Automobile crankshaft machining post-surface treatment method and device

Abstract

The application relates to a surface treatment method and device for a machined automobile crankshaft, and belongs to the technical field of surface treatment after machining of automobile crankshafts. The method comprises the following steps: S1, setting a grinding machine base, a workpiece rotating table, a flexible grinding executor, a state sensing system and a controller; S2, calibrating the total system delay time; S3, loading a standard three-dimensional geometric model, scanning a workpiece to obtain three-dimensional point cloud data, comparing and generating a removal allowance atlas, and identifying high-risk geometric mutation points; and S4, starting the flexible grinding executor, when it is detected that the high-risk geometric mutation point is about to be reached, the controller converts a feedforward pre-reading angle based on the total system delay time and the current angular velocity of the workpiece rotating table, and in advance, instructs an air pressure adjusting valve to exhaust to a safe idle speed pressure. The application calibrates the system delay and carries out feedforward control, and solves the problems of normal force overshoot and overcut damage caused by system delay at the geometric mutation point.

Description

Technical Field

[0001] This invention relates to the field of surface treatment after machining of automotive crankshafts, specifically a method and apparatus for surface treatment after machining of automotive crankshafts. Background Technology

[0002] The crankshaft is a critical component of an engine, and its radius (R-angle) root often retains burrs and machining marks after machining. Currently, traditional rigid grinding or manual polishing are the main methods for addressing these surface defects; however, these methods struggle to simultaneously achieve both efficient material removal and high-quality surface finish. Especially during high-speed crankshaft grinding operations, when the grinding device passes through areas of geometric discontinuity such as oil holes or steps—high-risk geometric abrupt changes—over-excessive normal contact force can easily occur, leading to over-cutting damage to the workpiece.

[0003] The root cause of this phenomenon is that there is an inherent system delay between the controller issuing the exhaust command and the actual reduction of the contact force of the actuator in the existing grinding system. When facing geometric abrupt changes on a high-speed rotating workpiece, the existing force control methods, which are mainly based on closed-loop adjustment of force sensor feedback, cannot respond in time and compensate for this system delay. As a result, the grinding force cannot be reduced to a safe level in a short time, ultimately leading to overshoot of the normal force and damage to the workpiece. Therefore, when dealing with surface defects at the root of the crankshaft radius, the existing technology faces the challenge of effectively avoiding overcutting damage to the workpiece at geometric abrupt changes while achieving high-efficiency grinding.

[0004] The information disclosed in the background section above is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for surface treatment of automotive crankshafts after machining, so as to solve the problems mentioned in the background art. Specifically, the technical solution of this invention includes:

[0006] S1. A grinding machine base, a workpiece rotary table, a flexible grinding actuator, a status sensing system, and a controller are provided. The flexible grinding actuator is mounted on the grinding machine base. The workpiece rotary table is used to clamp the crankshaft workpiece. The status sensing system includes a laser displacement sensor and a force sensor. The flexible grinding actuator includes a flexible airbag backplate and an air path controlled by a pressure regulating valve. The controller is electrically connected to the workpiece rotary table, the flexible grinding actuator, the pressure regulating valve, and the status sensing system.

[0007] S2. Calibrate the total system delay time, wherein the total system delay time is the time difference from the issuance of the exhaust command to the pressure regulating valve, to the reduction of the contact force monitored by the force sensor to a safe threshold.

[0008] S3. Load the standard three-dimensional geometric model, use the laser displacement sensor to scan the root of the R-angle of the crankshaft workpiece to obtain three-dimensional point cloud data, and compare it with the standard three-dimensional geometric model to generate a removal margin map. Based on the removal margin map, plan the adaptive grinding path, target normal contact force sequence, and identify high-risk geometric change points.

[0009] S4. Start the flexible grinding actuator, drive it to move along the adaptive grinding path, and execute control: The controller adjusts the air pressure of the flexible airbag backplate through the air pressure regulating valve according to the target normal contact force sequence, and performs feedback adjustment based on the feedback of the force sensor; when the high-risk geometric change point is detected to be approaching, the controller calculates the feedforward pre-reading angle based on the total system delay time and the current angular velocity of the workpiece rotary table, and commands the air pressure regulating valve to exhaust air to the safe idle pressure required to make the contact force lower than the safety threshold.

[0010] Preferably, step S3 is preceded by:

[0011] S3.1 The laser displacement sensor is used to collect at least three reference points on the crankshaft workpiece, and the rotation axis of the crankshaft workpiece is aligned with the coordinate system of the standard three-dimensional geometric model through a coordinate transformation algorithm.

[0012] Preferably, in step S4, the specific implementation of the feedback adjustment includes:

[0013] The controller calculates the target air pressure value based on the target normal contact force and a pre-established force-pressure mapping model, and then instructs the air pressure regulating valve.

[0014] The force sensor monitors the actual normal contact force in real time, and the controller compares the actual normal contact force with the target normal contact force to adjust the air pressure regulating valve in a closed loop.

[0015] Preferably, in step S2, the safety threshold is less than 1N.

[0016] Preferably, in step S4, activating the flexible grinding actuator includes:

[0017] The grinding belt drive wheel inside the flexible grinding actuator is activated and rotates in a constant linear speed of 15 m / s.

[0018] Preferably, in step S1, the force sensor is a six-dimensional torque sensor.

[0019] Preferably, in step S1, the laser displacement sensor is a non-contact probe based on the triangulation principle.

[0020] A surface treatment device for automotive crankshafts after machining, comprising:

[0021] Grinding machine base;

[0022] A workpiece rotary table, disposed on the grinding machine base, is used to clamp and rotate the crankshaft workpiece;

[0023] A flexible grinding actuator is movably mounted on the grinding machine base, the flexible grinding actuator including a flexible airbag backplate and a grinding belt;

[0024] An air pressure regulating valve is connected to the air passage of the flexible airbag backplate and is used to regulate the air pressure of the flexible airbag backplate.

[0025] The state sensing system includes a laser displacement sensor and a force sensor. The laser displacement sensor is used to scan the surface of the crankshaft workpiece, and the force sensor is used to monitor the normal contact force between the flexible grinding actuator and the crankshaft workpiece.

[0026] The controller is electrically connected to the workpiece rotary table, the flexible grinding actuator, the pneumatic regulating valve, and the status sensing system.

[0027] Preferably, the grinding machine base includes a three-axis linear guide rail, and the flexible grinding actuator is mounted on the three-axis linear guide rail; the workpiece rotary table includes a chuck for clamping one end of the crankshaft workpiece and a tailstock for supporting the other end of the crankshaft workpiece.

[0028] Preferably, the force sensor is disposed between the grinding machine base and the flexible grinding actuator, and is used to measure the three-dimensional spatial force and torque on the flexible grinding actuator.

[0029] This invention provides an improved method and apparatus for surface treatment of automotive crankshafts after machining, which has the following improvements and advantages compared with the prior art:

[0030] 1. This invention utilizes a laser displacement sensor to collect at least three reference points, and uses a coordinate transformation algorithm to align the rotation axis of the crankshaft workpiece with the coordinate system of the standard three-dimensional geometric model. This ensures that the subsequent three-dimensional point cloud data and the standard model are accurately compared in the same coordinate system, providing a foundation for accurately calculating geometric deviations and generating reliable removal margin maps.

[0031] 2. By comparing the 3D point cloud data with the standard model, a removal margin map is generated. Based on the map, an adaptive grinding path and target normal contact force sequence are planned, and high-risk geometric change points are identified to accurately locate the processing area, burrs, and machining marks. By identifying high-risk geometric change points, such as the edge of oil holes, the controller is informed in advance of the location that needs special treatment, providing a trigger signal for feedforward control.

[0032] 3. The time difference between issuing the exhaust command and the contact force monitored by the force sensor decreasing to below the safety threshold of 1N is calibrated, which is the total system delay time. This accurately quantifies the system's response time from the command to the safe reduction of the flexible airbag pressure. This is a key parameter for subsequent feedforward prediction and prevention of force overshoot. The controller commands the air pressure regulating valve based on the target normal contact force sequence and the pre-established force-pressure mapping model. The force sensor monitors the actual force in real time and adjusts the air pressure regulating valve in a closed loop to ensure that in the non-abrupt region, the flexible grinding actuator can conform to the continuous irregular shape of the workpiece and maintain a constant grinding pressure, thus ensuring surface quality and removal efficiency.

[0033] 4. When a high-risk geometric change point is detected, the controller calculates the feedforward pre-reading angle based on the total system delay time and the current angular velocity of the workpiece rotary table, and instructs the air pressure regulating valve to exhaust air to the safe idle pressure required to lower the contact force below the safety threshold. This achieves advance compensation for system delay. Before the geometric change point, the contact force of the flexible grinding actuator can safely pass the change point with very low force, avoiding force overshoot and overcutting damage caused by system delay. This solves the core problem of overcutting damage caused by normal force overshoot in the prior art. Attached Figure Description

[0034] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0035] Figure 1 This is a schematic diagram of the overall structure of the device;

[0036] Figure 2 This is a schematic diagram of the workpiece rotary table.

[0037] Figure 3 This is a structural diagram of the grinding machine base, the flexible grinding actuator, and the state sensing system;

[0038] Figure 4 This is a flowchart of the method of the present invention.

[0039] In the diagram: 100, grinding machine base; 110, three-axis linear guide; 200, workpiece rotary table; 210, chuck; 220, tailstock; 230, servo rotary motor; 300, flexible grinding actuator; 310, grinding belt drive wheel; 330, flexible airbag backplate; 340, air pressure regulating valve; 350, grinding belt; 400, status sensing system; 410, laser displacement sensor; 420, force sensor; 500, controller. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0041] Example 1:

[0042] Please see Figure 1-4 This invention provides a method for surface treatment of automotive crankshafts after machining, comprising:

[0043] S1. A grinding machine base 100, a workpiece rotary table 200, a flexible grinding actuator 300, a status sensing system 400, and a controller 500 are provided. The flexible grinding actuator 300 is mounted on the grinding machine base 100. The workpiece rotary table 200 is used to clamp the crankshaft workpiece. The status sensing system 400 includes a laser displacement sensor 410 and a force sensor 420. The flexible grinding actuator 300 includes a flexible airbag backplate 330 and an air path controlled by a pressure regulating valve 340. The controller 500 is electrically connected to the workpiece rotary table 200, the flexible grinding actuator 300, the pressure regulating valve 340, and the status sensing system 400.

[0044] S2. Calibrate the total system delay time, where the total system delay time is the time difference from the issuance of the exhaust command to the pressure regulating valve 340, and to the reduction of the contact force monitored by the force sensor 420 to the safety threshold.

[0045] S3. Load the standard three-dimensional geometric model, use the laser displacement sensor 410 to scan the root of the R-angle of the crankshaft workpiece to obtain three-dimensional point cloud data, and compare it with the standard three-dimensional geometric model to generate a removal margin map. Based on the removal margin map, plan the adaptive grinding path, target normal contact force sequence, and identify high-risk geometric change points.

[0046] S4. Start the flexible grinding actuator 300, drive it to move along the adaptive grinding path, and execute control: The controller 500 adjusts the air pressure of the flexible airbag back plate 330 through the air pressure regulating valve 340 according to the target normal contact force sequence, and performs feedback adjustment based on the feedback of the force sensor 420; when a high-risk geometric change point is detected, the controller 500 calculates the feedforward pre-reading angle based on the total system delay time and the current angular velocity of the workpiece rotary table 200, and in advance instructs the air pressure regulating valve 340 to exhaust air to the safe idle pressure required to make the contact force lower than the safety threshold.

[0047] In the embodiments of the present invention, for the burrs and machining marks present at the root of the R-angle after machining of automobile crankshafts, traditional rigid grinding or manual grinding methods are difficult to balance removal efficiency and surface quality. Especially when encountering discontinuous geometric shapes such as oil holes and steps under high-speed rotation, it is easy to generate excessive normal force, resulting in overcutting damage to the workpiece body. The surface treatment method for automobile crankshafts after machining provides a solution. The method is equipped with necessary mechanical structures and sensing components, including a grinding machine base 100, a workpiece rotary table 200, a flexible grinding actuator 300, and a status sensing system 400. The flexible grinding actuator 300 is inflated and deflated via an air passage controlled by a pressure regulating valve 340 through its internal flexible airbag backplate 330, allowing it to gently conform to the irregular surface of the workpiece. The laser displacement sensor 410 in the state sensing system 400 is used for non-contact scanning, and the force sensor 420 is used to monitor the contact force in real time. Before processing, the total system delay time is calibrated, which reflects the response time from when the controller 500 issues an exhaust command to when the actual pressure of the flexible airbag backplate 330 decreases to a safe state.

[0048] The total system delay time is a quantitative parameter that characterizes the response time from the controller 500 command to the actual safe reduction of air pressure in the flexible airbag backplate 330. It is the inherent nonlinear delay of the system. It is obtained through experimental calibration in step S2. This parameter is the key input for calculating the feedforward readout angle in step S4, and is used to compensate for the force overshoot caused by inertia and air path delay.

[0049] During processing, this method compares the three-dimensional point cloud data acquired by the laser displacement sensor 410 with the loaded standard three-dimensional geometric model to generate a removal margin map. This map is not only used to plan the adaptive grinding path and the corresponding target normal contact force sequence, but also specifically used to identify high-risk geometric change points such as oil hole edges. During grinding, the controller 500 adjusts the air pressure of the flexible airbag backplate 330 based on the feedback from the force sensor 420 to maintain the target normal contact force. On the other hand, when the controller 500 anticipates that it is about to reach a high-risk geometric change point, it uses the calibrated total system delay time and the current angular velocity of the workpiece rotary table 200 to calculate the feedforward pre-reading angle that needs to be acted in advance. Under this advance, it actively commands the air pressure regulating valve 340 to exhaust air to a safe idle pressure, so that the flexible grinding actuator 300 can safely pass the change point with very low force, avoiding force overshoot and overcut damage caused by system delay.

[0050] This calculation depends on the calibrated total system delay time. and the current angular velocity of the workpiece rotary table 200 The logical steps are as follows: Step 1: When the controller 500 detects that a high-risk geometric change point is about to be reached, it acquires the real-time angular velocity of the current workpiece rotary table 200. Step 2: Perform calculation: Feedforward pre-read angle = Step 3: Calculate the advance trigger position corresponding to this angle, and use this position as the trigger condition to command the pressure regulating valve 340 to exhaust gas in advance. The final output of the process is the feedforward pre-read angle, which is used to trigger the advance exhaust command in step S4 to compensate for system delay.

[0051] The steps preceding S3 include:

[0052] S3.1 At least three reference points are collected on the crankshaft workpiece using a laser displacement sensor 410, and the rotation axis of the crankshaft workpiece is aligned with the coordinate system of the standard three-dimensional geometric model through a coordinate transformation algorithm.

[0053] In this embodiment, the process of generating the removal margin map in step S3 has been enriched. To ensure that the three-dimensional point cloud data acquired by the laser displacement sensor 410 can be accurately compared with the standard three-dimensional geometric model in the same coordinate system, an alignment step is added before step S3. Specifically, the laser displacement sensor 410 collects at least three spatially fixed reference points on the crankshaft workpiece to be processed. These reference points can be specific marks or structural features on the workpiece. After the controller 500 acquires the coordinates of these physical reference points, it uses a coordinate transformation algorithm to match and calculate the corresponding reference points on the digitized standard three-dimensional geometric model, solves the actual clamping position and rotation axis of the physical workpiece, and aligns the coordinate system of the standard three-dimensional geometric model with it. This alignment process provides the foundation for subsequent accurate calculation of geometric deviations and generation of reliable removal margin maps.

[0054] The input to this processing flow originates from the spatial coordinates of at least three physical reference points on the crankshaft workpiece acquired by the laser displacement sensor 410, and the corresponding digital reference point coordinates in the standard 3D geometric model. The logical steps are as follows: Step 1: Calculate the normal vector and center point of the reference plane formed by the physical reference points to determine the actual spatial posture of the physical workpiece; Step 2: Calculate the normal vector and center point of the reference plane formed by the digital reference points to determine the ideal posture of the standard model; Step 3: Use rigid body transformation mathematical tools such as rotation matrix and translation vector to calculate the coordinate transformation matrix required to align the coordinate system of the physical workpiece to the coordinate system of the standard model; The final output of the flow is the aligned workpiece coordinate system, which is used for the accurate comparison of the 3D point cloud data and the standard 3D geometric model in the subsequent S3 step;

[0055] In step S4, the specific implementation of feedback adjustment includes:

[0056] The controller 500 calculates the target air pressure value based on the target normal contact force and a pre-established force-pressure mapping model, and then instructs the air pressure regulating valve 340.

[0057] Force sensor 420 monitors the actual normal contact force in real time, and controller 500 compares the actual normal contact force with the target normal contact force to adjust air pressure regulating valve 340 in a closed loop.

[0058] In this embodiment, the force control process in the conventional grinding area of ​​step S4 is refined. In areas where there are no high-risk geometric change points, the controller 500 performs adjustments based on feedback from the force sensor 420; specifically, the controller 500 obtains the target normal contact force at the current point from the planned target normal contact force sequence; since the contact force of the flexible airbag backplate 330 is determined by the internal air pressure, the controller 500 queries a pre-established force-pressure mapping model; this model, through prior experimental calibration, establishes the correspondence between the target normal force and the required air pressure value;

[0059] The purpose of the force-pressure mapping model is to determine the target normal contact force in non-abrupt regions. The model accurately estimates the target air pressure value that should be applied inside the flexible airbag backplate 330. This model is an empirical or semi-empirical model. The correspondence curve or lookup table between the normal contact force and the air pressure inside the airbag is established through experimental calibration under different grinding conditions. Overall, the model characterizes the nonlinear physical relationship between the internal air pressure of the flexible airbag and the normal contact force applied to the surface of the crankshaft workpiece through the grinding belt 350 when the flexible airbag expands in a confined space.

[0060] The controller 500 calculates the target air pressure value required to achieve the target force based on this model and instructs the air pressure regulating valve 340 to inflate the flexible airbag backplate 330. During this process, the force sensor 420 monitors the actual normal contact force generated between the grinding belt 350 and the workpiece surface in real time and feeds this actual force data back to the controller 500 at high speed. The controller 500 continuously compares the difference between the actual normal contact force and the target normal contact force. If the actual force is too small, it instructs the air pressure regulating valve 340 to increase the air supply pressure; if the actual force is too large, it instructs it to decrease the air supply pressure. In this way, the controller 500 adjusts the air pressure regulating valve 340 so that the flexible airbag backplate 330 can conform to the continuous irregular shape at the root of the R-angle and maintain a constant grinding pressure.

[0061] In step S2, the safety threshold is below 1N.

[0062] In this embodiment, the safety threshold used to calibrate the total system delay time in step S2 is explained. The safety threshold is set to be below 1N; this threshold is set based on the following considerations: during high-speed rotating grinding, especially when facing geometric change points, any significant contact force may lead to overcutting; setting the safety threshold to a value close to zero but easily detectable by the sensor, such as below 1N, ensures that the time measured when calibrating the total system delay time is the complete time required for the flexible airbag backplate 330 to completely degas from its working pressure, which may be tens of Newtons, to a safe state where almost no cutting force is generated; in step S4, when the controller 500 commands degassing in advance, this safety threshold is also used as a target to ensure that when the flexible grinding actuator 300 crosses a high-risk geometric change point, its contact force has been reduced to a level insufficient to damage the workpiece body.

[0063] The safety threshold is set to be below 1N, representing the minimum contact force level that is insufficient to cause substantial damage to the crankshaft workpiece during high-speed grinding. It serves as the termination condition for calibrating the total delay time of the system in step S2, ensuring that the measured time is the complete time from the working force to the safe state. In the feedforward control of step S4, the goal of the advance exhaust command is to reduce the contact force to this safety threshold before reaching the geometric change point.

[0064] In step S4, activating the flexible grinding actuator 300 includes:

[0065] The grinding belt drive wheel 310 inside the flexible grinding actuator 300 is activated and rotates in a constant linear speed of 15 m / s.

[0066] More preferably, the constant linear velocity is preset according to the crankshaft material, the 350 mesh size of the grinding belt and the required removal efficiency, for example, it can be adjusted in the range of 10 m / s to 25 m / s;

[0067] In this embodiment, the action of activating the flexible grinding actuator 300 in step S4 is supplemented. The flexible grinding actuator 300 internally houses a grinding belt drive wheel 310 and a grinding belt driven wheel, with the grinding belt 350 fitted onto its outer side. Before the grinding machine base 100 and the workpiece rotary table 200 begin coordinated movement to execute the adaptive grinding path, the controller 500 first activates the grinding belt 350 drive wheel within the flexible grinding actuator 300. This grinding belt drive wheel 310 is driven by a micro torque motor and operates at a preset constant linear speed, for example, 15 m / s, driving the grinding belt 350 in cyclic motion. The high-speed cyclic motion of the grinding belt 350 is the physical basis for material removal, while the air pressure control of the flexible airbag backplate 330 provides the normal contact force; the two combine to complete the grinding treatment of the root of the radius corner.

[0068] In step S1, the force sensor 420 is a six-dimensional torque sensor.

[0069] In this embodiment, the selection of the force sensor 420 in the state sensing system 400 in step S1 is explained. Specifically, the force sensor 420 can be a six-dimensional torque sensor, such as the ATIOmega-160. The selection of a six-dimensional torque sensor can not only accurately measure the contact force along the normal direction of the workpiece during the grinding process, which is crucial for the force control in step S4, but also monitor the frictional forces Fx and Fy along the tangential direction and the torques Mx, My, and Mz in the three directions. This additional dimensional information can be used to monitor the wear state of the grinding belt 350 or abnormal vibrations during the grinding process, providing richer data support for process optimization.

[0070] In step S1, the laser displacement sensor 410 is a non-contact probe based on the triangulation principle.

[0071] In this embodiment, the type of laser displacement sensor 410 in the state perception system 400 in step S1 is described. Specifically, the laser displacement sensor 410 can be a non-contact probe based on the triangulation principle, such as the Keyence LK-G5000. This model is merely an example and does not constitute a limitation. This type of sensor projects a laser beam onto the workpiece surface and calculates the distance by receiving the position of the reflected light. A non-contact probe based on the triangulation principle is chosen because it features high precision and a high sampling frequency, enabling it to quickly and accurately acquire high-density three-dimensional point cloud data of the R-angle root surface while the crankshaft workpiece rotates. This is necessary for generating a detailed removal margin map and accurately identifying high-risk geometric change points in step S3.

[0072] Example 2:

[0073] Please see Figure 1-3 A surface treatment device for automotive crankshafts after machining, comprising:

[0074] Grinding machine base 100;

[0075] The workpiece rotary table 200 is set on the grinding machine base 100 and is used to clamp and rotate the crankshaft workpiece.

[0076] The flexible grinding actuator 300 is movably mounted on the grinding machine base 100. The flexible grinding actuator 300 includes a flexible airbag back plate 330 and a grinding belt 350.

[0077] The air pressure regulating valve 340 is connected to the air passage of the flexible airbag backplate 330 and is used to regulate the air pressure of the flexible airbag backplate 330.

[0078] The state sensing system 400 includes a laser displacement sensor 410 and a force sensor 420. The laser displacement sensor 410 is used to scan the surface of the crankshaft workpiece, and the force sensor 420 is used to monitor the normal contact force between the flexible grinding actuator 300 and the crankshaft workpiece.

[0079] The controller 500 is electrically connected to the workpiece rotary table 200, the flexible grinding actuator 300, the pneumatic regulating valve 340, and the status sensing system 400.

[0080] In an embodiment of the present invention, a surface treatment apparatus for machined automotive crankshafts is provided, which implements the aforementioned method. The apparatus includes a grinding machine base 100 as its basic structure, and a workpiece rotary table 200 disposed on the grinding machine base 100. The workpiece rotary table 200 is used to clamp the crankshaft workpiece and drive it to rotate as needed. The apparatus also includes a flexible grinding actuator 300, which is movably mounted on the grinding machine base 100 to allow it to approach the workpiece. The core components of the flexible grinding actuator 300 are its internal flexible airbag backplate 330 and its external grinding belt 350. The flexible airbag backplate 330's expansion is controlled by an air passage connected to a pressure regulating valve 340, thereby pressing the grinding belt 350 against the workpiece surface. To achieve precise control, the apparatus is equipped with a state sensing system 400, which includes laser displacement. Sensors 410 and 420; laser displacement sensor 410 is deployed on flexible grinding actuator 300 for scanning the surface profile of crankshaft workpiece before and during grinding; force sensor 420 is used to monitor the normal contact force between flexible grinding actuator 300 and crankshaft workpiece in real time; controller 500, such as Siemens S7-1500 series PLC or Beckhoff C69xx series industrial PC (this model is only an example and does not constitute a limitation), electrically connects all the above moving parts and sensing parts, including workpiece rotary table 200, flexible grinding actuator 300, pneumatic regulating valve 340 and state sensing system 400. Controller 500 is responsible for executing steps S2, S3 and S4 in the aforementioned method, coordinating the movement of each part, processing sensor data, and executing a force control algorithm that includes feedforward prediction and feedback regulation.

[0081] The grinding machine base 100 includes a three-axis linear guide 110, and a flexible grinding actuator 300 is mounted on the three-axis linear guide 110; the workpiece rotary table 200 includes a chuck 210 for clamping one end of the crankshaft workpiece and a tailstock 220 for supporting the other end of the crankshaft workpiece.

[0082] In this embodiment, the specific structures of the grinding machine base 100 and the workpiece rotary table 200 are elaborated. To enable precise movement of the flexible grinding actuator 300 in three-dimensional space, the grinding machine base 100 includes a three-axis linear guide 110. The flexible grinding actuator 300 and the state sensing system 400 are mounted together on the motion slider of this three-axis linear guide 110. Driven by X, Y, and Z three-axis servo motors, it can achieve feed motion along the root of the radius (R-angle) and pressing motion in the normal direction. To ensure stable clamping and high coaxiality rotation of the crankshaft workpiece, the workpiece rotary table 200 includes a chuck 210 and a tailstock 220. The chuck 210 is mounted on the spindle end of the workpiece rotary table 200, used to clamp one end of the crankshaft workpiece and driven by a servo rotary motor 230. The tailstock 220 is mounted on the bed guide rail of the grinding machine base 100, used to rigidly hold the other end of the crankshaft workpiece, and works with the chuck 210 to ensure the rotational stability of the workpiece during the grinding process.

[0083] Force sensor 420 is disposed between grinding machine base 100 and flexible grinding actuator 300 to measure the three-dimensional spatial force and torque on flexible grinding actuator 300; state sensing system 400 is a combination of laser displacement sensor 410 and force sensor 420.

[0084] In this embodiment, the installation position and function of the force sensor 420 are described. The force sensor 420 is installed in series along the force transmission path. Specifically, it is positioned between the motion slider of the three-axis linear guide 110 of the grinding machine base 100 and the housing of the flexible grinding actuator 300. For example, the upper flange of the force sensor 420 is fixedly connected to the Z-axis slider of the three-axis linear guide 110, and its lower flange is fixedly connected to the housing of the flexible grinding actuator 300. This installation method ensures that all three-dimensional spatial forces and torques experienced by the flexible grinding actuator 300 when it contacts the workpiece in the grinding contour zone are measured by the force sensor 420. This deployment method ensures that the force sensor 420 can accurately monitor the normal contact force required in step S4, providing a reliable signal source for the force feedback adjustment of the controller 500 and the calibration of the total system delay time.

[0085] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for surface treatment of automotive crankshafts after machining, characterized in that, include: S1. A grinding machine base (100), a workpiece rotary table (200), a flexible grinding actuator (300), a state sensing system (400), and a controller (500) are provided. The flexible grinding actuator (300) is installed on the grinding machine base (100). The workpiece rotary table (200) is used to clamp the crankshaft workpiece. The state sensing system (400) includes a laser displacement sensor (410) and a force sensor (420). The flexible grinding actuator (300) includes a flexible airbag backplate (330) and an air path controlled by a pressure regulating valve (340). The controller (500) is electrically connected to the workpiece rotary table (200), the flexible grinding actuator (300), the pressure regulating valve (340), and the state sensing system (400). S2. Calibrate the total system delay time, wherein the total system delay time is the time difference from the issuance of the exhaust command to the pressure regulating valve (340) to the reduction of the contact force monitored by the force sensor (420) to the safety threshold; S3. Load the standard three-dimensional geometric model, use the laser displacement sensor (410) to scan the root of the R-angle of the crankshaft workpiece to obtain three-dimensional point cloud data, and compare it with the standard three-dimensional geometric model to generate a removal margin map, and plan an adaptive grinding path, target normal contact force sequence and identify high-risk geometric change points based on the removal margin map; S4. Start the flexible grinding actuator (300), drive it to move along the adaptive grinding path, and perform control: The controller (500) adjusts the air pressure of the flexible airbag backplate (330) through the air pressure regulating valve (340) according to the target normal contact force sequence, and performs feedback adjustment according to the feedback of the force sensor (420); when the high-risk geometric change point is detected to be approaching, the controller (500) calculates the feedforward pre-reading angle based on the total system delay time and the current angular velocity of the workpiece rotary table (200), and in advance instructs the air pressure regulating valve (340) to exhaust air to the safe idle pressure required to make the contact force lower than the safety threshold.

2. The surface treatment method for automotive crankshafts after machining according to claim 1, characterized in that, The steps preceding S3 include: S3.1 The laser displacement sensor (410) is used to collect at least three reference points on the crankshaft workpiece, and the rotation axis of the crankshaft workpiece is aligned with the coordinate system of the standard three-dimensional geometric model through a coordinate transformation algorithm.

3. The surface treatment method for automotive crankshafts after machining according to claim 2, characterized in that, In step S4, the specific implementation of the feedback adjustment includes: The controller (500) calculates the target air pressure value based on the target normal contact force and a pre-established force-pressure mapping model, and instructs the air pressure regulating valve (340). The force sensor (420) monitors the actual normal contact force in real time, and the controller (500) compares the actual normal contact force with the target normal contact force to adjust the air pressure regulating valve (340) in a closed loop.

4. The surface treatment method for automotive crankshafts after machining according to claim 1, characterized in that, In step S2, the safety threshold is less than 1N.

5. The surface treatment method for automotive crankshafts after machining according to claim 1, characterized in that, In step S4, activating the flexible grinding actuator (300) includes: The grinding belt drive wheel (310) inside the flexible grinding actuator (300) is activated to cycle at a constant linear speed of 15 m / s.

6. The surface treatment method for automotive crankshafts after machining according to claim 1, characterized in that, In step S1, the force sensor (420) is a six-dimensional torque sensor.

7. The surface treatment method for automotive crankshafts after machining according to claim 1, characterized in that, In step S1, the laser displacement sensor (410) is a non-contact probe based on the triangulation principle.

8. A surface treatment apparatus for machined automotive crankshafts, applied to the surface treatment method for machined automotive crankshafts as described in any one of claims 1 to 7, characterized in that, include: Grinding machine base (100); A workpiece rotary table (200) is disposed on the grinding machine base (100) for clamping and rotating the crankshaft workpiece; A flexible grinding actuator (300) is movably mounted on the grinding machine base (100). The flexible grinding actuator (300) includes a flexible airbag backplate (330) and a grinding belt (350). A pressure regulating valve (340) is connected to the air passage of the flexible airbag backplate (330) and is used to regulate the air pressure of the flexible airbag backplate (330). The state sensing system (400) includes a laser displacement sensor (410) and a force sensor (420), wherein the laser displacement sensor (410) is used to scan the surface of the crankshaft workpiece, and the force sensor (420) is used to monitor the normal contact force between the flexible grinding actuator (300) and the crankshaft workpiece; The controller (500) is electrically connected to the workpiece rotary table (200), the flexible grinding actuator (300), the air pressure regulating valve (340), and the status sensing system (400).

9. The surface treatment device for automotive crankshafts after machining according to claim 8, characterized in that, The grinding machine base (100) includes a three-axis linear guide (110), and the flexible grinding actuator (300) is mounted on the three-axis linear guide (110); the workpiece rotary table (200) includes a chuck (210) for clamping one end of the crankshaft workpiece and a tailstock (220) for supporting the other end of the crankshaft workpiece.

10. The surface treatment device for automotive crankshafts after machining according to claim 8, characterized in that, The force sensor (420) is disposed between the grinding machine base (100) and the flexible grinding actuator (300) and is used to measure the three-dimensional spatial force and torque on the flexible grinding actuator (300).

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