Hydraulic Powder Press Drive with Pre-Switched Pump Flow Control
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Solution Overview
Problem
Existing hydraulic drive devices for hydraulic presses, particularly powder presses, face challenges in preventing uncontrolled movements of press cylinders during switching, which complicates the design and control, leading to high costs and inefficiencies.
Innovation Solution
A hydraulic drive device with a press cylinder that includes a switching valve, a speed-controllable pressing movement pump, and a control unit. The device performs rapid movement when the switching valve is open and pressing movement when it is closed, with the pressing movement pump's conveyance rate increased before the switching valve closes to prevent uncontrolled movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a switching valve is used to separate rapid movement and pressing functions, then device complexity is reduced, but uncontrolled movements occur during valve switching
Solution Approach 1:
The control unit increases the conveyance rate of the pressing movement pump before the switching valve closes, so that fluid is already being supplied to the pressing chamber at an elevated rate prior to the valve transition. This preliminary action ensures that when the valve switches, there is no sudden pressure differential or uncontrolled fluid movement, thereby preventing uncontrolled cylinder movements while maintaining the simplified valve-based functional separation.
2Force
If a large piston area is used to generate high closing forces, then pressing force is improved, but volume flow increases requiring oversized pumps and valves
Solution Approach 1:
The system uses a speed-controllable pressing movement pump whose conveyance rate can be dynamically adjusted based on the operational phase. During rapid movement, the pump operates at lower conveyance rates, and during pressing movement, the control unit increases the conveyance rate before valve closure. This dynamic adjustment allows the system to achieve high closing forces with a large piston area while managing volume flow requirements efficiently, avoiding the need for continuously oversized pumps and valves.
3Speed
If switching valves are used to connect cylinder chambers cyclically, then rapid movement function is improved, but uncontrolled short-term movements occur during switching
Solution Approach 1:
The control unit monitors the operational state and timing of the switching valve, and based on this feedback, proactively adjusts the conveyance rate of the pressing movement pump. By detecting when the valve is about to switch and pre-increasing the pump conveyance rate, the system creates a feedback loop that prevents uncontrolled movements. This feedback mechanism ensures that the rapid movement function is maintained while eliminating the harmful uncontrolled short-term movements that occur during valve switching transitions.
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 solution effectively reduces uncontrolled movements of the press cylinder during the pressing process, simplifying the design and control while maintaining efficiency, thus lowering costs and improving process reliability.
Implementation Method 1
a (speed-controllable, in particular speed-regulable) pressing movement pump for conveying fluid for the pressing movement (into a corresponding chamber of the press cylinder)
Implementation Method 2
The high closing forces required for pressing require a correspondingly large piston area to generate a maximum pressing force at a predetermined maximum pressure
Data Source
AI summary
The invention relates to a hydraulic drive device (11) with at least one press cylinder, in particular a press synchronous cylinder, for a hydraulic press, preferably a powder press (10), wherein the hydraulic drive device is configured to guide a cylinder piston of the press cylinder in a rapid movement at increased speed towards a pressed part and to press the pressed part in a pressing movement at low speed, wherein the drive device comprises a switching valve (17), a controllable pressing movement pump (15), in particular a speed-controllable pressing movement pump (15) for conveying fluid for the pressing movement and a control unit (28) for controlling the pressing movement pump (15), wherein the drive device is configured to perform the rapid movement when the switching valve (17) is open and to perform the pressing movement when the switching valve (17) is closed, wherein the control unit (28) is configured to control the pressing movement pump (15) in such a way that a conveyance rate of the pressing movement pump (15) is already increased before the closing of the switching valve (17).