Feed control method for drilling process of titanium alloy and composite laminated material

Abstract

The application belongs to the technical field of aviation manufacturing and intelligent machining, and discloses a feed control method for drilling of titanium alloy and composite material laminated material. Before drilling, the equivalent friction representation model of the feed transmission chain is established by collecting the feed motor speed, current and feed position through the no-load movement. In the drilling process, the extended state observer is constructed based on the feed motor current and speed, the total load torque of the feed shaft is estimated online, and the net cutting torque is obtained. According to the feed position and the preset laminated thickness, the current machining stage is judged. When the tool is in the titanium alloy layer, the unipolar force limiting control mode is adopted to adjust the feed speed. When the tool is in the composite material layer, the bipolar constant force control mode is adopted to adjust the feed speed. The method does not need external axial force sensors or force platforms, can realize online estimation of the feed axial force and differential adaptive feed control, and is beneficial to improve the drilling quality of titanium / composite laminated material, reduce the machining damage and prolong the tool life.

Description

Technical Field

[0001] This invention belongs to the field of aerospace manufacturing and intelligent processing technology, and relates to a feed control method for the hole-making process of titanium alloy and composite material laminates. Background Technology

[0002] In the manufacturing of high-end aerospace equipment, components constructed by layering titanium alloys and carbon fiber reinforced composite materials (hereinafter referred to as "composite materials") are increasingly widely used. This type of laminated structure, by stacking and clamping titanium alloy plates and composite material plates and then drilling holes, can effectively utilize the complementary advantages of the two materials, taking into account the requirements of connection strength, structural integrity, and lightweighting. To achieve a strong mechanical connection between the layers, it is generally necessary to press each layer together and then drill holes at once, followed by fastening with riveting or bolts.

[0003] For the on-site process requirements of assembling large aircraft structural components, current drilling operations still largely rely on constant process parameters, such as spindle speed and feed rate. When operators use handheld pneumatic drills or automatic feed drills to drill holes, the parameters at each machining stage are usually kept constant, often based on the process specifications of a single material, either titanium alloy or composite material, or a compromise between the two. It is difficult to simultaneously adapt to the respective cutting characteristics of the two materials. Titanium alloys and composite materials respond significantly differently to machining axial forces: when machining titanium alloy layers, excessive axial forces can easily cause the temperature in the cutting zone to rise, leading to titanium alloy burns and rapid tool failure; composite material layers are mainly composed of brittle fibers and tough resins, and fluctuations in axial forces can easily cause interlayer stress concentration, leading to irreversible structural damage such as delamination, tearing, and burrs.

[0004] Unlike the aforementioned processing methods with fixed process parameters, existing technologies propose constant force feed or constant force machining schemes based on force feedback to control the axial force during hole making in titanium alloy and composite laminate materials. For example, in the patent "A Rotary Ultrasonic Vibration Micro-hole Machining Device with Constant Force Feed" (patent number CN 114393724A), the force feedback device directly measures the force between the tool and the workpiece, and adjusts the feed speed according to the constant force feed control algorithm to achieve constant force machining between the workpiece and the tool; in the patent "Omnidirectional Constant Force Machining Auxiliary Device for Cutting Machining" (patent number CN111941099A), a three-dimensional force sensor is set between the worktable and the moving slide to measure the three-dimensional machining force during the machining process, and the cutting parameters are finely adjusted by the moving slide drive device to stabilize the cutting force within a certain range. The aforementioned solutions based on external force feedback typically require the installation of force sensors, force measurement platforms, or dedicated auxiliary motion mechanisms on the equipment, which increases the system hardware cost and structural complexity. Furthermore, the installation, calibration, and protection of sensors and auxiliary devices in the confined space of aerospace assembly sites present significant challenges, hindering large-scale industrial application.

[0005] Furthermore, in the patent "A High-Efficiency Adaptive Machining Method for Lightweight Cabin Structures Based on Cutting Parameter Learning" (patent number CN 121857539A), a cutting parameter template database is established through orthogonal experiments, and ACM adaptive optimization technology is applied for adaptive learning and machining. This allows the feed rate to be adjusted in real time according to changes in machining power; that is, the feed rate decreases when the load is large and increases when the load is small. This method is mainly aimed at the high-efficiency adaptive machining of lightweight cabin structure components, focusing on achieving comprehensive optimization of machining efficiency and machining quality through cutting parameter learning and power sensing. However, in the drilling and hole making process of titanium alloy and composite material laminates, the axial feed load of the tool and the spindle power are not a simple linear mapping relationship, and the control requirements of different material layers are significantly different: composite material layers are more suitable for bipolar constant force control based on axial force deviation to suppress delamination damage and take into account machining efficiency; titanium alloy layers are more suitable for unipolar force limiting control to prevent axial force over-limit and thermal damage. The aforementioned adaptive machining methods based on cutting parameter learning or power sensing do not establish differentiated material layer identification and dual-mode feed control strategies for titanium alloy and composite material layers, nor do they form a layered optimization control method for constant force control of composite material layers and force-limiting control of titanium alloy layers. Therefore, existing technologies have not yet provided a feed control scheme that can adapt to the differentiated control requirements in the hole-making process of titanium alloy and composite material laminates.

[0006] Therefore, it is necessary to propose a feed control method for the hole-making process of titanium alloy and composite material laminates to overcome the dependence of existing methods on external force sensors, realize online estimation of feed axial force, and implement differentiated feed control of limiting force and constant force according to the different processing characteristics of titanium alloy and composite materials, thereby improving hole-making quality and tool life. Summary of the Invention

[0007] The purpose of this invention is to provide a feed control method for the hole-making process of a titanium alloy and composite material laminate, wherein the titanium alloy and composite material laminate refers to a laminate formed by stacking a titanium alloy layer and a carbon fiber reinforced composite material layer, which is used to estimate the axial force of the hole-making feed without setting an additional axial force sensor, and to perform force limiting control and constant force control respectively according to the different processing characteristics of the titanium alloy layer and the composite material layer.

[0008] The technical solution of this invention: A feed control method for drilling holes in a titanium alloy and composite material laminate, wherein the titanium alloy and composite material laminate comprises a titanium alloy layer and a composite material layer sequentially along the drilling feed direction, and the feed control method includes the following steps: Step S1: Before drilling, the feed mechanism is driven to move under no-load conditions along the drilling feed direction. The feed mechanism includes a feed motor and a transmission mechanism. The feed motor speed, feed motor current, and feed position are collected at different feed speeds. An equivalent friction characterization model of the feed transmission chain is established for the drilling feed direction. For the feed motor current collected during no-load movement, the feed motor torque constant is used... The feed drive chain friction torque is calculated, and the feed motor current and the feed drive chain friction torque satisfy the following relationship: ;in, For the first The frictional torque of the feed drive chain in each control cycle The feed motor torque constant is For the first The feed motor current for each control cycle; the equivalent friction characterization model is obtained by least squares fitting, and the friction torque of the feed transmission chain satisfies: ;in, To control the cycle number, For the first The frictional torque of the feed drive chain in each control cycle For the first The feed rate per control cycle The coefficient of viscous friction of the feed drive chain. For the Coulomb friction torque of the feed drive chain; Step S2: During the hole-making process, the feed motor current, feed motor speed, and feed position are collected in real time. An expansion state observer is constructed using the feed motor current as the input and the feed motor speed as the output. The total load angular acceleration of the feed axis is used as the online observation of the expansion state to obtain the first... Total load torque of the feed axis per control cycle ; Step S3, according to the first Frictional torque of the feed drive train per control cycle and the Estimated total load torque of the feed axis per control cycle The following formula yields the first... Net cutting torque per control cycle : Based on the conversion relationship between torque and axial force in the transmission mechanism, the net cutting torque is converted into the first... Estimated feed axial force per control cycle ; Step S4: Based on the feed position, workpiece surface reference position, and preset titanium alloy and composite material layer thickness, determine whether the tool is currently in the idle stage, titanium alloy layer, composite material layer, or drilling stage, and call the corresponding process parameters and control mode according to the determination result; For the first Feed position for each control cycle As the reference position on the workpiece surface, The thickness of the titanium alloy layer is preset. Preset the thickness of the composite material layer; when Less than When the tool is in the idle phase, it is determined that the tool is in the idle phase; when Not less than and less than When the cutting tool is in the titanium alloy layer, it is determined that the tool is in the titanium alloy layer; when Not less than and less than When the tool is in the composite material layer, it is determined that the tool is in the composite material layer; when Not less than When the tool is in the drilling stage, the feed rate is adjusted using a unipolar force limiting control mode when the tool is in the titanium alloy layer; when the tool is in the composite material layer, the feed rate is adjusted using a bipolar constant force control mode.

[0009] Furthermore, in step S2, the state variables of the extended state observer are defined as follows: , , ;in, The equivalent rotational inertia of the feed motor, The feed motor speed, The first derivative of the feed motor speed. This is the total load torque of the feed axis. The total load angular acceleration of the feed axis; the extended state observer is updated in a discrete form, satisfying: in, To control the cycle, , , To extend the state observer gain, For the first The current input term for each control cycle is calculated from the feed motor current. For input gain, For the first The measured speed of the feed motor in each control cycle For the first The estimated speed of the feed motor for each control cycle. For the first The estimated first derivative of the feed motor speed for each control cycle. For the first Estimated total load angular acceleration of the feed axis per control cycle For the first The estimated speed of the feed motor for each control cycle. For the first The estimated first derivative of the feed motor speed for each control cycle. For the first The estimated total load angular acceleration of the feed axis in the first control cycle is obtained, and the result is obtained according to the following formula. Total load torque of the feed axis per control cycle: .

[0010] Furthermore, in step S4, when the tool is in the titanium alloy layer, the unipolar force limiting control mode is implemented using a unipolar force limiting active disturbance suppression control algorithm, specifically including: S4011. Based on the estimated feed axial force values ​​of the current control cycle and the previous control cycle, calculate the estimated disturbance of the axial force variation in the titanium alloy layer: ;in, For the first Estimated perturbation of axial force variation in titanium alloy layer over one control cycle. For the first Estimated feed axial force for each control cycle This is the estimated feed axial force value from the previous control cycle. This is the equivalent control coefficient for the change in axial force caused by the adjustment of the feed rate of the titanium alloy layer. This is the adjustment amount of the titanium alloy layer feed rate in the previous control cycle; S4012, with the upper limit of axial force of titanium alloy layer As the force-limiting boundary, calculate the force-limiting error of the titanium alloy layer: ;in, For the first The limit force error of the titanium alloy layer in each control cycle; S4013, when Greater than At that time, based on the limit error of the titanium alloy layer and the estimated disturbance of the axial force change of the titanium alloy layer, the feed rate adjustment of the titanium alloy layer is calculated: ;in, For the axial force control bandwidth of the titanium alloy layer; when Not greater than At that time, Set to zero; S4014. The feed rate adjustment of the titanium alloy layer is unipolarly limited, so that it is only output in the deceleration direction; if Less than Then Take as ;like If it is greater than zero, then... Set to zero; if Not less than If the value is not greater than zero, then it remains unchanged. ;in, This is the maximum allowable deceleration adjustment amount for the titanium alloy layer, and Take positive values; S4015. Generate a titanium alloy layer feed rate command based on the basic feed rate of the titanium alloy layer and the titanium alloy layer feed rate adjustment amount: ;in, This represents the feed rate of the titanium alloy layer base.

[0011] Furthermore, in step S4, when the tool is in the composite material layer, the bipolar constant force control mode is implemented using a bipolar constant force active disturbance suppression control algorithm, specifically including: S4021. Based on the estimated feed axial force values ​​of the current control cycle and the previous control cycle, calculate the estimated disturbance of the axial force variation in the composite material layer: ;in, For the first Estimation of axial force variation disturbance of composite material layer in each control cycle This is the equivalent control coefficient of the composite layer feed rate adjustment on the axial force variation. This is the adjustment amount of the composite material layer feed rate in the previous control cycle; S4022, Target axial force of composite material layer As a constant force control benchmark, calculate the constant force error of the composite material layer: ;in, For the first The constant force error of the composite material layer in each control cycle The target axial force of the composite material layer; S4023. Calculate the feed rate adjustment of the composite layer based on the constant force error and the estimated disturbance of the axial force variation of the composite layer: ;in, For the first The adjustment amount of the composite material layer feed rate per control cycle Bandwidth for controlling axial force in composite material layers; S4024. The feed speed adjustment of the composite material layer is subject to bipolar limitation, causing it to output along either the acceleration or deceleration direction; if Less than Then Take as ;like Greater than Then Take as ;like Not less than and not greater than Then it will not change. ;in, This represents the maximum allowable deceleration adjustment amount for the composite material layer. This represents the maximum allowable speed adjustment for the composite material layer, and and All values ​​are positive. S4025. Generate a composite layer feed speed command based on the composite layer base feed speed and the composite layer feed speed adjustment amount: ;in, For the first The composite material layer feed speed command for each control cycle. This represents the feed rate of the composite material layer base.

[0012] The beneficial effects of this invention are: (1) This invention has the ability to estimate the feed axial force online without an external force sensor. By using the feed motor speed and current to estimate the total load torque of the feed shaft in real time through the extended state observer, and combining the equivalent friction characterization model of the feed transmission chain to solve the net cutting torque, the estimated value of the feed axial force is obtained, thereby eliminating the hardware dependence on force sensors or force measurement platforms; (2) The present invention achieves differentiated feed control for titanium alloy layer and composite material layer. A unipolar force limiting control mode and a bipolar constant force control mode are designed for the different processing characteristics of the two types of materials, respectively, to suppress axial force overshoot of titanium alloy layer and reduce axial force fluctuation of composite material layer, which is more in line with the material removal characteristics of the lamination hole making process, thereby effectively suppressing titanium alloy burn and reducing composite material hole wall delamination damage. Attached Figure Description

[0013] Figure 1 The flowchart illustrates the feed control method for the hole-making process of titanium alloy and composite material laminates provided by this invention. Detailed Implementation

[0014] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0015] Example A feed control method for drilling holes in a titanium alloy and composite material laminate is applied to an electric automatic feed drilling system. The electric automatic feed drilling system includes a feed motor, transmission mechanism, spindle, drill bit, control unit, and drive controller, without the need for an additional axial force sensor. The material being processed consists of a titanium alloy layer and a carbon fiber reinforced composite material layer sequentially stacked along the drilling feed direction, wherein the titanium alloy layer has a preset thickness. for The composite material layer has a preset thickness. for Using a diameter of Specialized drill bits for titanium alloys and composite materials are used for drilling. The position where the tool contacts the upper surface of the workpiece is used as the reference position of the workpiece surface. ,Pick The initial position of the tool is above the workpiece surface, that is Preset feed rate for titanium alloy layer Preset composite material layer feed speed Upper limit of axial force of titanium alloy layer Target axial force of composite material layer The hole-making process includes identification of the no-load friction characteristics of the feed drive chain, online estimation of the total load torque of the feed shaft, calculation of the feed axial force, material layer determination and control mode switching, unipolar force limiting control of the titanium alloy layer, and bipolar constant force control of the composite material layer. The specific steps are as follows: Step S1: Before drilling, drive the feed mechanism to move under no-load conditions along the drilling feed direction. The feed mechanism includes a feed motor and a transmission mechanism. Collect the feed motor speed, feed motor current and feed position at different feed speeds, and establish an equivalent friction characterization model of the feed transmission chain for the drilling feed direction.

[0016] Specifically, before the actual drilling, the control unit drives the feed mechanism sequentially... , , , , , and The feed rate is used for no-load motion, and the uniform motion segment at each feed rate is selected as the friction identification data segment. The sampling frequency is [missing information]. That is, control cycle For the feed motor current collected during no-load motion, the feed motor torque constant is used. The feed drive chain friction torque is calculated, and the feed motor current and the feed drive chain friction torque satisfy the following relationship: ;in, For the first The frictional torque of the feed drive chain in each control cycle The feed motor torque constant is For the first The feed motor current for each control cycle is then used. The least squares method is then used to linearly fit the feed drive chain friction torque at different feed speeds, yielding the feed drive chain friction torque that satisfies... ;in, To control the cycle number, For the first The feed rate per control cycle The coefficient of viscous friction of the feed drive chain. This refers to the Coulomb friction torque of the feed transmission chain.

[0017] Identified by no-load , Therefore, the first The frictional torque of the feed drive train in each control cycle can be expressed as: .

[0018] Step S2: During the hole-making process, the feed motor current, feed motor speed, and feed position are collected in real time. An expansion state observer is constructed using the feed motor current as the input and the feed motor speed as the output. The total load angular acceleration of the feed axis is used as the online observation of the expansion state to obtain the first... Total load torque of the feed axis per control cycle .

[0019] Specifically, let the state variables of the extended state observer be defined as: , , ;in, The equivalent rotational inertia of the feed motor, The feed motor speed, The first derivative of the feed motor speed. This is the total load torque of the feed axis. The total load angular acceleration of the feed axis; the extended state observer is updated in a discrete form, satisfying: in, To control the cycle, , , To extend the state observer gain, For the first The current input term for each control cycle is calculated from the feed motor current. For input gain, For the first The measured speed of the feed motor in each control cycle For the first The estimated speed of the feed motor for each control cycle. For the first The estimated first derivative of the feed motor speed for each control cycle. For the first Estimated total load angular acceleration of the feed axis per control cycle For the first The estimated speed of the feed motor for each control cycle. For the first The estimated first derivative of the feed motor speed for each control cycle. For the first The estimated total load angular acceleration of the feed axis in the first control cycle is obtained, and the result is obtained according to the following formula. Total load torque of the feed axis per control cycle: .

[0020] Pick , , , , .

[0021] Step S3, according to the first Frictional torque of the feed drive train per control cycle and the Estimated total load torque of the feed axis per control cycle The following formula yields the first... Net cutting torque per control cycle : Based on the conversion relationship between torque and axial force in the transmission mechanism, the net cutting torque is converted into the first... Estimated feed axial force per control cycle ; The transmission mechanism uses a ball screw drive, and the lead of the transmission screw is denoted as... The transmission efficiency of the transmission mechanism is denoted as Then the first The estimated feed axial force for each control cycle satisfies .Pick , Therefore, we can obtain .

[0022] Step S4: Based on the feed position, workpiece surface reference position, and preset titanium alloy and composite material layer thickness, determine whether the tool is currently in the idle stage, titanium alloy layer, composite material layer, or drilling stage, and call the corresponding process parameters and control mode according to the determination result; For the first Feed position for each control cycle As the reference position on the workpiece surface, The thickness of the titanium alloy layer is preset. Preset the thickness of the composite material layer; when Less than When the tool is in the idle phase, it is determined that the tool is in the idle phase; when Not less than and less than When the cutting tool is in the titanium alloy layer, it is determined that the tool is in the titanium alloy layer; when Not less than and less than When the tool is in the composite material layer, it is determined that the tool is in the composite material layer; when Not less than When the tool is in the drilling stage, the feed rate is adjusted using a unipolar force limiting control mode when the tool is in the titanium alloy layer; when the tool is in the composite material layer, the feed rate is adjusted using a bipolar constant force control mode.

[0023] , , .when When the control unit determines that the tool is in the idle phase, it approaches the workpiece surface using a rapid feed method; when At that time, the control unit determines that the tool is in the titanium alloy layer, and the spindle speed is set accordingly. feed rate And invoke the unipolar force limiting control mode; when At that time, the control unit determines that the tool is in the composite material layer, and the spindle speed is set to... feed rate And invoke the bipolar constant force control mode; when At this time, the control unit determines that the tool is in the drilling stage and performs a tool retraction action.

[0024] When the tool is in the titanium alloy layer, the unipolar force limiting control mode is implemented using a unipolar force limiting active disturbance suppression control algorithm, which specifically includes the following steps.

[0025] S4011. Based on the estimated feed axial force values ​​of the current control cycle and the previous control cycle, calculate the estimated disturbance of the axial force variation in the titanium alloy layer: ;in, For the first Estimated perturbation of axial force variation in titanium alloy layer over one control cycle. For the first Estimated feed axial force for each control cycle This is the estimated feed axial force value from the previous control cycle. This is the equivalent control coefficient for the change in axial force caused by the adjustment of the feed rate of the titanium alloy layer. This represents the adjustment amount of the titanium alloy layer feed rate in the previous control cycle; where, take .

[0026] S4012, with the upper limit of axial force of titanium alloy layer As the force-limiting boundary, calculate the force-limiting error of the titanium alloy layer: ;in, For the first The limiting force error of the titanium alloy layer in each control cycle; where, take .

[0027] S4013, when Greater than At that time, based on the limit error of the titanium alloy layer and the estimated disturbance of the axial force change of the titanium alloy layer, the feed rate adjustment of the titanium alloy layer is calculated: ;in, For the axial force control bandwidth of the titanium alloy layer; when Not greater than At that time, Set to zero; where, take .

[0028] S4014. The feed rate adjustment of the titanium alloy layer is unipolarly limited, so that it is only output in the deceleration direction; if Less than Then Take as ;like If it is greater than zero, then... Set to zero; if Not less than If the value is not greater than zero, then it remains unchanged. ;in, This is the maximum allowable deceleration adjustment amount for the titanium alloy layer, and Take positive values; where, take Therefore, the feed rate adjustment of the titanium alloy layer is only... ~ Output within the specified range.

[0029] S4015. Generate a titanium alloy layer feed rate command based on the basic feed rate of the titanium alloy layer and the titanium alloy layer feed rate adjustment amount: ;in, This represents the feed rate of the titanium alloy layer base. Wherein, we take... Therefore, after unipolar limitation, the feed rate command for the titanium alloy layer is located at... ~ Within the specified range, the unipolar force limiting control mode only outputs in the deceleration direction when the axial force exceeds the upper limit of the axial force of the titanium alloy layer, and does not actively increase the speed when it is below the force limiting boundary, thereby reducing the risk of axial force overshoot and thermal damage during the hole making process of the titanium alloy layer.

[0030] When the tool is in the composite material layer, the bipolar constant force control mode is implemented using a bipolar constant force active disturbance suppression control algorithm, which specifically includes the following steps.

[0031] S4021. Based on the estimated feed axial force values ​​of the current control cycle and the previous control cycle, calculate the estimated disturbance of the axial force variation in the composite material layer: ;in, For the first Estimation of axial force variation disturbance of composite material layer in each control cycle This is the equivalent control coefficient of the composite layer feed rate adjustment on the axial force variation. This represents the adjustment amount of the composite material layer feed rate in the previous control cycle; where, take .

[0032] S4022, Target axial force of composite material layer As a constant force control benchmark, calculate the constant force error of the composite material layer: ;in, For the first The constant force error of the composite material layer in each control cycle Let be the target axial force of the composite material layer; where, take .

[0033] S4023. Calculate the feed rate adjustment of the composite layer based on the constant force error and the estimated disturbance of the axial force variation of the composite layer: ;in, For the first The adjustment amount of the composite material layer feed rate per control cycle The bandwidth for controlling the axial force of the composite layer; where, take .

[0034] S4024. The feed speed adjustment of the composite material layer is subject to bipolar limitation, causing it to output along either the acceleration or deceleration direction; if Less than Then Take as ;like Greater than Then Take as ;like Not less than and not greater than Then it will not change. ;in, This represents the maximum allowable deceleration adjustment amount for the composite material layer. This represents the maximum allowable speed adjustment for the composite material layer, and and All are positive; among them, take positive values. , Therefore, the feed rate adjustment of the composite material layer can be achieved. ~ Bidirectional output within the range.

[0035] S4025. Generate a composite layer feed speed command based on the composite layer base feed speed and the composite layer feed speed adjustment amount: ;in, For the first The composite material layer feed speed command for each control cycle. This represents the feed rate of the composite material layer base. Wherein, we take... Therefore, after bipolar limitation, the composite layer feed rate command is located in ~ Within the specified range, the bipolar constant force control mode can output along the acceleration direction when the estimated feed axial force is lower than the target axial force of the composite material layer, and output along the deceleration direction when the estimated feed axial force is higher than the target axial force of the composite material layer. This allows the axial force during the hole-making process of the composite material layer to change stably around the target value, reducing the risk of delamination, tearing, and burrs.

[0036] During the processing of the titanium alloy layer and composite material layer, the control unit according to... or The system generates a final feed rate command and sends it to the drive controller, which then drives the feed motor to operate at the corresponding feed rate. During the idle phase, the control unit drives the feed mechanism to approach the workpiece surface at a preset rapid feed rate. During the drilling phase, the control unit executes a rapid retraction action. During the hole-making process, the spindle speed remains at a set value based on the material layer the tool is currently in. Once the tool has drilled through the current hole and completed retraction, the hole-making cycle ends, and the system resets to prepare for the next hole. The machining process ends when all holes have been drilled.

Claims

1. A method for feed control during the hole-making process of a titanium alloy and composite material laminate, characterized in that, The titanium alloy and composite material laminate consists of a titanium alloy layer and a composite material layer sequentially along the hole-making feed direction. The feed control method includes the following steps: Step S1: Before drilling, the feed mechanism is driven to move under no-load conditions along the drilling feed direction. The feed mechanism includes a feed motor and a transmission mechanism. The feed motor speed, feed motor current, and feed position are collected at different feed speeds. An equivalent friction characterization model of the feed transmission chain is established for the drilling feed direction. For the feed motor current collected during no-load movement, the feed motor torque constant is used... The feed drive chain friction torque is calculated, and the feed motor current and the feed drive chain friction torque satisfy the following relationship: ;in, For the first The frictional torque of the feed drive chain in each control cycle The feed motor torque constant is For the first The feed motor current for each control cycle; the equivalent friction characterization model is obtained by least squares fitting, and the friction torque of the feed transmission chain satisfies: ;in, To control the cycle number, For the first The feed rate per control cycle The coefficient of viscous friction of the feed drive chain. For the Coulomb friction torque of the feed drive chain; Step S2: During the hole-making process, the feed motor current, feed motor speed, and feed position are collected in real time. An expansion state observer is constructed using the feed motor current as the input and the feed motor speed as the output. The total load angular acceleration of the feed axis is used as the online observation of the expansion state to obtain the first... Total load torque of the feed axis per control cycle ; Step S3, according to the first Frictional torque of the feed drive train per control cycle and the Total load torque of the feed axis per control cycle The following formula yields the first... Net cutting torque per control cycle : Based on the conversion relationship between torque and axial force in the transmission mechanism, the net cutting torque is converted into the first... Estimated feed axial force per control cycle ; Step S4: Based on the feed position, workpiece surface reference position, and preset titanium alloy and composite material layer thickness, determine whether the tool is currently in the idle stage, titanium alloy layer, composite material layer, or drilling stage, and call the corresponding process parameters and control mode according to the determination result; For the first Feed position for each control cycle As the reference position on the workpiece surface, The thickness of the titanium alloy layer is preset. Preset the thickness of the composite material layer; when Less than When the tool is in the idle phase, it is determined that the tool is in the idle phase; when Not less than and less than When the cutting tool is in the titanium alloy layer, it is determined that the tool is in the titanium alloy layer; when Not less than and less than When the tool is in the composite material layer, it is determined that the tool is in the composite material layer; when Not less than When the tool is in the drilling stage, the feed rate is adjusted using a unipolar force limiting control mode when the tool is in the titanium alloy layer; when the tool is in the composite material layer, the feed rate is adjusted using a bipolar constant force control mode. In step S4, when the tool is in the titanium alloy layer, the unipolar force limiting control mode is implemented using a unipolar force limiting active disturbance suppression control algorithm, specifically including: S4011. Based on the estimated feed axial force values ​​of the current control cycle and the previous control cycle, calculate the estimated disturbance of the axial force variation in the titanium alloy layer: ;in, For the first Estimated perturbation of axial force variation in titanium alloy layer over one control cycle. For the first Estimated feed axial force for each control cycle This is the estimated feed axial force value from the previous control cycle. This is the equivalent control coefficient for the change in axial force caused by the adjustment of the feed rate of the titanium alloy layer. This is the adjustment amount of the titanium alloy layer feed rate in the previous control cycle; S4012, with the upper limit of axial force of titanium alloy layer As the force-limiting boundary, calculate the force-limiting error of the titanium alloy layer: ;in, For the first The limit force error of the titanium alloy layer in each control cycle; S4013, when Greater than At that time, based on the limit error of the titanium alloy layer and the estimated disturbance of the axial force change of the titanium alloy layer, the feed rate adjustment of the titanium alloy layer is calculated: ;in, Bandwidth for controlling axial force in titanium alloy layers; when Not greater than At that time, Set to zero; S4014. The feed rate adjustment of the titanium alloy layer is unipolarly limited, so that it is only output in the deceleration direction; if Less than Then Take as ;like If it is greater than zero, then... Set to zero; if Not less than If the value is not greater than zero, then it remains unchanged. ;in, This is the maximum allowable deceleration adjustment amount for the titanium alloy layer, and Take a positive value; S4015. Generate a titanium alloy layer feed rate command based on the basic feed rate of the titanium alloy layer and the titanium alloy layer feed rate adjustment amount: ;in, For the titanium alloy layer base feed rate; When the tool is in the composite material layer, the bipolar constant force control mode is implemented using a bipolar constant force active disturbance suppression control algorithm, specifically including: S4021. Based on the estimated feed axial force values ​​of the current control cycle and the previous control cycle, calculate the estimated disturbance of the axial force variation in the composite material layer: ;in, For the first Estimated perturbation of axial force variation in composite material layer over one control cycle For the first Estimated feed axial force for each control cycle This is the estimated feed axial force value from the previous control cycle. This is the equivalent control coefficient of the composite layer feed rate adjustment on the axial force variation. This is the adjustment amount of the composite material layer feed rate in the previous control cycle; S4022, Target axial force of composite material layer As a constant force control benchmark, calculate the constant force error of the composite material layer: ;in, For the first The constant force error of the composite material layer in each control cycle The target axial force of the composite material layer; S4023. Calculate the feed rate adjustment of the composite layer based on the constant force error and the estimated disturbance of the axial force variation of the composite layer: ;in, For the first The adjustment amount of the composite material layer feed rate per control cycle The bandwidth for controlling the axial force of the composite material layer; S4024. The feed speed adjustment of the composite material layer is subject to bipolar limitation, causing it to output along either the acceleration or deceleration direction; if Less than Then Take as ;like Greater than Then Take as ;like Not less than and not greater than Then it will not change. ;in, This represents the maximum allowable deceleration adjustment amount for the composite material layer. This represents the maximum allowable speed adjustment for the composite material layer, and and All values ​​are positive. S4025. Generate a composite layer feed speed command based on the composite layer base feed speed and the composite layer feed speed adjustment amount: ;in, For the first The composite material layer feed speed command for each control cycle. This represents the feed rate of the composite material layer base.

2. The feed control method for the hole-making process of titanium alloy and composite material laminates according to claim 1, characterized in that, In step S2, the state variables of the extended state observer are defined as follows: , , ;in, The equivalent rotational inertia of the feed motor, For the feed motor speed, The first derivative of the feed motor speed. This is the total load torque of the feed axis. The total load angular acceleration of the feed axis; the extended state observer is updated in a discrete form, satisfying: in, To control the cycle, , , To extend the state observer gain, For the first The current input term for each control cycle is calculated from the feed motor current. For input gain, For the first The measured speed of the feed motor in each control cycle For the first The estimated speed of the feed motor for each control cycle. For the first The estimated first derivative of the feed motor speed for each control cycle. For the first Estimated total load angular acceleration of the feed axis per control cycle For the first The estimated speed of the feed motor for each control cycle. For the first The estimated first derivative of the feed motor speed for each control cycle. For the first The estimated total load angular acceleration of the feed axis in the first control cycle is obtained, and the result is obtained according to the following formula. Total load torque of the feed axis per control cycle: .

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