Dual-Pump Die Cushion Pressure Control for Press Rigidity
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Solution Overview
Problem
In press machines, the die cushion pad is supported at a low pressure during collisions, resulting in unsatisfactory reaction forces and pushing forces for molded products, leading to inaccurate and rigid die cushion control.
Innovation Solution
A die cushion apparatus with dual hydraulic pumps, where the control unit adjusts the rotation speeds of the pumps to precisely control hydraulic oil flow and pressure, incorporating relief valves and pressure sensors to manage surge pressures and optimize die cushion control, enabling high accuracy and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a single-acting hydraulic cylinder is used to support the die cushion pad, then the structure is simple, but the die cushion pad is supported at low pressure resulting in unsatisfactory reaction force and pushing force
Solution Approach 1:
The hydraulic cylinder is divided into two independent hydraulic systems (first and second hydraulic circuits), each with its own pump, relief valve, and pressure sensor. This segmentation allows independent control of pressure on both sides of the piston, enabling high-pressure support while maintaining structural clarity through modular hydraulic circuits.
Solution Approach 2:
The patent employs dual hydraulic pumps (first and second hydraulic pumps) that can independently supply high-pressure hydraulic oil to respective ports of the hydraulic cylinder. This hydraulic configuration enables the die cushion pad to be supported at high pressure, generating sufficient reaction force and pushing force for accurate die cushion control.
2Manufacturing precision
If hydraulic pressure is increased to improve die cushion control accuracy, then control precision improves, but surge pressure generation becomes a problem
Solution Approach 1:
Pressure sensors (first and second pressure sensors) are installed in both hydraulic circuits to detect actual pressure in real-time. The control unit receives feedback from these sensors and adjusts pump rotation speeds accordingly, enabling precise pressure control that prevents surge pressure while maintaining high die cushion control accuracy.
Solution Approach 2:
The control unit dynamically adjusts the rotation speeds of the first and second hydraulic pumps based on detected pressure values. By changing the rotational speed parameter, the system can precisely control hydraulic pressure output, preventing surge pressure generation while maintaining high-pressure support for accurate die cushion control.
3Stability of the object's composition
If dual hydraulic pumps are used to control pressure on both sides of the piston, then die cushion control rigidity improves, but the system complexity increases
Solution Approach 1:
Both the first and second hydraulic pumps serve multiple functions: they supply hydraulic oil for pressure support, enable bidirectional piston movement, and can operate in reverse to prevent surge pressure. This multi-functionality justifies the dual-pump configuration by providing enhanced control rigidity while consolidating operational requirements into two versatile components.
Solution Approach 2:
The control unit dynamically adjusts the rotation speeds of both hydraulic pumps based on real-time pressure feedback from the pressure sensors. This dynamic control enables the system to maintain optimal pressure balance on both sides of the piston, achieving high die cushion control rigidity while adapting to varying operational conditions to prevent surge pressure.
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
The solution achieves high-accuracy and high-rigidity die cushion control by managing hydraulic pressures and suppressing surge pressures, enhancing the precision and stability of press molding processes.
Implementation Method 1
a first hydraulic pump configured to supply hydraulic oil to a first port of the hydraulic cylinder and drive the piston of the hydraulic cylinder upward; a second hydraulic pump configured to supply hydraulic oil to a second port of the hydraulic cylinder and drive the piston of the hydraulic cylinder downward
Implementation Method 2
a first relief valve configured to return to the oil tank the hydraulic oil discharged from the hydraulic cylinder through the first port; wherein the control unit rotates the first hydraulic pump reversely when the pressure of the hydraulic oil detected by the first pressure sensor is equal to or more than a set pressure for the first relief valve
Data Source
Figure 1
Figure 2
AI summary
A die cushion apparatus (200) includes: a double-acting hydraulic cylinder (210) configured to move a cushion pad (140) up and down; a first hydraulic pump (P1) configured to supply a hydraulic oil from an oil tank (T) to a first port (210a) of the hydraulic cylinder (210) and to drive a piston (212) of the hydraulic cylinder (210) upward; a second hydraulic pump (P2) configured to supply the hydraulic oil from the oil tank (T) to a second port (210b) of the hydraulic cylinder (210) and to drive the piston (212) of the hydraulic cylinder (210) downward; and a control unit (260) configured to control a rotation speed of the first hydraulic pump (P1) and a rotation speed of the second hydraulic pump (P2) and to control a flow rate and a pressure of the hydraulic oil which the first hydraulic pump (P1) supplies to the hydraulic cylinder (210) and a flow rate and a pressure of the hydraulic oil which the second hydraulic pump (P2) supplies to the hydraulic cylinder (210).