CLADDING TECHNOLOGY SHANXI CO., LTDExperimental and Simulation Research on Composite Lifting and Slewing Actions of Hydraulic Excavators
Literature Overview and Context
While this study focuses on hydraulic excavator operations rather than bimetal manufacturing directly, the underlying principles of composite hydraulic action dynamics, transient response characteristics, and system coordination are directly transferable to the design and operation of hydraulic forming and cladding equipment. The study under review investigates the dynamic behavior of hydraulic excavators when lifting and slewing actions are performed simultaneously, providing insights into the transient pressure and flow characteristics that arise from multi-actuator coordination. These insights are applicable to hydraulic multi-way valve systems used in bimetal forming presses, where simultaneous actuator actions create similar transient phenomena.
Core Technical Content
The research examines the coupled dynamics of the boom cylinder, arm cylinder, and slew drive when operating simultaneously. The key findings include:
- Flow interaction: When the boom and arm cylinders act simultaneously with the slew drive, the combined flow demand can exceed the pump's rated flow capacity, causing pressure drops that reduce actuator force and potentially trigger pressure relief valve activation.
- Pressure transient coupling: The pressure waves generated by rapid boom and arm movements propagate through the common hydraulic manifold and affect the slew drive pressure, causing momentary torque fluctuations.
- Energy dissipation: The simultaneous operation of multiple actuators increases the total power dissipation in the hydraulic system, leading to elevated fluid temperatures that affect viscosity and lubrication characteristics.
- Control stability: The interaction between the composite actions and the control system introduces dynamic coupling that can reduce the stability margin of individual actuator position control loops.
Key Technical Parameters
| Parameter | Typical Value | Effect on Composite Action Performance |
|---|---|---|
| Pump rated flow | 200–400 L/min | Must exceed sum of individual actuator demands |
| System pressure | 20–35 MPa | Pressure drop under composite load |
| Boom cylinder bore | 150–250 mm | Determines boom cylinder flow demand |
| Arm cylinder bore | 100–180 mm | Determines arm cylinder flow demand |
| Slew motor displacement | 50–150 mL/rev | Determines slew drive flow demand |
| Fluid temperature rise | 5–20 °C per cycle | Affects viscosity and system efficiency |
| Composite action response time | 200–800 ms | Depends on flow availability and control strategy |
Application to Bimetal Forming Equipment
The transient dynamics identified in this study have direct relevance to the hydraulic systems used in bimetal pipe forming and cladding operations:
| Excavator Component | Bimetal Forming Equivalent | Relevance |
|---|---|---|
| Boom cylinder | Main forming cylinder (axial) | Large bore, high force, slow speed |
| Arm cylinder | Secondary forming cylinder (radial) | Smaller bore, moderate force |
| Slew drive | Clamping cylinder or positioning actuator | Rotary or linear motion, moderate force |
| Multi-way valve | Forming press valve manifold | Coordinates multiple actuator actions |
| Pump and accumulator | Forming press hydraulic power unit | Must supply combined flow demand |
The study demonstrates that when multiple actuators operate simultaneously, the peak pressure transient can exceed the steady-state pressure by 15–30 percent, depending on the rate of actuator movement and the hydraulic line geometry. This is consistent with findings from the multi-way valve transient study and reinforces the importance of accumulator buffering and staged valve sequencing in bimetal forming applications.
Control Strategy Implications
The research proposes several control strategies for managing composite action transients:
- Flow priority allocation: Assigning priority to the most critical actuator during composite actions to ensure it receives adequate flow while secondary actuators operate at reduced speed
- Pressure limiting: Implementing individual pressure limits for each actuator that sum to less than the system maximum pressure, preventing relief valve activation
- Adaptive control: Using real-time pressure and flow feedback to dynamically adjust valve spool positions and maintain stable operation during composite actions
- Pre-cooling: Ensuring the hydraulic fluid is at optimal temperature before initiating composite actions to minimize viscosity-related flow losses
Study Insights and Reflections
Although this study is conducted in the domain of construction machinery rather than bimetal manufacturing, the fundamental hydraulic dynamics of composite actuator operations are universal. The transient pressure and flow phenomena identified here are directly applicable to the design and optimization of hydraulic forming presses used for bimetal composite pipe production. The study's emphasis on flow interaction, pressure transient coupling, and control stability provides a valuable framework for understanding the challenges of multi-actuator coordination in high-pressure forming operations. Engineers involved in specifying hydraulic systems for bimetal manufacturing equipment should consider the composite action dynamics demonstrated here when selecting pump capacity, accumulator sizing, valve response characteristics, and control strategies. The practical takeaway is that hydraulic systems designed for simultaneous multi-actuator operation require significantly more careful analysis than systems with single-actuator operation, and the margin between acceptable and unacceptable performance is often narrower than initially anticipated.