now S2: According to the grinding process parameters and grinding wheel parameters, the grinding trajectory (x, y) of the grinding wheel abrasive is calculated, and the abrasive phase difference γ is solved according to the abrasive particle spacing, so as to obtain the undeformed chip thickness F(x), and perform normalization processing, and determine the shape of the epicycloidal heat source according to the proportional relationship between the heat source size and the undeformed chip thickness; S3: Calculate the actual grinding contact arc length l according to the motion state of the abrasive particles and the elastic-plastic principle c ; In the formula, F n is the unit normal grinding force, R r is the roughness factor, B represents the grinding wheel width, E s 、E w are Young's modulus of the grinding wheel and workpiece, μ s , μ w are the Poisson's ratios of the grinding wheel and the workpiece respectively; calculate the workpiece convection heat transfer coefficient h w , Among them, β w is the thermal characteristic coefficient of the workpiece, where λ w is the workpiece heat transfer coefficient, ρ w is the workpiece density, v w represents the linear velocity of the workpiece, and v w =2πn w , C1 is related to the size of the Peclet number, and when Pe<0.2, C1=0.76; when 0.2≤Pe≤10, When Pe≥10, C1=1.06; S4: According to the rotation speed of the grinding wheel and the workpiece, the linear iteration method is used to solve the Reynolds equation to obtain the grinding fluid pressure distribution p in the grinding contact area. After meeting the convergence condition, the finite difference method is used to solve the average flow velocity u of the grinding fluid, and then the workpiece convection heat transfer coefficient h is obtained. w ; S5: Determine the heat flow distribution ratio of the grinding contact arc area, and determine the Reynolds number Re according to the average flow velocity u of the grinding fluid. ρ l Indicates the grinding fluid density, h l Re represents the characteristic thickness of the grinding fluid, η represents the viscosity coefficient of the grinding fluid; the flow state of the grinding fluid is determined according to Re, when Re>2300, it is determined to be a turbulent state, when Re>2300, it is determined to be a laminar state, and the convective heat transfer coefficient of the grinding fluid h is calculated. f ; S6: Solve the energy distribution ratios of workpiece-grinding wheel and workpiece-grinding chips respectively, and then obtain the energy distribution ratio R entering the workpiece w ; In the formula, r0 and k g represents the effective contact radius and thermal conductivity of the abrasive particles, v s represents the grinding wheel linear speed, and v s =2πn s , α w is the thermal diffusivity of the workpiece, and Among them, λ w is the workpiece heat transfer coefficient, ρ w Indicates the workpiece density, c w Indicates the specific heat capacity of the workpiece; shear strain Maximum undeformed wear chip thickness a gmax Expressed as S7: Solve for the total heat source intensity q m , calculate the heat flux distribution state q(ξ) of the epicycloidal heat source according to the grinding wheel abrasive trajectory; S8: Based on the heat flux distribution state q(ξ) of the epicycloid heat source and the heat distribution ratio coefficient R w And the actual length of the grinding contact arc l c , the moving heat source method is used to solve the temperature field of cylindrical grinding. The temperature rise T(x,z) at any point on the workpiece is expressed as 2. The method for solving the temperature field of cylindrical grinding with epicycloidal heat source varying with process parameters according to claim 1, characterized in that: In S2, the process of solving the wear particle trajectory equation is as follows: S201: According to the grinding process parameters and the grinding wheel parameters, the grinding track (x, y) of the grinding wheel abrasive is calculated, and the abrasive phase difference γ is solved according to the abrasive spacing. In the workpiece coordinate system, the parameterized equation of the abrasive track is expressed as x=(r s +r w -a p )cos(ω w t)+r s cos[±ω s t-(n-1)γ] (11a) y=(r s +r w -a p )sin(ω w t)+r s sin[±ω s t-(n-1)γ] (11b) In the formula, for abrasive particle a, n=1, for abrasive particle b, n=2, t represents the movement time, ω w and ω s denote the angular velocity of the workpiece and the grinding wheel respectively. According to the parameterized equation, the above parameterized equation is expressed in the form of y=f(x); S202: According to the adjacent abrasive particle trajectory equation, the shape equation of the undeformed chip is written as: F(x)=f(x)-f γ (x) (12) Where f(x) is the equation of the ideal trajectory a, f γ (x) is the equation of the adjacent ideal trajectory b; and F(x) is related to the grinding depth a p , grinding wheel linear speed v s , workpiece linear speed v w and the parameters between adjacent trajectories; S203: Normalize the heat source curve coordinates and the heat flow in the grinding contact arc area S204: Determine the shape of the epicycloidal heat source according to the proportional relationship between the size of the heat source and the thickness of the undeformed wear chips.

3. The method for solving the temperature field of cylindrical grinding with epicycloidal heat source varying with process parameters according to claim 2, characterized in that: In S4, the workpiece convection heat transfer coefficient h w The solution process is as follows: S401: Solve the Reynolds equation by linear iteration method to obtain the grinding fluid pressure distribution p in the grinding contact area The boundary pressure of the lubricated contact domain meets the condition p l (x s ,y)=p l (x e ,y)=p l (x,y s )=p l (x,y e )=0 (15) In the formula, x s and x e They represent the inlet and outlet coordinates of the bearing raceway outer cylindrical grinding lubrication calculation domain along the grinding fluid inlet direction (x direction), and y s and e They respectively represent the inlet and outlet coordinates of the bearing raceway external cylindrical grinding lubrication calculation domain along the grinding wheel width direction (y direction); S402: Determine whether the calculated pressure iteration meets the convergence condition In the formula, and are the grinding fluid pressures calculated for the previous iteration and the current iteration, ε lp is the pressure convergence accuracy, which is defined as ε lp =1.0×10 -4 , when the convergence condition is met, the solution is completed, otherwise the grinding fluid pressure is corrected and the solution is returned to step S401; In the formula, k p is the grinding fluid pressure factor, k p =0.05; S403: Use the finite difference method to solve the average flow velocity u of the grinding fluid: S404: Obtaining the workpiece convection heat transfer coefficient h w ; Among them, β w is the thermal characteristic coefficient of the workpiece, where λ w is the workpiece heat transfer coefficient, ρ w is the workpiece density, v w represents the linear velocity of the workpiece, and v w =2πn w , C1 is related to the size of the Peclet number, and when Pe<0.2, C1=0.76; when 0.2≤Pe≤10, When Pe≥10, C1=1.

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4. The method for solving the temperature field of cylindrical grinding with epicycloidal heat source varying with process parameters according to claim 3, characterized in that: In S7, the heat source distribution state solution process is as follows: S701: First calculate the total grinding heat source intensity q m q m =F t v s (20) According to the heat source distribution ratio, the equivalent cycloidal heat source intensity acting on the workpiece is q w =R w q m ; S702: Calculate the heat flux intensity distribution state in the grinding contact arc area: Where ξ is the actual position of the contact arc, q(ξ) is the actual heat flux intensity, and A w is the heat source shape coefficient introduced, which is used to determine the maximum position of the heat source and the heat source distribution state, and is obtained by integration; S703: Calculate the total heat flow into the workpiece

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