An aircraft rivet cold heading forming system and method

Abstract

An aviation rivet cold upsetting forming system and method, the system comprising a cold upsetting machine main body, a multi-channel force sensor array, a signal acquisition and processing module, a control unit and a multi-point adjustable locking mechanism. The method comprises: symmetrically arranging force sensors at multiple locking points of the die mounting seat, and real-time acquisition of load signals during the cold upsetting cycle of each point; calculating a load eccentricity vector reflecting the die eccentric load state according to the load signals, and determining the eccentric load amount and direction; when there is eccentric load, independently adjusting the locking force of each locking point in the cold upsetting machine return gap, generating a reverse torque by increasing the locking force in the opposite direction of the eccentricity and reducing the locking force in the eccentricity direction, and driving the die position compensation. The present application realizes online real-time monitoring and non-stop dynamic adjustment of the cold upsetting die eccentric load, can significantly improve the coaxial precision of aviation rivet forming, prolong the service life of the die, and avoid error accumulation and batch quality accidents.

Description

Technical Field

[0001] This invention belongs to the field of metal forming technology, specifically referring to a cold heading forming system and method for aerospace rivets. Background Technology

[0002] As critical fasteners for aircraft structural connections, the cold heading precision of aviation rivets directly affects the fatigue life and sealing performance of the connected structure. During the cold heading process, factors such as uneven cut surfaces and the upsetting ratio can generate a component force perpendicular to the axis of the metal billet. This results in uneven lateral loads on the upper and lower dies, known as die eccentricity. This eccentricity can cause misalignment between the rivet head and shank, and in severe cases, can induce microcracks, endangering aviation safety.

[0003] However, existing cold heading equipment generally uses a fixed mold locking structure, which lacks both online monitoring methods to perceive the mold's stress state in real time during continuous production and the ability to dynamically adjust the mold position without stopping the machine. The mold condition can only be indirectly judged through periodic stop-and-spot inspections, and re-alignment after deviations are detected typically takes more than two hours, with adjustment accuracy relying on individual experience and making it difficult to guarantee consistency. If off-center loading persists for a long time, it will accelerate the uneven wear of the mold's guiding components, leading to a continuous deterioration of accuracy. In multi-station continuous processing, it can also cause errors to accumulate station by station, ultimately resulting in batch quality accidents. Summary of the Invention

[0004] In view of the above situation and to overcome the defects of the prior art, the present invention provides a cold heading system and method for aerospace rivets, which at least partially solves the above problems.

[0005] In a first aspect, the present invention provides a method for cold heading of aerospace rivets, applied to a cold heading machine, comprising the following steps: Force sensors are symmetrically arranged at multiple locking points of the upper mold mounting base of the cold heading machine to collect the load signals of each locking point in real time during the cold heading forming cycle. The load eccentricity vector characterizing the off-center loading state of the mold is calculated based on the load signals collected from each locking point. Based on the load eccentricity vector, determine the eccentricity and direction of the mold. When the off-center load exceeds the set threshold, during the return stroke of the main slide of the cold heading machine, the working pressure of the clamping actuator corresponding to each clamping point is independently adjusted. By increasing the clamping force in the opposite direction of the off-center vector and decreasing the clamping force in the direction of the off-center vector, a reverse torque is generated to drive the mold position compensation and counteract the off-center load.

[0006] Furthermore, the step of calculating the load eccentricity vector specifically includes: extracting the peak values ​​of the load signals of each locking point within the same cycle and the time offset of each peak value; establishing a coordinate system with the mold center as the origin, calculating the equivalent point coordinates of the resultant force based on the difference in the load peak values ​​of each locking point, and the distance and direction of the coordinates deviating from the origin constitute the load eccentricity vector.

[0007] Furthermore, the steps for determining the off-center load and direction of the mold include: setting a first threshold and a second threshold; when the off-center distance of the load off-center vector is less than the first threshold, it is determined to be a normal state; when the off-center distance is greater than or equal to the first threshold and less than the second threshold, it is determined to be a mild off-center load state, and the pressure adjustment is performed; when the off-center distance is greater than or equal to the second threshold, it is determined to be a severe off-center load state, and an alarm or shutdown is triggered.

[0008] Furthermore, the step of determining the off-center load and direction of the mold also includes: comparing the time offset of the peak load at each locking point; when the maximum difference between the time offsets corresponding to each locking point exceeds the preset ratio of a single working cycle of the cold heading machine, it is determined that there is an inclined contact between the upper mold and the lower mold.

[0009] Furthermore, the method also includes a closed-loop verification step: in the next cold heading cycle after the clamping force adjustment is completed, the force sensor is used to collect verification load data to verify whether the actual clamping force has reached the target value in a closed loop, and fine-tuning is performed based on the verification results.

[0010] Secondly, the present invention also provides an aerospace rivet cold heading forming system, including a cold heading machine body and a cold heading die assembly, and further comprising: A multi-channel force sensor array is symmetrically installed at multiple locking points on the upper die mounting base of the cold heading machine to independently collect the load signal of each locking point at the moment of cold heading. The signal acquisition and processing module is electrically connected to the multi-channel force sensor array and is used to synchronously acquire and process load signals. The multi-point adjustable clamping actuator includes an independently controlled force application unit corresponding to each clamping point, which is used to adjust the clamping force of the corresponding clamping point; The control unit is electrically connected to the signal acquisition and processing module and the mold clamping actuator. It is used to calculate the load eccentricity vector based on the processed load signal to determine the off-center load state, and control each of the force application units to perform asymmetric mold clamping force adjustment within the return gap of the cold heading machine to compensate for the off-center load of the mold.

[0011] Furthermore, the multi-channel force sensor array includes at least four symmetrically distributed force sensors, which are piezoelectric force sensors or strain gauge force sensors.

[0012] Furthermore, the multi-point adjustable mold-locking actuator consists of multiple independently controlled hydraulic mold-locking cylinders, and the working pressure of each mold-locking cylinder is independently adjusted through a hydraulic servo control system.

[0013] As an alternative, the multi-point adjustable clamping actuator consists of multiple independently controlled servo electric cylinders, which change the clamping force by adjusting the output torque of the torque motor.

[0014] Furthermore, the system can be applied to a multi-station cold heading machine, where each station is independently configured with the multi-channel force sensor array and mold clamping actuator, and is uniformly connected to the control unit via a fieldbus to perform decentralized adjustment and centralized monitoring of the mold status of each station.

[0015] Through the above technical solution, the present invention realizes online monitoring and dynamic adaptive adjustment of the off-center loading state of cold heading dies. It can restore and maintain the high-precision alignment state of the dies without interrupting production, effectively solving the problems of decreased accuracy and shortened die life caused by off-center loading in the prior art. Attached Figure Description

[0016] Figure 1 This is a flowchart of the cold heading method for aerospace rivets according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the cold heading forming system for aerospace rivets according to an embodiment of the present invention; Figure 3 This is a distribution diagram of the multi-channel force sensor array on the upper mold.

[0017] The components include: 1. Cold heading machine body; 2. Upper mold; 3. Lower mold; 4. Multi-channel force sensor array; 5. Signal acquisition and processing module; 6. Mold locking actuator; and 7. Control unit.

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] like Figure 2 and Figure 3 As shown, the aviation rivet cold heading system provided in this embodiment of the invention is an improvement on the conventional multi-station cold heading machine, with modifications to its mold locking and adjustment auxiliary devices. The system includes a cold heading machine body 1, a cold heading mold assembly, a multi-channel force sensor array 4, a signal acquisition and processing module 5, a control unit 7, a multi-point adjustable mold locking actuator 6, and a hydraulic servo control system. The cold heading machine body 1 includes a frame, a main slide block, a feeding mechanism, and a multi-station turntable, etc., for feeding, cutting, and forging metal billets. The cold heading mold assembly includes an upper mold 2 and a lower mold 3, mounted on the mold mounting base of the cold heading machine.

[0022] In one specific embodiment of the present invention, the system is built based on a five-station cold heading machine, whose main slide operates at a frequency of 120 times per minute. At the first station, the heading head forming station, a piezoelectric force sensor is installed at each of the four locking points between the upper die 2 mounting base and the machine frame. These four force sensors are symmetrically distributed at 90° angles at the four corners of the mounting base, hereinafter referred to as channel A, channel B, channel C, and channel D, respectively. Each force sensor has a range of 200 kN and a sampling frequency of 2000 Hz to meet the requirement of collecting no less than 10 data points per forming cycle at the cold heading machine's operating frequency of 120 times per minute.

[0023] The multi-channel force sensor array 4 is used to independently acquire the impact load signals borne by each locking point during cold heading. The signal acquisition and processing module 5 is electrically connected to the multi-channel force sensor array 4. It integrates signal amplification circuits, filtering circuits, and a 16-bit analog-to-digital converter to synchronously acquire the analog force signals from each channel and convert them into digital signals. This module is connected to the control unit 7 via an EtherCAT industrial fieldbus to ensure high-speed, low-latency data transmission.

[0024] The control unit 7 employs an embedded industrial controller, internally storing preset load eccentricity determination algorithms and pressure compensation calculation models. The multi-point adjustable mold-locking actuator 6 consists of four independently controlled miniature hydraulic mold-locking cylinders, each corresponding to a locking point of one of the four force sensors mentioned earlier. The hydraulic pressure of each mold-locking cylinder can be independently adjusted within the range of 0 to 25 MPa, with an adjustment response time of less than 50 milliseconds. The hydraulic servo control system, composed of servo valves and a hydraulic pump station, receives pressure commands from the control unit 7 and independently regulates the pressure of the four mold-locking cylinders.

[0025] Based on the above system, such as Figure 1 As shown, the cold heading method for aerospace rivets of the present invention is implemented according to the following steps.

[0026] First, after installing the new cold heading die assembly, initial die alignment is performed. The operator uses a dial indicator to check the static alignment accuracy of the die, ensuring the deviation is less than 0.01 mm. Then, the hydraulic pump station is started, setting the initial working pressure of all four clamping cylinders to 15 MPa. Under no-load conditions, the cold heading machine is manually operated to complete one die-closing action. The multi-channel force sensor array 4 collects the basic pressure distribution at each clamping point during the die-closing process and records it as the initial reference value. For example, the recorded initial reference values ​​are: 15.2 MPa for channel A, 15.0 MPa for channel B, 14.9 MPa for channel C, and 15.1 MPa for channel D. This reference data is stored in the control unit 7 as a reference for subsequent off-center load determination.

[0027] During continuous cold heading production, the multi-channel force sensor array 4 synchronously acquires the impact load signals borne by each locking point in each cold heading cycle. The signal acquisition and processing module 5 amplifies, filters, and performs analog-to-digital conversion on the acquired force signals to form the load data sequence for each channel. Taking a typical cycle in continuous production as an example, the peak load data of each channel and their occurrence times are as follows: The peak load of channel A is 178 kN, and the peak occurs 2.3 milliseconds after the reference time t. The peak load of channel B is 165 kN, and the peak time is t+2.5 milliseconds; The peak load of channel C is 142 kN, and the peak time is t+3.1 milliseconds; The peak load of channel D is 155 kN, and the peak time is t+2.7 milliseconds.

[0028] After receiving the above data, control unit 7 performs load eccentricity feature extraction and calculation. First, it calculates the average value (Favg) of the load peak values ​​for each channel: Favg=(FA+FB+FC+FD) / 4=(178+165+142+155) / 4=160KN; Next, establish a planar coordinate system with the mold center as the origin. Let channel A be located in the positive X-axis direction, channel C in the negative X-axis direction, channel B in the positive Y-axis direction, and channel D in the negative Y-axis direction. Calculate the load difference ΔFx in the X-direction and the load difference ΔFy in the Y-direction: ΔFx = FA - FC = 178 - 142 = 36 kN; ΔFy = FB - FD = 165 - 155 = 10 kN; Further calculate the equivalent point of application coordinates Xe and Ye of the eccentric vector, using the following formula: Xe = K * (ΔFx / Favg); Ye = K * (ΔFy / Favg); Where K is a proportionality coefficient related to the mold geometry. Through offline calibration tests, the displacement-load difference proportionality coefficient K of this mold system in the X and Y directions was measured to be 0.12 mm. This coefficient comprehensively reflects factors such as the distribution radius of the clamping cylinder and the stiffness of the mold mounting base; its physical meaning is the equivalent offset of the mold center corresponding to the ratio of unit load difference to average load. Substituting the data, the following calculation is obtained: Xe=0.12*(36 / 160)=0.027mm; Ye=0.12*(10 / 160)=0.0075mm; Therefore, the formula for calculating the eccentricity e is: e=√(Xe²+Ye²)=√(0.027²+0.0075²)≈0.028mm; The direction angle θ of the eccentric vector is defined as the angle between the eccentric vector and the X-axis direction, and its calculation formula is as follows: The direction angle of the eccentric vector θ = arctan(Ye / Xe) = arctan(0.0075 / 0.027) ≈ 15°; That is, it is biased towards the positive X-axis direction where channel A is located. At the same time, control unit 7 also calculates the time offset characteristics of the peak load occurrence for each channel. The peak time difference between channel A and channel C is: ΔtAC = 2.3ms - 3.1ms = -0.8ms; The time offset data indicates that the upper die 2 and the lower die 3 have an inclined contact in the X direction, and the channel A side contacts the blank before the channel C side.

[0029] After completing the above calculations, the control unit 7 determines the off-center load state. In this embodiment, the preset first threshold is 0.02 mm, serving as the boundary for slight off-center load; the second threshold is 0.05 mm, serving as the boundary for severe off-center load. The currently calculated eccentricity e is 0.028 mm, falling between the first and second thresholds. Therefore, the mold is determined to be in a slight off-center load state, requiring the activation of the dynamic compensation adjustment program. Simultaneously, the control unit 7 also determines the time offset. When the maximum difference between the time offsets corresponding to each locking point exceeds a preset proportion of a single working cycle of the cold heading machine (approximately 500 milliseconds), it is considered that there is significant tilting contact. In this embodiment, this preset proportion can be set according to process requirements, for example, set to two-thousandths of the working cycle, corresponding to a difference threshold of approximately 1 millisecond. Currently, the time difference between channel A and channel C is 0.8 milliseconds, approaching a level requiring attention.

[0030] When it is determined that the mold is under eccentric load and needs adjustment, the control unit 7 calculates the required working pressure compensation for each locking point based on the direction and magnitude of the eccentric vector. Since the eccentric vector points in the direction of channel A, i.e., the positive direction of the X-axis, the adjustment strategy is to increase the clamping force of the corresponding locking point in the opposite direction of the eccentric vector, i.e., in the direction of channel C, while decreasing the clamping force of the corresponding locking point in the direction of the eccentric vector, i.e., in the direction of channel A. The non-uniform distribution of the clamping force generates a reverse torque, which pushes the upper mold 2 to move slightly to counteract the eccentric load. The specific compensation calculation is as follows: The pressure adjustment for channel A is -1.0 MPa, which means it is reduced from the reference pressure of 15 MPa to 14 MPa. The pressure adjustment for channel C is +1.0 MPa, which means it increases from 15 MPa to 16 MPa. The pressure in channels B and D remains constant at 15 MPa.

[0031] The specific adjustment amount of the working pressure at each locking point is calculated by control unit 7 based on the direction and magnitude of the load eccentricity vector. Its core control logic lies in establishing the correspondence between the eccentricity vector and the pressure compensation value of each locking point, in order to generate a restoring torque capable of counteracting the eccentric load. The specific calculation method is explained below: First, a pressure regulation sensitivity coefficient S is defined, with units of megapascals per millimeter (MPa / mm), representing the amount of pressure change required to compensate for a unit eccentricity (1 mm). This coefficient S is related to the structural rigidity of the cold heading machine mold mounting system, the effective area of ​​the mold locking cylinder, and the radius of the locking point distribution, and can be obtained through pre-calibration tests. Under the structural conditions of the five-station cold heading machine used in this embodiment, the sensitivity coefficient S, measured through calibration, is approximately 71.4 MPa / mm.

[0032] Subsequently, based on the calculated components (Xe, Ye) of the eccentric vector along each axis of the coordinate system, the required theoretical pressure compensation for each corresponding axis is calculated. The calculation formula is as follows: ΔPx=S*Xe; ΔPy=S*Ye; Substituting the data from this embodiment: Given Xe = 0.027 mm, Ye = 0.0075 mm, and sensitivity coefficient S = 71.4 MPa / mm, the theoretical pressure compensation difference required in the X-axis direction is calculated to be: ΔPx = 71.4 × 0.027 ≈ 1.93 MPa (approximately 2.0 MPa); The theoretical pressure compensation difference required in the Y-axis direction is: ΔPy = 71.4 × 0.0075 ≈ 0.54 MPa (Due to the small value, the Y-axis pressure will not be adjusted in this cycle). Then, the axial compensation difference is distributed to two locking points positioned opposite each other along this axis. The distribution principle is: increase the clamping force in the opposite direction of the eccentric vector, and decrease the clamping force by an equal amount in the direction of the eccentric vector. Therefore, for the X-axis direction (the direction of the line connecting channels A and C), the pressure adjustment for channel A is -ΔPx / 2, and the pressure adjustment for channel C is +ΔPx / 2. This yields the specific adjustment command for this cycle: the pressure in channel A decreases by approximately 1.0 MPa, and the pressure in channel C increases by approximately 1.0 MPa. Since the offset in the Y-axis direction is minimal for channels B and D, their current pressure remains unchanged for this cycle.

[0033] It should be noted that the specific value of the sensitivity coefficient S varies depending on the equipment. However, those skilled in the art, guided by the technical solution of this invention, can obtain an accurate coefficient suitable for the specific cold heading machine by performing a simple calibration step on the machine (e.g., manually adjusting the clamping force on one side to generate a known pressure difference, measuring the resulting minute displacement, and then deducing the value of S). This allows them to achieve the dynamic compensation adjustment function described in this invention. Therefore, the above description makes the technical solution of this invention clear, complete, and achievable for those skilled in the art.

[0034] During the return stroke of the main slide of the cold heading machine after completing one upsetting operation, control unit 7 sends the aforementioned pressure command to the hydraulic servo control system via fieldbus. The return stroke time of the main slide of the cold heading machine is approximately 120 milliseconds, while the adjustment response time of the hydraulic clamping cylinder is less than 50 milliseconds. Therefore, pressure adjustment can be completed within the return stroke interval without interrupting the continuous production cycle.

[0035] In the next cold heading cycle, the multi-channel force sensor array again collected load data at each locking point to verify the adjustment effect. After adjustment, the peak load values ​​of each channel tended to be more uniform. Channel A is 158KN, Channel B is 162KN, Channel C is 161KN, and Channel D is 159KN. Control unit 7 recalculates the eccentricity, obtaining e≈0.007 mm. This value is less than the first threshold of 0.02 mm, indicating that the mold has returned to normal alignment, and the closed-loop verification is successful. If the actual verification load still deviates from the target value beyond the allowable range, control unit 7 will continue to fine-tune and correct until the accuracy requirements are met. The above steps are executed cyclically in each cold heading cycle, achieving continuous monitoring and adaptive dynamic adjustment of the cold heading mold's off-center load state during continuous production.

[0036] In another specific embodiment, the system provided by this invention is extended to all stations of a multi-station cold heading machine. Because the forming forces at different stations in cold heading vary significantly—for example, the forming force of the upsetting head at the first station is large, while the forming forces at subsequent shaping and punching stations are relatively small—the reference pressure and judgment threshold of the clamping cylinder at each station are set independently. The system connects the force sensors and clamping actuators of each station to a central controller via an industrial fieldbus, enabling centralized monitoring and decentralized adjustment of the mold status at multiple stations.

[0037] In another alternative embodiment, the multi-point adjustable mold-locking actuator 6 uses a servo electric cylinder instead of a hydraulic mold-locking cylinder. The locking force of each servo electric cylinder is achieved by adjusting the output torque of a torque motor, and the force sensor is a strain gauge sensor integrated into the front end of the electric cylinder. The advantage of this alternative is that the position control accuracy of the servo electric cylinder is higher, reaching the 0.001 mm level, and the system structure is simpler, eliminating the need for complex hydraulic circuits. Its adjustment response time is less than 30 milliseconds, making it particularly suitable for high-speed cold heading machines with a working frequency of over 180 times per minute. The specific control method is similar to the aforementioned hydraulic embodiment, the only difference being that the drive method of the actuator is changed from hydraulic pressure regulation to motor torque regulation.

[0038] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0039] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for cold heading of aerospace rivets, applied to a cold heading machine, characterized in that, Includes the following steps: Force sensors are symmetrically arranged at multiple locking points of the upper mold (2) mounting base of the cold heading machine to collect the load signal of each locking point in real time during the cold heading forming cycle. The load eccentricity vector characterizing the off-center loading state of the mold is calculated based on the load signals collected from each locking point. Based on the load eccentricity vector, determine the eccentricity and direction of the mold. When the off-center load exceeds the set threshold, during the return stroke of the main slide of the cold heading machine, the working pressure of the clamping actuator corresponding to each clamping point is independently adjusted. By increasing the clamping force in the opposite direction of the off-center vector and decreasing the clamping force in the direction of the off-center vector, a reverse torque is generated to drive the mold position compensation and counteract the off-center load.

2. The method according to claim 1, characterized in that, The step of calculating the load eccentricity vector further includes: Extract the peak value of the load signal at each locking point within the same cycle and the time offset of each peak value; A coordinate system is established with the center of the mold as the origin. The equivalent point of application of the resultant force is calculated based on the difference in the peak load of each locking point. The distance and direction of this coordinate from the origin constitute the load eccentricity vector.

3. The method according to claim 2, characterized in that, The step of determining the off-center load and direction of the mold further includes: Preset a first threshold and a second threshold; When the eccentricity of the load eccentricity vector is less than the first threshold, it is determined to be in a normal state; When the eccentricity is greater than or equal to the first threshold and less than the second threshold, it is determined to be a slight off-center load state, and the pressure adjustment is executed. When the eccentricity is greater than or equal to the second threshold, it is determined to be a severe off-center load state, triggering an alarm or shutdown.

4. The method according to claim 2, characterized in that, The steps for determining the off-center load and direction of the mold also include: Compare the time offset of the peak load at each locking point; When the maximum difference between the time offsets corresponding to each locking point exceeds the preset ratio of a single working cycle of the cold heading machine, it is determined that there is an inclined contact between the upper mold (2) and the lower mold (3).

5. The method according to claim 1, characterized in that, The method further includes: In the next cold heading cycle after the clamping force adjustment is completed, the force sensor collects and verifies the load data to verify whether the actual clamping force has reached the target value in a closed loop, and makes fine adjustments based on the verification results.

6. A cold heading forming system for aircraft rivets, comprising a cold heading machine body (1) and a cold heading die assembly, characterized in that, Also includes: A multi-channel force sensor array (4) is symmetrically installed at multiple locking points on the mounting base of the upper mold (2) of the cold heading machine, for independently collecting the load signal of each locking point at the moment of cold heading; The signal acquisition and processing module (5) is electrically connected to the multi-channel force sensor array (4) and is used to synchronously acquire and process load signals; The multi-point adjustable clamping actuator (6) includes an independently controlled force application unit corresponding to each clamping point, which is used to adjust the clamping force of the corresponding clamping point; The control unit (7) is electrically connected to the signal acquisition and processing module (5) and the mold clamping actuator (6). It is used to calculate the load eccentricity vector according to the processed load signal to determine the off-center load state, and control each of the force application units to perform asymmetric mold clamping force adjustment within the cold heading machine return gap according to the determination result, so as to compensate for the mold off-center load.

7. The system according to claim 6, characterized in that, The multi-channel force sensor array (4) contains at least four force sensors that are symmetrically distributed, and the force sensors are piezoelectric force sensors or strain force sensors.

8. The system according to claim 6, characterized in that, The multi-point adjustable mold clamping actuator (6) consists of multiple independently controlled hydraulic mold clamping cylinders, and the working pressure of each mold clamping cylinder is independently adjusted by the hydraulic servo control system.

9. The system according to claim 6, characterized in that, The multi-point adjustable clamping actuator (6) consists of multiple independently controlled servo electric cylinders, which change the clamping force by adjusting the output torque of the torque motor.

10. The system according to claim 6, characterized in that, The system is applied to a multi-station cold heading machine. Each station is independently configured with the multi-channel force sensor array (4) and the mold clamping actuator (6), and is uniformly connected to the control unit (7) through the fieldbus, so as to perform decentralized adjustment and centralized monitoring of the mold status of each station.

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