Extrusion Press Electro-Hydrostatic Control for Low-Oil Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Strand presses in the state of the art require large oil volumes due to high volume flows, leading to complex and costly hydraulic systems, space inefficiencies, and increased installation complexity, with existing methods for reducing oil volume being technically complex and prone to errors.
Innovation Solution
The implementation of an electrohydrostatic control system with compact drives and a separate drive for the press cylinder and shear tool, utilizing a combination of differential cylinders and electromechanical drives to reduce oil volume requirements and optimize space usage, allowing for alternation between different functionalities within the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If large volume flows are supplied by high-capacity pumps to achieve rapid traverse and compression movements, then the required movements and forces are achieved, but the oil volume in the reservoir must be 5 to 10 times greater than the installed pump delivery rate, leading to large and space-consuming reservoirs
Solution Approach 1:
The hydraulic system is segmented into multiple independent electro-hydrostatic units, each with its own pump and control system. This allows each unit to operate independently with smaller oil volumes, eliminating the need for a single large reservoir while maintaining the required rapid traverse speeds through coordinated operation of multiple units.
Solution Approach 2:
The electro-hydrostatic units are designed to perform multiple functions - they can supply oil for rapid traverse, power traverse, compression, and decompression operations. This multi-functionality allows a single unit with smaller oil volume to replace multiple specialized hydraulic systems that would require larger total oil volumes.
2Reliability
If degassed oil is used to reduce cavitation during pump suction and decompression, then cavitation is reduced, but the system becomes technically complex and costly with additional piping and degassing equipment
Solution Approach 1:
The electro-hydrostatic units incorporate self-priming pump designs and controlled startup sequences that automatically prevent cavitation without requiring external degassing equipment. The system serves itself by managing oil intake and pressure control internally, eliminating the need for complex degassing systems while maintaining reliability.
Solution Approach 2:
The control system performs preliminary actions by pre-conditioning the oil supply before it reaches the pump - including pressure regulation and air venting - to prevent cavitation from occurring in the first place. This proactive approach eliminates the need for reactive degassing equipment.
3Reliability
If large oil reservoirs are installed at heights of 2 to 3 meters above the extrusion press to improve pump suction, then suction conditions are improved, but the installation space requirements and structural complexity increase significantly
Solution Approach 1:
The system replaces the mechanical gravity-based oil supply (requiring elevated reservoirs) with an electro-hydrostatic pump system that actively delivers oil under pressure. This substitution eliminates the need for elevated installation while maintaining or improving suction conditions through controlled positive displacement pumping.
Solution Approach 2:
The electro-hydrostatic units act as intermediaries between the oil reservoir and the hydraulic actuators, providing controlled oil delivery without requiring the reservoir to be positioned at elevated heights. The intermediary pump system manages the oil flow and pressure, decoupling the reservoir position from the actuator performance.
4Productivity
If complex piping systems with large return lines are installed to handle required flow rates, then adequate oil circulation is achieved, but the piping system becomes expensive and requires significant customization and installation effort
Solution Approach 1:
The return line system is segmented into local return circuits for each electro-hydrostatic unit, allowing smaller diameter pipes to be used locally. Each unit's oil return can be handled by smaller piping, and these local circuits can be independently installed and connected, significantly reducing the overall piping complexity and installation effort compared to a single large centralized return line.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the necessary oil volume, simplifies piping, and decreases installation complexity and costs, while enabling efficient quick movements and reduced standstill times in the production process.
Implementation Method 1
the press cylinder is driven for a power traverse by an electro-hydrostatic control system
Implementation Method 2
utilizing a combination of differential cylinders
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an extrusion press (10, 20, 30) with a press cylinder (111), which is driven by a electro-hydrostatic control system (104) for a power mode and is connected to a separate drive (120) for a speed mode, a detector (115), which is connected to a hydraulic cylinder (117) for the power mode and to an additional separate drive (119, 300) for the speed mode, and a hydraulic cylinder (101) with a blocking device (103) for the drive of a shearing tool (102), wherein the hydraulic cylinder (101) is connected to the electro-hydrostatic control system (104), and the press cylinder (111), in the power mode, and the hydraulic cylinder (101) for the drive of the shearing tool (102) are controlled in an alternating manner via the common electro-hydrostatic control system (104).