A mechanical arm adaptive grinding temperature field modeling method, device, medium and equipment

Abstract

The present application relates to a kind of mechanical arm adaptive grinding temperature field modeling method, device, medium and equipment, belong to intelligent manufacturing field.Based on ball head radius and normal indentation of grinding head contact geometry model is constructed, effective heat source area coefficient is introduced to correct and obtain equivalent heat source area;Real-time signal is collected using mechanical arm end six-dimensional force sensor, and grinding counter torque is obtained after pre-processing, equivalent heat power is dynamically determined in combination with spindle speed and material heat distribution coefficient;According to the radial increase characteristics of sliding speed in contact area, a radial non-uniform disc heat source that satisfies the total heat power conservation is constructed, and a moving heat source model is established in combination with feed speed;With moving heat source as boundary, solve transient heat conduction model, obtain transient temperature field and highest temperature.The present application breaks through the limitation of traditional uniform heat source, combines force feedback and non-uniform heat generation restriction, realizes different working condition grinding heat input quantization, and provides model basis for grinding temperature prediction and thermal safety control.

Description

Technical Field

[0001] This invention relates to the field of intelligent manufacturing, specifically to a method, apparatus, medium, and equipment for adaptive grinding temperature field modeling of robotic arms. It is particularly suitable for the construction of contact heat sources, prediction of transient temperature fields, calculation of maximum grinding temperature, and thermal safety analysis of grinding processes when using ball head grinding heads for continuous feed grinding. Background Technology

[0002] Robotic arm grinding features a large workspace, programmable trajectory, and flexible machining posture, making it suitable for precision removal of complex curved surfaces, material grinding, and automated machining of difficult-to-machine areas. When the ball head of a grinding mill rotates at high speed and comes into contact with the material to be ground, the abrasive cutting, plowing, and friction convert mechanical energy into heat. Because the heat is concentrated in the localized contact area at the end of the grinding head, if the heat cannot be diffused to the surrounding material in time or carried away with the grinding debris, the temperature of the contact area and its adjacent areas will rise rapidly, thus affecting material properties, machining quality, and operational safety.

[0003] Existing grinding temperature modeling methods typically simplify the contact area as a uniform heat source and estimate grinding power using the nominal linear velocity of the grinding head's outer edge or an empirical friction coefficient. For ball-end grinding head contact conditions, the local sliding velocity within the contact area gradually increases from near the spindle axis towards the contact edge, and the actual heating area may be smaller than the projected area of ​​the complete geometric contact. Using the complete contact area and uniform heat flux distribution easily underestimates the local heat flux peak; using the nominal linear velocity and empirical friction coefficient, on the other hand, subjectes the heat input to strong parameter assumptions.

[0004] Furthermore, as the robotic arm continuously feeds along a predetermined trajectory, the grinding heat source moves across the material surface with the arm's motion, and the feed rate directly alters the heating time at fixed points on the material surface. If the coupling relationship between heat source movement, finite feed time, and the material's thermal diffusion capacity is ignored, it becomes difficult to accurately obtain the transient temperature field and the maximum grinding temperature during the grinding process. Therefore, it is necessary to establish a temperature field modeling method that considers contact geometry, measured grinding reverse torque, the moving disk heat source, and transient thermal conduction response. Summary of the Invention

[0005] In view of this, the present invention provides a method, apparatus, medium, and equipment for adaptive grinding temperature field modeling of robotic arms, to solve the problem of separation between the contact area of ​​the ball end mill, grinding heat input, spatial distribution of heat source, and heat source movement effect. This method is based on the ball end mill-material contact geometry, uses the grinding anti-torque obtained from a six-dimensional force and torque sensor to determine the grinding mechanical power, and establishes a radially non-uniform disk-moving heat source under the condition of total heat power conservation, thereby solving for the transient temperature field and maximum grinding temperature of the material.

[0006] An adaptive grinding temperature field modeling method for robotic arms includes:

[0007] S1. Establish a contact geometry model between the ball head grinding head and the material to be ground. Determine the geometric contact area of ​​the ball head grinding head on the material surface based on the ball head grinding head radius and normal indentation. Correct the geometric contact area using the effective heat source area coefficient to obtain the equivalent heat source area. Acquire the six-dimensional force and torque signals during the robotic arm grinding process. Determine the grinding counter-torque around the grinding head axis at the contact interface based on the six-dimensional force and torque signals. Determine the equivalent heat power entering the material based on the grinding counter-torque, spindle speed, and material heat distribution coefficient.

[0008] S2. Based on the equivalent heat source region and the equivalent heat power, and according to the distribution characteristics of the local sliding speed in the contact area of ​​the ball head grinding head increasing with the radial distance, a radially non-uniform disk heat source that satisfies the conservation of total heat power is constructed, and the position of the radially non-uniform disk heat source on the material surface is determined according to the feed speed of the robotic arm, thus obtaining a disk moving heat source model.

[0009] S3. Determine the thermal diffusivity of the material based on its thermal conductivity, density, and specific heat capacity. Use the moving heat source of the disk as the heat flow boundary condition on the material surface. Establish a transient heat conduction model under the action of the moving heat source. Solve the transient heat conduction model to obtain the transient temperature field during the grinding process of the robotic arm. Extract the highest grinding temperature from the transient temperature field.

[0010] In the above-described method, establishing a contact geometry model between the ball head grinding head and the material to be ground, determining the geometric contact area based on the ball head grinding head radius and normal indentation, obtaining the equivalent heat source area through the effective heat source area coefficient, and determining the grinding counter-torque, grinding mechanical power, and equivalent heat power entering the material based on the six-dimensional force and torque signals during the robotic arm grinding process, includes:

[0011] Based on the actual contact form between the ball head grinding head and the material to be ground, the ball head grinding head is equivalent to a smooth sphere with a certain radius. The material surface in the grinding contact area is approximated as a local plane, and a spherical-plane contact geometric model is established to provide a basis for calculating the geometric contact dimensions and heat source area.

[0012] Based on the spherical-plane contact geometry model, the radius of the ball head grinding head, and the normal indentation, the geometric contact radius and geometric contact projection area of ​​the ball head grinding head on the material surface are determined, and then corrected by the effective heat source area coefficient to obtain the effective heat source area and the equivalent heat source radius.

[0013] Based on the effective heat source area and the equivalent heat source radius, a six-dimensional force and torque sensor is set between the end of the robotic arm and the grinding spindle to synchronously collect the triaxial force signal and triaxial torque signal during the grinding process of the robotic arm, forming the raw data required for heat input identification.

[0014] Based on the triaxial force signal, triaxial torque signal, and the position of the grinding head contact point relative to the origin of the sensor coordinate system, the measured torque around the spindle axis is corrected by force arm correction, and outliers are removed and time averaged for the correction results during the stable grinding period to obtain the average grinding reverse torque.

[0015] Based on the average grinding reverse torque and spindle speed, the ball head angular velocity and grinding mechanical power are determined. Based on the distribution relationship of grinding heat among the grinding head, material and grinding chips, the material heat distribution coefficient is introduced to determine the equivalent heat power entering the material. This equivalent heat power, together with the equivalent heat source radius, is used as the input for step S2.

[0016] In the above-described method, based on the equivalent heat source region and equivalent heat power obtained in step S1, and according to the distribution characteristics of the local sliding velocity in the contact area of ​​the ball head grinding head increasing with radial distance, a radially non-uniform disk heat source that satisfies the conservation of total heat power is constructed. The instantaneous position of the disk heat source on the material surface is determined by combining the robotic arm feed speed, feed direction, and grinding trajectory, thereby establishing a disk-moving heat source model, including:

[0017] Based on the effective heat source area and equivalent heat source radius obtained in step S1, the irregular area where cutting, plowing and frictional heating actually occur between the ball head grinding head and the material to be ground is equivalent to a finite disk heat source acting on the material surface, and the spatial boundary of heat flow is defined by the equivalent heat source radius.

[0018] Based on the characteristic that the local sliding velocity in the contact area of ​​the ball head gradually increases from near the main shaft axis to the edge of the contact area, the radial non-uniform distribution form of the disk heat source is determined so that the heat flux density increases linearly from the center of the disk heat source to its edge, in order to characterize the radial variation law of the heating intensity in the contact area.

[0019] Based on the radial non-uniform heat flow distribution and the equivalent heat power obtained in step S1, the area integral relationship of heat flow density within the action area of ​​the disk heat source is established, and the heat flow density proportionality coefficient is determined according to the total heat power conservation condition, so that the heat flow density integral result is equal to the equivalent heat power entering the material.

[0020] Based on the radial non-uniform heat flow distribution after heat power normalization, as well as the feed speed, feed direction, initial heat source position and grinding time of the robotic arm, the instantaneous position of the disk heat source center on the material surface as time changes, and the instantaneous radial distance from the point to be calculated to the current heat source center is determined.

[0021] Based on the relationship between the instantaneous radial distance and the equivalent heat source radius, the Heaviside function is used to spatially truncate the radial non-uniform heat flow, so that the grinding heat flow only acts on the current disk heat source coverage area, thereby establishing a disk moving heat source model, which is used as the surface heat flow boundary condition in step S3.

[0022] In the above-described method, the step of determining the thermal diffusivity of the material based on its thermophysical properties, using the moving disk heat source established in step S2 as the heat flow boundary condition on the material surface, establishing a transient heat conduction model under the action of the moving heat source, and obtaining the transient temperature field and the transient maximum grinding temperature during the robotic arm grinding process by solving the transient heat conduction model includes:

[0023] The thermal diffusivity of the material is determined based on its thermal conductivity, density, and specific heat capacity. This diffusivity is used to characterize the internal conduction and diffusion capabilities of grinding heat after it enters the material. Furthermore, based on the characteristic that the grinding contact area is relatively small compared to the overall size of the material, the material near the contact area is equivalent to a semi-infinite body with an initial temperature.

[0024] Based on the semi-infinite body assumption, material thermal diffusivity and other thermal property parameters, a transient heat conduction control equation is established inside the material. The uniform temperature of the material before grinding is set as the initial condition, and the disk moving heat source established in step S2 is set as the heat flow boundary condition on the material surface.

[0025] The Peckle number of the moving heat source is determined based on the feed speed of the robotic arm, the equivalent heat source radius, and the thermal diffusivity of the material. This number is used to characterize the relative relationship between the movement of the heat source and the thermal diffusivity of the material. The dimensionless heating duration is determined based on the grinding action time, the equivalent heat source radius, and the thermal diffusivity of the material. This duration is used to characterize the heat accumulation within a finite time.

[0026] Based on the Pelet number, dimensionless heating time, initial material conditions, and Green's function of surface heat flux of a semi-infinite body, spatial and temporal integrations are performed on the temperature rise response generated by the moving heat source of the disk at different positions and at different times to obtain the transient temperature rise at any position inside the material as a function of grinding time.

[0027] Based on the superposition relationship between the transient temperature rise and the initial temperature of the material, the transient temperature field during the grinding process of the robotic arm is obtained. The maximum temperature value is searched within the set material calculation area and grinding time to obtain the transient maximum grinding temperature and its analytical prediction model, thus completing the construction of the adaptive grinding temperature field model of the robotic arm.

[0028] As can be seen from the above technical solutions, the present invention has the following beneficial effects:

[0029] This invention establishes a contact geometry model between the ball head grinding head and the material to be ground, introduces an effective heat source area coefficient to equivalently characterize the actual heating area, and obtains the grinding counter-torque based on six-dimensional force and torque signals, thereby determining the equivalent heat power entering the material. Simultaneously, based on the distribution characteristics of the local sliding velocity within the ball head grinding head contact area increasing with radial distance, a radially non-uniform disk-moving heat source that satisfies the conservation of total heat power is constructed. This disk-moving heat source is then combined with the material's thermal diffusion characteristics to establish a transient temperature field and transient maximum grinding temperature prediction model for the robotic arm grinding process. Compared to temperature prediction methods using fixed heat source area, uniform heat flow distribution, or empirical grinding power, this invention comprehensively reflects the coupling effects between the ball head contact geometry, actual grinding heat input, heat source spatial distribution, feed movement effect, and material thermal diffusion, improving the rationality and accuracy of robotic arm grinding temperature prediction and providing a model basis for grinding process parameter selection, temperature risk assessment, and thermal safety control. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort or labor.

[0031] Figure 1 This is a schematic diagram of the adaptive grinding temperature field modeling method for robotic arms provided in this invention example;

[0032] Figure 2 This is a general technical roadmap for adaptive grinding temperature field modeling of robotic arms provided in the embodiments of the present invention;

[0033] Figure 3 This is a schematic diagram of the grinding contact of the robotic arm provided in the embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the equivalent heat source radius for robotic arm grinding provided in this invention example;

[0035] Figure 5 This is a schematic diagram of the heat source action time during robotic arm grinding provided in this invention example;

[0036] Figure 6 This is a schematic diagram of the single-point transient temperature calculation process provided in this invention example;

[0037] Figure 7 This is a schematic diagram of the theoretical results of the transient single-point maximum temperature provided in the embodiments of the present invention;

[0038] Figure 8This is a schematic diagram of finite element simulation under a moving heat source provided in an embodiment of the present invention;

[0039] Figure 9 This is a schematic diagram of the finite element simulation results under a moving heat source provided in an embodiment of the present invention;

[0040] Figure 10 A schematic diagram of an adaptive grinding temperature field modeling device for a robotic arm provided in an embodiment of the present invention;

[0041] Figure 11 A schematic diagram illustrating the composition of the electronic device provided in the embodiments of this application; Specific Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] This invention provides a method for modeling the temperature field of adaptive grinding in robotic arms. Please refer to [the relevant documentation]. Figure 1 This is a schematic diagram of the adaptive grinding temperature field modeling method for robotic arms provided by the present invention. The method constructs a radially non-uniform disk moving heat source model by determining the equivalent heat source region and equivalent heat power, and establishes a transient heat conduction model to obtain the transient temperature field and the maximum grinding temperature during the robotic arm grinding process. Figure 2 The overall technical approach is shown, which specifically includes the following steps:

[0044] Step S1: Based on the contact relationship between the ball head grinding head and the material to be ground during the robotic arm grinding process and the characteristics of grinding heat input, establish a ball head grinding head-material contact geometric model, and determine the grinding reverse torque, equivalent heat source region, and equivalent heat power entering the material through six-dimensional force and torque signals, including:

[0045] Specifically, based on the contact relationship between the grinding head and the workpiece during the robotic arm grinding process, such as Figure 3 As shown. The ball-end grinding head is equivalent to a radius of... The sphere represents a local surface of the material as equivalent to a plane. When the grinding head is pressed into the material surface along the normal direction to a depth of... When the sphere intersects the plane, a contact circle is formed. Based on the geometric relationships of the spherical cap's cross-section, the radius of the contact circle... It can be represented as:

[0046]

[0047] In the formula, The geometric contact radius of the ball head grinding head on the material surface; The radius of the ball head grinding head; This is the normal indentation.

[0048] The geometric contact projected area is:

[0049]

[0050] Will Substituting, we get:

[0051]

[0052] In the formula, It represents the geometric contact projection area on the material surface.

[0053] Introducing the effective heat source area coefficient The effective heat source area is defined as:

[0054]

[0055] in:

[0056]

[0057] In the formula, This is the effective heat source area coefficient. When... When, it indicates that a complete circular contact projection area is used as the uniform heat source area; when When the actual effective heating area is smaller than the geometric contact projection area, the heat flow input is more concentrated.

[0058] Further define the equivalent heat source radius :

[0059]

[0060] but:

[0061]

[0062] It needs to be emphasized that, This represents the geometric contact radius between the ball head and the material, while This represents the radius of the equivalent disk heat source. For example... Figure 4 The shaded area in the image may actually represent part of the leading edge of the contact circle or a local arc area.

[0063] To simplify finite element loading and analytical calculations, a circular heat source of equal area is used to replace the actual irregular heating region. To describe the effective length of the heat source along the feed direction of the robotic arm, the effective heat source characteristic length is defined as:

[0064]

[0065] This feature length is used to estimate the time scale at which a fixed point on the material surface is enveloped by an effective heat source.

[0066] During grinding, mechanical energy is mainly converted into heat energy through abrasive cutting, plowing, and friction. For a high-speed rotating ball head grinding head, let the spindle speed be... (Unit: r / min), then the grinding head angular velocity is:

[0067]

[0068] When the grinding head axis is approximately along the normal to the material surface, the contact area is located near the end of the ball head, and the contact circle is located at a distance from the main axis. The local sliding speed at a point is related to the radial distance from that point to the axis of the main shaft:

[0069]

[0070] A six-dimensional force / torque sensor is used to synchronously acquire triaxial forces. With triaxial torque .

[0071] The inner distance of the contact circle from the main axis The local sliding velocity at a point is Let the surface density at this point resisting sliding be the local tangential traction (combined with friction and plowing). The local frictional heating power density is Integrating over the contact area yields the grinding machine power:

[0072]

[0073] This is precisely the first-order moment of the tangential traction at the contact interface relative to the spindle axis, i.e., the grinding counter-torque. Therefore, the power of the grinding machine can be directly expressed by the measurable reverse torque:

[0074]

[0075] Will Substituting the values, we obtain the model for the power of the grinding machine:

[0076]

[0077] Introducing the model heat distribution coefficient Then the equivalent heat power entering the material is:

[0078]

[0079] Will Treated as an independent uncertain parameter, the baseline is:

[0080]

[0081] And in

[0082]

[0083] Take within range Solve for the equivalent heat power and perform parameter influence analysis.

[0084] Step S2: Based on the distribution characteristics of the local sliding velocity increasing with radial distance within the contact area of ​​the ball head grinding head, and based on the equivalent heat source region and equivalent heat power, construct a radially non-uniform disk moving heat source model that satisfies the conservation of total heat power, including:

[0085] Determine the spatial distribution of this heat power on the effective heat source surface: local heat generation power density within the contact area. Factor As the radius increases from the center to the edge, the sliding velocity at the center approaches zero and that at the edge is the largest.

[0086] Since heat flux density increases with radius As the heat flux increases linearly, it appears conical when visualized vertically; therefore, the heat flux density is assumed to be linearly (conical) distributed along the radius.

[0087]

[0088] In the formula The effective heat source radius. Total power is determined by actual measurement. Unique and Determined, Independent The specific distribution; and the uncertainty of the heat flow shape is determined by the effective area coefficient. cover.

[0089] Conservation of total heat power Coefficient of determination:

[0090]

[0091] The peak value and average area of ​​the heat flux density at the edge of the cone are respectively:

[0092]

[0093]

[0094] That is, the peak heat flux at the edge of the conical distribution is 1.5 times the average value under the uniform assumption, thus capturing the local peak heat flux at the edge that is underestimated by the uniform assumption, while satisfying the condition that it is zero at the center and maximum at the edge. Effective area coefficient. Reflecting the degree of concentration of the actual heating area relative to the geometric contact projection area, the benchmark is taken as... and in Take within range Perform parameter impact analysis.

[0095] In the adaptive grinding process of the robotic arm, the ball head rotates at high speed driven by the spindle, while the robotic arm drives the grinding head to feed along a predetermined trajectory. For a fixed point on the model surface, the heat source does not remain permanently at that point, but rather sweeps past it as the robotic arm feeds. Therefore, the macroscopic feed rate... The temperature rise is affected by changing the heating time of a local area.

[0096] The effective heat source radius is .like Figure 5 As shown, when the heat source is at a feed rate When passing through a fixed point on the material surface, the timescale of the effective heat source envelope acting on that point can be expressed as:

[0097]

[0098] In the formula, This refers to the residence time of the effective heat source. When other parameters remain constant, the higher the feed rate, the shorter the local heating time; the greater the normal infeed, the larger the effective heat source size, and the longer the local heating time.

[0099] Assume the equivalent disk heat source along Direction by speed The location of the heat source center is:

[0100]

[0101] Instantaneous radial distance introduced to the current heat source center Then, the conical equivalent disk moving heat source model, which is consistent with the velocity field of the contact area, can be expressed as:

[0102]

[0103] In the formula, For the Heaviside function:

[0104]

[0105] On point When located inside the effective disk heat source external time .

[0106] Step S3: Based on the thermophysical parameters of the material to be ground and the moving heat source model of the disk, establish a transient heat conduction model under the action of the moving heat source, obtain the transient temperature field during the robotic arm grinding process, and extract the transient maximum grinding temperature, including:

[0107] The thermal diffusivity of a material is determined by its thermal diffusivity. Characterization:

[0108]

[0109] In the formula, The thermal diffusivity of the material; Thermal conductivity; Density; Specific heat capacity.

[0110] To characterize the relative relationship between the macroscopic moving speed of the equivalent disk heat source and the material's thermal diffusivity, the Peckle number of the moving heat source is introduced:

[0111]

[0112] Will Substituting into the equation, we get:

[0113]

[0114] In the formula, Based on the effective heat source radius Define the number of mobile heat sources Pelet.

[0115] Introducing a dimensionless heating duration (Fourier number) based on the effective heat source radius:

[0116]

[0117] In the formula, The heating time for a single continuous feed (determined by the feed path length and feed rate). and Together they determine the peak value of the transient temperature rise.

[0118] Considering that the material can be approximated as a semi-infinite body near the grinding contact zone, with an initial temperature of... The governing equation for transient heat conduction within the material is:

[0119]

[0120] The initial conditions are:

[0121]

[0122] On the surface of the material Above, the disk moves the heat source with heat flux density Function. The surface heat flow boundary condition of the contact area can be written as:

[0123]

[0124] Based on the Green's function for surface heat flux in a semi-infinite body, at any point inside the material... At any moment The temperature rise can be expressed as:

[0125]

[0126] in The temperature rise expression under the action of the moving heat source of the conical disk can be obtained as follows:

[0127]

[0128] in, This indicates that the following conditions are met:

[0129]

[0130] The transient maximum temperature of a material is defined as the maximum temperature rise over the entire computational domain and the entire heating process.

[0131]

[0132] In the formula, For the material calculation domain, Calculate the termination time for the grinding process.

[0133] To facilitate rapid calculation in parameter space, area-average heat flux is used. and effective heat source radius As a characteristic quantity, the transient maximum temperature rise is expressed in dimensionless response form:

[0134]

[0135] In the formula, This is a dimensionless transient peak temperature rise function for a conical disk-shaped moving heat source. The function is obtained by advancing the time curve and taking its maximum value over the entire process; it comprehensively reflects the influence of the moving heat source velocity, heating duration, conical heat source shape, and material thermal diffusivity on the transient maximum temperature rise.

[0136] Depend on A prediction model for the transient maximum grinding temperature is given:

[0137]

[0138] Substituting the formula, we get:

[0139]

[0140] The above formula is the analytical prediction model for the transient maximum grinding temperature.

[0141] The algorithm flow of this temperature model is as follows: Figure 6 As shown, by inputting grinding process parameters, heat source parameters, and material thermophysical property parameters, the transient temperature rise of each spatial point under the action of a moving heat source is calculated, and the highest temperature and its corresponding location during the grinding process are extracted.

[0142] The algorithm's execution result is as follows Figure 7 As shown, the highest temperature distribution at various points within the grinding path range is illustrated; the finite element simulation results are as follows: Figure 8 and Figure 9 As shown, the temperature rises rapidly during the heat source entry stage, then tends to stabilize and fluctuate, consistent with the variation pattern of the theoretical model. By comparing the temperature peaks and trends of the two models, the heat distribution coefficient and effective heat source area coefficient are corrected, thereby improving the model's prediction accuracy for moving heat sources, non-uniform heat generation, and the maximum grinding temperature.

[0143] like Figure 10 As shown, this embodiment of the invention also provides a robotic arm adaptive grinding temperature field modeling device 1000, which includes a first processing unit 1001, a second processing unit 1002 and a third processing unit 1003.

[0144] The first processing unit 1001 is a contact geometry and grinding heat input determination unit, used to determine the geometric contact area and equivalent heat source area based on the radius of the ball head grinding head and the normal indentation, and to determine the grinding reverse torque, grinding mechanical power and equivalent heat power entering the material based on the six-dimensional force and torque signals.

[0145] The second processing unit 1002 is a disk-moving heat source construction unit, which is used to construct a radially non-uniform disk heat source that satisfies the conservation of total heat power based on the radial variation characteristics of the equivalent heat source area, equivalent heat power and local sliding speed in the contact area, and update the position of the disk heat source according to the robotic arm feed speed and grinding trajectory.

[0146] The third processing unit 1003 is a transient temperature field solving unit, which is used to establish a transient heat conduction model based on the material's thermal property parameters, take the moving heat source of the disk as the heat flow boundary condition on the material surface, solve the transient temperature field during the robotic arm's grinding process, and extract the highest grinding temperature.

[0147] like Figure 11 As shown, this embodiment of the invention also provides an electronic device 1100, which includes a processor 1101, a memory 1102, and a bus 1103. The memory 1102 is used to store computer programs or computer execution instructions, and the processor 1101 is used to call and execute the computer programs or computer execution instructions stored in the memory 1102 to implement the aforementioned adaptive grinding temperature field modeling method for robotic arms.

[0148] A second aspect of the present invention provides a robotic arm adaptive grinding temperature field modeling device, comprising:

[0149] The contact heat source and thermal power determination unit is used to establish the contact geometry model of the ball head grinding head and determine the equivalent heat source region and equivalent thermal power.

[0150] The disk-shaped moving heat source construction unit constructs a radially non-uniform disk-shaped moving heat source model based on the equivalent heat source region and equivalent thermal power.

[0151] The transient temperature field construction unit establishes a transient heat conduction model based on the disk moving heat source model and material thermophysical parameters, and obtains the transient temperature field and the highest grinding temperature.

[0152] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the adaptive grinding temperature field modeling method for robotic arms described in any of the preceding claims.

[0153] A fourth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the adaptive grinding temperature field modeling method for robotic arms described in any of the above-described methods.

[0154] This invention is described based on flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to specific embodiments. It should be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer programs can be provided to direct to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that instructions executable by the processor of the computer or other programmable data processing device generate instructions for implementing the flowcharts and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0155] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0156] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0158] Table 1 Relevant parameters of grinding materials

[0159] Parameter name Symbolic representation numerical values conductivity density Specific heat capacity

Claims

1. A method for modeling the temperature field of adaptive grinding in a robotic arm, characterized in that, The method includes: S1. Establish the contact geometry model between the ball head grinding head and the material to be ground, based on the radius of the ball head grinding head. and normal indentation Determine the geometric contact area of ​​the ball head on the material surface, and use the effective heat source area coefficient. The geometric contact area is corrected to obtain the equivalent heat source area and the equivalent radius of the disk heat source. Real-time acquisition of six-dimensional force and torque signals during the robotic arm's grinding process, combined with spindle speed. The grinding counter-torque around the grinding head axis at the contact interface is determined based on the six-dimensional force and torque signals, and the grinding counter-torque, spindle speed, and material heat distribution coefficient are used as the basis for this determination. Dynamically determine the equivalent thermal power entering the material ; S2. Based on the equivalent heat source region and the equivalent heat power, and according to the distribution characteristics of the local sliding velocity in the contact area of ​​the ball head grinding head increasing with radial distance, a radially non-uniform disk heat source that satisfies the conservation of total heat power is constructed, and based on the feed speed of the robotic arm... The position of the radially non-uniform disk heat source on the material surface is determined to obtain the disk moving heat source model; S3. Based on the thermal conductivity of the material ,density and specific heat capacity Determine the thermal diffusivity of the material Using the moving heat source model of the disk as the heat flow boundary condition of the material surface, a transient heat conduction model under the action of the moving heat source is established. By solving the transient heat conduction model, the transient temperature field during the robotic arm grinding process is obtained, and the highest grinding temperature is extracted from the transient temperature field. .

2. The adaptive grinding temperature field modeling method for robotic arms according to claim 1, characterized in that, In step S1: The ball head grinding head is equivalent to a radius of The smooth sphere approximates the surface of the material to be ground within the grinding contact area as a local plane, and the ball head's indentation along the normal direction of the material surface is determined based on this. The geometric contact radius is determined by utilizing the geometric relationship between the intersection of a sphere and a plane. and geometric contact projected area; introduce effective heat source area coefficient The geometric contact projection area is corrected to obtain the effective heat source area; the actual irregular heating area is equivalent to a disk heat source of equal area, and the equivalent radius of the disk heat source is determined based on the effective heat source area. : in, Used to determine the effective range of the disc heat source.

3. The adaptive grinding temperature field modeling method for robotic arms according to claim 2, characterized in that, In step S1: A six-dimensional force and torque sensor is installed between the end of the robotic arm and the grinding spindle, so that the axis of the sensor corresponds to the axis of the spindle of the ball head grinding head, and the three-dimensional force signal and three-dimensional torque signal during the grinding process are collected synchronously through the sensor. Based on the position of the contact point at the end of the ball head relative to the origin of the sensor coordinate system, and combined with the in-plane force measured by the sensor, the moment arm of the measured torque around the spindle axis is corrected to obtain the grinding counter-torque of the contact interface around the spindle axis of the ball head. By selecting a stable grinding period during the grinding process, abnormal data of the grinding back torque are removed and averaged over time to obtain the average grinding back torque. Determine the angular velocity of the ball head grinding head based on the spindle speed. The product of the average grinding counter-torque and the angular velocity is determined as the grinding mechanical power. And through the material heat distribution coefficient Determine the equivalent thermal power entering the material : The equivalent thermal power is the total thermal power input of the disk heat source, and it is dynamically refreshed with the real-time update of the six-dimensional force signal to achieve adaptive temperature field modeling.

4. The adaptive grinding temperature field modeling method for robotic arms according to claim 1, characterized in that, Step S2 includes: Based on the characteristic that the local sliding speed in the contact area of ​​the ball head end gradually increases from near the spindle axis to the edge of the contact area, the disk heat source is set to radial non-uniform heat flow distribution, so that the heat flow density increases linearly from the center of the disk heat source to the edge. Based on the feed speed of the robotic arm The feed direction and grinding trajectory determine the position of the disk heat source center as time changes, and the instantaneous radial distance between the point to be calculated on the material surface and the current disk heat source center is used. Determine the heat flux density of the moving heat source on the disk. : in, For material surface position At any moment heat flux density, This is the heat flux density proportionality coefficient determined based on the conservation of total heat power. Let be the Heaviside step function, when When, the Heaviside function is 1, when When the time is 0, the Heaviside function is set to 0; thus, a model of a moving disk heat source that moves with the feed motion of the robotic arm is established.

5. The adaptive grinding temperature field modeling method for robotic arms according to claim 1, characterized in that, Step S3 includes: Obtain the thermal conductivity of the material to be ground ,density and specific heat capacity And determine the thermal diffusivity of the material. ; The material near the grinding contact area is equivalent to having an initial temperature. Using the moving heat source of the disk as the heat flow boundary condition on the material surface, a transient heat conduction model under the action of the moving heat source is established for the semi-infinite body. The initial conditions are: ; Based on the robotic arm's feed speed Equivalent radius of the moving heat source on a disc and material thermal diffusivity Determine the number of Pelet mobile heat sources And based on the grinding action time Equivalent radius of the disk heat source and material thermal diffusivity Determine the dimensionless heating time ; Based on the Green's function for surface heat flux in a semi-infinite volume, spatial and temporal integrations are performed on the temperature rise generated by the moving heat source. The highest temperature is extracted within the computational domain and grinding time to obtain an analytical prediction model for the transient maximum grinding temperature. in, This is the transient maximum grinding temperature; This is a dimensionless transient peak temperature rise function, whose two inputs are the Peckle number of the moving heat source, determined based on the equivalent radius of the disk heat source. and dimensionless heating time .

6. A robotic arm adaptive grinding temperature field modeling device, characterized in that, include: The contact geometry and grinding heat input determination unit is configured to perform step S1 as described in any one of claims 1-3, in order to establish a contact geometry model between the ball head grinding head and the material to be ground, determine the effective heat source area, and determine the grinding counter-torque, grinding mechanical power and equivalent heat power entering the material based on the six-dimensional force and torque signals during the robotic arm grinding process. The disk-shaped moving heat source construction unit is configured to perform step S2 of any one of claims 1-4 to construct a radially non-uniform disk-shaped moving heat source model that satisfies the total heat power conservation based on the effective heat source region and the equivalent heat power. The transient temperature field solving unit is configured to perform step S3 of any one of claims 1-5, to establish a transient heat conduction model based on the thermal property parameters of the material, to use the moving heat source of the disk as the heat flow boundary condition on the material surface, to solve the transient temperature field during the grinding process of the robotic arm, and to extract the highest grinding temperature from the transient temperature field.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the adaptive grinding temperature field modeling method for robotic arms as described in any one of claims 1 to 5.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the adaptive grinding temperature field modeling method for robotic arms according to any one of claims 1 to 5.

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