Dual-Hydraulic Die Cushion Control for Stable Pre-Pressurization
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Solution Overview
Problem
Conventional die cushion devices experience issues with pre-pressurization of cushion pads at standby positions, leading to unstable positioning, bending of blanks, and variations in pre-pressurization forces, which affect processing accuracy and product quality.
Innovation Solution
A die cushion device with a first hydraulic cylinder and first hydraulic circuit for pressure control, and a second hydraulic cylinder and second hydraulic circuit for position control, allowing for precise pre-pressurization and positioning of the cushion pad at the die cushion standby position, ensuring consistent pressure and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If pressure oil is supplied to the lower chamber to pre-pressurize the cushion pad, then the cushion pad is pre-pressurized, but the cushion pad moves upward causing rising amount
Solution Approach 1:
A pilot-operated check valve is introduced as an intermediary component in the hydraulic circuit. This valve allows controlled communication between the upper and lower chambers, enabling the lower chamber to be pressurized while preventing uncontrolled upward movement of the cushion pad. The valve acts as a mediator that permits pressure equalization without allowing position deviation.
Solution Approach 2:
The system changes the pressure parameters dynamically by controlling the pilot pressure to the check valve. By adjusting the pilot pressure, the system enables pre-pressurization of the lower chamber while maintaining the cushion pad at the correct position, thus changing pressure conditions without causing position errors.
2Force
If hydraulic oil is prevented from flowing out from the upper chamber during pre-pressurization, then the lower chamber can be pressurized, but the hydraulic oil in the upper chamber is compressed causing cushion pad rise
Solution Approach 1:
The pilot-operated check valve serves as an intermediary that connects the upper and lower chambers during pre-pressurization. It allows hydraulic oil to flow from the upper chamber to the lower chamber in a controlled manner, preventing compression of oil in the upper chamber and eliminating cushion pad rise while maintaining position stability.
3Stress or pressure
If the cushion pad is moved upward during pre-pressurization, then the lower chamber pressure increases, but the die cushion standby position varies in each cycle
Solution Approach 1:
The pilot-operated check valve acts as a mediator that ensures consistent pressure transmission from the upper chamber to the lower chamber during pre-pressurization. This controlled pressure equalization prevents variations in the die cushion standby position across different cycles, improving reliability and consistency.
Solution Approach 2:
The system incorporates position detection and feedback control to monitor the cushion pad position during pre-pressurization. The feedback mechanism adjusts the pressure control to maintain the cushion pad at the correct standby position, preventing position variations and ensuring consistent die cushion force application.
4Stress or pressure
If the cushion pad rises during pre-pressurization, then the upper chamber pressure increases, but the pressure does not drop to the containment pressure level
Solution Approach 1:
The pilot-operated check valve enables controlled pressure equalization between chambers. It allows the upper chamber pressure to be reduced to the containment pressure level by facilitating controlled flow to the lower chamber, ensuring accurate die cushion force application without position deviation.
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 enables accurate positioning and pre-pressurization of the cushion pad, preventing blank bending, maintaining processing accuracy, and stabilizing product quality by ensuring consistent pre-pressurization forces across each cycle.
Implementation Method 1
a first hydraulic circuit configured to drive the first hydraulic cylinder... the first controller controls the first hydraulic circuit based on the first pressure command and the pressure detected by the first pressure detector
Implementation Method 2
a second hydraulic circuit configured to drive the second hydraulic cylinder... the second controller controls the second hydraulic circuit based on the second die cushion position command and the position of the cushion pad detected by the die cushion position detector
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The die cushion device according to the present invention includes a first hydraulic cylinder 120 and a second hydraulic cylinder 130 that are independently and simultaneously controlled. When a cushion pad 110 is pre-pressurized, pressure control is performed on the first hydraulic cylinder 120 via a first hydraulic circuit 140 so that a pressure in a lower chamber 120A of the first hydraulic cylinder 120 is pre-pressurized to a preset pressure, and position control is simultaneously performed on the second hydraulic cylinder 130 via a second hydraulic circuit 150 so that the cushion pad 110 is held in the die cushion standby position. A force with which the first hydraulic cylinder 120 moves the cushion pad 110 upward is balanced with a force with which the second hydraulic cylinder 130 moves the cushion pad 110 downward (a force for holding the die cushion standby position).