- The core of high-temperature handling fixtures is not simply "high temperature resistance", but coordination within limited space and cycle time.Clamping load-bearing, heat flow blocking, air path protection, structural stability and convenient maintenance。
- proposeHigh-temperature load-bearing area/insulation blocking area/low-temperature execution areaFunctional partition, combined with a composite heat insulation structure of heat-resistant clamping claws, ceramic wear-resistant layer, glass-ceramic breaking bridge, ceramic fiber layer, air thermal insulation groove and reflective protective cover.
- The equivalent thermal conductivity of composite insulation paths can be reduced to approximately 0.25 W/(m·K); Under the working condition of 650 °C, the root of the clamping jaw is ≤83 °C, the cylinder mounting surface is ≤55 °C, and the outer wall of the air hose is ≤68 °C. The main heat transfer heat flux density is about 98.7% lower than that of metal direct connection.
- The pneumatic circuit must be systematically protected:The compressed-air supply is far away from the heat source, metalized near the heat source, secondary insulation of the hose, rear-mounted components, and controllable pressure loss.;The air path thermal protection efficiency is about 76.9%.
Unit: Jiangsu Aurek Intelligent Technology Co., Ltd. (Lianyungang, Jiangsu) Category: Technical Research Contains complete formulas, tables and finite element results. The full PDF text can be downloaded at the end of the article or in the upper right corner.
00Abstract
For forging, heat treatment, die-casting, sintering and furnace-front automated production scenarios, high-temperature workpiece handling fixtures are prone to appearHeat is transferred along the clamping claw to the execution end, the temperature of the pneumatic system rises too high, the air line ages and fails, the sensor malfunctions, and the clamping reliability decreases.This paper proposes a composite heat-insulating fixture structure and air path protection design method for short-cycle handling of high-temperature workpieces. Based on the characteristics of high-temperature handling conditions, a heat transfer path model of the fixture system was established to clarify the functional partitioning principles of the high-temperature load-bearing area, the heat insulation blocking area, and the low-temperature execution area. The design was carried out from four levels: material matching, structural layout, heat insulation path control, and air path protection strategy, and a heat-resistant clamping claw, A composite insulation structure composed of a ceramic wear-resistant contact layer, a glass-ceramic insulation bridge, a ceramic fiber insulation layer, an air insulation tank and a radiation reflector; combined with equivalent thermal conductivity calculation and thermal-structure coupled finite element analysis, the temperature field, thermal stress and thermal deformation of different solutions were compared.
The results show that the proposed composite insulation structure can reduce the equivalent thermal conductivity of the main heat transfer path to approximately 0.25 W/(m·K); Under typical working conditions of a workpiece surface temperature of 650 °C, a single clamping time of 20 s, and an ambient temperature of 35 °C, the maximum temperature at the root of the clamp can be controlled within 83 °C, the temperature of the cylinder mounting surface within 55 °C, and the temperature of the outer wall of the pneumatic tubing within 68 °C. Compared with the metal integral direct connection solution, the main heat transfer heat flow density is reduced by approximately 98.7%, and the air path thermal protection efficiency reaches 76.9%, and the thermal deformation of the clamp end is controlled within 0.20 mm.
01Introduction
In processes such as forging, heat treatment, casting, die-casting, sintering and deep processing of steel, high-temperature workpieces need to be automatically transported with the help of manipulators, industrial robots, trusses or special fixtures during the heating, unloading, transfer, loading and unloading and process connection stages. Compared with normal temperature transportation, high temperature transportation is accompanied byEnhanced thermal radiation, significant contact heat transfer, concentrated thermal stress, shedding of oxide scale and thermal shockIn complex working conditions, the clamp must not only meet the requirements of clamping force, stiffness and positioning accuracy, but also must have good thermal insulation performance, stable air path protection and complete safety control.
Common problems with on-site high-temperature clamps are concentrated in four aspects: first, there is a continuous metal heat conduction path between the gripper and the actuator, forming an obvious thermal bridge; second, only the heat resistance of the gripper material is emphasized and system-level insulation is ignored; third, the air hose and pneumatic components near the heat source are unreasonably arranged, which is prone to hose hardening, air leakage and clamping failure; fourth, there is a lack of maintainability design, and the replacement of ceramic pads, heat shields, protective covers and air hose sheaths is complicated. Therefore, the core of high-temperature fixture design is not simply "high temperature resistance", but the overall planning of clamping load, heat flow interruption, pneumatic circuit protection, structural stability and convenient maintenance under limited space, mass and rhythm constraints.
02Research background and current situation analysis
2.1 Thermal action mechanism of high-temperature workpiece handling fixtures
The heat input of the fixture during high-temperature handling mainly comes fromContact heat transfer, radiation heat transfer and convection heat transferCategory three. Contact heat transfer occurs in the contact area between the clamping jaw and the workpiece, and is the main channel for high-temperature end heat to enter the fixture; radiation heat transfer cannot be ignored when the workpiece temperature exceeds 500 °C; convection heat transfer comes from the local flow field formed by high-temperature air in the workshop, hot air disturbance at the furnace mouth, and movement of the fixture. The coupling of the three makes the temperature field of the fixture obviously non-uniform, and the heat is transferred to the low temperature end along the connecting plate, screws, pins, guides and cylinder connectors. For pneumatic clamps, pneumatic tubing softening, joint seal failure, cylinder grease deterioration and sensor malfunction often occur before the strength failure of the metal structure. Therefore, air path protection and structural insulation are equally important.
2.2 Problems with existing high-temperature fixture design
Existing solutions mostly use overall heat-resistant steel or stainless steel structures, which are easy to process, but the continuous connection of high and low temperature end metals makes the thermal resistance small; the other type uses ceramic gaskets for local heat resistance, but if the selection, thickness and installation are improper, both heat insulation and reliability are limited. For example, alumina ceramics are wear-resistant, pressure-resistant, and high-temperature resistant, but their thermal conductivity is not low. They are more suitable as a contact wear-resistant layer rather than as a separate main thermal insulation layer. Ordinary PU, nylon, and rubber pneumatic tubing are prone to hardening, cracking, aging, and leakage under high-temperature radiation and hot air erosion. Therefore, high-temperature fixtures should not only rely on improving the temperature resistance level of a single component, but should comprehensively design from structural paths, insulation levels, pneumatic circuit layout and control logic.
2.3 Development Trend of High Temperature Fixture Design
With the increasing application of industrial robots and automated handling in the thermal processing industry, high-temperature fixtures are being replaced by single heat-resistant materials.Composite insulation, modular maintenance and safety interlockingDirection of development: The high-temperature end is made of heat-resistant alloy to bear the clamping load, the middle layer is made of low thermal conductivity material to form a thermal blocking bridge with the air cavity, the periphery is equipped with a reflective heat shield to reduce radiation input, the pneumatic and detection components are placed behind the low-temperature area, the pneumatic circuit near the heat source is combined with a metallization and heat-insulating sheath, and safety interlocking is achieved through pressure, temperature and clamping status signals. Combined with custom tooling engineering practice, this customized logic should be further expanded toIntegrated thermal–mechanical–pneumatic–control design。
03Design method of high temperature workpiece handling fixture
3.1 Design conditions and target parameters
The more common short-cycle handling conditions of high-temperature forgings/heat-treated parts are selected: after the workpiece is released from the furnace, the grabbing, transfer and placement are completed in a short time. The clamp is installed at the end of the robot or the end of the truss, and the pneumatic actuator is used as the clamping power source.
| Project | Parameter value | design significance |
|---|---|---|
| Workpiece surface temperature | 650 °C | Corresponding to short-term transportation conditions after being released from the furnace |
| ambient temperature | 35 °C | Consider the high temperature environment in the furnace workshop |
| Workpiece quality | 80 kg | Medium-sized forgings or heat-treated parts |
| Single clamping time | 20 s | Typical cycle times for robot or truss handling |
| cycle frequency | 30～40 cycles/h | Continuous production-line cycle time |
| Operating Air Pressure | 0.6 MPa | Common pneumatic execution pressure |
| Moving load acceleration | 2.0 m/s² | Consider start-stop shock |
| Clamping safety factor | ≥2.5 | Prevent slippage and thermal decay |
| Cylinder mounting surface temperature | ≤60 °C | Protect seals and lubrication status |
| air-line outer wall temperature | ≤70 °C | Prevent hose thermal aging |
| Thermal deformation of tooling end | ≤0.25 mm | Ensure repeated positioning and clamping stability |
Table 1 Typical high temperature workpiece handling conditions parameters
3.2 Clamping force calculation and structural load-bearing requirements
When using double-sided clamping, the normal clamping force required by the single-sided clamping jaw can be preliminarily checked according to the friction clamping model:
where Fn is the one-sided normal clamping force (N), S is the safety factor, m is the workpiece mass (kg), g is the acceleration of gravity, a is the acceleration of the moving load (m/s²), and μ is the high-temperature contact friction coefficient. Assuming S=2.5, m=80 kg, a=2.0 m/s², μ=0.35, the required clamping force on one side is approximately 3371 N; Considering the oxide scale, vibration impact, clamping jaw wear and friction coefficient fluctuation, the rated clamping force of one side in engineering design should not be less than 4.2 kN. 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.
3.3 Functional partition design principles
Divide the fixture into three functional areas:High temperature bearing areaDirect contact or close to the workpiece, responsible for clamping force, heat resistance and oxidation resistance;Thermal blocking zoneLocated between the gripper and the actuator, it reduces heat flow density, blocks thermal bridges and buffers thermal stress;low temperature execution areaArrange the cylinder, guide rail, valve manifold, sensor and robot connection structure to avoid direct action of high-temperature radiation. The key is to avoid mixing load-bearing, thermal insulation and performance functions in the same continuous metal structure.
3.4 Material selection and structural layout
| parts | Recommended materials | Main function | Reason for selection |
|---|---|---|---|
| Gripper-jaw front load-bearing member | Inconel 625 or heat resistant stainless steel | Withstand clamping loads and face high temperature radiation | High temperature strength, oxidation resistance, corrosion resistance |
| Workpiece contact layer | 96% alumina ceramic | Wear-resistant, pressure-resistant, reduces metal adhesion | Suitable for replaceable wear pads and not used as the sole primary insulation layer |
| Thermal insulation bridge block | Macor glass ceramic | Block heat transfer from the clamping jaw to the mounting base | Low thermal conductivity, machineable, suitable for positioning insulation blocks |
| Flexible insulation | ceramic fiber blanket | Reduce cavity conduction and radiation heat transfer | Low thermal conductivity, low heat capacity, thermal shock resistance |
| thermal insulation cavity | Air slot structure | Weaken continuous solid thermal bridges | Simple structure, low quality, can be combined with fiber layer |
| reflective shield | 304/316 stainless steel sheet | Shield radiant heat and protect air path | Easy to form, disassemble and replace |
| Low temperature end bracket | Stainless steel or low alloy steel | Provide installation and load-bearing stiffness | Good processability, but continuous thermal bridges need to be avoided |
| Pneumatic circuit near heat source | 316 stainless steel pipe or stainless steel braided PTFE hose | Improve temperature resistance and mechanical damage resistance | Suitable for short distance pipelines close to heat sources |
Table 2 Materials and functions of main components of the fixture
The front end of the clamping jaw is made of heat-resistant alloy to bear the main clamping load; the contact surface is equipped with a replaceable alumina ceramic wear-resistant pad; a Macor glass-ceramic thermal insulation bridge is installed between the root of the clamping jaw and the mounting base, and the air thermal insulation groove and ceramic fiber filling layer form a multi-level thermal resistance; a stainless steel thin plate reflective shield is installed on the outside. Screws, positioning pins and pressure plates are sources of thermal bridges that are easily overlooked. The high-temperature end screws should be prevented from directly penetrating into the low-temperature end mounting base. If necessary, segmented fastening, heat-insulating bushings, thin-neck screws or local section reduction should be used; the ceramic pads should be pre-tightened by surface contact and mechanically limited, and it is not advisable to rely on adhesives to withstand high-temperature shear.
04Thermal insulation performance analysis and optimization
4.1 Heat transfer model
The main heat transfer path from the clamping jaw to the mounting base can be estimated using a multi-layer flat plate series steady-state conduction model in the preliminary design stage:
Radiation heat transfer is estimated as follows:
In the formula, Q is the heat transfer (W), keq is the equivalent thermal conductivity, ε is the surface emissivity, and σ is the Stefan-Boltzmann constant. For 650 °C workpieces, radiant heat has a significant impact on the air hose, sensor and thin-walled structure. Contact heat insulation alone is not enough to ensure safety, and a reflective protective cover should be installed.
4.2 Calculation of equivalent thermal conductivity of composite insulation structures
Taking the equivalent heat transfer path on one side as an example, take the heat transfer area A=1200 mm², the high temperature side is 650 °C, and the low temperature side target is 35 °C. The parameters of the composite insulation layer are as follows.
| Hierarchy | material or structure | Thickness/mm | Thermal conductivity W/(m·K) | Thermal resistance L/k /(m²·K/W) |
|---|---|---|---|---|
| 1 | Inconel 625 heat-resistant gripper part | 3 | 17.5 | 0.00017 |
| 2 | Alumina ceramic wear pads | 5 | 24.7 | 0.00020 |
| 3 | Macor glass ceramic insulation blocks | 8 | 1.46 | 0.00548 |
| 4 | ceramic fiber insulation | 12 | 0.16 | 0.07500 |
| 5 | Equivalent layer of air thermal insulation tank | 4 | 0.085 | 0.04706 |
| total | Composite Insulated Path | 32 | 0.25 (equivalent) | 0.12791 |
Table 3 Composite insulation path parameters
From equation (3), the equivalent thermal conductivity of the composite insulation path is obtained:
Heat flow density per unit area:
One-sided heat transfer:
If metals of the same thickness are directly connected as a whole (average thermal conductivity is 20 W/(m·K)), the heat flow density is about 3.84 × 10⁵ W/m². In comparison, the composite insulation structure can reduce the heat flow density of the main heat transfer path.Reduced by approximately 98.7%. The real main insulation functions are the Macor insulation bridge, ceramic fiber layer and air insulation groove; alumina ceramics should be used as a contact wear-resistant layer rather than as a separate main insulation due to their high thermal conductivity.
4.3 Boundary conditions for heat flow simulation
| border project | value |
|---|---|
| Workpiece contact surface temperature | 650 °C |
| Workshop ambient temperature | 35 °C |
| natural convection heat transfer coefficient | 8 W/(m²·K) |
| High temperature workpiece radiant emissivity | 0.75 |
| Metal shield outer surface emissivity | 0.35～0.45 |
| clamp contact time | 20 s |
| Steady state check time | 1800 s |
| Air-hose outer surface safety targets | ≤70 °C |
| Cylinder mounting surface safety objectives | ≤60 °C |
Table 4 Boundary conditions for heat flow simulation
The thermal-structural coupling method is used: first find the temperature field, then import it as a structural load, superimpose the clamping force, gravity, dynamic load acceleration and constraint boundaries to solve for thermal stress and thermal deformation. The focus of the analysis is the temperature at the root of the gripper jaw, the thermal stress at the edge of the heat insulation block hole, the temperature of the cylinder mounting surface, the temperature of the outer wall of the air line and the end thermal displacement.
4.4 Finite element analysis results
| solution | Structural description | Maximum temperature at the root of the clamp jaw/°C | Maximum temperature of cylinder mounting surface/°C | Maximum temperature of outer wall of air line/°C | Maximum equivalent stress/MPa | End thermal deformation/mm | Evaluation |
|---|---|---|---|---|---|---|---|
| A | 304 stainless steel overall direct connection, no protection | 312 | 186 | 156 | 221 | 0.46 | Does not meet pneumatic safety requirements |
| B | Metal gripper + single layer ceramic pad | 168 | 104 | 121 | 138 | 0.29 | There is improvement, but the pneumatic line is still hot |
| C | Composite insulation structure + reflective shield | 83 | 54 | 62～68 | 118 (metal area)/42 (ceramic broken bridge area) | 0.18 | Meet continuous handling requirements |
Table 5 Comparison of thermal-structural analysis results of different structural schemes
Plan C has significant advantages in temperature control and deformation control: compared with plan A, the temperature at the root of the clamping jaw is reduced by about 73.4%, the cylinder mounting surface is reduced by about 71.0%, the outer wall of the pneumatic tubing is reduced by about 56% to 60%, and the thermal deformation at the end is reduced by about 60.9%. The main temperature drop is concentrated in the Macor insulation block, ceramic fiber layer and air insulation groove area. The maximum thermal stress is concentrated on the edge of the screw hole of the heat insulation block, the transition area of the clamping jaw step and the edge of the ceramic pad pressure plate: the maximum thermal stress of the Macor heat insulation block is about 42 MPa, which is within the safe range; the maximum equivalent stress at the root of the metal clamp jaw is about 118 MPa, which does not exceed the allowable value. The thermal deformation of the end is 0.18 mm, which is less than the design upper limit of 0.25 mm.
4.5 Key points for optimization of thermal insulation structure
- Reduce continuous solid thermal bridges: Avoid the high-temperature end screws from directly penetrating into the cylinder mounting base. If necessary, tighten in sections and use heat-insulating bushings and small-section connections.
- Separation of load-bearing and thermal insulation functions: Heat-resistant alloy load-bearing, ceramic pad wear-resistant, Macor and ceramic fiber heat insulation, reflector shielding radiation.
- Controlling tensile stress in ceramic parts: Ceramics have strong compression resistance but limited tensile/impact resistance. They should be pre-tightened by surface contact and not pressed with sharp corners. The screw holes should be chamfered and rounded.
- Set up maintainable insulation modules: Ceramic pads, thermal insulation fibers, reflectors and air-line sheaths are designed as modular wearing parts for quick replacement.
05Pneumatic-circuit protection design
5.1 General principles of pneumatic circuit protection
follow"The compressed-air supply is far away from the heat source, metalized near the heat source, secondary insulation of the hose, the actuator is arranged in the low temperature area, and the pressure loss state is controllable"Principle. pneumatic tubing and joints are often the weakest links in thermal failure. Air path protection should be designed simultaneously at the structural plan stage rather than as a later attachment. pneumatic tubing near the heat source should adopt a combination of back-heat side layout, metal pipe transition, thermal insulation sheath protection and reflector shielding.
5.2 Safety measures for compressed-air supply interface
The compressed-air supply interface should be arranged above the fixture, on the back side of the robot flange or at the fixed end of the equipment, with a straight-line distance of not less than 300 mm from the high-temperature workpiece; when space is limited, use a reflector, heat shield or structural shield to avoid direct radiation.
| Air supply interface unit | design measures | Main function |
|---|---|---|
| Manual stop valve | Set lock function | Reliably isolate the compressed-air supply during maintenance |
| Filter pressure reducing valve | The pressure is stable at 0.55～0.65 MPa | Ensure stable clamping force |
| One-way valve | Prevent pressure backflow | Avoid abnormal pressure relief |
| Pressure maintaining valve or small gas storage unit | Maintain short-term clamping after shutting off air | Prevent workpieces from falling instantly |
| Safety relief valve | Release in case of overpressure | Prevent pneumatic line from bursting |
| pressure sensor | Real-time detection of clamping pressure | Interlocked with robot safety logic |
| Temperature tag or thermocouple | Monitor interface area temperature | Identify local heat accumulation |
Table 6 Safety measures for compressed-air supply interface
For high-temperature workpieces that must be clamped and moved, it is recommended to use "Clamping holds priority"Pneumatic logic: When the power supply, compressed-air supply or control signal is abnormal, priority is given to maintaining clamping or mechanical self-locking, and is only allowed to be loosened when the workpiece reaches the safe placement area, is supported in place and the air pressure is stable.
5.3 Air-hose insulation design
The air hose near the heat source adopts three-level path control: ①Route control - arranged along the low temperature side and back heat side, without passing through the high radiation area directly in front of the clamping jaw; ②Material control - priority is given to 316 stainless steel hard pipe, stainless steel corrugated pipe or stainless steel braided PTFE within 100~300 mm of the heat source hose, move away from it and then transfer to an ordinary flexible air line; ③ External protection - the air line is equipped with a ceramic fiber casing, fiberglass silicone casing or stainless steel corrugated sheath, and a removable reflective baffle on the outside.
The thermal protection efficiency of the air line is evaluated as follows:
Taking the outer wall of the unprotected air hoses at 178 °C, after protection at 68 °C, and at an ambient temperature of 35 °C, the thermal protection efficiency reaches 76.9%, the temperature of the outer wall of the air line can be controlled within 70 °C, meeting the air path safety goal of continuous transportation.
5.4 Thermal protection design of pneumatic components
Prioritize "staying away from heat sources" instead of simply improving the temperature resistance level: the cylinder barrel is arranged in the low temperature zone, and the gripper jaw is driven through a heat-resistant connecting rod, lever mechanism or heat-insulating push rod; a ceramic heat insulation sleeve and a thin-walled metal heat insulation cap are installed between the piston rod and the high-temperature gripper jaw. The solenoid valve, speed control valve and manifold are arranged on the back of the robot's wrist, the side of the truss slide or the fixed end of the equipment. Only the necessary short air paths are reserved at the clamp end. When the radiation at the furnace mouth is strong, low-flow compressed air of 20 to 40 L/min can be used to form a purge air curtain outside the heat shield, and the nozzle should avoid the direction of the oxide scale splash. Pipes in high-temperature areas can be equipped with visual temperature labels. If the temperature exceeds 80 °C, the machine should be shut down for inspection.
06Safety Assessment and Industrial Applications
6.1 Failure modes and risk control
The safety assessment covers four types of risks: mechanical, thermal, pneumatic and control.
| failure mode | Possible Causes | main consequences | control measures | Suggested quantitative indicators |
|---|---|---|---|---|
| Workpiece slips | Insufficient clamping force, oxide scale falling off, air pressure drop | Equipment damage or personal injury | Improved safety factor, V-shaped groove/mechanical limit, pressure maintaining valve | Single-side clamping force ≥4.2 kN; air pressure <0.45 MPa. Handling is prohibited |
| Thermal aging of air line | The air hose is close to the heat source and lacks heat insulation cover | Air leakage, pipe burst, clamp pressure loss | Back heat side wiring, metal pipe replacement, thermal insulation sheath | Air-line outer wall ≤70 °C |
| Cylinder seal damage | The temperature of the cylinder rises too high and the piston rod conducts heat | Sluggish movement and reduced clamping force | Rear-mounted cylinder, heat-insulating push rod, reflective cover | Cylinder mounting surface ≤60 °C |
| Ceramic pad cracked | Thermal shock, point contact, pressure plate stress concentration | The contact surface is damaged and the clamping is unstable. | Surface contact preload, rounded corner transition, replaceable modules | Ceramic tensile stress safety factor ≥3 |
| Thermal deformation of gripper jaws | The temperature gradient is too large and the structure is asymmetrical | Clamping offset load and positioning error | Symmetrical insulation, adding stiffeners, and simulation verification | End thermal deformation ≤0.25 mm |
| Personnel burns | Missing protective cover and exposed high temperature surface | personal injury | Heat shields, warning signs, interlocking areas | Contactable outer surface ≤55～60 °C |
| Sensor malfunction | High temperature, heat radiation, cable aging | Action logic error | Sensor rear, metal hose, electrical insulation | Sensor mounting surface ≤50 °C |
Table 7 Main failure modes and control measures
6.2 Industrial application scenarios
This solution can be applied to many types of high-temperature automated handling:Forging loading and unloading(round bar, billet, die forging, heat-resistant alloy clamp + ceramic pad + mechanical step support);Heat treatment and transportation(Material frames, trays, shafts/disks, etc., focusing on strengthening radiation protection and remote placement of air hoses);Die casting/post-casting processing(Enhanced oxide scale, flash and thermal particle impact protection, and the reflector cover can be quickly replaced). The high-temperature fixture at the end of the six-axis robot should control mass, center of gravity offset and heat transfer at the same time. The cylinder/valve manifold/sensor should be as close as possible to the back of the robot flange. The installation space of the truss or gantry handling fixture is large, and a thicker insulation cavity and external valve box solution can be used.
6.3 Project implementation suggestions
- Establish a heat source inventory during the design phase: Record the workpiece and furnace mouth temperature, residence time, oxide scale splash direction, robot path and contact area.
- Infrared temperature measurement and thermocouple verification at prototype stage: Arrange points at the root of the clamping jaw, the cylinder mounting surface, the outer wall of the pneumatic tubing, the valve island plate and the sensor mounting surface, and record the temperature rise curve after continuous operation for no less than 2 hours.
- Cycle life test before mass production: At least 10000 no-load cycles and 2000 simulated heat-source clamping cycles; inspect ceramic pads for cracks, fasteners for loosening, air lines for hardening, seals for leakage, and repeatability.
- On-site maintenance institutionalization: Inspect ceramic pads every shift and thermal-insulation fibers weekly; inspect air-line protective sleeves monthly and replace them whenever damaged. If the air-line outer wall exceeds >80 °C or the cylinder mounting surface exceeds >70 °C, stop the machine immediately and investigate.
- Control system safety interlock: Clamping, air pressure, robot in place and workpiece support in place signals form a closed loop; high-speed handling is not allowed when the air pressure is insufficient, the clamping is not in place or the temperature exceeds the limit.
07Conclusion and outlook
Conclusion:(1) The high-temperature handling fixture should adopt a functional partition design, dividing the high-temperature load-bearing area, the thermal insulation blocking area and the low-temperature execution area; (2) The composite insulation structure is more effective than a single heat-resistant material; (3) The equivalent thermal conductivity of the composite insulation path can be reduced to about 0.25 W/(m·K), and the main heat transfer heat flux density is about 98.7% lower than that of metal direct connection; (4) The cylinder mounting surface is ≤55 under 650 °C working conditions. ℃, the outer wall of the air line is ≤ 68 °C, which is sufficient for continuous operation; (5) The pneumatic-circuit protection must be systematically designed, and simply improving the temperature resistance level is not enough to solve the problem; (6) Focus should be placed on maintainability, and key insulation parts should be modularized and regularly inspected and replaced.
Outlook:In the future, a thermal fatigue life model of the ceramic-metal connection interface can be established, actual measurements and comparisons of different insulation material combinations can be carried out to form a selection database, and temperature sensing, air pressure monitoring and clamping force feedback can be integrated into the control system to achieve predictive maintenance and digital safety assessment of high-temperature handling fixtures.
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