Composite brake drum precision turning equipment and method based on PCBN cutter

Abstract

The invention relates to the technical field of metal cutting, in particular to composite brake drum precision turning equipment and method based on a PCBN cutter, and the method specifically comprises the steps that the temperature change and wall thickness distribution in the brake drum machining process are monitored in real time, and the distance between each area and the bottom of the brake drum and the distance between the cutter position and each area position at each moment are combined; constructing a regional comprehensive deformation degree; based on the difference between the regional comprehensive deformation degrees of different regions of each part, the regional deformation difference degree of each part is determined, the historical fluctuation condition of the regional deformation difference degree of each part at the current moment is analyzed, the parameter adjustment coefficient of each part at the current moment is determined, and cutting parameters are optimized in real time according to the coefficient; turning the brake drum; and non-uniform deformation caused by non-uniform wall thickness, heat accumulation and structural constraint can be effectively weakened, the stability of the machining process is improved, and therefore the machining quality of the composite brake drum is improved.

Description

Technical Field

[0001] This application relates to the field of computer-aided design technology, specifically to a precision turning equipment and method for composite brake drums based on PCBN tools. Background Technology

[0002] With the increasing demands for braking safety and durability in commercial vehicles, especially heavy-duty trucks and large buses, and the development of lightweight technology, composite brake drums (also known as "bimetallic brake drums" or "ring-mounted brake drums") have emerged and are widely used. As a core component of the automotive braking system, composite brake drums are often integrally cast from gray cast iron HT250 / HT300 or similar materials. Their inner walls, stops, and other critical parts require extremely high dimensional accuracy and surface roughness. Currently, the industry primarily uses PCBN cutting tools for turning, leveraging their high hardness, high wear resistance, and high-temperature resistance to achieve efficient machining.

[0003] In the precision turning process of composite brake drums, the wall thickness along the axial direction is not uniformly distributed, resulting in local abrupt changes. Different wall thickness areas have varying sensitivities to deformation, and the degree of deformation is also related to the location of the area. The closer to the drum opening, the smaller the constraint force, and the easier it is to deform. Simultaneously, due to differences in the thermal expansion coefficients of composite materials, varying structural constraints, and uneven heat transfer during cutting, the deformation between different areas may be inconsistent, leading to uneven deformation. This uneven deformation generates additional thermal stress at the joint surfaces and connection points, further exacerbating deformation accumulation and causing the dimensional deviations of the machined workpiece to exceed tolerances. Traditional methods often use fixed cutting parameters for machining, which cannot adaptively adjust based on real-time monitoring data during the machining process, affecting the accuracy of the machined workpiece. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a precision turning device and method for composite brake drums based on PCBN tools. The specific technical solution adopted is as follows: In a first aspect, embodiments of this application provide a method for precision turning of a composite brake drum based on PCBN tools, the method comprising the following steps: The brake drum is divided into different parts based on its structure, and each part is further divided into multiple regions; the cutting parameters of each part of the brake drum are acquired in real time during the turning process; and the thickness and temperature of each region are collected in real time. Analyze the temperature rise and thickness of each region at each time point, and combine the distance between each region and the bottom of the brake drum to construct the regional deformation sensitivity of each region at each time point; Based on the distance between the tool position and the position of each region at each time, and combined with the difference in the deformation sensitivity of the regions, the comprehensive deformation degree of each region at each time is constructed; based on the difference in the comprehensive deformation degree of different regions of each part at each time, the degree of regional deformation difference of each part at each time is determined; based on the historical fluctuation of the degree of regional deformation difference of each part at the current time, the parameter adjustment coefficient of each part at the current time is determined. The cutting parameters for each part are adjusted based on the parameter adjustment coefficient at the current moment, and subsequent cutting is performed.

[0005] In one embodiment, the process of obtaining the regional deformation sensitivity is as follows: The heat accumulation factor for each region at each time point is constructed based on the temperature rise of each part during the cutting time period before each time point; the distance between each region and the bottom of the brake drum is recorded as the first distance. Based on the thickness of each region at each time, the first distance, and the heat accumulation factor, the regional deformation sensitivity of each region at each time is constructed. The regional deformation sensitivity is positively correlated with the first distance and the heat accumulation factor, and negatively correlated with the thickness.

[0006] In one embodiment, the process of obtaining the heat accumulation factor is as follows: Calculate the difference between the temperature of each region at each time point and the corresponding initial temperature, and record it as the first difference; obtain the length of the cutting time period before each time point for each part; calculate the average temperature of each region at each time point over all time points within the cutting time period; The heat accumulation factor for each region at each time point is determined based on the first difference, the time length, and the average temperature. The heat accumulation factor is directly proportional to the first difference and the average temperature, and inversely proportional to the time length.

[0007] In one embodiment, the process of obtaining the overall deformation degree of the region is as follows: The distance between the tool position at each moment and the center coordinates of each region is recorded as the second distance; The product of the inverse proportional mapping function of the second distance of each region at each time and the deformation sensitivity of the region is taken as the comprehensive deformation degree of each region at each time.

[0008] In one embodiment, the process of obtaining the degree of regional deformation difference is as follows: Obtain the minimum value of the overall regional deformation of all regions at each time point, and construct the degree of regional deformation difference of each region at each time point based on the difference between the overall regional deformation of each region and the minimum value.

[0009] In one embodiment, the expression for the degree of regional deformation difference is: In the formula, This represents the degree of regional deformation difference at the k-th location at time a, where N is the number of regions divided at the k-th location. This represents the overall deformation degree of the nth region at the kth location at time a. This represents the minimum overall deformation of all regions at the k-th location at time a. This represents the set of all regions at the k-th location at time a, consisting of the overall deformation degrees of all areas. This is the normalization function.

[0010] In one embodiment, the process of obtaining the parameter adjustment coefficient is as follows: The degree of uneven deformation of each part at the current moment is calculated based on the degree of regional deformation difference of each part at each time within a preset time period before the current moment. The inverse proportional mapping value of the degree of influence of the non-uniform deformation is used as the parameter adjustment coefficient for each part at the current moment.

[0011] In one embodiment, the expression for the degree of influence of the non-uniform deformation is: In the formula, This indicates the degree of uneven deformation at the k-th location at time A; A represents the order value at time A; W represents the size of the preset historical time neighborhood window. This indicates the degree of regional deformation difference at the k-th location at time a; This represents the average difference in regional deformation at the k-th location across all time points within the historical time neighborhood window, with time A as the last element. This is the normalization function.

[0012] In one embodiment, the process of adjusting the cutting parameters for each part at the current moment is as follows: The product of the parameter adjustment coefficient of each part at the current moment and the initial cutting parameter of each part at the current moment is calculated as the adjusted cutting parameter of each part at the current moment.

[0013] Secondly, embodiments of this application also provide a precision turning device for a composite brake drum based on PCBN tools, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.

[0014] The embodiments of this application have at least the following beneficial effects: This application analyzes the thermal deformation behavior of each region during the turning process of the brake drum by real-time acquisition of cutting parameters. It analyzes the temperature rise and thickness changes in each region of the brake drum during processing, combined with the distance between each region and the bottom of the brake drum, to construct a region deformation sensitivity. Based on this region deformation sensitivity, and combined with the distance between the tool position and each region position at each moment, a comprehensive region deformation degree is constructed. Based on the differences in the comprehensive region deformation degrees of different regions in each part, the degree of regional deformation difference in each part is determined, and the deformation situation of that part is analyzed. Based on the historical fluctuations of the degree of regional deformation difference in each part at the current moment, the parameter adjustment coefficient of each part at the current moment is determined, and the cutting parameters are optimized in real time according to this coefficient. This effectively reduces non-uniform deformation caused by uneven wall thickness, heat accumulation, and structural constraints, improves the stability of the processing, significantly improves the dimensional accuracy of the workpiece, and thus improves the processing quality of the composite brake drum. Attached Figure Description

[0015] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A flowchart illustrating the steps of a precision turning method for a composite brake drum based on PCBN tools, provided in one embodiment of this application; Figure 2 A schematic diagram illustrating the process of obtaining regional deformation sensitivity; Figure 3 This is a flowchart illustrating the steps of a precision turning method for a composite brake drum based on PCBN tools. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by this application to achieve the intended inventive objective, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the precision turning equipment and method for composite brake drums based on PCBN tools proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0019] The following description, in conjunction with the accompanying drawings, details the specific scheme of the precision turning equipment and method for composite brake drums based on PCBN tools provided in this application.

[0020] Please see Figure 1 The diagram illustrates a flowchart of a precision turning method for a composite brake drum based on a PCBN tool according to an embodiment of this application. The method includes the following steps: Step S1: Divide the brake drum into different parts according to its structure, and divide each part into multiple regions; acquire the cutting parameters of each part of the brake drum in real time during the turning process; and collect the thickness and temperature of each region in real time.

[0021] First, the brake drum workpiece to be processed is divided into regions. Specifically, the thickness variation of the brake drum workpiece is analyzed along the central axis of the brake drum. Based on the locations of abrupt thickness changes, the brake drum is divided into multiple parts: the inner ring of the drum opening, the outer ring of the drum opening, the middle of the drum body, the transition section at the bottom of the drum body, and the drum bottom. Each part is further divided into N regions along the radial direction. Specifically, the division along the radial direction is as follows: in a top view of the brake drum, the brake drum is circular. This circular shape can be divided into N sectors along its radius. The corresponding region of each part within each sector is its respective region. The central axis of the brake drum represents its height, extending from the drum bottom to the drum opening. In this embodiment, the value of N is set to 10. In other embodiments of this application, the implementer can set the value of N according to the actual situation.

[0022] During the turning process of the brake drum, the cutting parameters during the turning process are acquired in real time through the CNC system of the machine tool. The cutting parameters include feed rate and cutting speed.

[0023] A miniature infrared thermometer is used to scan the entire outer surface of the workpiece from a fixed angle to measure the surface temperature of each area of ​​each part of the composite brake drum in real time.

[0024] A laser scanner is used to perform non-contact full-size scanning of the workpiece, acquiring the wall thickness of the brake drum in real time during processing. The average wall thickness of each region at each time point is calculated and recorded as the average thickness. Laser thickness measurement is a well-known technique, and the specific process will not be described in detail.

[0025] In this embodiment, the acquisition frequency for each type of data is set to 20Hz to ensure time synchronization of all data sources. In other embodiments of this application, the implementer can set the data acquisition frequency according to the actual situation.

[0026] Furthermore, each parameter obtained above is normalized using the minimum-max normalization method. There are many existing normalization algorithms, and implementers may also use other normalization methods to normalize each parameter. This application does not impose any specific restrictions.

[0027] Step S2: Analyze the temperature rise and thickness of each region at each time point, and combine the distance between each region and the bottom of the brake drum to construct the regional deformation sensitivity of each region at each time point.

[0028] During the precision turning of composite brake drums, the wall thickness along the axial direction is not uniformly distributed, exhibiting local abrupt changes. Different wall thicknesses show varying sensitivities to deformation; the thinner the wall, the faster the temperature rises, the lower the structural stiffness, and the weaker the resistance to deformation, making deformation more likely. Furthermore, the degree of deformation is also related to the location of the area; the closer to the drum opening, the weaker the constraint force, and the easier it is to deform. Simultaneously, due to differences in the thermal expansion coefficients of composite materials, varying structural constraints, and uneven heat transfer during cutting, deformation may be inconsistent between regions, leading to uneven deformation. Specifically, due to differences in deformation, constraints and tensions arise at the joint surfaces and connection points, creating superimposed thermal stress. The greater the deformation difference, the stronger this constraint and tension force (thermal stress), and the greater the impact of uneven deformation. When the deformation difference is small, deformation and shrinkage tend to synchronize in each region. Additionally, during the cutting process, the heat generated in the tool-workpiece contact area is conducted outwards from the contact point, with its effect decreasing with increasing distance. That is, the farther the current cutting point is from a certain area, the smaller the cutting heat effect on that area, and the weaker the corresponding deformation response.

[0029] Based on the above analysis, the regional deformation sensitivity of each region at each time point is calculated. The specific process is as follows: During the precision turning of composite brake drums, the wall thickness of the brake drum is not uniformly distributed along the axial direction, and there are some abrupt changes. Different thicknesses have different sensitivities to deformation. The smaller the wall thickness, the faster the temperature rises, while the structural stiffness decreases and the resistance to deformation weakens, making it more prone to deformation. The location of the deformation area is also related to the degree of deformation. For example, the wall thickness in the drum opening area is the thinnest, and it is in a cantilever state. Even a slight temperature rise can cause significant radial and axial deformation. On the other hand, the wall thickness in the drum bottom area is larger, and the structural support is stronger. The response to heat input is relatively weaker. The closer to the drum opening, the less constraint force this area experiences, and the more prone it is to deformation.

[0030] The heat generated during cutting mainly originates from the friction between the tool and the workpiece, as well as the plastic deformation of the material. Heat is conducted into the workpiece through the contact area, forming a non-uniform temperature field at different thicknesses and structures. The greater the heat flux density, the faster the temperature rises, the more significant the material expansion, and the stronger the deformation tendency.

[0031] Therefore, the heat accumulation factor for each region at each moment during the cutting process is calculated to reflect the cumulative effect of cutting heat absorbed by the workpiece during machining. Preferably, in this embodiment, the expression for the heat accumulation factor is: In the formula, This represents the heat accumulation factor of the nth region at the kth location at time a; The average temperature is denoted as the average temperature of the nth region of the kth part during the time interval from the start of cutting at the kth part to time a. This represents the temperature of the nth region at the kth location at time a; This represents the temperature of the nth region at the kth location before cutting; 'a' is the order value at time a. Indicates the data collection time interval; This is the normalization function. This represents the cumulative time from the start of processing at the k-th part to time a. It reflects the rate of temperature rise. The larger the value, the faster the temperature rises in that region per unit time, the more significant the material expansion, and the stronger the deformation trend. In this embodiment, the normalization function used is the maximum-minimum normalization method. In other embodiments of this application, implementers may use other normalization functions according to actual circumstances.

[0032] Furthermore, the brake drum is a rotating body with non-uniform wall thickness, its wall thickness varying in a stepped manner along the central axis. Wall thickness directly affects the heat capacity and stiffness of the cross-section; specifically, the thinner the wall, the faster the temperature rises, while the structural stiffness decreases, and the resistance to deformation weakens. In addition, the location of the area is also related to the degree of deformation. For example, the wall thickness is thinnest in the drum opening area, which is often in a cantilever state, and even a slight temperature rise can cause significant radial and axial deformation; while the wall thickness is larger in the drum bottom area, the structural support is stronger, and the response to heat input is relatively weaker. Therefore, the closer to the drum opening, the weaker the constraint force in that area, and the more easily deformation occurs.

[0033] Therefore, the deformation sensitivity of each region at each time point during the cutting process is calculated to reflect the deformation sensitivity of each region. Preferably, in this embodiment, the expression for the regional deformation sensitivity is: In the formula, This represents the regional deformation sensitivity of the nth region at the kth location at time a. This represents the heat accumulation factor of the nth region at the kth location at time a; This represents the average thickness of the nth region at the kth location at time a; This represents the height value of the center point of the nth region at the kth location, i.e., the coordinate value of that center point on the central axis of the brake drum; This indicates the height value of the center point of the drum bottom area, that is, the coordinate value of the center point of the drum bottom area on the central axis of the brake drum. This reflects the distance of the nth region at the kth location from the bottom of the drum along the central axis.

[0034] The thinner the area, the farther it is from the base of the drum. The larger the value, the more easily the region is deformed at time a. The larger.

[0035] Step S3: Based on the distance between the tool position and the position of each region at each time, and combined with the difference in the deformation sensitivity of the regions, construct the comprehensive deformation degree of each region at each time; based on the difference in the comprehensive deformation degree of different regions of each part at each time, determine the degree of regional deformation difference of each part at each time; based on the historical fluctuation of the degree of regional deformation difference of each part at the current time, determine the parameter adjustment coefficient of each part at the current time.

[0036] The above steps analyzed the deformation tendency of each region of the workpiece driven by the heat generated during the precision turning of the composite brake drum, quantifying the regional deformation sensitivity. In actual machining, the deformation of each region does not occur in isolation but affects each other. Furthermore, due to factors such as differences in the thermal expansion coefficient of composite materials, structural constraints, and uneven heat transfer, the deformation between regions may be inconsistent, resulting in uneven deformation. This leads to dimensional deviations and shape distortions in the machined workpiece. The different deformation amounts between regions create constraints and tensions at the joint surfaces and connection points, forming superimposed thermal stresses. The greater the deformation difference, the stronger this constraint and tension force (thermal stress), and the greater the impact of uneven deformation. When the deformation difference is small, the deformation and shrinkage of each region tend to be synchronized, the thermal stress is small, the secondary deformation is weak, and the dimensional deviation can be controlled within the allowable range after cooling. Simultaneously, during the cutting process, the heat generated in the contact area between the tool and the workpiece is conducted outwards from the contact point, and its influence decreases with increasing distance. In other words, the farther the current cutting point is from each region, the smaller the influence of the current cutting point on that region.

[0037] Based on the above analysis, the positional influence factor for each region at each time point is calculated to reflect the direct influence of the tool position on each region at each time point. Preferably, in this embodiment, the expression for the positional influence factor is: In the formula, This represents the positional influence factor of the nth region at the kth location at time a. This represents the coordinates of the tool's working position at time a. This represents the coordinates of the center point of the nth region at the kth location at time a. This represents the Euclidean distance between the tool's working position coordinates at time a and the center point coordinates of the nth region at the kth location at that time. The farther the cutting point is from each region at the current time, the smaller the impact of the current cutting on that region.

[0038] It should be noted that this application provides only one distance measurement method for the distance between the tool working position and each region at each time. There are many existing distance measurement methods, and implementers may also use other distance measurement methods to calculate the distance between the tool working position and each region at each time. This application does not impose any specific restrictions.

[0039] The overall regional deformation degree of each region at each time point is calculated based on the location influence factor and the regional deformation sensitivity. Preferably, in this embodiment, the expression for the overall regional deformation degree is: In the formula, This represents the overall deformation degree of the nth region at the kth location at time a. This represents the positional influence factor of the nth region at the kth location at time a. This represents the regional deformation sensitivity of the nth region at the kth location at time a.

[0040] It represents the overall deformation degree of a region, which is calculated by combining the location of the region and its deformation sensitivity, reflecting the severity of regional deformation.

[0041] Furthermore, due to factors such as differences in the thermal expansion coefficient of composite materials, structural constraints, and uneven heat transfer, the deformation between regions may be inconsistent, resulting in uneven deformation. This leads to dimensional deviations and shape distortions in the processed workpiece. As a result, due to the different deformation amounts between regions, constraints and tensions will be generated at the joint surfaces and connection points, forming superimposed thermal stresses. The greater the deformation difference, the stronger the constraint and tension force (thermal stress), and the greater the impact of uneven deformation. The smaller the deformation difference, the more synchronized the deformation and shrinkage of each region, the smaller the thermal stress, and the smaller the impact.

[0042] Therefore, the degree of regional deformation difference for each part is calculated based on the overall deformation difference of each region. Preferably, in this embodiment, the expression for the degree of regional deformation difference is: In the formula, This represents the degree of regional deformation difference at the k-th location at time a, where N is the number of regions divided at the k-th location. This represents the overall deformation degree of the nth region at the kth location at time a. This represents the minimum overall deformation of all regions at the k-th location at time a. This represents the set of all regions at the k-th location at time a, consisting of the overall deformation degrees of all areas. The normalization function is defined as follows: The greater the difference in deformation between regions, the greater the degree of non-cooperative deformation of the workpiece. In this embodiment, the normalization function used is the maximum-minimum normalization method. In other embodiments of this application, the implementer may use other normalization functions according to the actual situation.

[0043] The greater the difference in deformation between regions, the greater the degree of non-cooperative deformation of the workpiece, indicating that the deformation in that part is more uneven.

[0044] Deformation differences can occur at any moment, and their effects accumulate and propagate. Uneven deformation occurring at a certain cross-section at a particular moment may affect the cutting state on subsequent toolpaths. This manifests as a greater degree of fluctuation throughout the machining process, more uneven deformation during machining, and more severe uneven deformation fluctuations experienced during machining, resulting in a more serious overall impact. A historical time neighborhood window is set; in this embodiment, the size W of the historical time neighborhood window is set to 10. In other embodiments of this application, the implementer can set the size of the historical time neighborhood window according to actual conditions. The degree of uneven deformation impact at each moment and at each location is constructed based on the degree of deformation difference in the region. Preferably, in this embodiment, the expression for the degree of uneven deformation impact is: In the formula, This represents the degree of uneven deformation at the k-th location at time A; A represents the order value at time A; W represents the size of the historical time neighborhood window. This indicates the degree of regional deformation difference at the k-th location at time a; This represents the average degree of regional deformation difference at the k-th location across all time points within the historical time neighborhood window, with time A as the last element. The normalization function is denoted as . In this embodiment, the normalization function used is the maximum-minimum normalization method. In other embodiments of this application, the implementer may use other normalization functions according to the actual situation.

[0045] The greater the fluctuation in the entire processing, the greater the unevenness of deformation during processing, the more intense the uncoordinated fluctuations in deformation experienced during processing, and the more severe the overall impact.

[0046] Furthermore, based on the degree of influence of the aforementioned non-uniform deformation, parameter adjustment coefficients for each part at each time point are constructed, expressed as follows: In the formula, This represents the parameter adjustment coefficient for the k-th part at time A. This indicates the degree of influence of uneven deformation at the k-th location at time A. The smaller the value, the more significant the interference from uneven deformation, requiring timely parameter adjustment.

[0047] Step S4: Adjust the cutting parameters of each part at the current moment based on the parameter adjustment coefficient, and then perform subsequent cutting.

[0048] The parameter adjustment coefficients calculated above This allows for real-time dynamic adjustment of cutting parameters, thereby suppressing machining errors caused by heat accumulation and uneven deformation, and improving the machining accuracy of the composite brake drum. The specific process is as follows: The expression for adjusting cutting parameters based on parameter adjustment coefficients is: In the formula, This represents the adjusted cutting parameters for the k-th part at time a. This represents the parameter adjustment coefficient for the k-th part at time a. This represents the adjusted cutting parameters for the k-th part at time a-1. The cutting parameters for each part at the start of cutting and before that time do not need adjustment. If the adjusted cutting parameters are less than the system's minimum cutting parameters, the minimum cutting parameters are used.

[0049] The original cutting parameter values ​​are adjusted using parameter adjustment coefficients. The smaller the value, the higher the risk of deformation in that area. At this time, the system automatically reduces the cutting parameter values, including cutting speed and feed rate, to reduce heat input and thus reduce cutting force and thermal load.

[0050] Once the workpiece is finished, the machine tool's CNC system automatically restores the cutting parameters to their initial settings, preparing for the next workpiece to be machined.

[0051] A schematic diagram of the process for obtaining regional deformation sensitivity is shown below. Figure 2 As shown; the flowchart of the above method is as follows. Figure 3 As shown.

[0052] Based on the same inventive concept as the above methods, this application also provides a precision turning device for composite brake drums based on PCBN tools, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described precision turning methods for composite brake drums based on PCBN tools.

[0053] In summary, this application provides a precision turning method for composite brake drums based on PCBN tools. By real-time acquisition of cutting parameters during the brake drum turning process, and by analyzing the temperature rise and thickness changes in different regions of the brake drum during processing, combined with the distance between each region and the bottom of the brake drum, the thermal deformation behavior of each region is analyzed to construct a region deformation sensitivity. Based on the region deformation sensitivity, and combined with the distance between the tool position and each region position at each moment, a comprehensive region deformation degree is constructed. Based on the differences in the comprehensive region deformation degrees of different regions, the degree of regional deformation difference in each region is determined, and the deformation situation of that region is analyzed. Based on the historical fluctuations of the degree of regional deformation difference in each region at the current moment, the parameter adjustment coefficient of each region at the current moment is determined, and the cutting parameters are optimized in real time according to this coefficient. This method can effectively reduce non-uniform deformation caused by uneven wall thickness, heat accumulation, and structural constraints, improve the stability of the processing, and thus significantly improve the dimensional accuracy of the workpiece, thereby improving the processing quality of the composite brake drum.

[0054] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this application. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0055] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0056] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A method for precision turning of a composite brake drum based on PCBN tools, characterized in that, The method includes the following steps: The brake drum is divided into different parts based on its structure, and each part is further divided into multiple regions; the cutting parameters of each part of the brake drum are acquired in real time during the turning process; and the thickness and temperature of each region are collected in real time. Analyze the temperature rise and thickness of each region at each time point, and combine the distance between each region and the bottom of the brake drum to construct the regional deformation sensitivity of each region at each time point; Based on the distance between the tool position and the position of each region at each time, and combined with the difference in the deformation sensitivity of the regions, the comprehensive deformation degree of each region at each time is constructed; based on the difference in the comprehensive deformation degree of different regions of each part at each time, the degree of regional deformation difference of each part at each time is determined; based on the historical fluctuation of the degree of regional deformation difference of each part at the current time, the parameter adjustment coefficient of each part at the current time is determined. The cutting parameters for each part are adjusted based on the parameter adjustment coefficient at the current moment, and subsequent cutting is performed.

2. The precision turning method for composite brake drum based on PCBN tools as described in claim 1, characterized in that, The process of obtaining the deformation sensitivity of the region is as follows: The heat accumulation factor for each region at each time point is constructed based on the temperature rise of each part during the cutting time period before each time point; the distance between each region and the bottom of the brake drum is recorded as the first distance. Based on the thickness of each region at each time, the first distance, and the heat accumulation factor, the regional deformation sensitivity of each region at each time is constructed. The regional deformation sensitivity is positively correlated with the first distance and the heat accumulation factor, and negatively correlated with the thickness.

3. The precision turning method for composite brake drum based on PCBN tools as described in claim 2, characterized in that, The process of obtaining the heat accumulation factor is as follows: Calculate the difference between the temperature of each region at each time point and the corresponding initial temperature, and record it as the first difference; obtain the length of the cutting time period before each time point for each part; calculate the average temperature of each region at each time point over all time points within the cutting time period; The heat accumulation factor for each region at each time point is determined based on the first difference, the time length, and the average temperature. The heat accumulation factor is directly proportional to the first difference and the average temperature, and inversely proportional to the time length.

4. The precision turning method for a composite brake drum based on PCBN tools as described in claim 1, characterized in that, The process for obtaining the overall deformation degree of the region is as follows: The distance between the tool position at each moment and the center coordinates of each region is recorded as the second distance; The product of the inverse proportional mapping function of the second distance of each region at each time and the deformation sensitivity of the region is taken as the comprehensive deformation degree of each region at each time.

5. The precision turning method for a composite brake drum based on PCBN tools as described in claim 1, characterized in that, The process for obtaining the degree of deformation difference in the region is as follows: Obtain the minimum value of the overall regional deformation of all regions at each time point, and construct the degree of regional deformation difference of each region at each time point based on the difference between the overall regional deformation of each region and the minimum value.

6. The precision turning method for a composite brake drum based on PCBN tools as described in claim 5, characterized in that, The expression for the degree of deformation difference in the region is: In the formula, This represents the degree of regional deformation difference at the k-th location at time a, where N is the number of regions divided at the k-th location. This represents the overall deformation degree of the nth region at the kth location at time a. This represents the minimum overall deformation of all regions at the k-th location at time a. This represents the set of all regions at the k-th location at time a, consisting of the overall deformation degrees of all areas. This is the normalization function.

7. The precision turning method for a composite brake drum based on PCBN tools as described in claim 1, characterized in that, The process of obtaining the parameter adjustment coefficient is as follows: The degree of uneven deformation of each part at the current moment is calculated based on the degree of regional deformation difference of each part at each time within a preset time period before the current moment. The inverse proportional mapping value of the degree of influence of the non-uniform deformation is used as the parameter adjustment coefficient for each part at the current moment.

8. The precision turning method for a composite brake drum based on PCBN tools as described in claim 1, characterized in that, The expression for the degree of influence of the non-uniform deformation is: In the formula, This indicates the degree of uneven deformation at the k-th location at time A; A represents the order value at time A; W represents the size of the preset historical time neighborhood window. This indicates the degree of regional deformation difference at the k-th location at time a; This represents the average difference in regional deformation at the k-th location across all time points within the historical time neighborhood window, with time A as the last element. This is the normalization function.

9. The precision turning method for a composite brake drum based on PCBN tools as described in claim 1, characterized in that, The process of adjusting the cutting parameters for each part at the current moment is as follows: The product of the parameter adjustment coefficient of each part at the current moment and the initial cutting parameter of each part at the current moment is calculated as the adjusted cutting parameter of each part at the current moment.

10. A precision turning device for a composite brake drum based on PCBN tools, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-9.

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