Multi-step automated riveting process control method and system for a rivet setting apparatus

Abstract

The application relates to the technical field of automatic control, and discloses a multi-step automatic riveting process control method and system of a riveting device, which comprises the following steps: a rivet is delivered through a rivet feeding mechanism, and the rivet is preliminarily processed; a riveting gun is controlled to move to a to-be-riveted hole position on a workpiece, and positioning and insertion feasibility diagnosis are performed; the rivet is fed into a riveting gun nozzle, and it is confirmed that the rivet is in place in the nozzle; it is confirmed that a gun head of the riveting gun is attached to the surface of the workpiece; a multi-stage riveting process closed-loop control is performed in the step, the multi-stage riveting process comprises a pre-tightening stage, a filling and forming stage and a fracture monitoring stage; based on the final displacement and the peak riveting force recorded in the fracture monitoring stage, the riveting result is comprehensively judged to be qualified or not by comparing with pre-stored standard displacement range and standard riveting force range; the riveting gun is controlled to perform a reset operation, and it is confirmed that the fractured rivet rod has been removed, the consistency and reliability of the riveting quality are significantly improved, and the generation of batch unqualified products is effectively avoided.

Description

Technical Field

[0001] This application relates to the field of automation control, and in particular to a method and system for controlling the multi-step automatic riveting process of riveting equipment. Background Technology

[0002] Riveting is widely used in manufacturing industries such as aerospace, automotive, and electronics due to its simple process and reliable connection. Traditional automated riveting equipment often uses simple stroke control or time control, that is, the riveting is considered complete after the rivet gun motor rotates a fixed number of times or runs for a fixed time.

[0003] However, this open-loop control method cannot cope with many variables in actual production, such as rivet manufacturing tolerances, workpiece sheet thickness differences, interlayer gap fluctuations, and minute changes in rivet lubrication. These variables can lead to unstable riveting quality, resulting in defects such as excessively loose or tight riveting, or even broken or incomplete rivets, which may cause product failure in severe cases.

[0004] In existing technologies, some methods have emerged that attempt to monitor quality, such as monitoring only the final breaking force or total displacement. However, these methods are "post-inspection," meaning that once an anomaly is detected, the defective product has already been produced, and intervention and adjustment during the riveting process are impossible. Furthermore, a single final parameter cannot fully reflect the internal process of rivet formation and lacks the ability to detect certain potential defects (such as internal damage caused by slight slippage of the rivet claws). Summary of the Invention

[0005] In order to enable precise segmented monitoring of the entire riveting process and to make dynamic decisions and adjustments based on real-time feedback, thereby ensuring the quality consistency of each riveting point from the source, this application provides a multi-step automatic riveting process control method and system for riveting equipment.

[0006] In the first aspect, this application provides a multi-step automatic riveting process control method for riveting equipment, adopting the following technical solution:

[0007] A multi-step automatic riveting process control method for riveting equipment, including:

[0008] Step S100: The rivet is fed through the rivet feeding mechanism and the rivet is initially processed;

[0009] Step S200: Control the rivet gun to move to the riveting hole on the workpiece and perform positioning and insertion feasibility diagnosis;

[0010] Step S300: Feed the rivet into the nose of the rivet gun and confirm that the rivet is in place inside the nose;

[0011] Step S400: Confirm that the head of the rivet gun is in contact with the surface of the workpiece;

[0012] Step S500: Perform closed-loop control of the multi-stage riveting process, which includes a pre-tightening stage, a filling and forming stage, and a fracture monitoring stage;

[0013] Step S600: Based on the final displacement recorded during the fracture monitoring stage and peak tensile force , with the pre-stored standard displacement range and standard tensile range Compare the results and make a comprehensive judgment on whether the riveting results are qualified.

[0014] Step S700: Control the rivet gun to perform a reset operation and confirm that the broken rivet rod has been removed.

[0015] By adopting the above technical solution, the riveting process is divided into logically clear and continuous control stages, and specific control objectives are set for each stage, achieving full-chain management of the riveting quality formation process. This method overcomes the shortcomings of single and isolated result detection methods in existing technologies, enabling real-time capture and response to various abnormal working conditions during the riveting process. This transforms post-inspection into process assurance, significantly improving the consistency and reliability of riveting quality and effectively avoiding the generation of batches of defective products.

[0016] Optionally, the positioning and insertion feasibility diagnosis in step S200 includes:

[0017] The robotic arm is controlled to drive the gun head to move toward the workpiece hole. The movement is carried out in a low-speed and torque-limited mode.

[0018] The axial displacement of the gun head is monitored in real time by a displacement sensor. ;

[0019] The axial displacement Theoretical displacement calculated based on location information Compare, if the difference Exceeding the preset tolerance range If so, it is determined to be an abnormal hole position.

[0020] By adopting the above technical solution and using the compliant control strategy of "low speed + torque limitation", early detection of hole position abnormalities is achieved. On the one hand, it avoids rivet bending or workpiece scratches caused by forced positioning in traditional methods. The configurability of tolerance parameters allows the system to adapt to fields with different precision requirements. On the other hand, it can advance the problem detection node from the riveting execution stage to the positioning stage, reducing waste in subsequent processes.

[0021] Optionally, confirming the rivet is in place in step S300 includes:

[0022] The rivet is fed into the nose of the rivet gun using a pneumatic rivet feeding mechanism;

[0023] Real-time acquisition of rivet detection sensor signals located in the rivet feeding area of ​​the nose nozzle;

[0024] If within a specified time period after the start of the feeding action If the detection signal is received, it is determined that the rivet has been successfully positioned; if no signal is received within the time limit, it is determined that the rivet feeding has failed and an alarm is triggered.

[0025] By adopting the above technical solutions, the fault self-diagnosis and self-recovery of the nail feeding process are realized through electrical linkage control. The simple presence detection is upgraded to process monitoring with time windows, which effectively distinguishes between normal delivery and blockage. The reverse air blowing mechanism can solve most minor jamming problems and reduce the frequency of manual intervention. Fault code management facilitates quick location and maintenance, and shortens the average fault handling time in the nail feeding process.

[0026] Optionally, confirming the contact between the gun head and the workpiece surface in step S400 includes:

[0027] Control the rivet gun with constant light pressure Continuously press against the workpiece surface;

[0028] The actual contact pressure is monitored by a pressure sensor built into the nozzle. When the actual pressure stabilizes at the light pressure... When the deviation is within the allowable range, the bonding is considered complete.

[0029] By adopting the above technical solutions, the different bonding requirements of workpieces with different materials are solved. The statistical steady-state judgment replaces the single-point threshold judgment, avoiding misjudgment caused by vibration. The material parameter library enables the system to have rapid model change capability and can also ensure the consistency of the riveting start state, providing a reliable benchmark for subsequent tensile-displacement analysis.

[0030] Optionally, the pre-tightening stage in step S500 includes:

[0031] Control the rivet gun motor to run until the real-time tension sensor reading reaches the preload threshold. ;

[0032] Monitoring from the start of riveting to the completion of... displacement increment ;

[0033] like Exceeding the preset range If so, it is determined that there is an abnormal gap in the workpiece interlayer.

[0034] By adopting the above technical solutions, early warning of assembly problems is achieved. Through the quantitative analysis of displacement increments, assembly oversights that are difficult to detect by the naked eye are indirectly detected. Linked with the production traceability system, a complete quality data chain is constructed, and data support is also provided for process optimization. For example, adjusting the gasket thickness tolerance based on statistical results can reduce the rework rate caused by assembly errors.

[0035] Optionally, the filling and molding stage in step S500 includes:

[0036] Controlling the operation of the riveting gun motor to make the real-time collected tension-displacement curve match the pre-stored standard curve;

[0037] Calculating the similarity parameter R between the real-time curve and the standard curve in real time. The calculation formula is:

[0038]

[0039] Where, is the sampling point of the standard curve, is the sampling point of the real-time curve, and are the average values of the corresponding sequences respectively;

[0040] If R is lower than the similarity threshold , it is determined that the riveting process is abnormal.

[0041] By adopting the above technical solutions, the subjective judgment of curve morphology is transformed into an objective quantitative index through mathematical modeling, which can effectively capture the subtle changes in curve morphology, has high sensitivity, and can gradually build a fault diagnosis knowledge base through the abnormal mode filing function, providing data basis for supplier quality assessment, and advancing the discovery time of material batch problems from the original post-production sampling inspection to the production process.

[0042] Optionally, the fracture monitoring stage in step S500 includes:

[0043] Continuously monitoring the reading of the tension sensor until it is monitored that the tension value drops suddenly from the peak by more than the fracture threshold ;

[0044] Recording the displacement at the time of sudden tension drop as the final displacement ;

[0045] The comprehensive determination in step S600 includes:

[0046] If the final displacement is within , and the peak tension is within , it is determined that the riveting is qualified;

[0047] Otherwise, it is deemed unqualified, and the reason code for unqualification is recorded.

[0048] Optionally, confirming the removal of the broken nail rod in step S700 includes:

[0049] The pneumatic valve is opened to spray airflow into the nozzle of the rivet gun.

[0050] By monitoring changes in airflow pressure using a barometric pressure sensor, if the pressure drops to the baseline value within a time window, it is confirmed that the nail has been blown away.

[0051] Secondly, this application provides a multi-step automatic riveting process control system for riveting equipment, which adopts the following technical solution:

[0052] The multi-step automatic riveting process control system for riveting equipment runs a program of the multi-step automatic riveting process control method for riveting equipment described in any one of the above-mentioned methods.

[0053] In summary, this application includes at least the following beneficial technical effects:

[0054] This application achieves full-chain management of the riveting quality formation process by dividing the riveting process into logically clear and continuous control stages and setting specific control objectives for each stage. This method overcomes the shortcomings of single and isolated result detection methods in existing technologies, and can capture and respond to various abnormal working conditions in real time during the riveting process. This transforms post-inspection into process assurance, significantly improving the consistency and reliability of riveting quality and effectively avoiding the generation of batches of non-conforming products. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the multi-step automatic riveting process control method of the riveting equipment in this application. Detailed Implementation

[0056] The embodiments of this application are described in detail below, and examples of the embodiments are shown in the accompanying drawings.

[0057] In the description of this specification, the references to "certain embodiments," "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples" refer to specific features, structures, materials, or characteristics described in connection with the described embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] This application discloses a multi-step automatic riveting process control method for riveting equipment, referring to... Figure 1 , including:

[0059] Step S100: The rivet is fed through the rivet feeding mechanism and the rivet is preliminarily processed;

[0060] Step S200: Control the rivet gun to move to the riveting hole on the workpiece and perform positioning and insertion feasibility diagnosis;

[0061] Step S300: Feed the rivet into the nose of the rivet gun and confirm that the rivet is in place inside the nose;

[0062] Step S400: Confirm that the head of the rivet gun is in contact with the surface of the workpiece;

[0063] Step S500: Perform closed-loop control of the multi-stage riveting process, which includes a pre-tightening stage, a filling and forming stage, and a fracture monitoring stage;

[0064] Step S600: Based on the final displacement recorded during the fracture monitoring stage and peak tensile force , with the pre-stored standard displacement range and standard tensile range Compare the results and make a comprehensive judgment on whether the riveting results are qualified.

[0065] Step S700: Control the rivet gun to perform a reset operation and confirm that the broken rivet rod has been removed.

[0066] At the start of the riveting task, the vibratory feeder transports the rivets. During this stage, the rivets can be sheared, and then pneumatically blown into the rivet gun through the feed tube. This divides the riveting process into logically clear and continuous control stages, with specific control objectives set for each stage, achieving full-chain management of the riveting quality formation process. This method overcomes the shortcomings of existing technologies' single, isolated result detection methods, enabling real-time capture and response to various abnormal conditions during the riveting process. It transforms post-inspection into process assurance, significantly improving the consistency and reliability of riveting quality and effectively avoiding the generation of batches of defective products.

[0067] Optionally, the positioning and insertion feasibility diagnosis in step S200 includes:

[0068] The robotic arm controls the riveting gun nozzle to approach the workpiece hole at a low speed of 5 mm / s and a limiting torque of 5 N·m. During this process, the system accurately calculates the axial displacement of the gun head using a high-resolution encoder built into the servo motor. Simultaneously, based on the three-dimensional coordinates of the workpiece surface provided by the vision camera, the theoretical distance from the starting point to the workpiece surface, i.e., the theoretical displacement, can be calculated. .

[0069] When the tip of the gun is smoothly inserted into the hole, it can penetrate a certain distance without lateral resistance until the gun flange contacts the workpiece surface. At this point, the axial displacement... It will be very close to the theoretical displacement. .

[0070] If the orifice is blocked, the nozzle will not reach its theoretical displacement. The point where it collides with the workpiece surface will cause the torque to increase instantaneously, and It will be much smaller .

[0071] If the hole is severely misaligned, the gun head may be subjected to lateral pressure during movement, triggering the mechanical arm's torque protection, which could also lead to... abnormal.

[0072] The axial displacement Theoretical displacement calculated based on location information Compare, if the difference Exceeding the preset tolerance range The system immediately stops and issues an alarm for "abnormal hole position," thus preventing damage to the equipment or workpiece caused by forced riveting.

[0073] By adopting the above technical solution and using the compliant control strategy of "low speed + torque limitation", early detection of hole position abnormalities is achieved. On the one hand, it avoids rivet bending or workpiece scratches caused by forced positioning in traditional methods. The configurability of tolerance parameters allows the system to adapt to fields with different precision requirements. On the other hand, it can advance the problem detection node from the riveting execution stage to the positioning stage, reducing waste in subsequent processes.

[0074] Optionally, confirming the rivet is in place in step S300 includes:

[0075] The rivet is fed into the rivet gun nozzle via a pneumatic feeding mechanism. A microswitch or photoelectric sensor can be installed at the outlet of the feeding tube. When the rivet passes by, it triggers the microswitch or blocks the photoelectric beam, generating a pulse signal. If the system receives this pulse signal within 200ms after the valve opens, it determines that the rivet has been successfully positioned. If no signal is received within the time limit, it is determined that the rivet feeding has failed (possibly because the rivet is stuck in the tube or has run out). The system will issue an alarm indicating "rivet not in place" and will not start the riveting process to prevent "dry firing" and damage to the sleeve.

[0076] Alternatively, it can be configured such that if no signal is received after a certain timeout following a nail feed, the control unit immediately cuts off the air supply and initiates reverse air blowing for 0.1 seconds. After eliminating the nail jamming fault, it automatically retryes. After two consecutive failures, the system locks and reports a "nailing feed abnormality" fault code.

[0077] By adopting the above technical solutions, the fault self-diagnosis and self-recovery of the nail feeding process are realized through electrical linkage control. The simple presence detection is upgraded to process monitoring with time windows, which effectively distinguishes between normal delivery and blockage. The reverse air blowing mechanism can solve most minor jamming problems and reduce the frequency of manual intervention. Fault code management facilitates quick location and maintenance, and shortens the average fault handling time in the nail feeding process.

[0078] Optionally, confirming that the gun head is in contact with the workpiece surface in step S400 includes:

[0079] Control the rivet gun with constant light pressure Continuously press against the workpiece surface;

[0080] The actual contact pressure is monitored by a pressure sensor built into the nozzle. When the actual pressure stabilizes at the light pressure... When the deviation is within the allowable range, the bonding is considered complete.

[0081] For example, when the nozzle contacts the workpiece, the control system collects pressure data at a frequency of 50Hz. When the pressure values ​​at 10 consecutive sampling points are stable within the range of 33-37N (fluctuation rate < ±5.7%), it is determined that the fit is reliable.

[0082] For workpieces made of different materials, the system can automatically call preset parameters: aluminum alloy parts =30N, high-strength steel components =60N.

[0083] By adopting the above technical solutions, the different bonding requirements of workpieces with different materials are solved. The statistical steady-state judgment replaces the single-point threshold judgment, avoiding misjudgment caused by vibration. The material parameter library enables the system to have rapid model change capability and can also ensure the consistency of the riveting start state, providing a reliable benchmark for subsequent tensile-displacement analysis.

[0084] Optionally, the pre-tightening stage in step S500 includes:

[0085] The rivet gun motor can be controlled to operate at a speed that can be reduced to 1000 RPM and switched to torque control mode until the real-time tension sensor reading reaches the preload threshold. This means that the rivet head is fully pressed against the workpiece;

[0086] During this process, monitor and record from the start of riveting to the completion of the process. displacement increment ;

[0087] like Exceeding the preset range If the upper limit is reached, it is determined that there is an abnormal gap in the workpiece interlayer;

[0088] like Below the preset range If the lower limit is too low, it may mean that there is interference between the workpiece or the rivet, and the system will issue an alarm accordingly.

[0089] By adopting the above technical solutions, early warning of assembly problems was achieved. Through quantitative analysis of displacement increments, assembly oversights that are difficult to detect with the naked eye were indirectly detected. Linked with the production traceability system, a complete quality data chain was constructed, and data support was also provided for process optimization. For example, adjusting the shim thickness tolerance based on statistical results can reduce the rework rate caused by assembly errors.

[0090] Optionally, the filling and molding stage in step S500 includes:

[0091] The rivet gun motor is controlled to match the real-time acquired tension-displacement curve with a pre-stored standard curve. During this stage, the motor enters a position-tension dual closed-loop control mode. The system retrieves the standard tension-displacement curve corresponding to the current rivet type (e.g., POP® 3.2mm) from the process parameter library. This curve defines the theoretical value of the tension and the allowable fluctuation range at each displacement point. The lower-level controller (PLC) compares the currently acquired (L, F) data points with the standard curve in real time and dynamically adjusts the motor's torque output using a PID algorithm to make the actual curve fit the standard curve as closely as possible.

[0092] The similarity parameter R between the real-time curve and the standard curve is calculated in real time. The calculation formula is as follows:

[0093]

[0094] in, These are the sampling points for the standard curve. For real-time curve sampling points, and These are the average values ​​of the corresponding sequences;

[0095] If R is lower than the similarity threshold If the value is 0.85, the riveting process is considered abnormal. The possible causes are uneven lubrication of the rivets or wear and slippage of the rivet claws. The system will immediately terminate the riveting and issue an alarm.

[0096] By adopting the above technical solution, the subjective judgment of the curve morphology is transformed into an objective quantitative index through mathematical modeling, which can effectively capture the subtle changes in the curve morphology, with high sensitivity. Moreover, the fault diagnosis knowledge base can be gradually constructed through the abnormal mode archiving function, providing a data basis for the supplier quality assessment, and advancing the discovery time of material batch problems from the original post-production sampling inspection to the production process.

[0097] As the displacement of the pull rod continues to increase, the pulling force F continues to rise until it reaches the peak (for example, 4500N). The system controls the motor to maintain this peak force for a period of time (for example, 50ms), which is the fracture monitoring stage.

[0098] The fracture monitoring stage in step S500 includes:

[0099] Continuously monitor the readings of the tensile force sensor until it is detected that the tensile force value drops suddenly from the peak and drops by more than the fracture threshold ;

[0100] Record the displacement at the time of the sudden drop in tensile force as the final displacement ;

[0101] The comprehensive judgment in step S600 includes:

[0102] If the final displacement is within , and the peak tensile force is within , then the riveting is judged to be qualified;

[0103] Otherwise, it is judged to be unqualified, and the unqualified reason code is recorded.

[0104] Optionally, the confirmation of the removal of the fractured nail rod in step S700 includes:

[0105] Control the pneumatic valve to open and spray air into the nose of the rivet gun;

[0106] Monitor the change in air pressure through the air pressure sensor. If the pressure drops to the baseline value within the time window, it is confirmed that the nail rod has been blown off. Thus, a complete automatic riveting cycle is completed.

[0107] The embodiment of the present application also discloses a multi-step automatic riveting process control system for riveting equipment, which runs a program of the multi-step automatic riveting process control method for riveting equipment described in any one of the above.

[0108] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A multi-step automatic riveting process control method for riveting equipment, characterized in that, include: Step S100: The rivet is fed through the rivet feeding mechanism and the rivet is initially processed; Step S200: Control the rivet gun to move to the riveting hole on the workpiece and perform positioning and insertion feasibility diagnosis; Step S300: Feed the rivet into the nose of the rivet gun and confirm that the rivet is in place inside the nose; Step S400: Confirm that the head of the rivet gun is in contact with the surface of the workpiece; Step S500: Perform closed-loop control of the multi-stage riveting process, which includes a pre-tightening stage, a filling and forming stage, and a fracture monitoring stage; Step S600: Based on the final displacement recorded during the fracture monitoring stage and peak tensile force , with the pre-stored standard displacement range and standard tensile range Compare the results and make a comprehensive judgment on whether the riveting results are qualified. Step S700: Control the rivet gun to perform a reset operation and confirm that the broken rivet rod has been removed; The step S300, which confirms that the rivet is in place, includes: The rivet is fed into the nose of the rivet gun using a pneumatic rivet feeding mechanism; Real-time acquisition of rivet detection sensor signals located in the rivet feeding area of ​​the nose nozzle; If within a specified time period after the start of the feeding action If a detection signal is received, it is determined that the rivet has been successfully positioned; if no signal is received within the time limit, it is determined that the rivet feeding has failed and an alarm is triggered. The step S400, which confirms that the gun head is in contact with the workpiece surface, includes: Control the rivet gun with constant light pressure Continuously press against the workpiece surface; The actual contact pressure is monitored by a pressure sensor built into the nozzle. When the actual pressure stabilizes at the light pressure... When the deviation is within the allowable range, the bonding is considered complete.

2. The multi-step automatic riveting process control method for riveting equipment according to claim 1, characterized in that, The positioning and insertion feasibility diagnosis in step S200 includes: The robotic arm is controlled to drive the gun head to move toward the workpiece hole, and the movement is carried out in a low speed and torque limiting mode. The axial displacement of the gun head is monitored in real time by a displacement sensor. ; The axial displacement Theoretical displacement calculated based on location information Compare, if the difference Exceeding the preset tolerance range If so, it is determined to be an abnormal hole position.

3. The multi-step automatic riveting process control method for riveting equipment according to claim 1, characterized in that, The pre-tightening stage in step S500 includes: Control the rivet gun motor to run until the real-time tension sensor reading reaches the preload threshold. ; Monitoring from the start of riveting to the completion of... displacement increment ; like Exceeding the preset range If so, it is determined that there is an abnormal gap in the workpiece interlayer.

4. The multi-step automatic riveting process control method for riveting equipment according to claim 1, characterized in that, The filling and molding stage in step S500 includes: Control the operation of the rivet gun motor so that the real-time acquired tension-displacement curve is matched with the pre-stored standard curve; The similarity parameter R between the real-time curve and the standard curve is calculated in real time. The calculation formula is as follows: in, These are the sampling points for the standard curve. For real-time curve sampling points, and These are the average values ​​of the corresponding sequences; If R is lower than the similarity threshold If so, the riveting process is deemed abnormal.

5. The multi-step automatic riveting process control method for riveting equipment according to claim 1, characterized in that, The fracture monitoring stage in step S500 includes: Continuously monitor the tension sensor readings until the tension value is detected to drop from its peak value. A sudden drop exceeding the fracture threshold ; Record the displacement at the moment of sudden drop in tension as the final displacement. ; The comprehensive determination in step S600 includes: If the final displacement is within and the peak tensile force is within , the riveting is determined to be qualified; Otherwise, it is deemed unqualified, and the reason code for unqualification is recorded.

6. The multi-step automatic riveting process control method for riveting equipment according to claim 1, characterized in that, The step S700, which confirms the removal of the broken nail rod, includes: The pneumatic valve is opened to spray airflow into the nozzle of the rivet gun. By monitoring changes in airflow pressure using a barometric pressure sensor, if the pressure drops to the baseline value within a time window, it is confirmed that the nail has been blown away.

7. A multi-step automatic riveting process control system for riveting equipment, characterized in that, A program that runs a multi-step automatic riveting process control method for a riveting device as described in any one of claims 1-6.

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