Rigid-flexible switching type four-door hinge mounting tool and method based on pneumatic sequential logic

Abstract

The invention discloses a rigid-flexible switching type four-door hinge installation tool and method based on pneumatic sequential logic, and relates to the technical field of automobile manufacturing equipment, and the rigid-flexible switching type four-door hinge installation tool comprises a positioning and clamping operation module, a ground pushing chassis module and a pneumatic sequential logic floating module. The floating module comprises a three-dimensional decoupling mechanism, a normally-closed self-resetting mechanism and a normally-open delaying locking mechanism. The pneumatic control system is provided with three parallel branches including a reset unlocking branch, a clamping operation branch and a delay locking branch with a one-way sequence valve, and a pure pneumatic logic time sequence is constructed by utilizing the characteristic that an opening threshold value is set between dynamic pressure and stable pressure. By means of the scheme, accurate switching of pushing rigidity, positioning flexibility and tightening rigidity can be automatically achieved only through on-off of a single air source, complex electrical control is abandoned, the rigid and flexible requirement contradiction in follow-up assembly is effectively solved, vehicle body damage caused by time sequence disorder is avoided, and hinge installation accuracy and equipment reliability are improved.

Description

Technical Field

[0001] This application relates to the field of automotive manufacturing equipment technology, and in particular to a rigid-flexible switching four-door hinge installation fixture and method based on pneumatic timing logic. Background Technology

[0002] On the automotive assembly line, the installation precision of the door hinges is a key factor determining the subsequent door assembly quality, opening and closing feel, and overall vehicle surface gaps and differences. Because the vehicle body is typically in continuous motion on the production line, and the sheet metal parts inevitably have manufacturing tolerances and positional fluctuations, the mounting fixtures must possess sufficient flexibility and freedom when docking with the vehicle body. This flexibility allows for adaptive floating to eliminate positioning errors and ensures that the main locating pin can smoothly insert into the vehicle body's reference holes.

[0003] However, while simply adding a floating mechanism solves the problems of jamming and rigid interference during positioning and alignment, it introduces a contradiction of insufficient system rigidity in subsequent processes. Specifically, during positioning and bolt tightening, the electric tightening tool applies enormous axial pressure and tangential reaction torque. If the fixture remains in a flexible floating state at this time, the external force will cause displacement or elastic yielding, resulting in misalignment of the hinge installation position and affecting the consistency of assembly accuracy. Simultaneously, if the mechanism remains in a free-floating state during the fixture's movement on the ground, it will lead to instability of the center of gravity and violent shaking, increasing the difficulty of handling and safety risks for operators. Therefore, an ideal installation fixture needs to exhibit high rigidity during the pushing and tightening stages, and high flexibility during the positioning and alignment stages.

[0004] To address the aforementioned rigid-flexible switching requirements, existing technologies generally employ a hybrid electrical control scheme. This involves placing displacement sensors, proximity switches, or vision inspection systems on the fixture to identify the operational status and feeding signals back to a PLC controller. The controller then drives a solenoid valve to switch the pneumatic path to control the locking mechanism's action. This approach, relying on electrical components and sensor feedback, has drawbacks: First, the introduction of an electrical control system complicates the fixture structure, increasing manufacturing costs and maintenance difficulty. Second, mobile fixtures must carry heavy power and signal cables, limiting operator mobility. Third, in specific production environments with explosion-proof requirements, such as painting workshops, the application of electrical equipment is restricted. Finally, the reliability of the electrical logic depends on sensor accuracy; if the signal is interfered with by the environment or malfunctions, it can easily lead to disordered action timing (such as premature locking before complete alignment), resulting in irreversible quality accidents such as enlarged positioning holes and sheet metal damage. Therefore, the industry needs a low-cost, high-reliability solution that abandons complex electrical control and relies solely on pure mechanical and fluid logic to achieve precise rigid-flexible switching. Summary of the Invention

[0005] The purpose of this invention is to provide a rigid-flexible switching four-door hinge installation fixture and method based on pneumatic timing logic, which at least solves the problem that existing follow-up assembly fixtures usually rely on complex electrical sensing and control systems to realize the timing of actions, resulting in high equipment costs and difficult maintenance. At the same time, it solves the problem of conflicting requirements for the rigidity and flexibility of the mechanism in different operation stages such as ground pushing and transportation, positioning and alignment, and bolt tightening.

[0006] This invention provides the following solution:

[0007] The first aspect of the present invention provides a rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic, which mainly includes a positioning and clamping operation module, a ground pushing chassis module, and a pneumatic timing logic floating module connected between the positioning and clamping operation module and the ground pushing chassis module.

[0008] The pneumatic timing logic floating module includes a three-dimensional decoupling mechanism for realizing spatial degrees of freedom, a normally closed self-resetting mechanism for maintaining initial alignment, and a normally open hysteresis locking mechanism for performing rigid locking. The device is also equipped with a pneumatic control system, which includes a main control valve and three branches connected in parallel to the output of the main control valve: a reset / unlock branch, a clamping operation branch, and a hysteresis locking branch. The reset / unlock branch is directly connected to the normally closed self-resetting mechanism to release mechanical alignment; the clamping operation branch is connected to the pneumatic clamping unit within the positioning and clamping operation module to drive the clamping action; the hysteresis locking branch is connected in series with a one-way sequence valve, the output of which is connected to the normally open hysteresis locking mechanism, using the timing difference established by pressure to control the locking action.

[0009] In terms of specific structural implementation, the three-dimensional decoupling mechanism adopts a Z-axis lifting guide component mounted on the ground-pushing chassis module and an X / Y-axis horizontal floating component connecting the Z-axis lifting guide component and the positioning and clamping operation module. The Z-axis lifting guide component achieves vertical guidance and gravity compensation through the cooperation of vertical guide columns, linear bearings, and gravity balance cylinders; the X / Y-axis horizontal floating component achieves floating in the horizontal plane through cross-shaped slide rail pairs.

[0010] The normally closed self-resetting mechanism is designed to maintain a rigid connection of the device in the absence of an air source. Specifically, it includes a reset cylinder fixed to the fixed side of the three-dimensional decoupling mechanism, a reset cone pin connected to the piston rod of the reset cylinder, and a positioning cone sleeve fixed to the moving side. A reset spring is installed inside the reset cylinder; in the absence of air supply, the spring force pushes the reset cone pin into the conical inner hole of the positioning cone sleeve, eliminating the mechanism's clearance.

[0011] The normally open hysteresis locking mechanism is implemented by a pneumatic clamp, which is installed on the side of the guide post of the Z-axis lifting guide assembly and the side of the slide rail of the X / Y-axis horizontal floating assembly. This pneumatic clamp is a pneumatic pressurized locking type structure; after compressed air is introduced, it generates frictional force to lock the guide rail or guide post. Its air inlet receives a pressure signal from the output of the one-way sequence valve.

[0012] The core of the pneumatic control system lies in the construction of pressure timing logic. The opening pressure threshold of the one-way sequence valve is set between the dynamic pressure of the clamping operation branch and the steady-state pressure of the system. The dynamic pressure of the pipeline refers to the fluid pressure during the process of the pneumatic clamping unit driving the gripper to contact the workpiece and perform adaptive movement, while the steady-state pressure of the system refers to the static pressure established in the pipeline after the clamping action is completed. Based on this pressure setting, when the pneumatic clamping unit performs the action, the pipeline pressure is lower than the opening pressure threshold, and the normally open hysteresis locking mechanism remains released, allowing the positioning and clamping operation module to flexibly and adaptively align with the vehicle body position; when clamping is completed and the airflow stops, the pressure rises and exceeds the opening pressure threshold, the one-way sequence valve opens and drives the normally open hysteresis locking mechanism to switch the fixture to a rigid locking state.

[0013] Furthermore, the positioning and clamping operation module adopts a rectangular frame structure, integrating the first to fourth pneumatic clamping components corresponding to the four door hinge installation positions, as well as the main positioning pin for determining the reference position. The clamping operation branch is equipped with a flow control valve to regulate the action speed, and the hysteresis locking branch is equipped with a one-way exhaust throttle valve or a fast exhaust valve downstream of the one-way sequence valve to ensure that the locking mechanism releases before or simultaneously with the clamping mechanism during pressure relief and reset.

[0014] A second aspect of this invention provides a rigid-flexible switching four-door hinge installation method based on pneumatic timing logic. Using the aforementioned fixture, the following workflow is achieved through single-source on / off control:

[0015] During the initial reset and rigid push phase, the system is in a non-ventilated state. The normally closed self-resetting mechanism is locked under the action of spring force, eliminating the movement gap of the three-dimensional decoupling mechanism and forcibly fixing the positioning and clamping operation module at the geometric center position, so that the fixture is in a rigid state to facilitate ground push and coarse positioning.

[0016] During the air circuit activation and flexible release phase, the main control valve is opened, and compressed air is preferentially filled into the reset and unlocking branch with lower flow resistance, driving the normally closed self-reset mechanism to release the mechanical lock on the three-dimensional decoupling mechanism, so that the positioning and clamping operation module enters a three-dimensional flexible floating state that can move freely.

[0017] During the flexible insertion and adaptive alignment phase, compressed air enters the clamping operation branch, driving the positioning and clamping operation module to perform the clamping action. In this process, the positioning and clamping operation module utilizes a flexible floating state to adaptively displace itself in accordance with the cooperation between the main positioning pin and the vehicle body positioning hole. At this time, due to the cylinder movement, the pipeline pressure is at a low dynamic pressure level, below the opening pressure threshold of the one-way sequence valve. The normally open hysteresis locking mechanism remains in the released state, not interfering with the adaptive alignment process.

[0018] During the pressure threshold triggering and rigid locking phase, once all clamping cylinders have completed their actions and the pistons have stopped moving, the pressure inside the pipeline rapidly rises and exceeds the opening pressure threshold. The one-way sequence valve then opens, allowing high-pressure gas to drive the normally open hysteresis locking mechanism, locking the motion degrees of freedom of the three-dimensional decoupling mechanism and switching the fixture to a rigid support state.

[0019] During the anti-disturbance tightening stage, the operator tightens the hinge bolts under the rigid support provided by the normally open hysteresis locking mechanism. The frictional holding force generated by the pneumatic clamp is greater than the tangential interference force applied by the tightening tool, ensuring installation accuracy.

[0020] During the unloading and automatic centering phase, the main control valve is closed to depressurize the system. The normally open hysteresis locking mechanism releases first due to pressure loss, restoring the mechanism's flexibility; then the clamping cylinder retracts; finally, the normally closed self-resetting mechanism, under the action of the reset spring, drives the reset cone pin to push out, automatically pushing the positioning and clamping module back to the geometric center position and re-establishing a rigid connection, completing the operation cycle.

[0021] The above solution achieves the following beneficial technical effects:

[0022] This application constructs a pneumatic control system comprising three parallel branches: reset unlocking, clamping operation, and delayed locking. By utilizing the hydrodynamic characteristics of setting the opening pressure threshold of a one-way sequence valve between the dynamic pressure of the pipeline and the steady-state pressure of the system, it achieves automatic timing switching from flexible unlocking to adaptive alignment to rigid locking using only a single air source. This eliminates the need for traditional electrical sensor detection and solenoid valve control circuits, thereby reducing explosion-proof and wiring costs. Furthermore, it physically ensures that the locking action necessarily lags behind the positioning and clamping action, avoiding the risk of assembly interference caused by timing disorder.

[0023] This application employs a combined design of a normally closed self-resetting mechanism and a normally open hysteresis locking mechanism, effectively resolving the contradiction in the rigidity requirements of the fixture during the follow-up assembly process. The normally closed self-resetting mechanism utilizes spring potential energy to eliminate mechanism backlash, ensuring that the fixture maintains rigid alignment during the ground-pushing phase without an air source, facilitating rapid movement and coarse positioning by the operator. Meanwhile, the normally open hysteresis locking mechanism utilizes pneumatic drive to generate high friction, ensuring sufficient rigid support to resist tool reaction forces during the tightening operation, thereby guaranteeing the positional accuracy and consistency of the hinge mounting points.

[0024] The integrated three-dimensional decoupling mechanism of this application, in conjunction with the gravity balance cylinder, enables the positioning and clamping module to be in a microgravity suspension state during the alignment stage. This structure reduces the contact resistance when the main positioning pin is inserted into the body reference hole, allowing the fixture to follow the body position deviation with low friction and adaptive floating. This effectively prevents body sheet metal deformation and positioning hole enlargement damage caused by the fixture's own weight or forced positioning, and improves the process adaptability on dynamic production lines. Attached Figure Description

[0025] Figure 1 This is a perspective view of the present invention;

[0026] Figure 2 This is a front view structural diagram of the present invention;

[0027] Figure 3 This is a schematic diagram of the pneumatic control system of the present invention;

[0028] Figure 4 This is a schematic diagram of the installation method of the present invention.

[0029] Among them, 1. Positioning and clamping operation module; 2. Ground pushing chassis module; 3. Pneumatic timing logic floating module. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] See attached document Figure 1 To be continued Figure 2 The present invention provides a rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic, including: a positioning and clamping operation module 1, a ground pushing chassis module 2, and a pneumatic timing logic floating module 3 connected between the positioning and clamping operation module 1 and the ground pushing chassis module 2.

[0032] The positioning and clamping module 1 is the terminal component of the entire installation system, used to grip and position the four door hinges. The positioning and clamping module 1 includes a rectangular frame structure with clamping mounting plates vertically arranged on both sides. Pneumatic clamping units are integrated on the clamping mounting plates. Each pneumatic clamping unit includes a first pneumatic clamping assembly, a second pneumatic clamping assembly, a third pneumatic clamping assembly, and a fourth pneumatic clamping assembly, corresponding to the installation positions of the four door hinges on the vehicle body. Each pneumatic clamping assembly includes a clamping cylinder and a gripper mechanism connected to the piston rod of the clamping cylinder. The gripper mechanism is used to position and clamp the door hinges. The positioning and clamping module 1 also has at least one main positioning pin, which is inserted into a reference positioning hole on the side panel of the vehicle body to determine the reference position of the positioning and clamping module 1 relative to the vehicle body.

[0033] The ground-pushing chassis module 2 serves as the mobile carrier for the entire equipment, supporting the superstructure and moving it on the ground or along the production line. The ground-pushing chassis module 2 includes a chassis frame and several casters mounted beneath the chassis frame. The chassis frame is welded from metal profiles and has a rectangular structure, possessing sufficient rigidity to support the weight of the superstructure. At least two casters are equipped with foot brakes to secure the equipment in a stationary position. Operating handles are also provided on the chassis frame for operators to push the equipment forward.

[0034] The pneumatic timing logic floating module 3 is located between the ground-pushing chassis module 2 and the positioning and clamping operation module 1, and is used to switch between flexible connection and rigid locking between the two. The pneumatic timing logic floating module 3 includes: a three-dimensional decoupling mechanism, a normally closed self-resetting mechanism, and a normally open hysteresis locking mechanism.

[0035] The three-dimensional decoupling mechanism is used to realize the translational degrees of freedom of the positioning and clamping operation module 1 relative to the ground-propelling chassis module 2 in the three directions of the spatial rectangular coordinate system: the X-axis, Y-axis, and Z-axis. Specifically, the three-dimensional decoupling mechanism includes a Z-axis lifting guide assembly and an X / Y-axis horizontal floating assembly. The Z-axis lifting guide assembly is mounted on the ground-propelling chassis module 2 and includes a vertical guide column and a mating linear bearing, used to support the positioning and clamping operation module 1 and allow it to move vertically.

[0036] The Z-axis lifting guide assembly also integrates a gravity balance cylinder or constant force spring assembly. The output force of the gravity balance cylinder is designed to counteract the gravity of the positioning and clamping module 1. The back pressure of the gravity balance cylinder is set via a precision pressure regulating valve, ensuring that the positioning and clamping module 1 is in a state of microgravity or suspension in the Z-axis direction. This ensures that during the flexible insertion stage, only a minimal vertical guiding force is needed to drive the module up and down, avoiding damage to the vehicle body positioning holes caused by the gravity component due to excessive weight. The X / Y-axis horizontal floating assembly connects the Z-axis lifting guide assembly and the positioning and clamping module 1, and includes an X-axis slide rail pair and a Y-axis slide rail pair. The X-axis and Y-axis slide rail pairs are arranged in a cross shape to achieve two-dimensional floating in the horizontal plane.

[0037] At the end of the stroke of the X-axis and Y-axis slide rail pairs, mechanical limit blocks or elastic buffers are respectively installed to limit the maximum floating range (e.g., ±15mm) of the three-dimensional decoupling mechanism in the horizontal plane. The design value of this floating range is slightly larger than the maximum position deviation of the car body allowed by the production line process, which ensures that all potential alignment errors are covered and prevents excessive stretching of internal pipes or disengagement of the mechanism from the guide rail due to excessive floating.

[0038] The normally closed self-resetting mechanism is used to forcibly hold the positioning and clamping module 1 at its geometric center position relative to the ground-pushing chassis module 2 when no external force is applied or in a non-operating state. The normally closed self-resetting mechanism includes a reset cylinder, a reset cone pin, and a positioning cone sleeve. The positioning cone sleeve is fixed to the moving side component of the three-dimensional decoupling mechanism, and the reset cylinder is fixed to the fixed side component of the three-dimensional decoupling mechanism. The reset cone pin is connected to the piston rod end of the reset cylinder; the reset cone pin has a conical outer surface, and the positioning cone sleeve has a matching conical inner hole.

[0039] Considering that frequent switching between rigid and flexible surfaces can lead to wear on the contact surfaces, the contact surfaces of the reset cone pin and the positioning cone sleeve are both carburized and quenched or nitrided, achieving a surface hardness of HRC58 or higher. Furthermore, the inner bore of the positioning cone sleeve is designed with a large-angle taper (e.g., 60°-90°). This angle design ensures sufficient guiding range while preventing frictional self-locking during self-resetting, ensuring smooth retraction to the geometric center under spring force. The reset cylinder is a single-acting spring reset cylinder with an internal reset spring.

[0040] When no compressed air is input, the return spring pushes the piston rod of the return cylinder to extend, causing the return cone pin to insert into the positioning cone sleeve. The conical surface engagement eliminates the gap in the X / Y direction horizontal floating components, achieving mechanical rigid alignment. When compressed air is introduced into the return cylinder, the return cone pin retracts and disengages from the positioning cone sleeve, releasing the alignment constraint.

[0041] A normally open hysteresis locking mechanism is used to lock the motion degrees of freedom of a three-dimensional decoupling mechanism under specific operating conditions. The normally open hysteresis locking mechanism includes several pneumatic clamps, which are respectively installed on the guide post side of the Z-axis lifting guide assembly and the slide rail side of the X / Y-axis horizontal floating assembly. The pneumatic clamps are pneumatically pressurized locking type (i.e., normally open type), unlike the traditional spring brake type. In the de-aired state, a gap is maintained between the brake block and the guide rail or guide post, allowing relative movement; after compressed air is introduced, the internal piston pushes the brake block to press against the guide rail or guide post, generating frictional resistance to lock the movement. Combined with the use of a Z-axis gravity balance cylinder, this configuration allows the system to remain flexible in the air-deprived state, facilitating the operation of the reset mechanism. The air inlet of the pneumatic clamp is associated with the air circuit of the pneumatic clamping unit through the air circuit control system.

[0042] To quantify the locking capability of the normally open hysteresis locking mechanism, let the effective frictional contact area of ​​the pneumatic clamp be... The coefficient of friction is The input compressed air pressure is The maximum static friction force generated by the pneumatic clamp. The following relationship must be satisfied:

[0043] ;

[0044] When tightening bolts, the maximum tangential interference force applied by the tightening tool to the door hinge is assumed to be... To ensure that the positioning and clamping module 1 does not shift during the tightening process, the following must be met:

[0045] ;

[0046] Right now:

[0047] ;

[0048] This relationship serves as the basis for selecting normally open hysteresis locking mechanisms and setting working pressure, ensuring that the system has sufficient rigidity to resist external loads in the locked state.

[0049] The positioning and clamping module 1, the ground pushing chassis module 2, and the pneumatic timing logic floating module 3 are integrated into one unit by bolting or welding to form a complete installation fixture. The fixture is also equipped with a pneumatic control interface for connecting to an external air source and controlling the air supply to the pneumatic clamping unit, the normally closed self-resetting mechanism, and the normally open hysteresis locking mechanism.

[0050] See attached document Figure 3 The pneumatic control system and logic architecture of this embodiment aim to enable each actuator to operate in a predetermined sequence by relying solely on the pressure establishment order and pressure threshold determination in the air circuit, without relying on feedback from electrical sensors.

[0051] The pneumatic control system includes: an air source interface, a main control valve, a reset / unlock branch, a clamping operation branch, and a hysteresis lock-up branch. The air source interface connects to the workshop's compressed air pipeline network, and an air source treatment assembly is connected in series thereafter. This assembly includes a filter, a pressure reducing valve, and an oil mist lubricator, used to purify and stabilize the input compressed air, outputting a stable system operating pressure. The main control valve is a two-position three-way manual directional valve or a foot valve, located downstream of the air source treatment component. It serves as the master switch for the entire control loop, used to switch the system between the working state and the reset state.

[0052] One end of the reset / unlock branch is directly connected to the working port of the main control valve, and the other end is connected to the air inlet of the reset cylinder in the normally closed self-reset mechanism. No delay or throttling elements are installed in the reset / unlock branch, or a large-diameter one-way throttle valve (with one-way flow direction pointing towards the cylinder) is installed to ensure that compressed air can quickly fill the reset cylinder with minimal flow resistance at the moment the main control valve opens. Since the reset cylinder typically has a short stroke and small volume, this branch first establishes sufficient working pressure to overcome the reset spring force after system startup, driving the reset cone pin to retract, allowing the positioning and clamping module 1 to release the mechanical centering lock before other actions occur, entering a flexible floating state.

[0053] The clamping operation branch and the reset / unlock branch are connected in parallel to the working port of the main control valve. The end of the clamping operation branch is connected to the rodless chamber (or mold closing chamber) of each clamping cylinder in the first, second, third, and fourth pneumatic clamping assemblies. A flow control valve (such as a one-way throttle valve) is installed on the clamping operation branch to regulate the action speed of the clamping cylinders and prevent the grippers from closing too quickly and impacting the door hinges. After the main control valve is opened, compressed air enters each clamping cylinder through the flow control valve, pushing the piston rod to extend and perform the clamping action. During this process, because the cylinder piston is in motion, the air pressure in the clamping operation branch is in a dynamic change stage and has not yet reached the system steady-state pressure. .

[0054] The hysteresis lock-up branch is also connected in parallel to the main control valve's operating port, but its input end is connected in series with a normally closed one-way sequence valve. The outlet of the one-way sequence valve is connected to the inlet of each pneumatic clamp in the normally open hysteresis lock-up mechanism. The one-way sequence valve has an adjustable opening pressure threshold. The one-way sequence valve is equipped with a graduated pressure adjustment knob and a locking nut, allowing operators to adjust the pressure according to actual main air source pressure fluctuations without disassembling the pipeline. Make fine adjustments. Enable pressure threshold. The following fluid dynamic conditions must be met for the setting:

[0055] ;

[0056] in, To measure the dynamic pressure in the pipeline during the process of the clamping cylinder pushing the gripper to contact the hinge and making adaptive adjustments. This refers to the system's operating pressure (steady-state pressure).

[0057] Based on this setting, during the piston movement and fine-tuning phase of the clamping cylinder, the pipeline pressure is lower than... The one-way sequence valve remains closed, the pneumatic clamp has no air pressure input and remains released, allowing the positioning clamping module 1 to adapt its position according to the clamping reaction force. Once all clamping cylinders have completed their clamping action and the pistons have stopped moving, the airflow in the pipeline stops, and the pressure rapidly increases from... rebounded to When the pressure exceeds When the one-way sequence valve opens automatically, high-pressure gas is supplied to the pneumatic clamp, which drives it to lock the guide rail and achieve rigid locking.

[0058] Downstream of the one-way sequence valve, a one-way exhaust throttle valve can also be connected in parallel to the delayed locking branch. This valve is used to control the discharge speed of compressed air in the pneumatic clamp when the system is depressurized and reset, ensuring that the release action of the locking mechanism is slightly delayed or synchronized with the release action of the clamping mechanism, thus preventing accidental unlocking before the load is removed.

[0059] Preferably, a quick-release valve is installed at the exhaust end of the hysteresis locking branch or the air inlet of the pneumatic clamp. When the system main control valve switches to the depressurization state, the quick-release valve can bypass the flow resistance of the long-distance pipeline and directly discharge the compressed air in the pneumatic clamp to the atmosphere. This design ensures that during the reset phase, the release action of the rigid lock is significantly earlier than the release action of the clamping cylinder, completely eliminating the risk of mechanical jamming when the gripper retracts due to residual locking force.

[0060] By configuring the parallel topology and component parameters of the reset / unlock branch, clamping operation branch, and hysteresis locking branch, a pure pneumatic logic timing sequence is constructed: from the opening of the main control valve to the action of the reset cylinder (flexible unlocking), to the action of the clamping cylinder (flexible adaptive), to pressure establishment, to the opening of the sequence valve, and to the action of the clamp (rigid locking). This logic architecture directly converts the completion state of the mechanical action into a pressure signal, triggering subsequent actions and ensuring absolute synchronization and interlocking of the processes.

[0061] See attached document Figure 4This embodiment details the specific operation process and method of installing door hinges on a follow-up production line (such as a skateboard line or treadmill line) using the aforementioned device. This method achieves automatic cyclic switching of the fixture state between rigid pushing, flexible positioning and rigid locking through a single air source on / off control.

[0062] The specific work process includes the following steps:

[0063] Step S1: Initial reset and rigid push.

[0064] Before the operation begins, the equipment is not connected to the air source or the main control valve is closed, and the internal air pressure of the system is zero. At this time, the pneumatic clamp in the normally open hysteresis locking mechanism is in the loose state due to the lack of air pressure; the reset cylinder in the normally closed self-resetting mechanism loses pressure, and its internal reset spring releases potential energy, pushing the reset cone pin to fully push out and insert into the positioning cone sleeve.

[0065] The resetting cone pin and the positioning cone sleeve engage to generate a wedge-shaped self-locking force, eliminating the sliding clearance of the X / Y direction slide rail pair in the three-dimensional decoupling mechanism and forcibly locking the positioning clamping module 1 at the geometric center position of the ground-pushing chassis module 2. At this time, the entire fixture is in a highly rigid state. The operator holds the handle and pushes the fixture, moving synchronously with the vehicle body on the conveyor belt. Due to the rigid connection, the fixture's center of gravity is stable, eliminating inertial swaying during the pushing process. The operator can quickly adjust the fixture's position so that the main positioning pin is roughly aligned with the reference positioning hole area on the side of the vehicle body.

[0066] Step S2: Gas path activation and flexible release.

[0067] When the main locating pin approaches the vehicle body locating hole, the operator opens the main control valve. Compressed air quickly fills the reset and unlocking branch, driving the reset cylinder piston to retract and causing the reset cone pin to disengage from the locating cone sleeve. Once the cone surface engagement is released, the mechanical rigid constraint of the positioning clamping operation module 1 relative to the ground-pushing chassis module 2 is severed, and the system enters a three-dimensional flexible floating state. At this time, the positioning clamping operation module 1 is supported only by the three-dimensional decoupling mechanism and has translational degrees of freedom with extremely low frictional resistance along the X, Y, and Z axes.

[0068] Step S3: Flexible insertion and adaptive alignment.

[0069] Simultaneously, compressed air enters the clamping operation branch via the flow control valve, driving the piston rods of the clamping cylinders of each pneumatic clamping component to extend. Before the grippers close, the operator utilizes the system's flexibility to push the main locating pin fully into the vehicle body's reference locating hole. During this process, if there is a positional deviation between the fixture and the vehicle body, the guiding force generated by the contact between the main locating pin and the locating hole will drive the suspended positioning and clamping operation module 1 to undergo a slight displacement, automatically compensating for alignment errors in the X / Y / Z directions.

[0070] Subsequently, the clamping cylinder continues to operate, driving the grippers to grab the pre-placed four door hinges and press them against the vehicle body mounting surfaces. The reaction force generated during the clamping process further fine-tunes the posture of the positioning clamping module 1 until the mounting surfaces of the four hinges achieve a stress-free state of complete contact with the vehicle body sheet metal surface. At this stage, due to the continuous replenishment of airflow in the pipeline and the dynamic pressure build-up process, its value has not yet reached the opening threshold of the one-way sequence valve. Therefore, the hysteresis locking branch remains closed, and the system always maintains flexibility to allow the above adaptive adjustment to occur.

[0071] Step S4: Pressure threshold triggering and rigid locking.

[0072] Once all clamping cylinders have completed their action, the grippers firmly press the hinges onto the vehicle body, and the main locating pin is fully engaged with the locating hole. The cylinder volume then remains constant, and the fluid in the air system transitions from a dynamic pressure state to a static pressure state. The pipeline pressure rapidly increases and approaches the steady-state pressure of the air source. When the pressure value exceeds the preset activation threshold... At this time, the one-way sequence valve opens instantaneously, activating the hysteresis locking branch. High-pressure gas enters the pneumatic clamp of the normally open hysteresis locking mechanism, driving the brake block to lock the Z-axis guide column and X / Y-axis slide rails. At this point, the fixture completes a secondary switch from a flexible state to a rigid state, and the positioning and clamping module 1 is physically locked in the self-adaptive alignment position, forming a stable rigid support structure.

[0073] Step S5: Anti-disturbance tightening operation.

[0074] The operator uses an electric tightening gun to tighten the fixing bolts of each door hinge in sequence. During this process, the axial downward pressure and tangential reaction torque generated by the tightening tool are entirely borne by the fixture, which is already in a rigid locking state. Because the friction braking torque applied by the pneumatic clamp is greater than the tightening disturbance torque, the positioning and clamping module 1 will not shift or elastically retract, thus ensuring the positional accuracy of the hinge mounting points and the consistency of the Z-axis height.

[0075] Step S6: Uninstall and automatically revert to center.

[0076] After tightening is completed, the operator closes the main control valve. The system pipeline is depressurized, the one-way sequence valve is reversed to shut off, or the air is released through the bypass one-way valve. The pneumatic clamp first loses pressure and releases, allowing the positioning clamping module 1 to regain its flexibility while still connected to the vehicle body, releasing the stress remaining during installation. Then the clamping cylinder retracts to release the hinge. Finally, as the pressure is completely released, the spring force in the reset cylinder takes over again, pushing the reset cone pin out.

[0077] As the operator pulls the device backward to detach it from the vehicle body, the reset cone pin locates and engages with the positioning cone sleeve. Utilizing the guiding effect of the wedge-shaped surface, the off-center positioning clamping module 1 is automatically pushed back to the center position of the ground-pushing chassis module 2, and a rigid connection is re-established, completing a full work cycle and awaiting the next operation.

[0078] This embodiment analyzes the principle of rigid-flexible switching mechanism based on aerodynamic timing logic and provides the basis for setting key control parameters to verify the feasibility and stability of this technical solution at the physical level.

[0079] The core of this invention lies in utilizing the pressure hysteresis effect caused by the compressibility of gas, and in conjunction with pressure control elements, transforming a single input signal into a sequence of actions with a strict time order. The physical basis of its control logic lies in the graded setting of the action pressure of different branches within the system.

[0080] First, regarding the critical conditions for switching between rigidity and flexibility, the system must ensure flexibility during the clamping adaptation phase and rigidity during the tightening phase. The steady-state pressure of the air supply is defined as follows: (The factory air supply is typically 0.5-0.6 MPa), the dynamic pressure of the clamping cylinder during the process of pushing the load is defined as... Because the gas expands during cylinder movement and there is flow resistance in the pipeline, at this time... It must be lower than The opening pressure threshold of a one-way sequence valve is defined as follows: .

[0081] To ensure that the timing logic is not disrupted, that is, to prevent the locking mechanism from prematurely actuating before the clamping cylinder has reached its position or is still undergoing fine-tuning, the parameters... The setting must follow the pressure window principle, meaning its value should lie between the dynamic pressure and the steady-state pressure. Specifically, the set value... The following inequality must be satisfied:

[0082] ;

[0083] in, To provide a safety margin to prevent false triggering due to pressure fluctuations, This refers to the pressure loss in the piping system. In practical applications, it is usually... Set to air source pressure 75%-85%. For example, when the gas source pressure... MPa, cylinder dynamic pressure At MPa, the opening pressure of the sequence valve will be... The pressure is set to 0.45 MPa. This setting ensures that the locking mechanism only gains actuation energy after the clamping action is completely finished, the airflow stops, and the pressure has fully recovered, thus forcibly implementing a logical closed loop of alignment first and then locking at the physical level.

[0084] Secondly, based on the mechanical model analysis of the anti-disturbance rigidity maintenance, the locking mechanism must possess sufficient braking force to resist external disturbances during the tightening operation. It is assumed that the maximum tangential disturbance torque experienced by the positioning and clamping module 1 during tightening is equivalent to a linear thrust. This force primarily originates from the reaction torque of the electric tightening gun. The normally open hysteresis locking mechanism applies positive pressure to the guide rail via a pneumatic clamp. Utilizing friction To balance .

[0085] Positive pressure of pneumatic clamp From input air pressure (During the locking phase) Effective pressure area acting on the pneumatic clamp Genesis, i.e. Let the coefficient of static friction between the friction pair (brake block and guide rail) be... The maximum static friction holding force that the system can provide is:

[0086] ;

[0087] To ensure that the rigid locking mechanism does not fail, the stability condition must be met. ,in For safety factors (usually 1.5-2.0), the selection criteria for pneumatic clamps can be derived as follows:

[0088] ;

[0089] This inequality shows that by rationally selecting the cylinder diameter and friction material of the pneumatic clamp, it is entirely possible to use the existing air source pressure to provide a locking force that is much greater than the tightening disturbance force, thereby achieving high rigidity support solely through pneumatic friction without the need for additional mechanical locking pins.

[0090] In summary, this invention achieves precise matching Based on the system pressure characteristics and the design of actuator parameters based on the tribological model, an adaptive mechanical-pneumatic coupling system without electrical control intervention was constructed, which in principle solved the contradiction between stiffness and flexibility in follow-up assembly.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic, characterized in that, It includes a positioning and clamping operation module (1), a ground pushing chassis module (2), and a pneumatic timing logic floating module (3) connected between the positioning and clamping operation module (1) and the ground pushing chassis module (2). The pneumatic timing logic floating module (3) includes a three-dimensional decoupling mechanism, a normally closed self-resetting mechanism, and a normally open hysteresis locking mechanism; the fixture also includes a pneumatic control system, which includes a main control valve, a reset and unlock branch, a clamping operation branch, and a hysteresis locking branch; one end of the reset and unlock branch is connected to the main control valve, and the other end of the reset and unlock branch is connected to the normally closed self-resetting mechanism; one end of the clamping operation branch is connected to the main control valve, and the other end of the clamping operation branch is connected to the pneumatic clamping unit in the positioning and clamping operation module (1); one end of the hysteresis locking branch is connected to the main control valve, and the hysteresis locking branch is connected in series with a one-way sequence valve, the output end of the one-way sequence valve is connected to the normally open hysteresis locking mechanism.

2. The rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic according to claim 1, characterized in that, The three-dimensional decoupling mechanism includes a Z-axis lifting guide assembly and an X / Y-axis horizontal floating assembly; the Z-axis lifting guide assembly is mounted on the ground-pushing chassis module (2), and the Z-axis lifting guide assembly includes a vertical guide column, a linear bearing that cooperates with the vertical guide column, and a gravity balance cylinder; the X / Y-axis horizontal floating assembly is connected between the Z-axis lifting guide assembly and the positioning and clamping operation module (1), and the X / Y-axis horizontal floating assembly includes an X-axis slide rail pair and a Y-axis slide rail pair arranged in a cross shape.

3. The rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic according to claim 2, characterized in that, The normally closed self-resetting mechanism includes a reset cylinder, a reset cone pin, and a positioning cone sleeve; the reset cylinder is fixed to the fixed side component of the three-dimensional decoupling mechanism, and a reset spring is provided inside the reset cylinder; the reset cylinder is connected to the reset and unlocking branch; the positioning cone sleeve is fixed to the moving side component of the three-dimensional decoupling mechanism, and the positioning cone sleeve has a conical inner hole; the reset cone pin is connected to the piston rod end of the reset cylinder, and the reset cone pin has a conical outer surface that mates with the positioning cone sleeve.

4. The rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic according to claim 2, characterized in that, The normally open hysteresis locking mechanism includes a pneumatic clamp; the pneumatic clamp is installed on the side of the guide post of the Z-axis lifting guide assembly and the side of the slide rail of the X / Y-axis horizontal floating assembly; the pneumatic clamp is a pneumatic pressurized locking type, and the air inlet of the pneumatic clamp is connected to the output end of the one-way sequence valve in the hysteresis locking branch.

5. The rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic according to claim 1, characterized in that, The positioning and clamping operation module (1) includes a rectangular frame structure and a pneumatic clamping unit disposed on the rectangular frame structure; the pneumatic clamping unit includes a first pneumatic clamping assembly, a second pneumatic clamping assembly, a third pneumatic clamping assembly and a fourth pneumatic clamping assembly; each of the pneumatic clamping assemblies includes a clamping cylinder and a gripper mechanism connected to the piston rod of the clamping cylinder, the clamping cylinder being connected to the clamping operation branch; the positioning and clamping operation module (1) is also provided with a main positioning pin.

6. The rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic according to claim 1, characterized in that, A flow control valve is provided on the clamping operation branch; a one-way exhaust throttle valve or a fast exhaust valve is connected in parallel downstream of the one-way sequence valve in the hysteresis locking branch.

7. The rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic according to claim 1, characterized in that, The one-way sequence valve has an opening pressure threshold; the opening pressure threshold is set between the pipeline dynamic pressure in the clamping operation branch and the system steady-state pressure of the pneumatic control system; the pipeline dynamic pressure is the pressure value during the clamping action of the pneumatic clamping unit; the system steady-state pressure is the pressure value after the pneumatic clamping unit completes the clamping action.

8. The rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic according to claim 4, characterized in that, The pneumatic clamp has an effective frictional contact area; the product of the effective frictional contact area, the friction coefficient of the pneumatic clamp, and the steady-state pressure of the system is greater than the maximum tangential interference force applied by the external tightening tool.

9. The rigid-flexible switching four-door hinge installation fixture based on pneumatic timing logic according to claim 1, characterized in that, The ground-pushing chassis module (2) includes a chassis frame and casters installed below the chassis frame; the chassis frame is provided with an operating handle.

10. A method for installing a rigid-flexible switching four-door hinge based on pneumatic timing logic, characterized in that, The rigid-flexible switching four-door hinge mounting fixture based on pneumatic timing logic as described in any one of claims 1 to 9 includes the following steps: S1. Initial reset and rigid push: In the unventilated state, the normally closed self-reset mechanism is locked, eliminating the gap of the three-dimensional decoupling mechanism and fixing the positioning and clamping operation module (1) at the geometric center position. S2, Gas Path Activation and Flexible Release: Open the main control valve, reset the unlocking branch to fill with gas, drive the normally closed self-reset mechanism to unlock, and the positioning clamping operation module (1) enters the flexible floating state; S3, Flexible insertion and adaptive alignment: The clamping operation branch is inflated, driving the positioning clamping operation module (1) to perform clamping action and adaptive displacement with the vehicle body position. At this time, the pipeline pressure is lower than the opening pressure threshold of the one-way sequence valve, and the normally open hysteresis locking mechanism remains loose. S4. Pressure threshold triggering and rigid locking: When the clamping action is completed, the pipeline pressure rises and exceeds the opening pressure threshold, the one-way sequence valve opens, driving the normally open hysteresis locking mechanism to lock the three-dimensional decoupling mechanism. S5. Anti-disturbance tightening operation: Tighten the hinge bolts under the rigid support of the normally open hysteresis locking mechanism; S6. Unloading and Automatic Centering: The main control valve is closed to release pressure. The normally open hysteresis locking mechanism resets before the normally closed self-resetting mechanism. Under the action of spring force, the normally closed self-resetting mechanism drives the positioning clamping operation module (1) to return to the geometric center position.

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