- The safe release of industrial handling clamps is not "release when the air is cut off";No mis-release when the air is lost, controlled re-release: Keep the load in case of abnormality, and then release it at a low speed, diagnosable and resettable after interlocking is met.
- Complete loss-of-air protection is provided byMechanical self-locking, geometric support, pneumatic circuits pressure maintenance, leak detection, pressure attenuation monitoring, release interlock, operation management and maintenance resetTogether - Just "add a gas tank" or "install a pressure switch" is not enough.
- Clamping force based onEquivalent load methodCheck: Taking into account the handling acceleration, emergency stop impact, lower limit of friction coefficient and clamping jaw wear; under the internal test setting of 300 kg high-temperature parts, the target total normal clamping force is not less than approx. 36.7 kN。
- Loss of gas protection shouldmulti-signal diagnosis: P1/P2/P3 pressure monitoring, pressure drop rate judgment, gripper jaw displacement, locking in place and support confirmation jointly participate in safety decision-making; the total response to air loss locking is recommended to be ≤150 ms.
Organization: Jiangsu Aurek Intelligent Technology Co., Ltd. (AUREK Intelligent Technology Research Group, Lianyungang, Jiangsu) · Validation period: 2023.05–2026.04 · Resource type: Enterprise Engineering Methods. This documentnot equivalent to third-party certification, type testing, customer acceptance, or quality certification documents; the parameters are calculated values, test-record values, or engineering recommendations and must be verified for each project. The full PDF can be downloaded at the end of the page or from the upper-right link.
00Abstract
Industrial handling tooling units are widely used in scenarios such as Pneumatic Industrial Manipulator, pneumatic handling systems, robot end effectors, vacuum lifting systems, and special machine loading and unloading. Their safe release and loss-of-air protection designs are directly related toFalling workpieces, equipment collisions, personnel burns and production line shutdownsrisk. Aiming at the risk of clamping force attenuation and unexpected release that may occur under sudden drops in compressed-air supply pressure, air hose rupture, valve group abnormalities, and control signal failure, this article proposes a design method for air loss protection and safe release of industrial handling clamps.
This method emphasizes "No mis-release when the air is lost, controlled re-release” design logic: after loss of air, first maintain the grip, stop handling, and inhibit release while suspended. Perform low-speed, diagnosable, resettable release only after the workpiece is securely seated, the tooling is in a safe position, the manipulator or robot is in an approved release pose, personnel are in a safe area, and the control system satisfies all release interlocks. For pneumatic grippers, mechanical grippers, vacuum tooling, expanding tooling, hook tooling, tilting tooling, and high-temperature workpiece tooling, this article systematically addresses gripping-force calculations, mechanical self-locking, geometric support, pneumatic pressure retention, leakage detection, pressure-decay monitoring, release interlocks, maintenance reset, and engineering validation. The stated pressures, times, gripping forces, slip distances, and response times are engineering reference values or compiled internal test values and require project-specific verification against the workpiece, tooling structure, compressed-air supply conditions, motion profile, and site safety requirements.
01Introduction
In industrial automated handling systems, the clamp is usually located at the end of a Pneumatic Industrial Manipulator, pneumatic balance crane, truss manipulator, industrial robot, cantilever crane or special machine loading and unloading mechanism. It is a key execution unit to achieve workpiece clamping, loading, posture conversion, transfer and release. Different from ordinary positioning tooling, industrial handling clamps not only need to meet the clamping requirements under rated working conditions, but also need tocompressed-air supply failure, control anomalies, gripper wear, workpiece bias, high temperature radiation and maintenance misoperationsand avoid further expansion of risks under foreseeable abnormal conditions.
In pneumatic handling clamps, compressed-air supply pressure usually assumes functions such as clamping force establishment, clamping jaw drive and release execution. If the clamp design relies only on air pressure for maintenance, once the main compressed-air supply is suddenly interrupted, the air hose is ruptured, the quick connector is disconnected, the valve core is stuck, the release valve malfunctions, or the clamping chamber leaks, the clamping force may drop rapidly, causing the workpiece to slip, fall, or impact. For high-temperature castings, forgings and heat-treated parts, due to the high temperature of the workpiece, the large amount of surface oxide scale, the large fluctuations in the friction coefficient, and the inability of personnel to intervene at close range, the design of outgassing protection and safe release is particularly important.
02Research objects and boundary conditions
2.1 Research objects
The research object of this article is custom handling tooling in industrial handling scenarios and their safe release, air loss protection and engineering verification methods, which mainly includePneumatic clamping type, clamping type, vacuum gripping type, inner support type, hook type, flip type, high temperature workpiece handling fixtureand other non-standard industrial handling tooling units. Applicable equipment includes Pneumatic Industrial Manipulator, pneumatic balancing cranes, truss manipulators, industrial robot end effectors, special machine loading and unloading handling mechanisms, cantilever crane supporting handling fixtures and vacuum suction and lifting systems.
2.2 Boundary conditions
This article focuses on the study of pneumatic clamps and composite handling clamps inLoss of air, leakage, accidental release and maintenance resetThe state-of-the-art design method does not replace risk assessment, mechanical strength calculation, control system safety verification, on-site commissioning and customer acceptance in specific projects. There are great differences in the quality, size, surface condition, temperature, center of gravity position, clamping method, handling movement curve, on-site cycle time, personnel working methods and compressed-air supply conditions of different workpieces. Therefore, the loss-of-air protection plan must be individually designed, checked and verified based on the actual situation of the project.
03Loss-of-air risks and typical failure modes
The risks of industrial handling fixtures not only come from the self-weight of the workpiece, but also from handling acceleration, emergency stop impact, attitude changes, gripper wear, reduced friction coefficient, high temperature radiation, workpiece center of gravity shift and personnel misoperation. For clamping, clamping, inner support, vacuum gripping, hook and flip clamps, although the failure modes are different, their common risks are as followsDecreased holding capacity, unexpected release, malfunction or inability to safely reset。
| No. | failure mode | Description of main risks |
|---|---|---|
| 1 | The main compressed-air supply is suddenly interrupted | When the pressure supply to the clamping cylinder disappears, without mechanical locking or pressure-maintaining measures, the clamping force may decline rapidly. |
| 2 | Main compressed-air supply pressure drops slowly | The clamping force gradually decreases, and if there is no low-pressure warning, the machine may continue to be transported without knowing it. |
| 3 | Air-hose rupture | The branch pressure drops rapidly, which may cause the clamping chamber to lose pressure or the actuator to malfunction. |
| 4 | quick connector disconnect | It often manifests as instantaneous leakage and needs to be identified through the pressure drop rate and pressure threshold. |
| 5 | Valve core stuck | This may result in incomplete clamping, incomplete release or mis-exhaust. |
| 6 | Release valve malfunction | If the release interlock is insufficient, unintended release may occur when the workpiece is suspended. |
| 7 | Clamping chamber leakage | The clamping force decays slowly, possibly causing the workpiece to slip. |
| 8 | Gas tank or one-way valve failure | The local pressure holding capacity is reduced and the air loss holding time is shortened. |
| 9 | Pressure sensor misalignment | The control system may misjudge the clamping or air loss status. |
| 10 | gripper-jaw wear | The contact area, friction coefficient and geometric limiting capability are reduced. |
| 11 | High temperature damages air line, seals, and sensors | It may cause air leakage, signal drift, or abnormal operation. |
| 12 | Operator mistakenly presses release button | Without dual confirmation and a support interlock, the load could be released inadvertently while suspended. |
| 13 | Maintenance status incorrectly started | When maintenance personnel are in a dangerous area, malfunction of the clamp may cause injury. |
| 14 | Workpiece released inadvertently before it is securely seated | The workpiece may fall directly and is the key prevention and control target of the release interlock. |
| 15 | Center of gravity shift causes eccentric load slip | Eccentric loads increase the force on one side of the gripper, which may induce rotation, overturning or slipping. |
Table 1: Gas loss risk and typical failure modes
Therefore, the design of loss-of-air protection cannot only be understood as "adding a gas storage tank" or "installing a pressure switch." Complete loss-of-air protection should be provided byMechanical self-locking, geometric support, pneumatic line pressure maintenance, leak detection, pressure attenuation monitoring, release interlock, operation management and maintenance reset processconstitute together.
04Design principles for safe release and loss-of-air protection
The safe release and loss-of-air protection of industrial handling tooling units should be followedRisk first, structural intrinsic safety, mechanical redundancy, pneumatic circuits maintenance, condition monitoring, control interlocking, controlled release, maintainable reset and testable verificationprinciple. Safety release is not to release when the air is cut off, but to maintain the load under abnormal conditions, and perform a controllable, low-speed, diagnosable, and resettable release action after the workpiece is supported, personnel are evacuated, the position is confirmed, and the control system meets the release conditions.
Intrinsic safety should minimize dependence on pneumatic holding alone through V-grooves, contoured supports, under-supports, side stops, limit stops, and heat-resistant jaws; mechanical redundancy should combine wedge self-locking, spring-loaded locking pins, pawl mechanisms, geometric supports, and limit stops to provide passive retention after loss of air; control interlocks should permit release only after workpiece-support confirmation, tooling-position confirmation, manipulator or robot pose confirmation, personnel-safety-zone confirmation, pressure-status confirmation, and sensor-signal consistency confirmation.
| Contrast Dimensions | standard pneumatic tooling | Air loss protection safety clamp |
|---|---|---|
| Clamping and holding method | It mainly relies on the continuous supply of pressure by the cylinder. | Air pressure maintenance + mechanical lock + geometric support + pressure detection + release interlock combination design. |
| Air-supply shutoff response | The clamping force may decrease as the pressure decreases. | Priority is given to stopping transportation, mechanical locking, maintaining clamping, and prohibiting hanging release. |
| Release conditions | Often triggered by a single button or ordinary valve control. | Interlock conditions shall include workpiece-seated confirmation, position confirmation, pose confirmation, personnel safety, and pressure status. |
| Leak detection method | Rely more on pressure gauges or manual observation. | P1, P2, P3 pressure monitoring, pressure drop rate judgment and signal consistency diagnosis. |
| maintenance safety | Maintenance status may depend on operating procedures. | Set safety pressure relief, manual reset, maintenance confirmation and false start protection. |
| Suitable Applications | Suitable for low-risk, light-load, and stable compressed-air supply scenarios. | Suitable for high temperature, heavy load, suspended handling, posture changes and non-standard handling scenarios. |
| Dependence on personnel/compressed-air supply | higher. | Lower, release needs to be confirmed by interlocking conditions, pressure holding and mechanical maintenance reduce dependence on the stability of a single compressed-air supply. |
Table 2 Comparison between ordinary pneumatic clamps and air loss protection safety clamps
05Clamping force calculation method and representative engineering verification calculation
5.1 Basic logic of calculation
The clamping force design should consider the workpiece's own weight, handling acceleration, emergency stop impact, orientation changes, lower limit of friction coefficient, high temperature oxide scale, clamping jaw wear and eccentric load. For friction clamping type clamps, clamping force calculationIt is not appropriate to estimate based on static weight only, the equivalent load method should be used：
where Fe In order to consider the equivalent load (N) after handling action and impact; m is the mass of the workpiece (kg); g is taken as 9.81 m/s²; a is the maximum acceleration of handling (m/s²); φ is the emergency stop impact correction coefficient, which needs to be checked according to the handling action curve and braking characteristics. Target total normal clamping force:
where Ntotal is the target total normal clamping force (N); Ks is the clamping force safety factor; μmin As the lower limit of friction coefficient, high temperature, scale, oil dirt, wear and surface roughness changes should be considered. Cylinder theoretical output force:
where Fc is the effective output force of the cylinder (N); P is the working pressure (Pa); A is the effective area of the piston (m²); η is the transmission efficiency; Fr are sealing resistance, spring resistance and mechanism friction resistance (N). If the clamping force is amplified by force-increasing mechanisms such as wedges, toggle levers, and eccentric mechanisms, the transmission ratio, efficiency, wear, jamming, thermal expansion, release resistance, pin shear, elastic deformation of the clamping jaw, and load-bearing capacity under air loss locking conditions should also be checked.
5.2 Representative project verification and accounting examples
The following calculation examples are organized according to the internal engineering verification records and engineering accounting standards of the Erek Intelligent Technology Research Group from 2023.05 to 2026.04. The relevant values still need to be reviewed with the original records, project design documents and on-site safety requirements, and are not used as unified design parameters for all projects.
| Project | Internal test finishing value |
|---|---|
| Workpiece type | High temperature iron castings or forgings |
| Workpiece quality | 300 kg |
| Overall reference dimensions | 900 mm × 450 mm × 250 mm |
| Workpiece surface temperature/ambient temperature | 250 °C / 25 °C |
| Workpiece center of gravity offset | ≤80 mm |
| Maximum acceleration of handling | 0.3 g |
| Emergency stop impact correction coefficient φ | 1.2 |
| Minimum friction coefficient μ under high temperature oxide scale conditionsmin | 0.25 |
| Clamping force safety factor Ks | ≥2.0 |
Table 3 Representative high temperature and heavy load condition test settings (organized from 2023.05 to 2026.04)
Substitute into equation (1) and equation (2):
Therefore, under this internal test setting, the target total normal clamping force is recommendedNot less than 36.7 kN. If double-sided clamping is used, the theoretical target clamping force on one side is about 18.4 kN; taking into account the wear of the clamping jaw, air pressure fluctuation, thermal deformation, center of gravity shift and manufacturing assembly deviation, the target clamping force on one side can be calculated according to 20～22 kN As an internal test finishing value. High-temperature workpieces should not rely entirely on friction. V-shaped grooves, step limits, envelope supports or bottom supports should be used first, so that the clamping force and geometric limits share stability.
06Mechanical self-locking and safety release mechanism design
Mechanical self-locking is not intended to replace the control system;Passive safety layer in out-of-air condition. The control system is used to identify the status, perform interlocking and manage the release process; the mechanical self-locking is used to maintain the load-bearing state of the clamp when the compressed-air supply or control signal is abnormal, preventing the clamping jaw from immediately releasing due to pressure attenuation. For high-temperature, heavy-load or suspended handling scenarios, it is recommended to use wedge self-locking, spring lock pins, pawl mechanisms, geometric supports and limit stops to form a composite mechanical redundancy.
The release action should be divided into two stages:The mechanical locking is released in the first stage, and the claw is controlled in the second stage.. The system can only allow the lock pin, pawl or wedge to be unlocked after confirming that the workpiece has been supported, the tooling is in a safe position, the manipulator or robot is in a position that allows release, the person is in a safe area, the pressure state is normal and the locking state can be diagnosed. The controlled opening claw should be opened at low speed through throttle exhaust, proportional control or mechanical speed limit to avoid impact or bounce caused by instantaneous release. Emergency manual release must be based on the support of the workpiece. It should be equipped with a protective cover, double-action mechanism, special key or mechanical confirmation process, and must not become a source of accidental release.
| Parameter items | Engineering reference values/recommended verification indicators | design description |
|---|---|---|
| wedge angle | 5°～7° | Taking both self-locking ability and release resistance into consideration, the state of the friction surface needs to be considered. |
| Lock pin entry time | ≤100 ms | Used for rapid mechanical locking after loss of air or power. |
| Total response time of air loss lock | ≤150 ms | Recommended verification metrics from exception identification to lockout completion. |
| Normal controlled release time | 0.8～1.5 s | Avoid impact or bounce caused by instant release. |
| Normal release and claw opening speed | ≤80 mm/s | Used to reduce impact during controlled release after workpiece seating is confirmed. |
| Emergency manual release claw opening speed | ≤50 mm/s | Manual release should be slow, abortable and confirmable. |
| Maximum elastic deformation of the jaw end | ≤0.2 mm | It needs to be checked based on the length, material and stress state of the clamping jaw. |
| Lock pin shear safety factor | ≥3.0 | It is used to check the key bearing capacity under air loss maintenance state. |
| Safety factor of wedge contact surface | ≥1.5 | Contact stress, wear and lubrication conditions need to be considered. |
| Maximum equivalent stress of main load-bearing parts | ≤60% of the allowable stress of the material | As a reference boundary for structural strength design. |
Table 4 Mechanical structure engineering reference indicators
Insulation pads, heat-resistant clamping jaws, metal hoses, heat radiation-proof wiring and sensor protection should also be considered for high-temperature workpiece fixtures. Air hoses, seals and sensors should be arranged on the weak side of heat radiation as much as possible, and the risk of thermal damage should be reduced through metal hoses, thermal insulation sheaths or thermal insulation panels.
07Pneumatic line pressure maintenance and leak detection design
Pneumatic line pressure maintenance and leakage detection should focus on "Air supply filtration, local pressure maintenance, abnormal isolation, pressure monitoring, controlled exhaust and maintenance pressure relief"Expand. The typical air path protection unit includes a filter pressure reducing component, a one-way valve, a pressure maintaining valve, a gas storage tank, a safety stop valve, a throttle exhaust valve, a safety exhaust valve, as well as a main pressure sensor P1, a branch pressure sensor P2, a clamping chamber pressure sensor P3, pressure drop rate judgment, leakage level identification and high temperature area pneumatic tubing protection.
| Parameter items | Engineering reference value / compiled internal test value | Description |
|---|---|---|
| Rated air supply pressure | 0.5～0.7 MPa | It is suitable for common industrial compressed air conditions and needs to be calibrated according to the on-site compressed-air supply. |
| Test initial air supply pressure | 0.60 MPa | Used for internal testing initial state setting. |
| Low voltage warning threshold | P1 < 0.45 MPa, lasting ≥200 ms | Recognizes insufficient air supply and inhibits the start of a new cycle. |
| Loss-of-air protection trigger pressure | P1 < 0.35 MPa or P2 < 0.35 MPa | Triggers stop of handling, mechanical locking and prohibition of release. |
| Rapid leak trigger conditions | Pressure drop rate ≥0.08 MPa/s | Identify sudden leaks such as air-line rupture and disconnected joints. |
| Pre-clamping pressure | 0.18 MPa (approximately 30% of rating) | For use in soft contact stages. |
| Normal clamping pressure | 0.60 MPa | Used to simulate normal clamping conditions. |
| Pressure control allows fluctuations | ±5% (approximately ±0.03 MPa) | Suggested verification indicators for pressure stability. |
| Pressure sampling period/recording frequency | ≤20 ms / ≥50 Hz | For pressure decay and rapid leak identification. |
| Main compressed-air supply - branch abnormality judgment | |P1−P2| > 0.08 MPa, lasting ≥300 ms | Identify abnormalities in the main compressed-air supply and branch air paths. |
| Clamping cavity abnormality judgment | |P2−P3| > 0.10 MPa, lasting ≥300 ms | Identify clamping chamber leaks or valve block abnormalities. |
Table 5: Pneumatic-System Engineering Reference Values and Compiled Internal Test Values
The pressure decay rate is determined by the following formula:
where Rp is the pressure decay rate (MPa/s), ΔP is the pressure change, and Δt is the sampling time interval. When the pressure drop rate reaches or exceeds the internal test trigger value of 0.08 MPa/s, it can be used as a rapid leak trigger condition; for slow leaks, a graded alarm threshold can be established based on the pneumatic circuit volume, sealing form and holding time. If there is an abnormal pressure difference between P1, P2, and P3 and the timeout persists, it should be determined that the sensor, valve group, or pneumatic line is abnormal, and the system will enter a conservative safety state.
08Control logic and release interlock conditions
Release conditions should include at leastWorkpiece support confirmation, fixture position confirmation, manipulator or robot posture confirmation, clamping status confirmation, locking status confirmation, personnel safety area confirmation, release command confirmation, pressure status confirmation and sensor signal consistency confirmation. Before workpiece support is confirmed, the system shall reject a release command; if sensor signals conflict, the system shall enter a conservative safe state—stop handling, maintain the grip, and inhibit release.
| response level | Trigger condition | System response |
|---|---|---|
| First-level warning | P1 < 0.45 MPa, lasting ≥200 ms | Low voltage alarm, prohibiting new cycle start. |
| Secondary protection | P1 < 0.35 MPa or P2 < 0.35 MPa | Stop transportation, mechanically lock, and prohibit release. |
| Three-tier emergency-stop system | Pressure drop rate ≥0.08 MPa/s, or abnormal gripper jaw displacement | Stop immediately, engage the locking pin, maintain the grip, and inhibit release while suspended. |
| reset condition | Pressure restored, leakage eliminated, workpiece securely seated, manual confirmation complete, lock reset, sensor signals consistent, and work area safe | Allows access to controlled release, re-clamping or manual handling processes. |
Table 6: Out of gas response logic
The control logic should follow "Exception priority retention and release must be confirmed" principle. Especially in scenarios where high-temperature workpieces or heavy-loaded workpieces are handled, it is forbidden to directly equate interruption of the compressed-air supply with a release command.
09Risk Analysis and FMEA
FMEA can be used to identify key risks in the design of loss-of-air protection, prioritize risks, and generate improvements. This article uses severity S, occurrence degree O, detection degree D and risk priority number RPN to conduct internal engineering assessment, RPN = S × O × D. The scores in the table below areExample of an internal engineering assessment model, used for program comparison and risk ranking, and needs to be re-evaluated according to specific projects.
| failure mode | S | O | D | Initial RPN | Improvement measures | After improvement |
|---|---|---|---|---|---|---|
| The main compressed-air supply is suddenly interrupted | 5 | 4 | 4 | 80 | One-way valve, pressure maintaining valve, mechanical lock, air loss prohibiting release | 20 |
| The main compressed-air supply slowly decreases | 4 | 3 | 4 | 48 | Low pressure warning, prohibition of new cycles, pressure trend monitoring | 16 |
| Air-hose rupture | 5 | 3 | 4 | 60 | Pressure drop rate detection, metal hose, anti-swing pipe, mechanical locking | 15 |
| quick connector disconnect | 5 | 3 | 4 | 60 | With lock connector, P2 monitoring, connector anti-disconnection | 15 |
| Release valve malfunction | 5 | 3 | 4 | 60 | Support interlocking, double confirmation release, safety output monitoring | 12 |
| gripper-jaw wear | 4 | 4 | 3 | 48 | Replaceable wear-resistant blocks, wear scales, and regular inspections | 18 |
| The lock pin is not in place | 5 | 3 | 3 | 45 | Double position detection, dust-proof lock pin, transportation prohibited due to failure | 15 |
| Pressure sensor misalignment | 4 | 3 | 4 | 48 | P1/P2/P3 cross-check, periodic calibration | 16 |
| High temperature radiation damage air line | 5 | 3 | 3 | 45 | Metal hose, insulation jacket, temperature recording | 15 |
| Artificial accidental release | 5 | 3 | 4 | 60 | Protective cover, double action, special key, support confirmation | 12 |
| Maintenance status incorrectly started | 5 | 3 | 3 | 45 | Maintenance mode, lockout and tagout, manual reset confirmation | 15 |
| Release command received while the workpiece is unsupported | 5 | 3 | 4 | 60 | Support sensor, position interlock, release command rejection | 10 |
| Clamping chamber leakage | 4 | 4 | 3 | 48 | P3 monitoring, pressure drop rate judgment, leakage classification alarm | 16 |
| Gas tank or one-way valve failure | 4 | 3 | 4 | 48 | Pressure holding test, one-way valve regular inspection, air loss maintenance test | 16 |
Table 7: Example of FMEA for air loss protection of industrial handling fixtures (RPN is an internal assessment model of the enterprise and is not used as a third-party certification conclusion)
Scoring convention (company internal template): S=5 indicates that it may cause serious personal injury, major equipment damage or high-temperature workpiece falling; the recommended disposal threshold is RPN ≥ 50 must be corrected and retested/specially reviewed, 30 ≤ RPN < 50 requires project review and clarification of responsible persons and residual risks, RPN < 30 can be tentatively accepted but included in inspection and archiving.
10Test verification plan
The following content supports pre-delivery design validation, parameter refinement, and risk review; its conclusions must be supported by original test records and calibration information.
| test items | Test purpose | Acceptance concerns |
|---|---|---|
| Rated clamping test | Verify clamping capacity under rated working conditions | There is no abnormal slippage and the deformation of the clamping jaw is within the allowable range. |
| Dynamic handling test | Verify holding ability under acceleration and emergency stop impact | The workpiece has no obvious slippage and the locking state is stable. |
| loss-of-air test | Verify main air supply interruption protection logic | Stop carrying, mechanically lock, and prohibit release. |
| slow leak test | Verify low pressure warning and leak identification | It can alarm in different levels and prohibit new cycles. |
| Quick leak test | Verify response to air-hose rupture or connector disengagement | Trigger emergency stop, keep clamping, and prohibit hanging release. |
| Support interlock test | Verify rejection of release before workpiece seating is confirmed | The system refuses to release. |
| controlled release test | Verify low-speed release after workpiece seating is confirmed | Release is smooth, with no significant impact or bounce. |
| High temperature radiation test | Verify component status in high temperature environments | No obvious thermal damage or abnormal alarm. |
| Life cycle test | Verify the durability of jaws, lock pins, valve blocks, and seals | There is no abnormal wear or functional failure of key components. |
| Maintenance reset test | Verify manual confirmation and reset process after failure | Automatic circulation is prohibited before reset, and the status will be consistent after reset. |
Table 8: Enterprise recommended verification plan (recommended to record P1/P2/P3, pressure drop rate, clamping jaw displacement, slip amount, response/release time, etc.)
11Engineering Verification Practices and Representative Records
From 2023.05 through 2026.04, the AUREK Intelligent Technology Research Group at Jiangsu Aurek Intelligent Technology Co., Ltd. performed and documented engineering verification for custom Pneumatic Industrial Manipulators, pneumatic handling systems, and industrial handling tooling. The work examined whether grip is retained as supply pressure falls; rapid leaks or disconnected fittings trigger protection promptly; mechanical locking retains the load after loss of air; controlled release prevents inadvertent release while suspended; support, position, and personnel-safety interlocks are effective; the air-receiver and valve-manifold combination supports safe stopping and controlled release; and components remain safe in high-temperature service. The design-and-verification workflow is as follows:
The research team used a 300 kg high-temperature workpiece as the representative test load at an initial supply pressure of 0.60 MPa. Low pressure, air-supply loss, rapid leakage, unintended release, and controlled release were tested to verify load retention, mechanical-lock response, and release-interlock logic. The table below summarizes the engineering validation:
| No. | Test conditions | Key settings | Recorded results (compiled internally) |
|---|---|---|---|
| 1 | Normal air supply clamping | P=0.60 MPa, keep for 15 minutes | 15 min slippage 0.28 mm; P3 ≈ 0.594 MPa |
| 2 | Low voltage warning | P1 < 0.45 MPa, lasting ≥200 ms | P1=0.446 MPa, alarm after 236 ms |
| 3 | Main compressed-air supply decreases slowly | 0.60→0.35 MPa / 10 s | 10.2 s Enter the second level protection and lock is completed |
| 4 | The main compressed-air supply is suddenly cut off | drops to 0 MPa within 0.5 s | Total locking response 104 ms, 5 min slip 0.62 mm |
| 5 | Rapid leakage of clamped branch circuit | P3 0.60→0.25 MPa / 3 s | Pressure drop rate ≈0.116～0.118 MPa/s, three-level emergency stop |
| 6 | quick connector disconnect | P2 dropped to 0.10 MPa within 1 s | P2 drops to 0.35 MPa for about 496 ms, the lock pin is in place |
| 7 | Release valve malfunction | The workpiece is suspended and the support confirmation is invalid. | Release output has no action, the tooling remains clamped |
| 8 | Release after the workpiece is securely seated | Release time 0.8～1.5 s | Controlled claw opening 1.12 s, maximum claw opening speed 68 mm/s |
| 9 | High temperature radiation test | 250 °C heat source for 30 minutes | The surface of the air hoses is 57 °C, the sensor housing is 48 °C, and there is no abnormal alarm. |
| 10 | Maintenance reset simulation | Pressure recovery 0.60 MPa, manual confirmation | Automatic circulation is prohibited before reset, and the status is consistent after reset. |
Table 9. Representative engineering-validation conditions and record summary (2023.05–2026.04)
12Engineering Application Analysis
The outgassing protection and safe release method proposed in this article can be used in high-temperature forging handling, casting cleaning and transfer, heat treatment loading and unloading, robot end clamps, large plate or box handling, Pneumatic Industrial Manipulator custom tooling, pneumatic balancing crane clamps, vacuum gripping handling clamps, automobile parts handling, and workpiece handling scenarios such as motor stators, boxes, plates, tires, and battery compartments.
From the perspective of engineering application, the fixture scheme should not only be designed based on "can be clamped", but should also consider:Whether the load is retained after loss of air, inadvertent release is inhibited by interlocks, controlled release is smooth, and maintenance state can be reset safely, and whether high temperature, dust, oil pollution and air supply fluctuations will reduce the design margin. For vacuum gripping fixtures, attention should be paid to vacuum maintenance, suction cup aging, surface roughness and leakage monitoring; for hook fixtures, attention should be paid to anti-decoupling, workpiece center of gravity and attitude restrictions; for flipping fixtures, attention should be paid to inertial loads and secondary locking during the flipping process; for inner support fixtures, attention should be paid to inner support contact surface wear, tension force attenuation and workpiece inner hole size fluctuations.
13Conclusion and outlook
Conclusion:(1) The primary goal of air loss safety design is to maintain clamping, rather than immediate release; (2) Mechanical self-locking, geometric support and air path pressure maintenance should be used in combination. Single air pressure maintenance is difficult to cover air line rupture, joint disengagement, valve group abnormality and control signal failure; (3) The clamping force design should consider dynamic impact, lower limit of friction coefficient, high temperature impact and gripper jaw wear, and check according to more conservative values; (4) Gas loss protection should use multi-signal diagnosis (P1/P2/P3, pressure drop rate, gripper jaw displacement, locking in place, support confirmation to participate in decision-making) and should not rely on a single pressure gauge; (5) Safe release must be based on workpiece support and personnel safety confirmation. The system should reject the release command when conditions are not met; (6) Test verification should cover scenarios such as loss of compressed air, leakage, dynamic handling, controlled release, and maintenance reset.
Outlook:Future work may address identification of high-temperature friction coefficients, gripper-wear monitoring, pressure-decay-curve modeling, digital test records, predictive maintenance, and verification of safety-control performance. On complex production lines, the tooling-release interlock can be integrated into the line-wide safety-control architecture to coordinate validation across the tooling, manipulators, tooling supports, personnel safety zones, and maintenance modes.
14Related Standards and Compliance References
The following standards are only used as a reference framework for design, review and verification; whether they are applicable, applicable terms and compliance conclusions should be jointly determined by project risk assessment, control system safety design, on-site verification and customer requirements. Unless there is formal testing, calculation and signing data, it is not appropriate to state that "this article has met a certain standard".
| Category | Reference standards/documents | focus |
|---|---|---|
| Machinery Safety Risk Assessment | ISO 12100 / GB/T 15706 | Hazard identification, risk estimation, risk reduction and residual risk description. |
| Safety related control systems | ISO 13849-1、IEC 62061 | Release interlock, lock in place, support confirmation, emergency stop and diagnostic coverage; PL/SIL determined by project. |
| Pneumatic system safety | ISO 4414 / GB/T related | compressed-air supply interruption, energy storage release, pressure maintenance, exhaust, maintenance pressure relief and malfunction prevention. |
| Robotics and collaborative safety | ISO 10218、ISO/TS 15066 | Robot posture, personnel safety area, end effector release interlock. |
| Internal regulations of the enterprise | Risk assessment form, test records, FMEA, spot inspection and maintenance procedures | Internal responsibility closed loop, test archiving, maintenance reset and residual risk confirmation. |
Table 10: Related standards and compliance references
15References
- ISO 12100:2010. Safety of machinery—General principles for design—Risk assessment and risk reduction[S].
- ISO 13849-1. Safety of machinery—Safety-related parts of control systems—Part 1: General principles for design[S].
- IEC 62061. Safety of machinery—Functional safety of safety-related control systems[S].
- ISO 4414. Pneumatic fluid power—General rules and safety requirements for systems and their components[S].
- ISO 10218 / ISO/TS 15066. Robots and robotic devices—Safety requirements / Collaborative robots[S].
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